[Bigger ATV Tires and Clutch Needs]

This is very helpful information, Nevada ATV, and welcome to the posts! 

 

I have a friend in engineering at Chrysler/Jeep powertrain, and Ray is an avid ATV guy.  He's talked about Dalton Clutch, and they do extreme ATV riding with engine performance mods and suspension work.  Oversized tires I'm sure get into that mix.

 

I'll see if Ray has time to enter this discussion, he can "do the math", too!

 

Moses

[4.0L Jeep Six: Cylinder #1 Misfire Trouble Code]

JJ, sounds like that new Mopar TPS made a huge difference...Good news! 

 

The battery cable is very important, actually both negative and positive cables must be in good shape, as this is a D.C. system where both "hot" and "ground" circuits need the same amperage carrying capacity.

 

You need a consistent 12.4V or higher (12.6V or higher is a fully charged battery) for the PCM to be happy.  A bad cell in the battery or an open at a battery cable can stop the engine from running—even if the alternator still functions properly.  We experienced this with an intermittent 10.5-volt reading on the XJ Cherokee's battery.  The engine would barely keep running.  A replacement battery immediately eliminated the issue.

 

Looking forward to your posts, JJ!

 

Moses

[Picking a Trailer to Haul the Jeep Wrangler]

You've done your homework to this point, Joe Mac!  Keep us posted on your choices...

 

Moses

[Driving Your Dodge Ram Cummins for Fuel Efficiency!]

Well, you're certainly opening my eyes to the value of humor in these posts!  Keep it up, Megatron...

 

The Gear Vendors is definitely an option to consider before you change axle gears.  Here's some quick math on the Gear Vendors 0.78 ratio overdrive with your 48RE automatic transmission and a change to 5.13:1 axle gearing:  At your favorite highway cruise speed of 75 mph, if you use the Gear Vendors overdrive plus your 48RE's overdrive, with 37" tires (560 revs per mile) and 5.13 axle gearing, your engine speed would be 1932 rpm. 

 

From my experience with our 3500, this could be close to the optimal cruise rpm for maximum fuel efficiency at this weight, height and speed.  If you needed passing or pulling power, without the need to floor your 48RE for a forced downshift to third gear, you'd simply kick out the Gear Vendors overdrive and be at 2478 rpm.

 

This is the best of both worlds and does target your 75 mph cruise speed.  If you slow down to even 70 mph, you'd be at 2313 rpm with the 48RE's overdrive and direct gear on the Gear Vendors.  Apply the 0.78 Gear Vendors overdrive, and engine rpm would drop to 1803 rpm.  You get the picture, this looks like some targeted rpm options for optimal fuel efficiency and still above the torque peak rpm in all cases.

 

By the way, it's very nice of me to help spend your income on items like a Gear Vendors overdrive!  Kidding aside, this could pay big in fuel savings and also offer some incredible torque and pulling options as a split-shifter.  Neither you nor I currently have the advantage of the latest 8-speed automatics—unless you toss the Gear Vendors overdrive into the equation!  This is the wave. 

 

Again, here is a copy of the Gear Vendors link I provided in my last missive: Gear Vendors overdrive when practical.  Gear Vendors is in the gear business, and they build an impressive case for torque gains through nothing more than gear ratio changes and split shifting.  The OEMs have obviously gotten the message with the new wave of 6- to 8-speed automatic transmissions—which will make manual transmissions in light- and medium-duty trucks a thing of the past.  Before taking the plunge, consider your GVCW (gross vehicle combination weight) with the trailer in tow and the stamina you can expect from a Gear Vendors overdrive.

 

As for winter oil changing and specs, consider the wide range of climates and engine operating temperatures that OEMs address.  Oil recommendations must be generalized and take into account the temperature range from startup to warmed operating temperature under load.  Dicey choices!  0- or 5-wt. motor oil is great for cold pour in Alaska—but not for the very same engine running at 195-degrees F thermostat temperature once it warms up.  Minus 50 F to 195 F is a wide temperature range—from cold start to fully warmed up—a typical Fairbanks, Alaska day in the dead of winter!

 

Regarding the 80 mph method of getting the engine to rpm, save the speeding ticket.  (Try running to 80 mph on some secluded road and let me know whether the engine likes it...Watch your rear view mirrors for flashing red and blue lights.)   Note that when you increase load like with a trailer in tow, you may need horsepower in addition to torque.  The Cummins 5.9L ISB engine is under no stress at stock 7,800 pound curb weight and OEM height;  loping along at 1,600-1,900 rpm seemed just fine under that scenario, with road speed peaking around 69 mph.

 

To push our "billboards" down the road at 80 mph creates high rolling and wind resistance.  You did the math perfectly for your 37" tires, 3.73 stock gears and 80 mph in 0.69 overdrive:  1,922 rpm.  The question is whether the engine would be happy at that rpm under heavier loads. 

 

I used to periodically run our truck to 100 mph in a sprint up a particularly secluded highway in the desert.  The grade was over 6%, and I would start at the bottom around 65 mph and accelerate to 100 before the crest of the relatively short grade.  With the truck's current weight, the lift, tire drag and even the right axle gearing, the engine would perform this feat under load now—even with nothing in the bed but the auxiliary fuel tank.  Times change—we still like the look and utility, though, right? 

 

Now we're talking about the constraints that drive Cummins to declare that our engines should never run below 1,900 rpm under load, and they want to see us running 2,100-2,400 rpm with "commercial" loads.  Driving your lifted truck 80 mph is a pretty good load, perhaps comparable to "commercial use" standards. 

 

Here's engine performance data on the Cummins ISB 24-valve 5.9L inline six: http://www.cumminsdieselspecs.com/24v.html.  Our engines peak their horsepower around 2,900 rpm.  Most ISB commercial applications have 3,200 rpm governors.  Chrysler and Cummins added a couple hundred rpm for those Ram owners who think they're driving a gasoline powered vehicle, even though the engine's power has fallen off considerably and shifting to the "next gear up" would be a better idea. 

 

The horsepower rpm is worth considering.  While peak fuel efficiency at a light load is 1,600 rpm, without getting into physics, we can assume that if we continue adding a load to the engine, we will need more horsepower.  An H.O. engine peaks at 325 horsepower, quite impressive and requiring 17.2:1 compression.  So, you're right in suspecting that as the load rises, fuel efficiency suffers. 

 

Of course it takes more power to move over four and a half tons of mass at 80 mph.  Then there is the aerodynamic (lack of?) drag coefficient we know is lurking.  In terms of drag coefficient, all I could drum up on line was for a stone stock model year 2000 Ram 3500 4WD Quad Cab:  0.48 rating.  If you'd like to see how this stacks up against other vehicles, ranging from sleek race car models to popular econo-boxes designed for peak fuel efficiency, or even some SUVS (much like our trucks), check out this well-done Wiki entry: http://en.wikipedia.org/wiki/Automobile_drag_coefficient.

 

The cool thing about the diesel engines in our Ram trucks is that the torque stays well up there from 1,600 rpm to at least 2,700 rpm!  This means that unlike a gasoline engine, the torque and horsepower don't go separate ways with advancing engine speed.  Diesel technology does require a re-think on the part of gasoline "performance" enthusiasts who see horsepower figures as an end all:  Unlike diesel torque rise, high horsepower figures are only attainable at higher rpm.

 

This even applies to the popular Jeep 4.2L/4.0L hybrid "stroker motor".  Begin with a reliable inline six.  Build a "hot" stroker for 300-plus horsepower, and discover that to achieve this kind of power, you'll be pushing the torque and horsepower peak rpm way up the scale.  Here are figures for an exotic Jeep 5.0L stroker gasoline engine built from a 4.0L inline six block with a custom stroker crankshaft and 11.5:1 compression:  344 horsepower @ 5300 rpm and 384 lb/ft torque @ 4000 rpm.  Great performer for sand drags—lousy power curve for the Rubicon Trail!

 

The analogy for a Cummins diesel is that maximum high performance/horsepower builds (those short lifespan engines that Gale Banks talks about) mean spinning the engine to oblivion to achieve peak power.  Gone is the famous torque rise that distinguishes a long stroke commercial diesel engine—or a stock 4.2L Jeep inline six for that matter—from the typical gasoline engine...

 

Regarding the principles of water/methanol injection and its history, here's a nice ditty: http://en.wikipedia.org/wiki/Water_injection_(engines).  A water/methanol injection kit like the one offered by AEM reminds me of one of my earliest freelance magazine pieces.  We had a '73 Chevy K10 4x4 SWB pickup with a 350 V-8.  I installed a "solution"  injection kit that was popular in the '70s.  That somewhat sophisticated system came with a thick carburetor base gasket that had small orifice tubes running into the throttle bores.

 

A needle bleed valve at the glass solution jar metered the water/alcohol mix.  A slight bubbling indicated proper adjustment and flow.  Pretty slick, actually, the device did what water and alcohol/methanol injection will:  On a gasoline engine, it cooled and condensed the incoming fuel/air charge, reduced ping or detonation, allowed for more spark advance and better power, and permitted use of higher compression ratios.  Such a device allows fuel timing and compression changes on a diesel as well. 

 

Not often mentioned, during the combustion process, the water/alcohol or methanol solution will remove carbon from the combustion chambers, valves and piston crowns.  Upon the 350 V-8 teardown, the cylinder heads and upper engine looked virtually "new".  In this modern era of electronic fuel and spark management, carbon buildup is a virtual non-issue.  In the era of the Quadrajet carburetor, however, fuel enrichment and "venturi effect" made carbon deposits at the upper cylinder and combustion chamber areas a chronic engine problem. 

 

Fuel efficiency improved dramatically, the 350 V-8, gasoline powered truck delivered as much as 18 mpg with 3.08 gears, a 1:1 fourth gear ratio in the SM465 four-speed and 33" diameter tires.  Performance improved noticeably from added spark advance—without signs of ping/detonation.

 

For your diesel, this injection would act like an additional intercooler, keeping exhaust gas temps lower for less stress when trailering or hauling a load.  The upper engine would be cleaner, possibly extending engine life.  As with GDiesel fuel, crankcase contamination from incomplete combustion would be decreased.  Combustion would be more thorough.

 

Is this enough to outweigh the cost of methanol/water injection?  Can't say for sure, but this is why I buy GDiesel locally for 10-12 cents a gallon more than other low-sulfur diesel pump fuels.  I'm "banking" on the engine yielding a cleaner tailpipe, cleaner crankcase (lab tested the oil at Pape Cat, it's holding up much longer and shows fewer contaminants at change intervals) plus extending engine life.  If water/methanol were used for this purpose, I might buy it... 

 

Moses

[Picking a Trailer to Haul the Jeep Wrangler]

Hi, Joe Mac...We all look forward to your thoughtful and insightful questions!  You've done your homework on this trailer purchase!

 

The camper is one more reason for a lightweight trailer, and your extension hitch makes the trailer's handling important.  When you load the trailer make sure the torsion bars accommodate the trailer and offset the camper weight.  A unique advantage of the equalizing hitch is that it spreads your 6500# or so trailer load over the entire set of axles: the truck's front axle (IFS in your case with a Chevrolet), the massive beam rear axle with hefty springs, plus two trailer axles.

 

View the equalizer hitch as a set of torsion bars that link the two vehicle frames (trailer and truck) together.  An alternate, maybe more descriptive name is a "load distribution hitch".  The hitch and torsion bars spread weight over all of the axles and spring sets.  This levels the entire load through the force applied at the torsion bars. 

 

Envision all the tongue weight that would otherwise be on the hitch ball without these bars.  The desired tongue weight is typically 500-600 pounds for a Class III platform hitch; 1000 pounds with a WD or equalizing/weight distributing hitch.  (See this detailed Reese description of hitch ratings: http://www.reese-hitches.com/learning_center/general-towing-classes.) 

 

Your Silverado 3500 truck likely has a Class IV or V rated hitch, which raises these ratings, as described at the Reese link.  However, you also carry a hefty camper, which loads the tow vehicle substantially and reduces its overall weight capacity.  This is where Gross Vehicle Weight Rating is critical, per axle, when determining the actual load on your truck. 

 

Without these bars spreading the load between the two frames and all axles, the trailer tongue weight would grossly exceed the safety rating for the truck's OEM platform hitch!  Add a camper, and your rear springs would be taxed to the limit.

 

Think of torsion bars as tensioning beams.  When you adjust the bars for just the right set and hitch ball height with the loaded trailer, the weight that would otherwise be on the hitch ball gets distributed over the two frames.  This actually transfers or "distributes" the load to each of the axles.  In the process, as the torsion bars apply tension to offset a particular load, you will discover an amazing side effect:  The truck and trailer rise and set together!  This stabilizes the handling and helps eliminate the bucking and hitch dive that occur without an equalizing/load distribution hitch!

 

Rick Preston, owner of Rick's RV at El Cajon, California taught me about the value of an equalizing hitch in the late 'eighties.  I had a Land Cruiser FJ40 project for OFF-ROAD Magazine and a long term (one year) test of a StarCraft 21' travel trailer.  The FJ40 had a 90-inch wheelbase, very short coupled for trailer pulling.  To offset this liability, we installed a platform hitch (featured in my Toyota Truck & Land Cruiser Owner's Bible, Bentley Publishers) to accept a load distribution Draw-Tite hitch assembly. 

 

The Land Cruiser was well equipped on the performance side, a 383 Chevrolet stroker V-8 transplant with a Ranger Torque Splitter transmission between the Toyota gear box and engine.  I had also installed Saginaw power steering...On 33" tires and 10" rims, the track width was safe for towing!  So, off we went to join the Toyota Land Cruiser folks at Diaz Lake near Lone Pine, California in the late fall. 

 

Thanks to the load distributing hitch and a sway control brake, we got there in one piece.  The side and head winds blew 45-55 mph across the Mojave Desert, yet the 'Cruiser and travel trailer tracked straight as an arrow.  We even marveled about the 4x4 and trailer smoothing out the rolling dips and rises on old U.S. Highway 395 between Adelanto and Inyokern.

 

So, the WDH is a necessity, not an option, Joe Mac.  Enjoy the highways and trails, we'll enjoy the updates on your plans!

 

Moses

[4.0L Jeep Six: Cylinder #1 Misfire Trouble Code]

JJ, this is good news...Trust tomorrow's drive will prove equally productive. 

 

The TPS should be considered a "perishable" wear item.  Think of the duty cycle and how many times that stem has wound up and down the tension and voltage curve in 250K miles.  In my own experience, the TPS and the wire from the crankshaft position sensor to the engine harness can deteriorate over time and create "gremlin" issues like you experienced. 

 

Another issue on engines with rear main seal seepage is engine oil on the toothed ring for the crank position sensor or on the sensor pickup itself.  Each can cause erratic error messages that often dance around the actual problem.

 

We're awaiting your update and optimistic.  It certainly was productive to change this TPS, and your Mopar parts choice assures accurate calibration of the new TPS.

 

Please share the follow-up!

 

Moses

[Picking a Trailer to Haul the Jeep Wrangler]

Hi, Joe Mac, and welcome to the forums!  I'll jump into this discussion, and let's encourage others to join...

 

We have a steel trailer with wooden deck boards, and it has served well.  From experience and considering your weight over the road, however, I would definitely pick the aluminum trailers for ride quality, lighter weight and lower maintenance through time.

 

I'm sure the Kaufman is a great trailer and would hold a load very well.  I like the removable fender for getting into and out of the Jeep on the trailer.  However, the weight and load capacity are more than you need for hauling a Jeep TJ Wrangler around.  If this is your anticipated load, the added fuel costs pulling a heavy duty steel trailer would not be practical.  You could haul a smaller backhoe with the Kaufman!

 

On that note, I would get the 18-foot aluminum trailer, as it will haul a longer JK Wrangler, even the Unlimited at 116-inch wheelbase, if you ever consider the next model.  (If Jeep brings out a diesel JK Wrangler Rubicon, that might be appealing, although trailering your TJ means that gasoline cost is not much of an issue.)  A trail modified 4-door Wrangler with popular accessories, by the way, could easily tip the scale around 5,500 pounds, so the 18-foot aluminum trailer would just do it!

 

Unless you're being price constrained, get the super deal on an aluminum trailer.  I trust it's not a dovetail?  My experience and watching others, I would avoid the dovetail and opt for ramps and more tail end ground clearance.

 

Unless you have considered a Hensley hitch, the heavy duty Reese that you share in the link is great.  I've used a similar Drawtite hitch forever, and the loaded torsion bars often eliminate the need for a sway control apparatus.  The Reese looks like it might do the same.  Ask Reese if they recommend a sway control (brake) with this hitch arrangement.

 

My two cents!

 

Moses

[Driving Your Dodge Ram Cummins for Fuel Efficiency!]

Thanks for airing these questions, Megatron!  Given your truck's weight and lift, as we have discussed, the rpm at 65 mph is too low—but only because of the truck's modified curb weight and wind resistance.  I'm not double-speaking, you're at an optimal rpm at 65 mph for extraordinary fuel efficiency with a stone stock '06 Cummins Ram 4x4. 

 

Proof:  Before I horsed around with 1200-plus pounds of upgrades and a 4-inch lift, in the summer of 2011 I drove to Portland, Oregon from the Reno, Nevada area for the launch of the Jeep JK Wrangler 2012 model (new Jeep Wrangler 3.6L Pentastar V-6 and other changes—see the magazine's JK Wrangler HD video coverage).  I consciously held to 65-69 mph with stock 3.73 gears and tires just under 32" diameter.  The truck had its stock curb weight and height (approximately 7,800# unloaded). 

 

Result:  I nailed 25 mpg fuel economy from Reno to the mid-Willamette Valley, Oregon!  Best mileage on a long trip ever, including climbs over the Siskiyou Passes and the numerous secondary highway grades between Reno and the I-5 access from Highway 89.  This was not the "Plains" and surely not one-sided in terms of grades.

 

That said, if I attempted the 1,600-1,750 rpm under the truck's current curb weight and fully fueled load, worse yet when pulling a trailer, I would expect sluggish performance and mileage.  Our Ram 3500 has stone stock tuning to this day, no exhaust upgrades, chips or modifications whatsoever.  I drove this rpm range to achieve this exceptional mileage in stone stock form; however, the truck would suffer with that gearing and current 35" tires. 

 

Today, cruising at 1,900-2,000 rpm peak, I can coax 21-23 from the truck with the 9,100-plus pound rolling package, unloaded and fully fueled, driving uniform gradient highways...Managed 23 mpg down the I-5 from Sacramento to the 41 Junction en route to Advance Adapters at Paso Robles in January. Held speed to an agonizing 65 mph to achieve this, got passed like I was standing still by the traffic!  Pushed to 68-70 and paid for it immediately:  19-20 mpg with 35" tires, 0.69 overdrive and the 4.56:1 gears.

 

Last year's trip across northern Nevada's I-80, through Elko to Salt Lake City and on to Moab, I did manage 22-23 mpg at 65 mph on I-80.  Frankly, the Bonneville Salt Flat and Great Salt Lake Basin is tortuous at this speed, although I did have plenty of big truck company in the slow lane.  This is the price for maximum fuel efficiency.  Diesel engines are rpm and load sensitive!  For that matter, gasoline engines fare as bad or worse under load.

 

We really enjoy the truck and its "look".  (Objectively, folks at trade shows and the Moab Jeep Safari rubberneck to see this Ram 3500 Quad Cab, as I'm sure they do your Mega Cab!)  To a degree, I'm willing to "pay the price". However, my days of 70-75 mph trailer-toting with the XJ Cherokee on board en route to Moab, expecting 17-18 mpg, are over.  I'll still expect 15-16 mpg with a trailer in tow, fully loaded, but only after my change to 4.56:1 gears and "governing" speed to a maximum 65 mph when towing.  Wind is a much larger factor with the 4" lift and 35" tires, an obvious fuel mileage variable...

 

As a footnote to the trailer toting mileage, I lugged a toy hauler to Johnson Valley for the 2012 King of the Hammers race week coverage.  I still had the OEM 3.73 gearing (like you do) and did respect California's strictly enforced 55 mph speed limit for trucks and trailers, holding speed to a limp along 58-59 mph peak.  I thought the mileage would be great.  Wrong—mileage fell to 12-13 mpg, the worst ever for this truck's trailer pulling and a 7,500# (loaded) trailer.  It's all about the right gearing and keeping that diesel happy under load! 

 

This raises a point we haven't touched yet.  You're weighing the 4.56 versus 4.88 gearing choice for your 37" tires.  How about this idea: Install a Gear Vendors overdrive behind the transfer case!  The auxiliary overdrive only works in 2WD High range, but you could run 4.88s or, better yet, 5.13 replacement gears in the AAM 11.5 and 9.25 inch axles with the use of the Gear Vendors overdrive when practical—including split shifting on grades with a trailer load.  See the interesting torque gains described at the Gear Vendor's website.  I've linked directly to the Dodge Ram section.

 

Gear Vendors is a 0.78 ratio or 22% overdrive, which could only be used minimally in tandem with your 0.69 overdrive gear.  Final drive equivalent in overdrive/overdrive would be 5.13 x .69 x .78 = 2.76:1.  This compares to 4.88 x .69 = 3.36:1 [48RE overdrive without Gear Vendors OD]; or 5.13 x .69 [48RE overdrive without Gear Vendors OD] = 3.54.  Your OEM gearing factors currently as: 3.73 x .69 = 2.57.  Of course, we haven't targeted engine rpm and your tire diameter yet...We can play with the gearing equation and see if this makes sense.

 

Cost aside, the Gear Vendors overdrive is a consideration if you're on the fence here.  ..I've got a one-piece driveline at 140.5" wheelbase, you're longer based with a two-piece driveline.  Plenty of room for a Gear Vendors unit in either case.  For my truck with its current 4.56:1 gearing and 35" tires, I'd have gains like 1) the double overdrives when running empty at cruise or 2) when pulling a hefty load, I could use the Gear Vendors overdrive with the 48RE in 3rd gear (22% versus 31% overdrive, a 9% reduction advantage).  You haven't changed gears yet, so there are more options to consider.

 

I like your seasonal fuel efficiency question!  Like the intercooler, winter cold air creates denser oxygen content, which increases power.  If your climate is humid in the summer, you may get an additional intake air cooling effect and, therefore, denser oxygen content in the intake stream.  A denser charge means improved combustion and, at least theoretically, better fuel efficiency if you can keep your foot out of the more responsive throttle! 

 

Another factor to weigh is the OEM or aftermarket computer "chip" tuning that takes advantage of a denser IAT reading by changing injector pulse width.  This could also work another way: When winter intake air is cold and dense, the injectors flow more fuel to create the right air/fuel ratio. The result is more fuel consumption and peak throttle response.

 

I believe the winter fuel efficiency loss is also due to lubricant viscosity and cold pour, especially in the axles.  (Transfer case lube and ATF are now largely synthetic and wider-range viscosity, typically with a lower weight ceiling.)  It's no small fact that OEMs now use lighter, multi-viscosity lubricants for CAFE ratings. The AAM axles call for 75W-90 weight lube.  My choice of running 75W-140 Mopar gear lube for severe duty use may, in fact, create a loss in fuel efficiency—especially in the winter. 

 

Don't get carried away with this factor, though, unless we're including engine oil viscosity.  See this technical paper for interesting details on fuel efficiency as it relates to motor oil viscosity: http://www.instituteofmaterials.com/paper/FEIPaper.PDF.  I'm running Mopar 15W-40 year round with use of a winter block heater to avoid startup damage.  Frankly, this could be a source of higher fuel use in winter.  The 5.9L Cummins engine can drop from 195-degrees F to the bottom of the temp gauge during a 30-minute groceries stop! 

 

Another factor, perhaps significant in our case with oversized tires, is rolling resistance.  In winter, the advertised or usual static cold tire pressures can create drag.  On frigid highways in chilling air, the tires do not reach the predicted temperatures for pressure calculations.  In the summer, there is less rolling resistance as inflation pressures rise due to ambient and road surface temperature increases.  Sadly, tire pressure is fixed (unless you have a Humvee and can air and deflate on the fly!).  You cannot inflate tires to the summer over-the-road pressures for winter use—the tires would be deformed and wear quickly on their tread centers from "over-inflation".  They would also be a terrible hazard with minimal road surface contact!

 

As for engine operating temperatures, and this is a factor, it does take "forever" for the Cummins engine to warm when ambient temp is sub-zero to 40-degrees F.  This is not a coolant thermostat issue, although 18-wheeler shutter-stats like you hint would be helpful.  The Cummins ISB engine has a huge cooling capacity!  Forget letting the engine idle to warm up, it will take forever to reach operating temperature.

 

On that note, I'll emphasis that I do use a block heater all winter.  The truck is not a daily driver, but on any day with a planned run, I plug in the block heater the night before.  Under a carport with a Battery Tender hooked up whenever the truck parks, let's say it is a 10-degree F morning:  The engine coolant's startup temperature will be around 120-130 degrees F with the block heater. 

 

Warmer weather (a whopping 35-degree F, let's say), start-up temperature will be around 140-degrees F.  That noted, I start the engine and always wait for the oil to circulate sufficiently before rolling.  It will sometimes take from Fernley (home base) to four miles West on I-80 before the engine reaches thermostat temperature.  During this entire time, I hold engine speed to no more than 1,500 rpm under light throttle load.  I expect this diesel engine to last for 500,000 miles, enough to bury the initial cost difference over a gasoline engine—and also to save a small fortune through fuel mileage gains over that number of miles.

 

So, summer does bring better fuel efficiency.  In my case, I've also switched to GDiesel, a natural gas altered fuel.  (See my coverage of GDiesel in an article and HD video interview at the magazine.)  By breaking down long chain molecules to more combustible form, this fuel does deliver mileage gains.  Even better, I do not engulf other motorists in soot when I launch into the throttle during passing. 

 

Yes, my truck's exhaust, even without the later catalytic converter and exhaust stream additives, is clean, without visible smoke—black or white.  While some clean-up can be produced through ECM programming, that's only to a degree.  I use GDiesel and avoid mixing it with conventional low-sulfur fuel.  (GDiesel is actually the very same low-sulfur base fuel, reprocessed with a patented method.  You can mix the two in a pinch.)  Fortunately, I can make it to Moab from Fernley and back home on one fill of the main tank plus the 75 gallon auxiliary Transfer Flow tank in the bed.

 

Thanks for the questions, Megatron...Others are welcome to jump into the discussion and share their experiences!

 

Moses

[4.0L Jeep Six: Cylinder #1 Misfire Trouble Code]

Sounds like you've been busy and committed to a solution, JJ!  I like your pursuit of a leak down tester; this will demystify the engine's condition and seek out a possible compression loss that could cause a misfire.  Trust the tool will pay for itself on this engine work and other projects.  I've had my Snap-On MT324 for decades and am always pleased with its pinpoint diagnosis.

 

Your new codes do hint of a TPS switch problem.  I had a specific TPS switch issue/code around 110K miles on our XJ Cherokee.  I purchased an aftermarket Brand-X replacement, and it worked for a short time before causing a misfire string that resembled a short or burned wiring from the crankshaft position sensor.  Anyway, I sourced a second TPS from AutoZone on a Sunday, their own "brand", installed it, and no trace of a problem since. 

 

Some offshore stuff works, sometimes not.  As just one example, let's consider the oxygen sensor.  For Jeep and other Chrysler products, I specifically recommend genuine Mopar or at least ND brand as a direct crossover.  Denso was the OEM supplier to Chrysler, and oxygen sensors have very sensitive ohms feedback, heating functions and such.  See my article, this also applies to other electronic components in the fuel-and-spark management system: http://www.4wdmechanix.com/Use-OEM-Mopar-Oxygen-Sensors!.html.

 

I'd try a TPS, even though I'm set against "parts replacing" experiments.  The TPS is a wear item and prone to fail long before your 250K miles on the TJ Wrangler.  This would be the first order of business to see if the other two codes clear as well.  You'll find the TPS easy to replace; think of it as a spring loaded voltage rheostat or potentiometer.  The TPS fits one way with a slight tension as you install the switch and rotate it into position.

 

Your TPS does not require a voltage calibration, it's a straightforward replacement.  Exercise precaution with the aging plug connector.  Make sure the O-ring seats properly.  I use automotive dielectric grease on the plug connector contacts for a moisture barrier.  Considering how many issues can begin with a defective TPS, this is a good place to start.

 

It's actually good that you don't have several cylinders randomly showing misfire codes or acting up. That kind of issue is usually the PCM itself.  In any case, let's go a step at a time.  You might also run a continuity and voltage drop test on the injector plug at this nemesis #1 injector.  See this Geo Tracker post and my reply for more details on voltage drop tests and electrical circuit testing:  http://www.4wdmechanix.com/forums/topic/115-geo-tracker-sending-torque-converter-clutch-solenoid-code/.  Use a good quality digital volt-ohmmeter for these tests.

 

This approach will get results.  I would also disconnect the plugs at the PCM carefully, inspect the contacts and clean them only as needed, using electrical contact cleaner. Use automotive dielectric grease for a moisture and corrosion barrier when reconnecting these plugs.  Take your time with old connector clips and fragile lock release connections.  Protect these plastic parts. 

 

Let us know how this progresses.  I'm curious about the cylinder leak down results, too!

 

Moses

[CJ Versus YJ Wrangler: Which Jeep 4x4 and Engine to Buy?]

Thanks for adding so much filler detail from your experience, Megatron!  Rich now has a wealth of information.  I back up everything you share here.

 

4.0L EFI is a must, the BBD carburetor on the 4.2L CJs and '87-'90 YJ drives an entire aftermarket in EFI conversions that cost an ample sum. And like you share, there's not that much mystery and no threat in electronic fuel and spark management these days.

 

You're absolutely right about the 4.0L inline six conversion.  At the magazine, I feature the welding and fit involved in converting a 2.5L YJ into a 4.0L.  After the Jeep CJ era, AMC/Jeep and Chrysler decided to make unique frames for inline four- and six-cylinder engine applications.  On AMC/Jeep CJ's, the V-8s, fours and inline sixes simply required different, bolt-in frame adapters.  Actual frames were identical...

 

Installing an inline six in place of a YJ or TJ Wrangler's four-cylinder engine is no less complex than a V-8 conversion—see the Advance Adapters 'LS' Chevy V-8 into a Wrangler.  Four-cylinder YJ models make good candidates for a V-8, although the four-cylinder YJ's AX5 transmission does not meet the torque rating of an AX15.  A V-8 into a four-cylinder chassis begs the use of a 4L60E or 700R4 automatic.  Advance Adapters is your source for the conversion parts.

 

Transmission wise, the YJ has the 904/999 Chrysler three-speed automatic without overdrive. The '91-'95 features an AX15 manual transmission behind the 4.0L inline six.  It's a proven transmission that I detail in the 209-step, two part how-to rebuild article at the magazine.

 

Good point about the axle housings for the lower (numerically higher) gears. This is a well taken point for those wanting 4.56 or 4.88 gears in their YJ Wrangler. These larger ring gears will only fit Dana 30 axles designed for OEM 3.73 or 4.10 gear sets and Dana 35 axles with 3.55, 3.73 and 4.11 OEM gears.  (Yes, they did use a 4.10 front with a 4.11 rear axle.  This is common for many 4x4s and has to do with axle design or, in some cases, the use of two manufacturers.  These YJs all use Dana axles.)  The YJ Wrangler featured at the magazine's tech how-to was originally a 2.5L TBI with the lower gear ratios that Megatron describes.

 

Great description of tire needs.  The YJ Wrangler project at the magazine is my son-in-law's '87 that I built up—lucky him, eh?  We stayed with the 30 front and 35 rear, ARB Air Lockers at each end with Superior Axle shafts for "Super" status; 33" tires, 4.56:1 gears, and he's gone all over Moab and elsewhere. 

 

Think of it this way:  Sure, both the Dana 35 and 30 are small, but when you're off-roading, the 231 transfer case delivers 50/50 torque split to the axles.  The Dana 35 rear only needs to tolerate 1/2 the torque it gets when the Jeep is on the highway in 2WD high range!  So, these axles will work as long as the axle tubes remain straight...An axle truss can help here.

 

Megatron is right about the NP231, too.  Durable for a chain drive transfer case, hardly a weak point!  I cover the NP/NV231 transfer case rebuild and SYE kit install at the magazine if you want details on what we're talking about here.  A reduction gear set for this transfer case can take low range down a notch for those oversized tires.  Then there's the Atlas transfer case—the ultimate transfer case solution.  For a stock 4.0L inline six, the NP231, in good condition, will last indefinitely.  Parts are readily available for rebuilding.

 

Megatron is pragmatic and right: The Dana 60 monster axle housings hang so low that any real ground clearance gain requires 40" diameter tires to accomplish!  Megatron's 35" tires with a Dana 35 or 30 axle makes perfect sense for useful ground clearance.  Strange how these 60s got beneath Wranglers and CJs in the first place.  An AMC Model 20 or Dana 44 axle is more than enough.  60s are a lot of unsprung weight mass and very costly to build and adapt.

 

Thanks, Megatron, you've sparked interest and inspired others to jump into this discussion!

 

Moses

[Driving Your Dodge Ram Cummins for Fuel Efficiency!]

I must still like writing...Spent time doing a fresh reply at your new questions—guess they're well covered now!

 

Moses

[Dodge Ram 3500 with 48RE Automatic Transmission Shudders on Take-Off]

We each have read or heard enough about the 48RE failures and aftermarket heavy duty replacement parts solutions to be skeptical. Worse yet for me, I tried to discuss the 48RE with a Mopar engineer at Moab.  We were test driving new Ram Power Wagons with the 5/6 speed automatics on Poison Spider Mesa Trail, and I could see his eyes glaze over.  This was a look I've seen many times as a professional, when manufacturers move on from a product and no longer have an interest in talking about "old technology".  He may have thought I was a 2005 Dodge Ram 3500 4x4 collector.  After all, the truck was six model years old!

 

Chrysler's now on to better things, including abandonment of the time-honored A727 transmission architecture with an overdrive thrown into the mix.  I remind myself that we saw the A727 Torqueflite behind 426 hemis in muscle cars, tucked into Class A motorhomes behind the 413 and 440 wedge-head V-8s, and joined to the original 12-valve Cummins in the earliest Cummins-Dodge Ram trucks.  Does the planetary overdrive really make that much difference?  Well, I do have suspicions about plastic accumulator pistons ("weight saving?") and stamped sheet metal looking band struts.

 

The driveline issues are a possibility, the angle gauge will eliminate guesswork.  You should be an expert after dealing with drivelines in a 94-inch wheelbase YJ Wrangler with a spring-over lift plus 6-inch spring lift!  For the record, the steeper a driveline angle (side view) and U-joint angles, the less torque the driveline can handle.  These physics reflect the angle of the U-joints and the torque needed to rotate them on a tilt.  Minimizing and matching driveline angles increases the life of U-joints and the torque capacity of the driveline.  1-1/2 to 2-degrees angle would be the least.  Less than that will not keep the needle bearings rotating.

 

Check out my 11.5" AAM axle rebuild and setup of the 4.56:1 ring and pinion gear set.  You'll find that the ring gear backlash setting is quite close for an axle/ring gear this large.  I did follow that setting with success.  The OEM 3.73 gears (bought the truck new) did have noticeable backlash like you describe.  That is gone now, the pinion backlash feels normal, and there is no "clunk" on forward to reverse gear changes.  It's rather annoying for an axle to have pinion clunk, though it's not necessarily a defect—especially on larger ring-and-pinion gear sets.

 

When you check that rotational play at the driveline, make sure you're not adding the differential gear play into the mix.  Move the shaft lightly to the points of first resistance.  That's the actual pinion shaft backlash.  If you're not hearing a whine on acceleration or coast, there's not likely a wear issue.  Check the axial/side movement of the pinion shaft, too.  As a point of interest, the 11.5" AAM axle is very stout, a proven G.M. design.

 

When you do swap gear sets, you can address the backlash issue.  Inspect the differential gears for play, too.  That's the time to make remedy.  As a footnote, changing the ring-and-pinion gear ratios will take a huge load off your 48RE.  The take-off shudder may diminish or disappear, an indication of torque converter loads.  You now have me paying attention to my truck's take-offs, and there is a moment of torque pull.  This could be the torque converter, it's high on the list of 48RE OEM parts "ready to go at any time"...

 

Write books?  You know what they say, "You're only as good as your last book—or next success!"  I say, after seven books that include best sellers, "Why not quit while you're ahead?"

 

Moses

[Oversized Tires Can Create "Too Much Overdrive!"]

Your questions make perfect sense and are welcome!  My opening volley on this topic reflects my perspective, and I'll elaborate in more detail...

 

Best axle gear ratio is a somewhat loaded question and does consider tire diameter.  I wrote magazine Q&A columns for fifteen years in the 4WD Jeep, 4x4 truck and muscle car fields.  Gearing was a constant question with tangible solutions.  In the late '80s, I got a nifty calculator program from Wolverine, intended for camshaft selection, tire sizing and the right gearing choice.  Though DOS based and no longer accessible (thanks to Microsoft 7 and up), that program provided a great calculator utility.

 

Fortunately, there are similar calculators for axle gearing and tire diameter now online.  Here is one downloadable software calculator that you can trust.  It's directly from Cummins and includes your '06 Cummins 5.9L ISB Dodge Ram 4x4 Mega Cab—directly from the source: http://www.powerspec.cummins.com/site/home/index.html.  You'll find a great calculator for Cummins' commercial diesel engines.  Note: I use the earlier version 4.2.4 software for the 5.9L ISB engine; the latest version only covers the 6.7L ISB, although this engine is similar in most ways for this calculation.

 

I use this program, and it's very cool, addressing tire diameter, axle gearing (include the 0.69 ratio for overdrive on the 48RE) and engine rpm.  Cummins has a recommendation for optimal commercial performance, which is actually close to the weight and load factors you and I anticipate: occasional towing, hefty accessorizing, the lift (which makes our trucks like pushing a billboard down the road) and both town and, primarily in my case, highway use. 

 

There's one caveat when using the PowerSpec program: The program aims at commercial haulers.  Cummins wants to see a higher rpm (2100-2400) than I prefer.  My approach for maximum fuel efficiency with a modified truck weight similar to ours (9000-9300 pounds curb weight) and the 5.9L H.O. ISB engine is in the neighborhood of 1900-2000 rpm at highway cruise.  I see a prompt and notable drop in fuel mileage for engine speeds over 2000 rpm—although power remains great between fuel stops!

 

For gasoline powered trucks or a trail Jeep, here's a quick reference chart that you'll find useful: http://www.jeep4x4center.com/calculators/.  The chart's baseline is 65 mph with a 1:1 high gear ratio.  You need to factor the overdrive ratio into the final engine speeds at cruise.  Multiply the rpm times 0.069 for your 48RE transmission.  We have a significant 31% overdrive. 

 

There are other calculators online that allow for plugging in the overdrive ratio variable (0.69, 0.75, 0.85, etc.).  Here is one that offers space for the overdrive ratio in the equation: http://www.4lo.com/4LoCalc.htm.

 

As for picking between 4.10, 4.56 and 4.88 gears (the only ring-and-pinion options for the AAM axles) in your specific truck, the answer is subjective.  I'll tackle the question, though, and will share what I believe each of these ratios will deliver with your 37" tires:

 

1) 4.10:1 would nearly restore your gearing to the OEM level with stock diameter tires; still some overdriving effect, more like OEM tires with 3.55 gears instead of 3.73:1.  I would definitely not use this gearing for trailer pulling.  Town traffic would be sluggish, too.

 

2) 4.56:1 would be quite livable, all around.  Acceleration would be slightly better than OEM tires and gearing at the OEM curb weight and normal cab height.  This is my gearing now for 35" tires, and I know that a change to 37" would be feasible.  I'm spinning the engine close to 2,000 rpm at 65 mph...To drive at 75, like you want, the Cummins calculator actually thinks the engine should spin faster—I think it would be right on for performance and reasonable fuel efficiency at this load.  (I'm figuring 37" tires at 560 revs per mile.  Is this correct for your tires?  Confirm for calculations.)  560 revs per mile and 4.56 gears in overdrive cruise mode would put your engine at 2202 rpm for 75 mph and 1909 rpm at 65 mph.  This would deliver peak fuel efficiency at 65 mph and decent performance at 75 mph, a satisfying all around choice for your truck with the 5.9L ISB engine.

 

3) 4.88:1 would be okay if you trailer all the time and would like to hold speed at 65-70 mph while towing.  (You could push to 70 mph if fuel costs do not sway your thinking.)  Acceleration in stop-and-go would be impressive, the load on the engine and 48RE transmission would be less.  Extra piston travel per mile could reduce lifespan of the 5.9L engine; however, the reduced load would likely offset this...If I had a 9-horse trailer, this would be my gearing, holding the truck to 65 mph and keeping the engine and horses happy!

 

As for target mph on the highway, that's a subjective question, too.  You have a plan for 70-75 mph at cruise, and with a trailer, that would keep the engine at Cummins' recommended 2100-2400 rpm range in overdrive.  While I repeatedly emphasize the 1600-1900 rpm "sweet spot" for fuel efficiency, there is the realistic lugging factor that places the engine under stress below 1900 rpm when toting severe loads.

 

So, I think you'll be happiest with 4.56:1 gearing at 37" diameter tires.  I can feel with our truck that it's doing just what I wanted: Delivering trailer pulling torque, adequate horsepower and peak fuel efficiency at 65 mph.  4.10:1 would have restored the tire/gearing to stock, but as I've noted, this truck is way too heavy and tall at curb (unloaded with fuel in auxiliary tank) to survive on stock equivalent gearing.  I've equated my modified truck to pulling a tent trailer—all of the time!

 

As for highway versus town driving, you need to consider both.  Town driving is getting the mass rolling.  Highway is keeping that mass rolling.  Both impact fuel efficiency and loads on the engine.  Again, the 4.56:1 will enable town driving without taxing the powertrain much.  4.88:1 would make town driving easier, especially when moving a big trailer from a dead stop; however, the highway cruise engine speeds you plan would make 4.88:1 wasteful on fuel.  (2,357 rpm at 75 mph in overdrive is near peak rpm for Cummins commercial use recommendations.)

 

You're right about dyne tests to confirm power curves on a dramatically altered engine with camshaft modifications, fuel timing changes, added turbo boost and other alterations.  Let me start by saying "chips" will not dramatically alter the torque rise on a diesel engine.  Tuning measures will unleash suppressed power, but the curve shape will be similar.

 

Camshaft, compression or turbo mods are another story, as changes here can move the power curve around.  Although everyone seems horsepower fixated, diesel power is all about the quick torque rise and peak at a lower rpm.  I believe the Cummins ISB engine has the edge here, a lower rpm, traditional diesel design suited for medium duty truck use and patterned after commercial truck and off-highway equipment performance.

 

That said, drive your Cummins diesel accordingly.  I have "redlined" our truck's engine to its advertised 3,400 rpm peak on less than a half-dozen occasions in 121K miles.  Redline is pointless when the engine's torque peak is at 1,600 rpm.  2,400 rpm should be a sensible peak, maybe 2,800 rpm on a lengthy grade with our trailer in tow—and certainly not for a sustained period.

 

Note: Gale Banks and I met after the Off-Road Expo in 2011.  I visited Banks Power at Azusa, and we talked.  Gale is a Duramax diesel dealer and strong advocate, and his descriptive for the Cummins ISB engine was, "We blow the cylinder head off the block on those engines!"  They do when drag racing with engines built for extreme output and competition—or even when running these engines "to destruction", presumably at redline for sustained periods.  I have known Gale for thirty years, and he is expert at high performance and race engineering.  By contrast, I served an apprenticeship with the Operating Engineers Union in the mid-'seventies, and we worked large highway construction jobs.  If we ran a 1693 Cat inline six off-highway equipment engine much over 1,500 rpm, we were in jeopardy of losing our job.  These engines peaked horsepower below 2000 rpm and peaked their torque just off-idle!

 

Trust this helps.  It's really not that complicated once you establish a firm goal.  Even with the four-speed automatic, I've gotten as good or better fuel efficiency with the 48RE as others with the NV5600 6-speed manual overdrive transmission.  We get the added advantage of a torque multiplying converter, too!  

 

I can assure owners with the manual transmission, Cummins engine and the right gearing that 22-25 mpg fuel efficiency is very attainable on the highway under light loads and at normal cruising speeds...It all comes down to driving technique.  Running empty, my upshift points would be between 1,400 and 1,600 rpm per gear.

 

Trust this helps and thanks for posing these questions!

 

Moses

[Hand Tool Choices and Why]

Many of my current hand tools date to the 'sixties. The oldest, to my recollection, is a Craftsman beam-bar 1/2-inch torque wrench that I bought in 1965—for $7.39 out of the Sears catalog! My most recent acquisition is a deep set, Pittsburgh axle nut set from Harbor Freight, intended for occasional use.

 

Tools have various functions and purposes, and their price and quality can range accordingly. When I first worked professionally as a light- and medium-duty truck mechanic, Proto tools were popular. By today's standards, that would be Craftsman or S&K quality. 

 

I ran a motorcycle repair shop at Carson City in the early 'seventies and discovered Snap-On and Mac Tools. Craftsman tools at the time offered an extraordinary lifetime warranty, and I have Craftsman sockets, ratchets and extensions still in my boxes to this day. I did, however, migrate to Snap-On for box ended wrenches, screwdrivers and a 3/8" tilting head ratchet.   

 

A Champion spark plug offset handle, swivel head ratchet wrench carries forth from the late 'sixties, pre-dating the Snap-On tools. The Champion 3/8" spark plug ratchet was a private label tool, likely built by Proto. It has weathered extremes of use and, in hindsight, abuse from excessive torque application on some occasions. Yet it survives.

 

When picking tools, the quality and warranty are important. So is the "feel" of a tool if you're working with it professionally, day in and day out. Cost aside, my best ratchets have been Craftsman, not Snap-On. The reverse levers on the Craftsman tools fit my fingers and hands much better than the ratchets I bought from Snap-On years ago. In fairness, Snap-On may have improved this design, or your hands may be happier with one design over the other.

 

Some hand tools are simply better quality. I mentioned Snap-On screwdrivers, their tips are exceptional and long lasting, handles feel right, and they prove superior. That said, however, the newer Craftsman "Professional" line of hand tools have come a long way for both fit and durability.

 

Tool boxes are another story altogether. Boxes often get purchased on the basis of brand names that carry cache. When I worked at a GMC truck dealership as a line mechanic, Snap-On tools, and especially its boxes, stood for a true professional investment. Since I believe a mechanic's worth is his or her work quality, boxes are not the end all for me.

 

I like Craftsman professional series boxes and have a shop full of them. Weight being a factor, if you want "big", you'll pay by the load capacity. Even the Harbor Freight U.S. General big boxes have a high load capacity and unloaded weight.

 

On that note, don't dismiss Harbor Freight—just be selective and know the "line" names. I've done very well with the black, six-point Pittsburgh impact sockets and knockoff tools like the ball-joint removal and installation kits. Pittsburgh brand often means something. For torque wrenches, however, I opt for contemporary high-end electronic types and quality, known brands like Mac, MATCO, Snap-On and such. 

 

It just depends on your intent and plans for the tools. If day in and out use is the plan, buy better. When it's a one-shot or rare project and everything appears acceptable with the tool, consider an inexpensive item. Harbor Freight's heavy steel products tend to be the best buy on this side of the ocean, especially at the price, though these products all come from the other side of the big water!

 

I'd be happy to elaborate on any aspect of tools, welding equipment or automotive testing/diagnostic equipment. I've been at this professionally for forty-six years and can cast a broad light. When time permits, I'm planning a tool box walk-through for the magazine's HD Video Network. The tour will cover all of my hand tools, air and impact tools, specialty tools and pullers, welding tools and diagnostic equipment.

 

I'll watch for your posts and reply! Ask away...

 

Moses 

[Geo Tracker Sending Torque Converter Clutch Solenoid Code]

Richie, you're welcome...The things I shared can be considered the "methodical" troubleshooting approach.  I like to work through "no cost" solutions before doing the "parts changing" routine. 

 

I think you'll nail this on the next round...Please keep us informed, others can benefit.

 

Something everyone needs to know about OBDII and code readers is that these codes are only a rough view and suggest defective "devices".  If the wiring or plug connections on these circuits are faulty, OBDII delivers the same trouble code.

 

When you go to a dealership or well-equipped independent shop that has higher end diagnostic tools, the test equipment is way more than a "code reader".  OBDII scan tools like Chrysler's DRBIII can actually interrogate and operate individual devices like the idle air control motor or individual sensors.  These kinds of tests sometimes make it cheaper to pay a shop to test the system than when you use an inexpensive code reader and begin a parts replacing approach.

 

Looking forward to your topics and posts!

 

Moses

[Geo Tracker Sending Torque Converter Clutch Solenoid Code]

Hi, 'Rent24', and welcome to the forums!  While I'd like others to participate and share their experiences with the TCC system on the Tracker and Sidekick, I'll jump-start this discussion... 

 

Since we're talking about the torque converter lockup here, let's begin with whether the torque converter is actually locking up.  You should have the 3-speed automatic with TC lockup.  The rule here is that the engine speed should be around 3400 rpm at 70 mph with the converter locked.  If it's around 4,000 rpm at 70 mph and cruising throttle, the converter clutch is not locking.  Rule out vacuum modulator vacuum leaks—a defective modulator or leaks will affect shifting points but typically not the converter lockup. 

 

You have replaced the relay and solenoid, so instead let's focus on the torque converter and wiring circuit.  From your description, you must be getting the PO740 diagnostic troubleshooting code.  If the converter clutch is not locking, and the converter itself is not defective, the problem is likely the wiring.  I would check the wiring circuit carefully with a volt-ohmmeter, since the P0740 OBDII code is related to the "circuit" for the TCC system.

 

What you want to do is check for voltage and also continuity and resistance.  I would isolate plug-to-plug segments of the wiring harness leading to the TCC relay, solenoid and the converter itself.  Begin with a wiring schematic for the system and determine the current flow for the TCC circuit.  In the transmission section of a shop manual, you will find a description of the transmission's shift modes and also the lockup point and functions of the torque converter.

 

Continuity and resistance (ohms) for a given wire(s) should be checked without the battery hooked up.  Disconnect the battery ground cable before running these continuity/resistance tests.  When you run the voltage tests on live circuits, you may need the key on; however, the engine should not be running.  Even if the Tracker is parked, you should chock the tires, use the parking brake and exercise the usual cautions if you test the wiring circuits in the various gear selector/shifter positions.

 

At plug socket voltage checks, you should get nearly the same voltage as the actual battery voltage (without the engine running).  If voltage "drops" significantly between the battery and the plug being tested, there's either an open or too much resistance—or there could be a poor ground in the system/circuit.  On a 12-volt D.C. system, ground circuits are as important as hot or positive side readings!

 

Voltage drops, especially the ground circuits, can be tested with a "lamp load test", too.  This is a relatively simple way to test wiring circuits, both negative and positive.  You can use an old headlamp for this test...On lighter gauge wiring, use a smaller light bulb that draws less amperage.  Tractor auxiliary lamps often work well here.

 

Begin with testing the lamp's glow when using a heavier circuit like the starter motor's cable and a good ground.  (Never generate sparks near the battery!)  Note the lamp's brightness.  Now test the TCC wiring circuit in question.  See how brightly the lamp burns.  If dimmer, there is a voltage drop in that circuit.  The drop can be corrosion, wear, an open or short, or simply bad connections.  Always make sure you use good grounding points when running lamp tests—this is D.C. and requires quality grounds.

 

If wires test okay, make sure connections are clean and not corroded.  Corrosion and corrosive "wicking" up the wiring insulation is a common issue in the Rust Belt and four-season climates with salted winter roads.  Use an electrical contact cleaner to remove corrosion, and be sure the plug connectors are free of corrosion and fitting snugly.  I use fresh dielectric grease on the plug contacts to keep moisture at bay—inexpensive insurance!

 

Since your P0740 DTC reading is consistent, you may have an open in the wiring circuit.  The most valuable diagnostic tool in this case will be a digital volt-ohmmeter.

 

Others are encouraged to jump into the discussion...Trust this helps, Rent24, let us know what you find!  Looking forward to your posts...

 

Moses

[Suzuki Sidekick Needs an Engine Swap]

Thanks for joining the forums, Deltas69!  Your '96 Suzuki/Geo Sidekick reminds me of the Rubicon Trail venture that I undertook with Steve Kramer from Calmini Products and a Chevrolet engineer—around the time your vehicle was on the assembly line!

 

This was the 1.6L SOHC doing more work than customary—the Rubicon Trail in the mid-'90s, these were the first two 4WD Geo Trackers to ever traverse this notorious route!  I drove both of the Trackers through this particularly rough stretch of a Sluice Box, moving the granite rocks with a Warn winch.

(Click on photos to enlarge...Photos viewable by all forum members—join us!)

 

There are several ways to go here.  Although you're talking about a direct Suzuki swap, I'd like to share a personally appealing option first: The VW TDI diesel can be swapped into your chassis.  See the Acme Adapters website for details, they describe this process very thoroughly.  Kits fit Suzuki models and also the Toyota 22R applications:

 

http://www.acmeadapters.com/faq.php

 

If cost is a consideration, unless you can find the VW TDI diesel engine at a reasonable fare, plus all of the peripheral swap parts discussed on the Acme Adapters website, this is not your path.  Find a cheap TDI engine, and this is a prospect.

 

Another non-Suzuki option is the 4.3L G.M. V-6 conversion.  This would press the engine bay space limits for a Sidekick, and I'd opt for an aluminum cylinder head version for weight savings.  Having lived and breathed a pair of essentially stock two-door models on the Rubicon Trail for two days and nights taught me respect for their frame integrity and overall stamina—that's a lesser concern.  Here is the website if you're curious: 

 

http://www.suzukiconversion.com/ and http://www.suzukiconversion.com/suzuki_tracker.htm

 

Nobody says the V-6 conversion is "easy", and cost aside, the TDI VW diesel swap is at least 40 hours of work.  The V-6 conversion would be at least that time.  Lightning Conversions has the scoop here.

 

As a footnote, your 16-valve Sidekick engine makes an excellent swap into the Samurai, and there are several conversion kits available.  It's not that the '96 1.6L SOHC engine is unreliable, the issue is power-to-vehicle weight ratio.

 

Thanks for indulging me, PJ!  I know you asked for a straight-up Suzuki swap answer, so I'll comply.  Suzuki used the 1.8L I4 with twin camshafts in the 1996 Sport Sidekick.  This upscale package has port fuel injection, 120 horsepower and improved torque over the 16-valve 1.6L.  There is also a 2.0L engine that both the Sidekick and Tracker introduced, with 127 and 130 horsepower output.  These are inline, twin-OHC fours.  A 2.5L V-6 Suzuki Grand Vitara engine pumps out 155 horsepower by 1999, when owners were demanding significant power gains to match the size and weight increases on these Suzuki models. 

 

That said, there are many kits to put your 1.6L four into a Samurai.  However, Tough Trail appears the only company making a kit to put the 2.0L DOHC four into your Sidekick chassis.  Here is the scoop:

 

http://www.trailtough.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=491&category_id=46&option=com_virtuemart&Itemid=53

 

Although you can do this swap yourself with a 2.0L engine and Vitara automatic transmission, a 2.0L "turnkey" installation by Trail Tough is available for $3,900.  I'm certain, from experience with swaps and the implied issues in the parts list provided by Trail Tough, that they can justify this cost.  You need to contact Trail Tough if you do have an interest in this swap, as I'm unclear about the components you need from the 2.0L donor model Sidekick, Tracker or Vitara.  Ask about necessary modifications beyond the engine installation.

 

Typically, these swaps can involve the computer, wiring harnesses, any interface changes between your chassis and the chassis of the donor engine, the engine/transmission mounts, shifter considerations, interlock and ignition devices, upgrade cooling, and so forth.  I can't speculate how involved this might be for the 2.0L four.  Trail Tough is certainly a source for details.  Their kit's components do indicate that there is a market and interest for this conversion.

 

If you do contact Trail Tough about this 1999-2002 J20 engine swap into your 1996 Sidekick, members at this forum would value your findings.  The 2.0L four is likely the most straightforward Suzuki-to-Suzuki engine and transmission conversion for the 1.6L Sidekick/Tracker. 

 

Chassis and electronics changes would make the 2.4L J24 engine of later years a more complex swap.  For one reason, many later vehicles have the VIN code embedded in the instrument cluster, computer and steering column/ignition key switch electrical circuits to help prevent vehicle theft.  This has made engine swaps much more complicated with regard to wiring and electronic requirements.

 

Although I mentioned the 4.3L G.M. V-6 swap as an outside approach, it is often easier to make that kind of swap than to sift through schematics and splice OEM wiring harnesses together for the electronic and electrical systems.  There are aftermarket wiring harnesses available for G.M. Vortec 4.3L V-6 engine installations.  Sources like Howell Engineering can make the 4.3L V-6 engine easier to install. 

 

Of course, you need engine and transmission mounts, an exhaust system, cooling system, emissions interface and other chassis-to-engine swap components.  Wiring includes the charging, starting, ignition and electronic fuel injection.  The throttle linkage and cruise controls (if present) must be sorted out, too.  Each of these areas demands attention and takes time, tools and equipment.  Even for a 2.0L Suzuki engine swap, I would closely compare the donor vehicle's engine and transmission installation before plunging into the swap project! 

 

Be aware that any vehicle emission inspection will expect, at bare minimum, an engine the same year or newer with a tailpipe emissions reading equal to or cleaner than your original engine in good operating condition.  These guidelines once applied only in California but have been adopted in many states. 

 

You will need to use a "referee" station in states like California for any engine change of this nature.  They will do a visual inspection to make sure the engine, exhaust, air intake and chassis have all their original emission devices in place.  Any aftermarket engine, exhaust or air intake parts must be approved for use in that state.

 

Looking forward to continuing this discussion!  We encourage others to share and participate... 

 

Moses

[Ford 8.8" Rear Disc Brake Conversion on 1986 Jeep CJ7 Dana 44]

A work in progress...Glad you're dealing with the E-brakes, you do need a backup and parking aid. 

 

Thanks for the kudos on the Jeep CJ Rebuilder's Manual (Bentley Publishers), the 1972-86 edition for your Jeep CJ-7.  I enjoyed getting to know your 4x4 club's members at my Bentley Publishers workshop in Cambridge, MA a few years back!  Glad we've kept the communication going since...

 

Moses

[Just Using a Jeep 258 Crankshaft with a 4.0L Jeep Inline Six Rebuild?]

Hi, Wayman, great to hear your plans...I'm not sure what machining and parts cost in your neighborhood, but let me emphasize this: It will cost almost the same to rebuild a Jeep 4.0L into a 4.6L stroker as it will to rebuild a stock 4.0L inline six thoroughly.

 

That said, the added cost, at bare bones budget, will be the pistons and 258 crankshaft core or casting.  You need the right pistons for the stroker, or you will not achieve proper piston height in the cylinders.  On the piston side, if you use a hypereutectic type at 8.7:1 static compression with a zero-deck, the cost difference will be minimal.  It will include block decking as part of the machining process to meet piston/deck height match.  In my Hewes Performance video interviews, you will hear Tony Hewes talk about the rod and crankshaft matches and which pistons the different approaches require: http://www.4wdmechanix.com/HD-Videos-Building-a-4.6L-Jeep-Inline-Six-Stroker-Motor.html.

 

On a very low budget, conceivably, you could get by with a 258 crankshaft (serpentine belt short snout version is easier and popular, saves cost here) and connecting rods, bearings, a timing chain set with sprockets, a new camshaft and lifters, pistons/pins and rings, valves and valve springs with retainers and keepers, a complete overhaul gasket set (Felpro simplifies here), and a new oil pump and screen (Melling high volume).  Hot tanking is a must, and this means new camshaft bearings, too.  Freeze plugs, a water pump and oil filter round this out.  This is a minimal parts list.

 

The minimal machining list after the hot tanking and camshaft bearing installation would be the cylinder head valve seat grinding, head decking, valve guide work (silicone bronze liners, minimally), block decking as needed for the stroker pistons, connecting rod and crankshaft reconditioning (as required) and piston fitting.  Boring and honing the cylinders and line boring the crankshaft centerline is typical fare for a quality rebuild.  Balancing reciprocating parts, if affordable, is a desirable add-on to the rebuild. 

 

You mention a new clutch, and you should also have the flywheel resurfaced (if acceptable for this flywheel's design and condition, provide me with details on the year and application flywheel, I'll comment back) or replace it with a new one.  As a reciprocally moving part, the flywheel would be among the balancing pieces...A crankshaft pilot bearing is required, one that will work with your later transmission and the 258 crankshaft.

 

Price machining locally, shop online for best buys on rebuild kits and pistons, etc.  Have your block and head casting assessed by a reputable machine shop before plunging.  Do you have a quality 258 crankshaft core already?  Make sure the crankshaft will turn and polish at 0.010" or 0.020" undersize on the rods and mains, optimally 0.010"/0.010".  If in a real pinch, and with a rougher crank core, 0.030" undersize is not terrible for an engine that will see reasonable use and not be desert racing.  Block wise, a 0.030" oversize is acceptable, 0.040" would be on the edge, and 0.060" oversize for a Jeep 4.0L is more than I would want for proper cooling.

 

Share your findings.  I'll comment objectively, I've been rebuilding engines professionally for 45 years and know what costs are reasonable.  I am happy to comment and encourage other members to jump in here with helpful suggestions and experiences with a low-dollar stroker motor rebuild!

 

Moses

[Ford 8.8" Rear Disc Brake Conversion on 1986 Jeep CJ7 Dana 44]

Glad you're happy...I am, too!  As for why disc brakes work well up hill or down, the reason is that they are not like drum brakes:  Drum brakes, at least modern, self-energizing types, feature a short shoe lining toward the front and a long brake lining toward the rear of the vehicle.  This design takes advantage of "self-energizing", drum rotational force to have the initial contact shoe press against the drum, stop at the anchor bolt and move outward from rotational force.  

 

Rolling forward, this self-energizing or rotational force is at the rear or long brake lining, which is forced against the drum.  With this same direction of rotation, the front or short lining brake shoe relies more upon hydraulic force from the wheel cylinder to push the forward lining against the brake drum.  Envision the long lining shoe wedged against the anchor at the top of the backing plate; with applied brakes, this shoe attempts to rotate with the drum and can only move outward; that mechanical force is significant and called "self-energizing".  It takes advantage of both hydraulic pressure and the physics of self-energizing force.

 

When you back the vehicle up with this short lead shoe and long rear shoe, the rotational force is the opposite: the short shoe exerts the extra energy of the rotational force (short shoe stops at the anchor bolt then pushes outward).  The long lining shoe (facing the rear of the vehicle) relies more on hydraulic force.

 

Where this is really evident is the emergency or parking brake on a self-energizing drum brake system with rear drum brakes that incorporate a mechanical emergency or parking brake function.  Ever notice that you can back the vehicle up with the rear drum E-brake on?  At least fairly easily.  When you try that moving forward, the vehicle immediately grabs or won't even move.  This, again, is the long shoe versus short shoe and self-energizing brake effect.  It works with either the hydraulic or mechanical (parking) brakes applied.  It also suggests not parking the vehicle uphill and relying totally on the drum brake parking brakes!

 

Note: Many rear disc brake systems now have a drum and shoe E-brake.  If the shoe lining length is equal on both shoes, the parking brakes should, theoretically, hold with equal force in either direction of rotation: uphill or down.

 

So, you're right!  With disc brakes at all four wheels, the brake apply pressure at each rotor remains the same, regardless of the vehicle's direction of movement.  There is, of course, the shift in vehicle weight bias when applying the brakes at speed or when the vehicle is aimed uphill or downhill.  At speed, weight and brake bias would go to the axle facing the direction of vehicle movement.  When on slopes, bias is at the axle that bears the most weight.  Weight bias changes with the degree of slope and direction your Jeep is pointed: uphill or downhill.

 

In addition to this, you have more effective brakes when backing up because the rear brake rotors and calipers apply more force than the original, self-energizing drum brakes were capable of doing when the drums rotate backwards!

 

Moses

[Dodge Dakota 4x4 Needs AX15 Transmission Extension Housing]

Thanks much for the feedback...I apply the same energy at the magazine website and forums as my journalism or book writing...We all deserve researched, accurate information!

 

I look forward to your family's participation at the forums.  Please share and encourage folks to join in the discussions!

 

Moses

[Ford 8.8" Rear Disc Brake Conversion on 1986 Jeep CJ7 Dana 44]

Ah, why didn't I consider the Explorer?  Smaller wheel bolt circle, four-wheel disc brakes, 8.8" rear axle!

 

Comparing master cylinders on the basic TJ Wrangler (disc front/drum rear brakes) versus a TJ Wrangler Rubicon (four-wheel disc brakes), I picked 2005 model year as an example.  Both brake systems use the same master cylinder that year:

 

1 04798157 1 MASTER CYLINDER, Brake

R4798157 Mopar Remanufactured Part

 

When you get to the proportioning valve, there are two part numbers for the 2005 Wranglers.  These two numbers apply to all models of the Wrangler, both disc front/drum rear and four-wheel disc brakes.  The proportioning is the same part number for each of these late systems.  (I describe the function of the proportioning valve in an earlier post at this topic, and you can see why the same valve works for both systems.) 

 

The Mopar part number distinction for the proportioning valve is not whether the vehicle has disc front/drum rear or four-wheel disc brakes.  One valve is for ABS models, the other valve is for non-ABS models:

 

VALVE, Proportioning
05083807AA  [bGK]  (anti-lock brakes)
05083808AA  [bGA,BRW]  (without ABS)

 

As for master cylinder bores, your stock 1986 CJ-7 master cylinder for power brakes can be either 1" diameter or 15/16" diameter, depending upon the cylinder manufacturer and vendor.  The Ford Explorer OEM master cylinder should have a 1-1/16" bore. 

 

The rear/drum brake reservoir and port is at the front of your CJ-7 master cylinder.  The bigger reservoir, closer to the firewall, is the disc front brake portion of the master cylinder.  Here is a photo with a nice description from one aftermarket master cylinder supplier:

 

This is a typical aftermarket replacement master cylinder for a 1986 Jeep CJ-7 4WD model with power booster.  The bore is 15/16", although some designs for this application are a 1" bore size.

(If you cannot open this photo, consider becoming a forum member for free—you'll have full access to all features and can join in the discussion, too!)

 

I researched bore sizing to determine how your Jeep CJ-7 brake master cylinder pressurizes the brake system then compared that with a 1996 Ford Explorer master cylinder—specifically to determine the braking system pressure that reaches the Ford Explorer rear disc brake calipers. 

 

The brake pedal leverage and power booster determine the mechanical pressure pushing against the master cylinder pistons.  What we want to know here is the fluid pressure that the master cylinder delivers to the rear disc brake calipers.  This is determined by the area of the master cylinder bore size. 

 

Let's assume that your CJ-7 Jeep cylinder is the smaller 15/16".  The formula for the area of the bore size would be Pi times the radius squared:

 

15/16" = 0.9375" bore diameter
15/32 = 0.46875" radius of bore
Pi = 3.14159265359

 

3.1416 (rounded up Pi)  x 0.46875 x 0.46875 = 0.69 square inch

 

For the Ford Explorer master cylinder area:

 

1-1/16" = 1.0625" bore diameter

17/32" = 0.53125" bore radius

Pi = 3.14159265359

 

3.1416 (rounded up Pi) x 0.53125 x 0.53125 = 0.8866 square inch

 

Expressed as pounds per square inch fluid pressure coming out of the master cylinder, let's apply 750 pounds of mechanical force, using the brake pedal leverage and power booster:

 

Jeep CJ-7 master cylinder fluid pressure into the system = 750 divided by .69 = 1087 PSI

 

Ford Explorer master cylinder fluid pressure into the system = 750 divided by .8866 = 846 PSI

 

With the same mechanical force of 750 pounds applied to the master cylinder pistons, the CJ-7 cylinder will pressurize the brake system at 1087 PSI, and the Ford Explorer master cylinder would pressurize the brake system at 846 PSI.  This is the fluid PSI pressure going to the front and rear brake calipers.  At that stage, the actual apply pressure of the caliper pistons against the rotor faces is determined by the bore size of the caliper pistons.

 

The actual pedal pressure/leverage point and brake booster in this case is stock CJ-7.  The difference in master cylinder bore sizes has the Ford Explorer rear disc brakes getting more apply pressure with your CJ-7 Jeep master cylinder than the same brakes would get on a Ford Explorer.  The end result is more brake pressure at the retrofit rear calipers in your CJ-7 than the brake pressure in a Ford Explorer—applying the same mechanical force (pedal and booster) at the master cylinder.

 

You should notice some difference with these rear discs over the OEM Jeep CJ-7 drum brakes.  From what you share, the good news is that you're apparently not over-powering the rear brakes, causing rear wheel lock up or running the risk of spinning the Jeep out on a slick surface.  Your CJ-7's beefy Scout II front axle, 35" tires, stiffer suspension, plus the shorter wheelbase and shorter overall length than a Ford Explorer, also contribute to the brake system's balance. 

 

The difference in master cylinder apply pressure is not dramatic, even less if your CJ-7 master cylinder is actually a 1" bore and not 15/16".  Your use of the late Jeep TJ Wrangler Rubicon four-wheel disc brake proportioning valve also helps keep brakes in balance front to rear.

 

By using the Jeep CJ-7 master cylinder with its slightly smaller bore, you've booster the brake pressure to the rear calipers when compared to a stock Ford Explorer.  This is all relative to the brake pedal and booster force.  The best test is the real world.  Overall, you do not want the rear wheels to lock up under hard braking or on a slick surface.  This makes the proportioning valve important.

 

If you had installed an aftermarket manual proportioning valve on the rear brake system, and adjusted the valve to prevent wheel lockup, the setting would likely be the same as how your brakes apply now.  The Jeep CJ-7 chassis dynamics are different than the Explorer, and the wheelbase is shorter.  You do not have symptoms of over-braking at the rear wheels...That's how the brakes and the proportioning valve should work!

 

As a footnote, you shared that you now have "new" rear calipers after the bleeder valve issue.  The photo at your earlier post shows an older caliper and rotor.  If these parts are used, the brake test results you get now may be different if you install new rotors, pads and calipers.  There could be an improvement in rear brake performance with all new parts.  If so, be cautious until you're certain that the rear brakes still will not lock up on slick surfaces or under hard braking.

 

Moses

[Ford 8.8" Rear Disc Brake Conversion on 1986 Jeep CJ7 Dana 44]

I see the dramatic difference in the original wheel bolt circle and your drilling new wheel stud holes for the Jeep 5 x 5.5" wheel bolt diameters.  Also see the "lathe cut-to-fit" of the rotor centers to fit your CJ-7 axle shaft hub. 

 

The 8.8" axle must be from a Crown Victoria RWD car?  Or a Mustang?  Curious what donor application, as I'm still trying to compare the master cylinder pressure differences between your CJ-7 Jeep master cylinder and the donor car.  What was the 1996 Ford donor model?

 

Moses

[Dodge Dakota 4x4 Needs AX15 Transmission Extension Housing]

Biggman100, thanks for joining the forums!  We value your input and participation...

 

For openers, the AX15 is used on the 1994 Dodge Dakota, Jeep XJ Cherokee, and the YJ Wrangler.  2.5L four-cylinder and 3.9L V-6 applications of the 1994 Dodge Dakota 4WD pickup truck use the AX15 Aisin transmission.  Dodge Dakota 4WD pickups with the V-8 engine use the NV3500 5-speed transmission. 

 

By parts listings, there are differences in complete transmission units from Mopar for each of these models.  Six-cylinder Jeep applications use the AX15; four-cylinder gasoline powered Jeep U.S. models use the lighter duty AX5.  The AX5 would not fit your Dodge Dakota—nor would it be reliable for that application.  Here are the 1994 Jeep parts listings that come up for Aisin Warner AX15 and AX5 transmissions:
 
COMPLETE 5-SPEED TRANSMISSION ASSEMBLIES FOR JEEP APPLICATIONS

Listings below can be either an AX5 or AX15, depending upon the engine application:

52108022  XJ 2.1 Turbo Diesel Engine 1994
52108121  X1,XJ 2.5 Turbo Diesel Engine. 1995
52108049  YJ,Y1 2.5L Four Cylinder Engine, 4WD
52108045  XJ, X1 2.5L Four Cylinder Engine, 2WD
52108046  X1 2.5L Four Cylinder Engine, 4WD, EGYPT, MALAYSIA
52108046  XJ 2.5L Four Cylinder Engine, 4WD
52108021  X1 2.5L Four Cylinder Engine, 4WD, CHINA, ARGENTINA, VENEZUELA,
MALAYSIA, EGYPT
52108050  Y1, YJ 4.0L Six Cylinder Engine
52108048  XJ, X1 4.0L Six Cylinder Engine, 2WD
52108047  XJ, X1 4.0L Six Cylinder Engine, 4WD
53009526  ZGZJZ1 4.0L Six Cylinder Engine
52109021  ZGZ1 2.5 Turbo Diesel

 

1994 DODGE DAKOTA 4WD PICKUPS USE THESE AX15 MOPAR REPLACEMENT TRANSMISSIONS:

 

52109035   1994-95

52109035   3.9L Engine, 1996

52108465   2.5L Engine, 1996

52108036   3.9L - 6 cyl. Gas

 
COMPLETE TRANSMISSION NV3500 FIVE SPEED FOR V-8 DODGE DAKOTA PICKUPS

53006633   4x2, Through 11/20/94
52108019   4x2, After 11/20/94
53006634   4x4 1994
52108120   4x4 1995-96
 
1994 Jeep XJ Cherokee and YJ Wrangler AX15 Adapter/Extension Housing for 4WD 

 

04636372  X1,XJ
04636373  YJ,Y1

1994 Dodge Dakota AX15 ADAPTER, Transmission 4WD

04636372  Dakota pickup

 

So, the extension/adapter housing you need can be a Jeep XJ Cherokee AX15 4WD type from an inline 4.0L six-cylinder model!  The extension housing differences for the AX15 relate to necessary adapter length, 4WD versus 2WD, motor mount location, clock position of the transfer case and other distinctions.
 
The complete AX15 transmission listings are also different and may contain ratio differences.  If curious, you could research the ratios for a Dodge 3.9L V-6 Dakota versus a Jeep Wrangler or XJ Cherokee application.  I have data on the YJ and TJ Wrangler and the XJ Cherokee transmission ratios from 1989 to 2000.
 
Advance Adapters sells brand new AX15 5-speed transmissions.  The Advance Adapters unit is a direct replacement for 1997-2000 Jeep TJ Wrangler AX15 (4.0L inline six-cylinder applications).  2001-up, the Jeep Wrangler 4.0L and the last XJ Cherokee 4.0L 4WD models use the NV3550 transmission, derivative of the NV3500.  A very insightful footnote at the Advance Adapters website catalog shares these details:
 
NOTE: These AX15 transmissions feature a 13 degree tailhousing rotation and are exact replacement transmissions for 1997-2000 Jeep TJ Wranglers. If installing this AX15 into Jeep Cherokee, the tailhousing rotation will be wrong. Cherokee transmissions have a 23 degree rotation tailhousing. The rotation difference will lead to install issues with the Cherokee NP231 transfer case shifter.
 
This is clearly the distinction on the Mopar extension housings.  Measure your transfer case rotation.  The Dakota 4WD should follow an XJ Cherokee 4WD tailhousing clock rotation.  Presumably, ground clearance and front driveline position/angle dictate the rotations.

 

Looks like your search for an extension/adapter housing just reached out to the Jeep XJ Cherokee 4WD with a 4.0L inline six.  Same part number!  I can confirm fit if you find an extension/adapter housing from another model year of the XJ Cherokee 4.0L 4WD AX15 5-speed transmission.

 

When the bolts snap, there's usually huge elongation or side load force.  Sounds like the Dakota 4WD pickup might have had a shock load or suspension bottoming episode from leaping and landing the truck.  Does it have a lift kit?  Sometimes the driveline angles or length of the drivelines will allow the slip collars and splines to collapse and bottom, exerting severe force on the transfer case, enough to break the case—or possibly snap transmission bolts.  
 
Moses

[Rear Disc Brake Conversions, Master Cylinder Needs and the Drum Brake Residual Pressure Valves]

On the shorter wheelbase Jeep CJs, brake proportioning seems less touchy.  Your CJ8 Scrambler is 103.4" wheelbase (stock), so the 4x4 is a candidate for more accurate brake proportioning, front to rear.  Glad the large drums brakes work this well with the disc front brakes.  Your Jeep's modified curb weight is considerable, my guess is around 4,800-5,200 pounds?

 

Thanks for sharing these details.  Other trail runners may make similar axle swaps to their CJs.  For the sake of fellow members and CJ builders, can you share the origins (model and year) of the front and rear retrofit axles and whether the brakes are stock for each axle?  I'm guessing that you're also using the stock CJ-7 master cylinder?  The axles look like their 3/4-ton truck track widths, what size tires are you running?  What's the approximate lift?  I know you've modified the springs considerably.

 

For forum members interested in seeing this CJ-8/Scrambler up close with its fresh 4.6L Hewes Performance stroker motor, here is a link to the magazine's HD video walk around of the Jeep and Mark's narrative: http://www.4wdmechanix.com/HD-Videos-Jeep-CJ-8-4.6L-Stroker-Power.html.  We featured this Jeep because it's the "real deal", a tough, no holds barred trail runner that constantly plies northern Nevada's back country and the toughest Sierra trails. 

 

Moses