Name is Mark, and I live at Reno. Wheeling since 1976, like 4x4s, ATVs, dirt bikes and my beloved, and sometimes hated, 1981 CJ8 Scrambler. Interested in all things Jeep!
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Posted by RareCJ8 on 09 April 2013 - 09:46 PM
Name is Mark, and I live at Reno. Wheeling since 1976, like 4x4s, ATVs, dirt bikes and my beloved, and sometimes hated, 1981 CJ8 Scrambler. Interested in all things Jeep!
Posted by Moses Ludel on 01 December 2013 - 02:55 PM
Wow, that spring comparison is graphic, thanks for the photo! The wire size on the smaller spring must be 1/4th the apply pressure...Apparently, there was excessive fuel pressure, and the leaking or by-passing regulator was "force feeding" the injector without the normal electronic opening and closing of the fuel flow.
Good observation, and good solution...Let's see where this leads now that the engine is flowing a more moderate amount of fuel. We'll see if the sensors are all back on line with normal closed loop function and air-fuel ratios.
Posted by Moses Ludel on 16 November 2013 - 09:42 PM
Thanks for the compliment, Josh. The TBI signal could be a factor, although the Seafoam has me looking at the oxygen sensor, EGR valve or an exhaust obstruction...The '89 YJ Wrangler is early OBD and awkward for testing the onboard diagnostics. If you do have access to a scan tool that will work with Chrysler's early OBD hookup, try getting a DTC trouble code from the ECU. You do have a diagnostic test plug on the Jeep engine bay wiring.
Make sure that the exhaust is unrestricted, and consider the EGR valve and oxygen sensor. Test parts before replacing them. Even though the oxygen sensor is a higher mileage "perishable", you should still make sure that it is defective before buying a new O2 sensor. Same with the EGR valve.
As the issue goes away when you sweep Seafoam through the vacuum hoses, this may be a clue. Seafoam flows through the combustion chambers and exhaust, which may be cleaning a sticky EGR valve or dirty O2 sensor. Unseated and stuck open, the EGR will generally cause a rough idle or low speed performance quirks. An EGR valve stuck shut will create upper cylinder heat and possibly erratic fuel mixtures. The EGR controls NOx and can affect other exhaust gases.
Considering your troubles to this point, the EGR valve would be worth testing. If you have a hand vacuum pump, you can quickly test the EGR with the engine idling. Attach the pump hose to the EGR. Pump down vacuum with the engine idling, enough to open the EGR valve. You should hear a change in engine speed and smoothness as you open the EGR valve at an idle. No changes would indicate that the EGR valve is either stuck or defective. The valve has a diaphragm that can be weak or leak with age.
Be cautious when working around the EGR valve, it gets very hot! Handle with care...If you attempt to remove and clean the EGR valve, do not soak the diaphragm in solvent or carburetor cleaner. Try to submerge the base of the EGR valve (metal parts only) in carburetor cleaner, and make sure you get the valve plunger to open and shut freely—and seat completely. Rinse away any solvent or carburetor cleaner before reinstalling the EGR valve and running the engine.
Posted by Moses Ludel on 28 October 2013 - 09:02 PM
The steering gear and linkage are vital safety concerns—yet the pitman arm on a 4WD Jeep or other light 4x4 truck can easily be installed incorrectly. With the popularity of oversized tires and suspension lift kits, many pitman arms get replaced long before there is a parts wear issue. A dropped pitman arm is often part of a suspension lift kit, and the pitman arm on a new or relatively new vehicle may get replaced with a dropped arm.
Here are some procedures that I use when installing a pitman arm:
1) Never turn the arm against either of the steering gear's extreme left or right turn positions. Force against the gear in these positions can damage the steering gear internal parts—the gear is not intended to absorb this kind of force at either end of the worm or ball nut's travel. I like to keep the steering gear and pitman arm close to the center or straight-ahead steering position during pitman arm removal and installation.
2) When removing the pitman arm nut on a typical steering gear, there is a lot of force required. It is easier on parts to use an air impact gun and socket to remove the nut, as there is less tendency for the pitman to rotate...If you have the steering gear removed from the vehicle, consider holding the arm in a large bench vise (with the gear assembly free) while loosening or tightening the nut.
3) Once the nut is removed, use the correct pitman arm puller tool to prevent damage to the steering shaft and other parts. Make sure the tool fits properly between the backside of the arm and the neck of the steering gear housing, with enough clearance to prevent damaging the housing/casting!
4) There is considerable force with the pitman arm secured on tapered splines, so use extreme caution with the puller tool. Once the initial tension relieves, the arm will come off readily.
5) Clean up the sector shaft splines as needed. It is critical that the new pitman arm fits properly, an interference fit that demands clean mating surfaces. If installing a powder coated aftermarket pitman arm, I always use a suitable drill motor-powered wire brush to remove the powder coating from the tapered seat and splines of the new pitman arm. (I remove paint here, too.) Don't damage or dull the spline teeth in the process!
Warning: If you mate a powder-coated part at the splines, you will get a false torque reading. There is a high likelihood that the pitman arm will loosen at the splines as steering force wears through the powder coating. If you have a powder-coated arm already installed, and if the arm has been in service, re-check the nut torque with the pitman arm in the straight ahead steering position.
6) Always use the required torque wrench and socket to bring the sector/pitman nut to proper torque. Again, make sure the arm is near the straight ahead steering position to prevent damaging the steering gear. The torque required is high, especially on a recirculating ball-and-nut power gear, much more than on a light-duty vintage Jeep cam-and-lever gear! Do not second-guess the torque setting. Use a factory or professional shop manual to determine the correct torque for the pitman/sector nut on your steering gear.
7) When reattaching steering tie-rods, make sure they are clean and free of debris. If the outer end of the new pitman arm has a tapered seat with powder coating or paint, I use a drill motor-powered wire brush to remove the powder coating and take the tapered seat to bare metal.
8) Attach a clean tie-rod ball stud to the pitman arm tapered seat, using the correct type nut (typically castellated or flanged self-locking) that comes with the tie-rod end. Flanged, self-locking nuts are often one-time use only. Consult the factory workshop manual for recommendations on replacing fasteners or use of thread locking liquid. Always use OEM grade hardware and fasteners.
9) Align steering joints, adjusting sleeves and tie-rod ends so that the ball studs are on center with the steering linkage aligned. Make sure none of the joints bind or run out of travel over the full range of steering turn positions and angles. Make sure that parts do not interfere with each other.
10) I always recheck the torque on the pitman and tie-rod fasteners after a short time in service. This is a safety precaution that may catch a part requiring a slight re-torque.
Again, this is all about safety. Use of oversized tires places an even bigger load on these parts...
Posted by biggman100 on 25 October 2013 - 10:54 AM
Jim, i would definitely add trailer brakes. The trailer might turn out to be compact and not very heavy, but fully loaded it might end up extremely heavy, and push against the truck, and cause the trucks brakes to work harder, and especially on big hills would definitely be worth it to have.
Posted by Moses Ludel on 24 October 2013 - 02:38 PM
Thanks for your enthusiasm around my books, Jim...I'm very pleased that we have these "forums" to share our common interests! Looking forward to the dialogue...
Posted by Moses Ludel on 24 October 2013 - 02:36 PM
Yea, another trailer guy! You, me and RareCJ8...Thanks for sharing, Jim...RareCJ8 will jump in, I'm sure! So will Biggman100...
Posted by Rollbar on 24 October 2013 - 10:52 AM
Posted by RareCJ8 on 22 October 2013 - 10:59 AM
looks good. like the ratchet strap! i too added a twin stick kit to my D300-- the comprehensive kit from advance adapters. Low front is fun but beware of serious axle wrap. Too bad its not easy to get 4 high front only w/out dropping the rear driveline. Now get us some trail action shots...
Posted by hobbs on 21 October 2013 - 07:13 PM
I am installing a front D44 front from a mid-70s Waggy in my 85 CJ-7. I have found some good write-ups on shortening the drivers side of the 44 to keep overall width the same. My current issue is that I want to convert the unit from the 6x5.5 Waggy pattern to the 5x5.5 CJ pattern. I have actually sourced a set of Ford outers, but am reading some things which concern me concerning later Waggy D44s maybe not being compatible because of some dimensional changes to the bearing. AS I am not sure of the year of the D44 I am now considering having a machine shop redrill some of the components on the Wagoneer outers to 5x5.5. Any opinions on the best way to achieve what I am trying to do? Thanks, hobbs
Posted by Moses Ludel on 27 July 2013 - 01:16 PM
All good points, Megatron, each deserves an explanation, so here we go...I'll begin by sharing that I ran a four-wheel alignment rack at a GMC truck dealership in the mid-'80s, the era of both beam front axle 4x4s and IFS 2WD and 4WD front ends. For fifteen years prior to that, I had been doing alignment with far less equipment than that new Hunter four-wheel, electronic light beam rack. Fifteen years after the dealership stint, I taught wheel alignment at the adult vocational training level and merged my varied equipment experiences, which reflect in what I'm now sharing.
It's great to use precision four-wheel alignment equipment. However, "computer" alignment equipment is also limited in many ways. For example, you describe aftermarket wheels, suspension and tires, and you're right, of the three (assuming the suspension kit is as adjustable as yours), the wheel offset is the most critical modification. Because your truck falls outside the OEM guidelines built into the software for modern alignment equipment, many shops will avoid doing your truck's alignment.
Reasons for refusal include "liability", "unpredictable results" and "possibility of abnormal tire wear"—regardless of the alignment procedure. In many cases, the shop simply doesn't know what they can do to address or compensate for your modifications...After all, this is the era of plug-and-play. Follow the flow charts or stare at the computer screen or scanner. Wait long enough, and maybe an answer will materialize...That's not going to happen here!
For now, let's suspend judgment about why your truck and millions of other 4x4s are in this predicament. You've installed all of this hardware, and it's time to make the vehicle track as safely as possible—and for the tires to last.
As for front axle lateral alignment, your adjustable track bar is a real asset. Alignment does reference from the rear axle, and for good reason. The term "thrust" is just what it sounds like: The rear axle on a RWD vehicle is the traction point, pushing the frame and the entire vehicle forward from the rear. Unless you're driving backward, your rear-drive truck requires the front axle to align squarely under thrust. (Thus the term "thrust alignment"!) The axles must be square, in any case.
To illustrate, draw a line forward and perpendicular to the centerline of the rear axle. This follows the driveline in approximate terms—unless the driveline is offset like with a side-drive transfer case. This line of force, aimed forward and perpendicular to the rear axle, becomes the reference point for the front axle's position. The front axle ends up parallel to the rear axle, which is simple to visualize on beam axle trucks like our Ram 3500 models. The front axle must also align sideways or laterally, the reason for your adjustable track bar.
Whether the frame is perfectly square or not, if the front axle is parallel to the rear axle (plane view from the top), and if the axles center laterally with each other, you can align the truck's front end. The frame should be square, though, because an out-of-square frame would place the springs, suspension arms and steering linkage at odd angles with the axles.
So, let's start with a square frame, no collision damage, and a rear axle that sets squarely in the truck. It's much easier with our leaf sprung, beam rear axle: The centering points for the rear axle are simply the leaf spring center bolts and the axle's spring perch holes—plus any spacer block alignment holes or pins.
Rear axle in place, you can use the string-in-diamond method for setting the beam front axle's position for both parallel to the rear axle and laterally on center. I used the string method for two illustrated how-to articles at the magazine: my Jeep XJ Cherokee 6-inch long arm installation at the "Jeep XJ Cherokee & MJ Comanche 4WD Workshop" (see the left panel menu) and also the Jeep TJ Wrangler Rubicon Full-Traction Ultimate 4-inch lift. The XJ Cherokee is similar to our Dodge Ram trucks with link-and-coil front suspension and leaf springs at the rear. Both Jeep vehicles have beam axles front and rear.
Critical to a string-in-diamond beam axle alignment is finding precise reference points at each of the axles. You must have a reference point at each side of the front axle that is truly equal distance from the axle's centerline. The rear axle on our trucks is simple: Use the leaf spring center bolts as the rear reference points. On a Jeep TJ or JK Wrangler, there are matching suspension points that are equidistant from the rear axle's centerline.
The front axle should align with equal string lengths to the rear axle, measured in cross or "diamond". This means measuring from the front axle's left side reference point to the right rear spring center bolt, then from the front axle's right side reference point to the rear axle left side spring center bolt.
This measurement must be very accurate. Even 1/16"-1/8" variance can make a difference. If there are obstacles under the chassis that prevent an accurate measurement, you may need to relocate your reference points or even make "extensions" from the reference points to below the obstacles...For these measurements, you can have the axles suspended to full drop, which may help the string lines clear the transfer case skid plate, the exhaust or any other objects in the way.
Be creative. It's crucial that your four reference points reflect equal distances from the center of each beam axle outward to each axle's reference points. Strings then measure in cross between the front and rear axle reference points.
Again, the end game here is to have the axles parallel and tracking in line with each other. When the front axle is offset laterally, one way or the other, we call this "dog tracking".
Note: Don't be confused if one axle's track width is actually slightly wider than the other axle with the wheels in place. Some trucks (G.M. beam axle 4x4s come to mind) were designed this way, typically with the front axle slightly wider than the rear. I won't digress into "why" this was the design, simply know that if your reference points match side to side on each axle, and if you run the string lines in cross to matching points at the opposite axle, you will determine both the square and lateral alignment of the two axles.
Checking for square with two strings-in-cross is a simple function of geometry. If anyone is having difficulty understanding the principle, draw a perfect square on a piece of paper; now draw an "X" from opposite corners, intersecting at the middle. Measure the length of each "X" line. It will be equal. If you now use a rectangle instead of a square, the results will also be two equal length, intersecting lines. Play with this, and then transfer the "X" lines to your truck's chassis: On your long wheelbase Dodge Ram 3500 truck, the beam axles represent the short ends of a rectangle.
The most elaborate "4-wheel" alignment machine will not produce any more accurate results than doing a string line test properly. Once you get the axles square, you can concentrate on a front wheel alignment. This, as you say, is not rocket science, and it's even easier with a beam front axle.
Camber, in particular, is factory pre-set on a beam axle. Camber measurement indicates the degree to which the axle beams, steering knuckles and ball joints are in alignment. As you mention, you can make camber corrections with off-set ball joints, or eccentric ball-joint seats, and a source for such parts is Specialty Products Company.
Caution: I am against "bending" beam axles to correct slight camber issues unless a racing, weld-on truss is part of the straightening process. (Be aware, too, that welding on a truss is a good way to warp an axle and alter camber!) Consider the axle tube and center section materials plus the original stress that caused the axle to bend. There are metallurgical changes that take place with cold or hot bending. If you need to correct for a slightly bent or out-of-spec axle beam, use offset ball-joints or eccentric ball-joint seats. Make sure the bend did not stress-fracture the axle pieces. Toss out the axle housing if in doubt—you can transfer internal pieces and add-on goodies to a new housing. (See the magazine's many axle rebuilding articles and the HD videos on axle setup.)
Be aware that beam front axles come from the factory with +/- camber often slightly beyond the factory recommended camber degree range. I have seen this on Dana Jeep front axles, typically at the short beam side with more factory welding. An extra 1/8 to 1/4-degree camber at one side is not earthshattering and likely was acceptable during OEM axle assembly and installation. This will not impair vehicle handling and has negligible effect on tire wear if you rotate your tires on time. If you are adjusting caster and camber with offset ball-joints or eccentric ball-joint seats, bring both the caster and camber within their recommended degree ranges.
To answer your questions about "do-it-yourself" alignment, go no further than these three features that I've done at the magazine. They each get brisk traffic, addressing alignment goals with inexpensive solutions for doing your own alignment work.
First is the ‘DIY’ feature on a beam front axle wheel alignment. This is a useful article for understanding the principles of front wheel alignment as well as a 'how-to' on using an affordable SPC Off-Road Fastrax 91025 gauge kit designed for tires to 44" diameter. Click here to see this DIY how-to and equipment article.
For those on a shoestring budget, a single gauge kit will do. You can even improvise on the need for turn plates. SPC suggests using plastic sheeting beneath the front tires for a slip surface. On a beam axle, you can unload the weight slightly with the use of two floor jacks, raising the weighted axle evenly and just enough to take the heavy load off the front wheels and tires. This provides easier wheel turning.
There is also a photo closer to home, my Dodge Ram 3500 4x4 alignment after installing the Mopar lift kit. Here, I purchased inexpensive front turn plates ($100 for the pair!) from Gil Smith Racing at New York. Gil is a personable family guy, and these plates do the job despite the massive front end weight of the Cummins engine, 9.25" beam axle and 500 pounds of Warn bumper with M12000 winch and stainless wire.
For the Dodge Ram alignment, I added a second Fastrax 91025 alignment gauge kit from SPC to make toe setting easier and quicker. This way, you can use the winged braces and separate gauges at each side of the truck during the alignment procedure. This eliminates the need to swap a single gauge set from one side to the other.
Last, but surely not least, is the HD video walk-through of alignment on a Jeep TJ Wrangler Rubicon. You'll like this for both a visual orientation and added quips about the process. In this HD video, I do use the double alignment gauge sets from SPC and the Gil Smith turn plates. You’ll see how this speeds up the process.
Some additional pointers on doing your own alignment at this level: 1) make sure the floor is flat in both directions or compensate when taking the measurements with the bubble gauges, 2) make sure the turn plates are thin (like the Gil Smith type) or if you spring for more commercial type turn plates (available from several sources, do a Google search under "wheel alignment turn plates"), make sure you raise the rear of the truck to compensate for the turn plate height at the front. Even with a 140.5" or longer wheelbase, a sloping or leaning truck will throw off your camber and caster readings with the SPC 91025 bubble gauges...If you want to add a touch of professionalism, purchase a pair of rear slip plates from Gil Smith Racing that will enhance the work and raise the truck's back end to match the front turn plates.
As you mention, always save the toe-in setting for last. Camber and caster angle must be right, with the vehicle setting at static (curb) height on the ground, before setting toe. I use factory toe-in and caster angle settings, and the Dodge Ram handles very well. And, yes, caster is important, this and steering axis inclination (SAI) are what return the front wheels to center after coming out of a corner.
The surest sign of too little caster angle is a vehicle that requires turning the steering wheel back to center after a turn. I'm at 4-degrees positive caster on the Dodge Ram 3500, closer to 7-degees positive on the XJ Cherokee. More can sometimes be better for off-pavement turning radius; however, factory specs are the best for normal tire wear and handling in general.
I mentioned another specification that is of concern during alignment: steering axis inclination (SAI). We can go into this if you want, but the important thing to note for DIY alignment purposes is that strange caster and camber angle readings over the full turning arcs (illustrated in the XJ Cherokee alignment how-to article and shown in the TJ Wrangler HD video coverage) are an indication of a bent steering knuckle on a later beam axle 4x4 or a bent spindle on 2WD and vintage 4WD vehicles.
On alignment equipment that will identify SAI error, if all measurements are correct and SAI is off, we inspect the steering knuckle, spindle or unit bearing hub for damage. Make sure any strange readings are not from bad steering knuckle ball joints or worn wheel/hub bearings! Better yet, inspect for ball joint, wheel bearing and unit hub bearing wear before attempting the alignment. Check steering linkage for loose joints, too.
This is ground school, we can go from here. As a light- and medium-duty truck fleet mechanic in the late 'sixties, I began aligning my own beam axle Jeep CJ3A and vintage '55 Ford F100 at home. On these vehicles, toe-in could be set with nothing more than a tape measure. If you do wheel alignment with turn plates, the steering linkage and suspension will be unloaded, and the measurements will be that much more accurate. Add rear wheel slip plates and Fastrax gauges, and you can emulate a "pro" alignment!
Even on the vintage 2WD and 4WD fleet trucks with beam axles, I did quick, rough-in beam axle wheel alignments with nothing more than a tape measure or a portable, adjustable "toe bar". Floor jacks were placed evenly under the axle at each side. I would lift the axle beam just enough to "unload" the wheels and tires. Before setting toe, I made sure the wheel bearings and kingpin bushings or bearings were in good shape and adjusted properly.
Tape measure alignments on the trail are often necessary when someone bows a tie-rod on a tall rock or snaps a tie-rod in half. A Ready Welder tie-rod repair at Moab's Rose Garden is just one place where your tape measure alignment skills would be popular. This can get a vehicle home from the trail and tracking down the road safely to a wheel alignment shop. When using just a tape measure for toe-set, make sure you follow the tread pattern closely at the front and rear midline of the tires.
When using turn plates to unload and center up the steering linkage and suspension, it helps to bounce the front end. Push down on the front bumper a few times—the bumper is conveniently located at waist height on your Mega Cab!
If necessary, use a pair of floor jacks under the beam front axle to take weight off the wheels and tires, then lightly rock the steering wheel at its center position before setting the front tires and steering wheel to straight ahead. This will unload the steering linkage for more accurate alignment settings.
When using a tape measure only (not the Fastrax 91025's wing arms), always measure matching tread points. Measure as close to the midline (3 and 9 o'clock) of the tires as possible. Avoiding obstacles is sometimes difficult, but midline of the tires is preferred. Always set toe-in, followed by centering up the steering wheel. You center the steering wheel by adjusting the steering linkage sleeves—never by removing the steering wheel and repositioning it!
Caution: The steering wheel spokes are factory set to align with the center or “high” point of the steering gear in the straight ahead steering position. Bring the front wheels into alignment with the centered steering gear and steering wheel—not the other way around! If the steering wheel has been repositioned from factory, find the precise center point of the steering gear. Position the steering wheel there before aligning the front wheels to straight ahead. This also applies when making fine steering wheel position changes after an alignment: Adjust the steering linkage sleeves, do not reposition the steering wheel! Always check toe-in again when you center the steering wheel.
To illustrate how well you can do a 4-wheel alignment with strings, a tape measure, a common spirit level and a protractor, I installed the Full-Traction Ultimate lift kit on the Jeep TJ Wrangler Rubicon in just that way! The job began with the vehicle on my hoist and as level/parallel to the ground as possible.
I placed a pair of adjustable tripod stands beneath each axle and raised the vehicle straight up, just enough to install the lift kit. The axles remained on the stands with cables and other chassis attachments still in place.
After installing the kit, including a bevy of adjustable link arms and a unique rear tri-mount suspension system, I used the string method to square the axles. The rear axle location, fortunately, was fixed by the kit’s design, so this became the reference for making everything square with the frame. The approach was similar to the rear leaf springs and center bolts on our Dodge Ram 3500 trucks. In our case, the rear springs and axle spring perches locate the rear axle squarely at the frame.
I set the caster with a quality bubble level and a 180-degree, indexed protractor. I set toe-in with vehicle weight on the axles and tripod stands, using a tape measure fore and aft (as close to 3 and 9 o'clock as practical) at the front tire midlines, keeping the tape as level and parallel to the floor as possible. In my view, this was all just a preliminary, rough adjustment.
The next stop was a friend's shop with a $40K alignment rack capable of 4-wheel "thrust" alignment. On the alignment rack, to everyone's surprise, the entire suspension system took only one-half turn of one threaded link arm tube to be fully square! Caster was on, camber (non-adjustable on a solid beam axle) was okay, toe-in and centering of the steering wheel were just routine, slight adjustments.
Caster angle was within spec and did, as you describe, provide an acceptable angle for the front/pinion U-joint flange. With a double-Cardan (CV) joint at the transfer case, there is some leeway on this front axle pinion joint angle, and the compromise is between caster angle and U-joint angle. Like you comment, caster usually wins if you want the vehicle to steer correctly!
For modified trucks with suspension lifts and oversized wheels and tires, there are two very important considerations for handling. First, the aftermarket wheels' offset and the tire diameter must provide the right intersect point with the ground. This is the “scrub radius”.
Visualize the front wheels pointed straight ahead. Draw a line through the ball-joint stud centerlines and observe where that line intersects the tire tread at the ground. This point must be similar to the OEM wheel/tire intersection point, or you will swing the tire on an odd arc during turns, resulting in strange handling and premature tire wear. Scrub radius impacts tire wear as well as handling.
Secondly, consider the arc of radius and caster angle changes as the front suspension (link arms in your case) rise and set. Arc of radius is why we do long-arm kits for dramatic lift. When we increase suspension travel, short arms exaggerate the caster angle changes as the suspension extends and compresses.
Long link arms are the solution for increased suspension travel. Longer arms will create less caster angle change over the suspension and axle’s arc of travel—or radius. Simply put, you can set the caster at static/curb weighted chassis height, and the caster angle does not vary excessively as the link arms move up and down with the axle.
When buying an aftermarket suspension lift kit or bigger/wider wheels and tires, consider these issues. In looking at your Mega Cab components, I really like the stamina and quality of the aftermarket joints, link arms and drop brackets! What you want at the end of the day is suspension that behaves as well as or better than OEM engineering—yet with the lift and tires you desire. Going beyond “looks”, the goal is to understand the demands and dynamics of vehicle suspension and handling. Doing your own wheel alignment is a good start.
As for the rear axle, the usual concern is pinion and driveline angles for U-joint survival. Within reason, you can rotate the axle housing for pinion angle change without affecting vehicle handling, as the rear drive axle’s shafts are not sensitive to caster. (If we were talking about a front wheel drive car or an IRS/AWD car, there would likely be provision for adjusting rear wheel caster, camber and even toe-set.) For our trucks, tall lift blocks at the rear leaf springs can create some issues, mainly traction and spring windup related.
So, you might skip the visit to the local 4-wheel alignment shop and the brief Car and Driver read—likely just long enough for the tech to discover that specifications for your lifted and modified '06 Dodge Ram 4x4 Mega Cab are nowhere to be found in the alignment machine's software program. As an option, consider the SPC Off-Road 91025 alignment equipment...Two kits work even better than one!
Used properly, this accurate, portable SPC setup can help you dial your front end alignment for both safety and good tire life. Bubble caster and camber gauges were an automotive industry standard for at least sixty years prior to light beam, infrared, RF and laser alignment equipment.
I entered the service and repair industry when we were still called "mechanics", and breaker point ignitions were the norm. Smaller shops used floating caster/camber bubble gauges that fit magnetically to the end of front wheel hubs! Professionally, I've spun wrenches all the way into the contemporary electronic fuel-and-spark management "technician" era. Electronic, beam four-wheel alignment equipment has been in vogue for more than three decades now...I find it advantageous to have walked in both worlds.
Beyond alignment, make sure that the wheel offset and tire diameter add up to a safe and tolerable "scrub radius”. As an alternative to Car and Driver, sift through this Wiki info about scrub radius and SAI. When you widen the wheel rims, you can only go inward so far. (Rotors, calipers and hubs limit the inward wheel position.) For that reason, wide rims almost always offset to the "negative" direction or outward. If there are wheel backspacing choices, match up the wheel width, backspacing and tire diameter wisely! The concern here is the scrub radius.
We lift our vehicles and mount oversize wheels and tires for a variety of reasons. In the end, we get to make the handling and safety corrections that these modifications require. Routine tire rotation is always essential, even more so when scrub radius and arc of radius get compromised. Once you dial the front end alignment to the best point possible, watch for ball-joint wear, wheel bearing or hub bearing wear and any tire issues. This can sometimes be the price for a lift and oversized tires. We can, however, reduce, minimize or even eliminate that risk and expense!
Posted by Moses Ludel on 26 July 2013 - 03:23 PM
Papa, I have lived and breathed Jeep 4WD vehicles for fifty years now and have authored three bestselling Jeep books (Bentley Publishers) that each earned a Mopar official part number. I still discover new Jeep information and facts!
I, too, taught, serving as an adult education level automotive/diesel and welding instructor at the Rite of Passage program before advancing to Director of Vocational Training and Site Supervisor of Education...My work with tough young men (often gang affiliated when they entered the program), many eager to learn and dedicate themselves to a productive life through technical training, proved challenging, humbling and, ultimately, highly rewarding. These students raised the bar for my effectiveness and sense of purpose, and I credit them with making me a better teacher...
Thanks very much for your comments, I value your feedback and am very pleased that the information serves well! Looking forward to your thoughtful topic posts.
Posted by Moses Ludel on 23 July 2013 - 12:10 PM
Hi, Papaobewon, thanks for posting your first topic! You have given us all an excellent opportunity to discuss the concerns around buying a used Jeep TJ Wrangler and aftermarket equipment.
There are many vehicles out there, as the TJ was extremely popular in its 1997-2006 production period. I'll describe some things to look at and question regarding this particular Jeep for sale. My intention is not to berate the vehicle or the individual offering this 1998 TJ Wrangler 2.5L Jeep for sale...
Here are two distinctly different Jeep TJ Wrangler profiles. At left, a hardcore trail runner does what you would expect—drives the hard trails and works the suspension thoroughly! At right, a very clean Jeep TJ Wrangler with hardtop boasts factory and mild aftermarket upgrades—for a very long life expectancy.
First, let me distinguish that a 2.5L YJ or TJ Wrangler has a different frame than the 4.0L six-cylinder frame. This is important if you decide that four-cylinder power is "not enough" for the weight or usage you have planned. With all of the accessories and add-ons that this Jeep features, the 4-cylinder engine is toting quite a package, so fuel efficiency will be only marginally better than a 4.0L six-cylinder model.
The 2.5L pushrod OHV engine is a great design, AMC's contribution that Chrysler carried forward until the introduction of the 2.4L high-tech engine. It does a good job when not taxed too much, and the axle gearing is 4.10/4.11:1 on these models with the larger case Dana 35 differential.
The transmission is an AX5, the lighter version of the AX designs yet with the right gearing for a four-cylinder engine. Six-cylinder models use the AX15, which does offer a higher torque rating. To use the AX5 with a six-cylinder engine, you would need an adapter. If you wanted to make that swap, the YJ or TJ Wrangler changeover involves relocating and building motor mounts because of the frame differences. (Click on the link to see my MIG welding project.) This includes differences in the location of the rear transmission mount as well, a lesser fix that involves the skid-plate/crossmember. For these reasons, it's very important to decide whether you want a four-cylinder versus a six-cylinder model at the onset.
In making that choice, there are a variety of motives. Some purposely buy a four-cylinder if they plan a V-8 and alternative transmission swap into the Jeep. Others believe the four-cylinder will get the job done and deliver better fuel efficiency, which it does to a degree—until the weight of the modified vehicle taxes the engine to the point of offsetting the fuel efficiency.
I'd like to draw attention to the performance curves of the 2.5L inline four versus the 4.0L inline six: The four develops its peak torque at a higher rpm, horsepower peaks at 5,400 rpm, a virtually unattainable speed under most driving conditions and surely not fuel efficient at that speed.
Compare the two engines and transmissions at: http://www.allpar.com/model/cj/specs.html. This is a 1997 Jeep TJ Wrangler spec readout, the same as the 1998 you're considering. Also noted is that some base models did not have power steering, I'm presuming this Jeep does? You need it.
As a footnote, even the 4.0L inline six has a stodgy torque rise in my view, peaking at 2,800 rpm. By contrast, the legendary 4.2L inline six that contributes its crankshaft to the 4.6L stroker motor build-ups reaches peak torque between 1,600 and 2,000 rpm, depending upon the year model. That's diesel-type torque and why the 4.6L stroker motor is so popular!
As for the off-road performance of the four-cylinder models, they do quite well. Gearing in low range makes the engine sufficient for the job, and the MPI (1991-up) version of the 2.5L fuel injection is quite stable in slow crawling.
I'll address each feature in the order you listed them in your post:
1) A rebuilt or remanufactured engine should have receipts. A remanufactured engine is sold as a long block or short block (without rebuilt cylinder head); the complete long block includes the cylinder head and is desired here. A rebuilt engine should have receipts for machine work as well as parts. We can discuss the details if receipts are available.
2) Since this is a four-cylinder model, it has the AX5 transmission as I described.
3) The description sounds good: a fresh engine, 138,000 miles, only 3,000 on the new engine. Black is an awkward color, draws heat and tends to oxidize faster. The peeling or "crazing" is not uncommon for a black vehicle exposed to a lot of sun or parked outside.
4) A 4-inch lift is common, the body lift is mild as is the motor lift; if done right, this is an asset for off-road use.
5) Swing-out tire carrier is a plus.
6) Aftermarket sound is nice if a quality system and installed properly; always concern about wiring during the installation, must be done right.
7) Tires and spare sound good, 31" is not radical, and the OEM 4.10/4.11 gears can tolerate this diameter tire well. Speedometer may have slight error if not corrected for the 31" tires, this can be remedied with a speedometer drive gear/tooth count change.
Note: It surprises me that there is this much suspension lift plus a body lift for only 31" diameter tires. A four-inch suspension lift will accommodate 33" tires, which would require a ring-and-pinion gear change to 4.56:1 or even 4.88:1 for restoring performance. Maybe this vehicle did have 33" tires at one point; otherwise, the combination chassis and body lift is actually excessive for 31" tires. (A two-inch suspension lift would be sufficient for 31" tires on a TJ Wrangler.) The 31x10.5 tires are likely on 8" rims, and that's really not much track width increase for the amount of lift. For this amount of lift, I would do a 10" rim with 33" tires to widen the track width and help restore the vehicle's center-of-gravity.
8) Adjustable track bar is desirable with a link-and-coil suspension lift. This allows precise alignment to eliminate axle offset or dog tracking. Suspension parts and axles need to match up and align when there is an aftermarket lift on link and coil suspension.
9) New shocks and stabilizer are a plus if "new" means quality replacement parts. Gas-charged shocks are preferred here, Bilstein or equivalent.
10) Long sway bar links needed to compensate for the 4-inch suspension lift.
11) Stronger control arms, if quality made, are a major improvement over the stamped steel OEM arms.
12) Cold air intake can improve performance. System should not permit exposure to water, however. Any open faced air filter should be kept away from the spray or slosh of water during stream crossings! Sucking water can cause engine hydro-locking and severe internal engine parts damage.
13) Quality fog lights can be useful for the trail; make sure they're quality with safe, proper wiring.
14) Same as windshield lights; great if done properly.
15) Diff guards are a real plus for off-roading in rocky terrain.
16) Full skid plates are a plus, too! This adds weight, though, and we're talking four-cylinder power in this case.
17) The security console is a real plus, especially when parking the vehicle with the top removed.
18) Okay on the tint if legal and visible. Not sure of the motive.
19) Receipts useful here. Quality parts should be verified. Is the clutch new, too? Flywheel new or re-surfaced? Should be included with an engine replacement or rebuild.
20) Hardtop, especially factory type, is a valuable accessory! These tops are expensive to purchase later, a hardtop has many advantages: weather protection, security, added value. Downside is weight, another tax on that 120 horsepower engine.
21) Undercoated frame can be okay. Is the vehicle at a climate without salted roads? If salted, inspect the chassis and body end to end for rust and any signs of body or frame rust exfoliation. Undercoating is great if applied for the right reasons—not to cover rust, though!
22) Clean title is a must...
23) Chipping paint is back to the black. If the price is right and you want to restore this vehicle cosmetically, you can do so.
Regarding your last questions, a MOAB sticker can be good or bad. I've been to Moab since the mid-'nineties and witnessed vehicles used moderately by responsible folks, and I have also seen vehicles pounded mercilessly and abused, even wrecked—often due to driver inexperience. That said, Moab does mean something—what it means depends upon the driving skill of the owner and which trails the Jeep took at Moab. The same applies to the Rubicon Trail, Fordyce, Sierra Trek and so forth.
Get underneath and inspect the Jeep end-to-end. The most critical and expensive areas are the frame and axles. Look for signs of collision repairs and trail damage, abuse and so forth. Aftermarket products like lift kits have "perishable" components such as urethane bushings, Heim joints and other pivot points. Drivelines are a source of trouble, and this Jeep TJ Wrangler should have a slip yoke eliminator (SYE) kit at the transfer case outlet to the rear driveline plus a CV-type rear driveshaft. If not, the rear driveshaft is at risk; U-joint life will be short, driveline vibration likely.
Look for signs of rock-sliding along the control arms and other symptoms of hard use. Look for scarred diff skid plates. See if the steering gear is loose by manually moving the pitman arm back and forth with the vehicle parked, its front wheels pointed straight ahead; drive the Jeep and feel for steering wander and suspension looseness. Signs of trail use are not, in themselves, a reason to pass up the vehicle; however, scarring and looseness do suggest the kind of use the vehicle has seen.
In addition to writing for the 4WD magazines, I wrote for Popular Hot Rodding and several other muscle car and high performance magazines in the 'eighties and 'nineties. My tech Q&A columns would often receive questions about purchasing a used muscle car or Corvette with "low mileage". If a muscle car had "only" 50,000 original miles, I would reply that this could potentially be 200 trips down a quarter-mile drag strip! For a 4WD trail vehicle, 138K miles could be many thousands of trail miles. Metaphor: The notorious Rubicon Trail is only 12 miles long. We can "do the math".
Although none of these comments are meant to discourage your purchase, a used trail vehicle is all about its history. Modified vehicles are typically intended for hard trail use, so you do need to adjust your purchase price to allow for any parts damage from trail pounding. I would test drive the vehicle with an ear toward axle/differential noises, transmission synchronizer noise and feel (including "jumping out of gear"), clutch and driveline response, plus the drivetrain play and sounds in 4WD low range.
Look closely at the front axle shaft joints in the steering knuckles. Steering knuckle ball-joints and steering linkage joints can be worn out by this mileage from a lot of trail crawling or oversized tires. Inspect the front brake calipers and rotors, they're visible. Look at the drivelines and check for worn U-joints, grease seepage and a torn boot. A major oil leak at the rear main seal can be a nuisance and ruin a clutch disk. Axle pinion shaft seals and the transfer case output seals are other areas to check.
Anticipate what you want to do with the Jeep and how the modifications impact your use—or dovetail with it. Also weigh the cost of outfitting a stone stock 1998 TJ Wrangler with these upgrades. Consider a stock vehicle with an extraordinary history, something like "driven on icy highways but never off-road," "driven only on graded gravel—occasionally," "used to get back and forth to work in the winter," "used to access a ski resort in the winter," "not sure what this lever position [4WD/low range] does, I've never used it" —fill in the blanks.
My brother-in-law found a 1999 Jeep TJ Wrangler, stone stock with 70K original miles, the auxiliary cloth top never installed, the hardtop never removed, the wheels and tires stock with one OEM tire replacement; the engine is a 4.0L with 3-speed 32RH automatic transmission—owned by a mature couple, they never went beyond a graded gravel road with the Jeep and used it primarily for basic highway transportation and winter driving. He paid $6500 for the Jeep. It is prime for any kind of personalization and modifications, virtually a "new" Jeep TJ Wrangler.
While this sounds extraordinary, it's not a Rubicon model. For "hardcore" wheeling, the Sport model could use a rear locker. (Note: Some non-Rubicon TJs actually have the Dana 44 rear axle with limited slip option.) There would be a need for a lift kit, 4" for 33" diameter tires. Then all of the other driveline, SYE and other modifications...The cost of parts—and labor if you sublet all of this work—must be considered.
It's not easy making these choices. The best way to approach this is as an "informed" buyer. I trust that these comments, the magazine and the forums help. I and many others can contribute additional comments and ideas, so please ask. It's for the benefit of everyone!
Posted by Moses Ludel on 19 July 2013 - 03:31 PM
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...
Posted by Moses Ludel on 16 July 2013 - 03:12 PM
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!
Posted by Moses Ludel on 16 July 2013 - 01:27 PM
I must still like writing...Spent time doing a fresh reply at your new questions—guess they're well covered now!
Posted by Moses Ludel on 16 July 2013 - 01:21 PM
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?"
Posted by Moses Ludel on 01 July 2013 - 11:34 PM
You described your take-off shudder well. For openers, this is not likely converter related, as the converter clutch is not active at this speed. If it is the converter, this means the converter clutch is dragging, in which case the symptoms would get steadily worse and cook the converter. If you do suspect the converter, I can share how to test it in the truck.
Some would jump to transmission issues like band adjustment or worn clutch packs, motor mount issues, with the Cummins especially, and surely this could contribute. Likely you have done the band adjustment during service work, though. There would also be a benefit to upgrading to the aluminum accumulator piston that I describe and install in my Sonnax survival upgrades. See that article at: http://www.4wdmechan...nsmissions.html. You'll see the accumulator piston change there, too.
I like your gut comparison to the Ford Powerstroke that lost its clutch and flywheel harmonic dampening with the solid flywheel and clutch install. You may have a similar harmonic or actual binding issue with the shudder you describe. This may come as a surprise, but I would look elsewhere for that load shudder when you get the truck moving: check the rear driveline/U-joint angles. You have a 6-inch lift on the truck, and I'll share some pointers here.
Your Mega Cab wheelbase likely uses the two-piece driveshaft. If so, the shaft from the transfer case to mid-shaft bearing is probably stock still. Maybe you've dropped the mid-shaft bearing to reduce driveline angle at the rear piece. In any case, the U-joint angles must "cancel each other", meaning that an angle at the transfer case should have the same cancellation angle at the other end.
A common issue with taller lifts is to not have the joint angles cancel properly. For example, there may be a straight shaft out of the transfer case and through the mid-shaft bearing. If so, the angle of the second/rear driveline should have U-joint angles that cancel each other (complementary angles) on the second or rear shaft.
Many think it's great to angle or rotate the rear axle pinion upward to reduce pinion joint angle. That only works if the angle either 1) matches the angle complement at the other end of the shaft (which is impossible) or 2) the front end of the shaft uses a double-Cardan or CV type joint as seen in the photo below. Also see this Jeep XJ Cherokee article at the magazine for a single piece driveline and 6-inch long arm lift: http://www.4wdmechan...nsion-Lift.html.
A CV/double-Cardan conversion joint at the front of a one-piece Jeep driveline. (This is a slip yoke eliminator kit or SYE approach.) Click on photo to enlarge. (If you cannot see the photo, join the forums, for free, and get full member access.)
Visualize a one-piece driveline. If the rear/pinion U-joint has little angle, the only way a lifted truck driveline will work is with a CV joint at the front of that shaft. The CV joint in this case has "self-cancelling angles". I will make the pinion joint angle 1.5-2 degrees. This slight tilt enables the rear U-joint bearings to rotate in their bearing caps. If you make the pinion and U-joint angle "zero", the U-joint will fail from lack of lubrication: The cross-shaft never rotates the needle bearings in their caps, and the joint quickly wears out.
So, beginning with your front shaft, the angle from the transfer case to mid-shaft bearing should be minor, just enough to rotate U-joint bearings. The rear driveline section U-joint angles must cancel each other (measure the same) if you have single-Cardan cross joints at each end. If a double-Cardan CV at one end and a single cross joint at the rear or pinion, put 1.5-2.0 degrees of angle on the rear U-joint.
Check your driveline angles and also the phase or alignment of the joints. If you have a single piece driveline with single Cardan U-joints, follow my guidelines for the cancellation of joint angles. A one-piece shaft with a CV/double Cardan at the front (SYE style) and rotated pinion at the rear should follow my guidelines for this type of shaft and joints.
U-joint crosses should line up with each other from the transfer case to the rear axle. If they do not, the driveline is "out of phase" and will vibrate, shudder or bind.
When you make these checks, the truck should either be on level ground or with the axles weighted on four stands (two at the front beam axle, two at the rear axle). U-joint angles are always with the truck "normally" weighted and spring heights at on-the-ground compression. You can check angles with an Angle Master gauge, I've even done it with an accurate protractor, plumb bob and level.
As a final note, you have shared that you're still running 3.73 axle gearing with the 37" oversized tires. This is enough to cause extreme take-off loads and maybe even the shudder you describe. The 3.73:1 gearing is marginal even with the factory tire diameters of less than 32". At your current ratios, the gearing is way out of balance.
Posted by Moses Ludel on 01 July 2013 - 10:11 PM
Thanks for the compliment, Megatron...I get academic and like to research procedures and options before tackling a project. This habit was firmly in place long before I became an automotive and truck journalist—or wrote seven Bentley Publishers automotive and motorcycle books...I believe it's important to diagnose and pinpoint an issue before replacing parts.
As we address the 48RE, let's share and compare findings. At this stage, a full rebuild seems many miles away on our unit. If and when I do go deeply into our transmission, it will likely be a "how-to" in either article or video format for the magazine, something like what I did with the AAM 11.5" and 9.25" axle builds.
If you dive into your transmission earlier than that, I'm here to answer questions.
Posted by Moses Ludel on 28 June 2013 - 05:26 PM
Thanks for catching this post...It's among my favorite subjects, as you might have guessed...
Once the axle gearing is correct, the other factors that drop fuel mileage on your '06 Ram 3500 Cummins would be 1) the increased vehicle height (kiss off aerodynamics of any kind!) and 2) the vehicle's weight over stock. I wound up in a similar situation with a 4" lift, 35" tires and a carload of "cool" accessories! Not sure of your accessories, I added approximately 1,350 pounds to my over-the-road, "unloaded" weight...kind of like perpetually pulling a well equipped tent trailer!
Hey, we all like the "look" and utility of a lifted and accessorized Ram 3500 4x4! Here, the truck we purchased new in October 2004 is undergoing a metamorphosis in 2011, getting ready for show time at the BFGoodrich Tires booth, Off-Road Expo at Pomona, CA! Let's see now, the lift, wheels and 35" tires, we'll add a utility fuel tank that takes us to Moab, Utah and back from the Reno, Nevada area...and that M12000 Warn winch will be a dandy when needed! Oops, there went the 25 mpg. Time for a 4.56:1 axle gear change out!
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Most have no idea how quickly the upgrades and accessory weight add up: Try oversized American Eagle wheels and BFG tires for at least 150# over stock including the spare; a Mopar lift kit after swapping out OEM parts for an added 50 pounds; a Warn M12000 winch for 140# (bare winch wound with wire rope); front and rear HD bumpers for an extra 300#; a Transfer Flow cross bed fuel tank with additional fuel on board: 75 gallons @ 7.1 lb/gallon for Low Sulphur diesel = 532.5 pounds when full plus the aluminized steel tank's weight! Oh, and I do like the three Bestop Treksteps for 60 pounds plus.
I'll comment on your gearing projections, just did the math...If your tire's revolutions per mile are around 560 (Toyo rating for several popular 37" diameter tires, confirm your exact revs per mile), then here are your engine speeds at practical road speeds in overdrive (0.69:1):
4.88 gears @ 70 mph = 2200 engine rpm
4.88 gears @ 65 mph = 2043 engine rpm
4.88 gears @ 55 mph = 1728 engine rpm
4.56 gears @ 70 mph = 2056 engine rpm
4.56 gears @ 65 mph = 1909 engine rpm
4.56 gears @ 55 mph = 1615 engine rpm
According to Cummins, you should use the 4.88:1 gears for a truck under 10000# GVWR and intended for 70 mph cruise. In my experience, though, if fuel mileage were your sole aim without carrying cargo or trailer pulling, I would suggest the 4.56 gearing. This would keep you "in the window" for maximum fuel economy. However, even a light travel trailer would immediately tip the scale toward taxing the engine, which could impact both fuel efficiency and engine life—plus overload the transmission (clutch if manual) and driveline.
Actually, with your 37" tires, the 4.56:1 ratio would be much like your 3.73:1 gears with the Ram 3500's stock tire size. (That was also before accessory add-ons and the lift, too!) In overdrive, that off-the-showroom floor truck fell well below Cummins' recommended 2,150 rpm at 65 mph baseline for fuel efficiency and commercial hauling. I'd again emphasize that 23-25 mpg highway was readily achievable with the stock tires, 3.73 gearing and no load at 65-69 mph (approximately 1800-1950 rpm).
If you pull a trailer very seldom and your add-on accessories weight is modest, fuel efficiency would be good between 55 and 70 mph with 4.56:1 gearing and 37" tires. If the add-ons are like mine, however, your truck has a load before you stack on cargo! The 4.56:1 gearing would not be low enough, you'd be better off with the 4.88:1 gears.
Note: This is why I opted for 4.56:1 with the 35" tires, rather than fiddle with 4.10:1, which would have been the direct correction for the bigger tires. We plan to pull a trailer on occasion—without destroying the powertrain. Also, as I've shared, between the lift height and added accessories weight, this is not the stock truck any more.
Your decision comes down to load and intended cruising speed. Considering the height and weight of your Ram 3500 Mega Cab, you'd likely be "happier", performance wise, with 4.88 gears. When you want fuel efficiency, hold the speed to 65 mph. If that's too slow and you want to "cruise" at 70-plus mph yet get the best fuel efficiency for that rate of speed, consider 4.56:1 axle gearing. You can see by the calculations that the engine would be in Cummins' recommended zone of 2100-2400 rpm when cruising at 72 mph (2114 engine rpm) with 4.56:1 gears in overdrive. With 4.88:1 gears at 72 mph in overdrive, the engine would spin 2263 rpm and eat up fuel.
Cruise speeds above 65 mph will eat fuel, regardless...Moving as much mass as our trucks at speeds above 65 mph requires increasingly more fuel. Base your choice on what cruise speed you find acceptable on the highway—the faster you go, the more fuel the engine will use...guaranteed!
The acceleration might be marginally better with 4.88:1 gears. In terms of gear stamina with a given ring gear size (11.5" and 9.25" in our case), the 4.56 gears are actually stronger due to the larger pinion gear head size. (This is slightly offset by the 4.88:1 additional gear reduction, which helps reduce load a bit.) Given our Ram 3500 ring gear sizes, the stamina distinction is not as severe—nothing like sticking 4.88:1 gears in a Dana 35 Jeep rear axle with a 7.625" diameter ring gear!
We can kick this around more, Megatron. Cummins recommends spinning the engine for "efficiency" and, at least commercially, does not want to "lug" the engine below 1900 rpm at highway cruising speeds. Note that a truck under 10000# GVWR with an H.O. 5.9L Cummins ISB engine is less susceptible to lugging than a Cummins ISB engine in a medium-duty truck.
If you're running an aftermarket performance module or "chip", or have done any other tuning or engine modifications, we need to discuss those variables, too...That could change the rpm scale for maximum performance and fuel efficiency, in turn shifting the rpm band for the gearing.