Moses Ludel

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Well, if it simplifies the install and hose matching, there's likely no harm in doing a 3/8" fitting on the pick up side. If you run 3/8", I do want your feedback on this, including pump heat in service. One way to take the "mystery" and second guessing out of this issue is to measure amperage draw at the pump while it's operating—using 5/16" versus 3/8" pick up hoses. This is a more scientific approach and would indicate the load on the pump. If there's a "restriction", as you suggest, with the use of a 5/16" hose and fitting, that will show up in higher amperage draw. The measuring device needs to read 1/10ths of an amp or smaller. To be clear, the rating on the pump should be with the furnished or intended fittings installed. Unless vendors are substituting smaller (5/16" versus 3/8" hose size) fittings—with the pump's flow rating based on the bigger fitting—there's little risk of "starving" the engine for fuel. If you have suspicions about the pump's intended input/output fuel fitting sizes, research the manufacturer's ratings and the fitting sizes recommended. Volume is an even smaller concern. We know the pump pressure and GPH flow rate. Based on that, if the rating is with the 5/16" fitting, it would be a moot point which fuel hose size you use. The 4.6L inline six cannot burn more fuel than what we understand to be the flow ratings for your pumps. As for 3/8" versus 5/16" hose flow rate, most concerns are on the pressure side, not the pick up side. Here's a link that has considerable research information on pressure drop and its relationship to distance: http://www.dultmeier.com/literature/fluid-flow.asp. You might want to wade through this material, it does address hose sizing, too. Note: Do take distance into account when sizing hose. If you plan to run hose for a long distance on the pressure side, consider the larger size hose. Also consider hose length when sizing the pick up side. From a strictly practical standpoint, the use of 3/8" hose was popular on multiple carbureted engines in the muscle car era. I've seen little use of that size hose for fuel supply on other production engine applications. For peace of mind, take a moment to measure the OEM steel fuel pipes furnished with your Mopar EFI kit, the supply and return pipes that connect at the rail end. Another consideration that you did not detail is the inside diameter of the furnished fuel pump fittings. If these fittings are barbed or step nipples, I would be concerned about the I.D. of the fitting. If the fittings are standard fuel type (clamp style) for 5/16" or 3/8" hose, then you should not have a restriction. Hose size and flow volume take fittings into account: You can't have a hose installation without a fitting! If the fitting I.D. is small, like a barbed fitting, I would step up the hose size to 3/8" and use the correct fitting for that size hose. Better yet, you have fuel flow under scrutiny by continually monitoring the fuel pressure at the EFI fuel rail. If you see fluctuations in the pressure, especially with a new regulator, you can suspect the fuel flow volume to the rail. Volume reflects pressure and flow rate, so each will be apparent in the pressure reading at your shiny new fuel pressure gauge on the dash! Can't wait to see that fuel pressure gauge in service...What an onboard diagnostic tool! Moses

Well, I'm not sure what your original motive was for the disc rear brake conversion, but the findings are not that surprising. Brake bias is to the front, and your Jeep CJ-7 has adequate factory disc brakes there. The drum rear brakes on a later CJ-7 were also sufficient for most uses. Are you satisfied that the brake apply pressure is sufficient at the rear brakes? Let's put some rays of sunshine into your effort around this 8.8" rear disc brake conversion. Since you went ahead and did it, the positive gains should be considered. For openers, disc brakes have several trail use advantages over drum brakes: 1) Resistance to fade in hard rock crawling and continual application of the brakes; this also applies to trailering. 2) Ability to immediately work well after crossing a stream, with less risk of damaged parts from water crossings. 3) Winter benefits over drum brakes (RareCJ8 laments his drum rear brakes); less risk of frozen parts or ice lock-up when parked. 4) Ease of service around pad changes; calipers are accessible. 5) Easier visual inspection for wear or defects; troubleshooting is quick and simple. 6) You have a contemporary brake system (8.8" Ford) with easy parts availability on a weekend—or in the middle of Podunk. What was the source/application for these rear disc brakes? I'd like to compare the OEM bore diameters between your CJ-7 master cylinder and the Ford application's master cylinder. To be completely fair about the effectiveness of the "new" disc rear brakes, let's determine whether the CJ-7 master cylinder is applying the same pressure to these rear calipers as the Ford OEM master cylinder. Again, your findings are not unusual. Rear braking on a late CJ-7 can be readily met with OEM drum brakes. Now, if you had the '55 Jeep CJ-5 featured in my Jeep CJ Rebuilder's Manual 1946-71 Edition, that would be another story. 9" x 1-3/4" brakes are inadequate, front or rear, by any standard! I've often noted, however, that 11" x 2" drum brake conversions work very well on the early Jeep CJ and military models. While disc brakes have many advantages, effective rear braking can be met, most of the time, with sufficiently sized drums and brake shoes. Moses

Thanks, I thought this info might be useful, folks often mix up parts in an effort to save cost and avoid expensive disc brake conversion "kit" approaches... I got the visual on "cement" mud around the huge brake drums or slushy freeze-ups in the winter! Those massive rear drum brakes on a CJ-8 Jeep Scrambler should be overkill, for sure. If you're using the stock master cylinder, there is likely less rear brake apply pressure than with a Ford E-van master cylinder. You can compare master cylinder bore diameters to get a better sense for this. There's also the concern around too much braking capacity at the rear. Your 10.25" Sterling axle is designed for a high gross weight application (E-van), and you might find that OEM discs for that kind of rear axle would provide too much braking force. The front axle and disc brakes are 3/4-ton capacity truck, right? When the time comes, we can kick around details on braking capacities for available front and rear brakes. What you want to avoid is "over-braking" at the rear, as rear lockup or bias can cause a vehicle to spin out, especially on loose or slick surfaces at speed. A classic stunt driving trick is to apply the rear parking/emergency brake on a very slick surface, without touching the brake pedal. The effect is dramatic: The vehicle immediately spins around. (Caution: Do not attempt this trick unless you're on a professional, slick skid pad. Uncontrolled, it can be very dangerous and even cause a vehicle rollover.) Spinout can occur with an over-braking bias toward the rear of the vehicle. Driving on an icy highway or slick trail, especially a downgrade, could be a recipe for disaster if you need to stop quickly. One way to offset this bias is use of a manual brake proportioning or metering valve, adjusted to reduce brake apply pressure at the rear. Some trucks even incorporate an OEM manual brake proportioning valve at the rear axle. Activated by a mechanical lever arm, the valve reduces brake apply pressure when the vehicle's rear end gets light (springs extend) during hard braking with front end dive. We had K2500 GMC Suburban 4x4s from the mid- to late-'80s that had this feature... We can discuss all of this further...Have a safe, fun 4th of July RareCJ8! Moses

Umm...On the suction side, a larger orifice would lift more fuel, and that could be a liability. Fuel is mass and volume, and the pump motor would work harder moving the higher volume of fuel, especially as the pump first starts its cycle. On the push side of the pump, they want the larger hose to prevent any restriction. Volume gets controlled by the pressure regulator at the EFI rail. In your two-rail system, the excess goes back to the tank. If you use a larger pickup hose, there could be more volume going back to the tank. There may be a sound engineering reason for that 5/16" inlet. Is it impractical or difficult to use a 5/16" pickup hose to the pump and 3/8" to the rail? Moses

There are many times when a pinpoint reading of brake hydraulic pressure is useful. Brake safety and vehicle handling require the right hydraulic force at each wheel of the vehicle—at the right time! Knowing precisely how much apply pressure is available at the master cylinder, combination valve, ABS system, wheel cylinders or disc brake calipers can help troubleshoot weak brakes, grabby brakes, brake pull, erratic handling under hard braking, hazardous wheel lock-up and more. Whether you tackle your own vehicle service or operate a 4x4, OHV or motorcycle shop that depends on customer satisfaction, one valuable tool for brake system diagnostics is a hydraulic pressure tester. Maybe you're installing a retrofit rear disc brake upgrade like some of our forum members. Or you put oversized tires on your 4x4 and now a major braking issue has developed...If you take brake work seriously or find yourself in need of pinpoint information on a brake system's performance, consider a hydraulic brake and ABS diagnostic tool kit like this: This tool kit can pay for itself quickly in pinpoint hydraulic brake system diagnosis. Click on images to enlarge. (If you cannot see the pictures, join the forums for free, and get full member access!) I find this tool valuable. You can separate hydraulic problems from mechanical issues, or ABS issues from defects in rotors, brake drums and friction materials. With the assortment of fittings, the kit can work on most domestic and import vehicles. If you're having trouble separating brake performance issues, don't waste time and money on parts replacing that fails to solve problems...Take the guesswork out of brake work. Know how the hydraulic system performs before you leave the shop or driveway—not by trial and error. Invest in the right diagnostic tools! Moses

Disc brake conversions are popular, and I cover that topic in my Jeep CJ Rebuilder's Manuals (1946-71 and 1972-86 Editions, Bentley Publishers). Whether the CJ has a four-drum system or a disc front/drum rear system, the master cylinder must be considered during a disc brake conversion. There are two master cylinder concerns when converting to disc brakes: 1) the piston bore size and fluid volume per stroke of the pedal and 2) any "residual valves" that might have been used for the drum brakes. For disc brakes to work, the master cylinder must have enough fluid displacement to apply the calipers and pads. Disc calipers use more brake fluid per pedal stroke than properly adjusted drum brakes. If the Jeep is a vintage CJ 4x4 with a single master cylinder and drum brakes, especially the 9-inch diameter drum system, the stock master cylinder will be inadequate for modern disc brake calipers. Drum or disc brakes, I'd want to get rid of the single master cylinder for safety sake, regardless! In converting to disc brakes, the best choice here should be a modern four-wheel disc brake type dual master cylinder retrofit. A retrofit can even be done using the original, through-the-floor brake pedal, as I illustrate in the 1946-71 Jeep CJ Rebuilder's Manual (Bentley Publishers). I fabricated a safe, sturdy mount for a later dual master cylinder—mounted beneath the floorboard like the stock master cylinder and actuated by the stock brake pedal. Sometimes, a disc/drum master cylinder will have adequate fluid displacement on the rear drum circuit to operate retrofit disc rear brakes. Again, this depends on the master cylinder's bore size and stroke per pedal application. The rear fluid reservoir is often smaller, so keep fluid at the recommended full level. On 1972-up Jeep CJs with four-wheel drum or disc front/drum rear brakes, you may be able to use the stock master cylinder with a disc brake conversion. Be aware, though, that some master cylinders will require removal of the residual valve(s) from the master cylinder ports. The "residual valve" is important on many drum brake systems. To keep the wheel cylinder cup lips expanded, which prevents fluid seepage from the wheel cylinder with the brakes released, a valve is built into the hydraulic system to hold "residual pressure" in the wheel cylinders when the brakes are released. Early single master cylinders and many four-wheel drum or disc/drum dual master cylinders have built-in "check" or "residual" valves. This residual pressure is below the tension of the brake shoe return springs. Residual pressure is simply to keep the wheel cylinders from drawing air or leaking fluid when the brakes are released. This pressure is typically around 12 PSI, well below brake shoe return spring tension. By design, disc brake calipers do not require residual pressure. The pads release pressure with the pedal release. There is adequate fluid available in the circuit to apply the brakes without lag or hesitation. Some disc brake hydraulic systems, do have very slight residual pressure to keep the pads close to the rotors at all times and improve brake response time during pedal application. This pressure would be around 2 PSI and not enough to cause premature pad wear, fade or overheated rotors. Note: If you're using a four-wheel drum or disc/drum CJ master cylinder, check the fluid line ports for a residual valve. Typically, this valve is simply a rubber plunger and balance spring at the back side of the tubing flare nut seat. With the brake lines removed from the master cylinder, you can see the rubber plunger through the passageway at the center of the tubing flare nut seat. This seat is removable for service and seat replacement. If you are curious how to safely remove the seat, I'd be happy to detail—ask here at the forum! Caution: When retrofitting from drum to disc brakes, you need to remove the drum brake residual valve(s). Earlier Jeep dual master cylinders for four-wheel drum brakes have residual valves at both the front and rear fluid line ports. OEM disc/drum brake systems can have a residual valve on the rear brake circuit. If the residual valve for drum brakes is left in place, the disc brake pads will drag on the rotors with the brake pedal released. This can cause excessive pad wear, brake fade and even wheel lockup. One disc brake conversion example is our fellow forum member "LastCJ7". He has a 1986 CJ-7 Jeep (disc front/drum rear factory brakes) and is converting to rear disc brakes. He's trying the CJ-7 dual master cylinder before considering a late Jeep TJ Wrangler Rubicon (four-wheel disc from the factory) master cylinder...LastCJ7 needs to make sure there is no residual valve holding pressure in the rear brake system with the brake pedal released. On later disc/drum master cylinders, there may not be a residual valve in the rear brake circuit. Many manufacturers have changed over to stiffer wheel cylinder cup expander springs with sturdier cup expanders. This measure keeps the rubber cups expanded with the brakes released and serves the same purpose as older residual valve systems. When converting to disc brakes, explore whether your original dual master cylinder uses a residual valve or valves. Vintage, single master cylinders have a check valve within the master cylinder to hold residual pressure in the system—one more reason why a single master cylinder is not a candidate for a disc brake conversion! Make sure the master cylinder's fluid displacement (per pedal stroke) will meet disc brake caliper requirements. If in doubt, retrofit a combination valve and master cylinder from a similar chassis—like retrofitting a Jeep TJ Wrangler Rubicon master cylinder and combination valve to a CJ-7 chassis. Summing up, make sure the brake hydraulic system is compatible with the disc brake calipers and rotors. Both the CJ-7 and TJ Rubicon are on a 94" wheelbase, each has beam axles and an inline six-cylinder engine, their curb weight is a close match, so they should have similar braking needs and characteristics...Jeep TJ Wrangler Rubicon brake components would be a good template for the CJ-7 wheelbase and four-wheel disc brakes. Moses

Curious to see how this works out with the full brake bleed. Comes down to whether you'll get enough stroke/fluid volume at the rear brake circuit while using a CJ-7 master cylinder. You need enough fluid per pedal stroke and adequate apply pressure at both the front and rear calipers. If this is not the case, consider the TJ Wrangler Rubicon four-wheel disc brake master cylinder! On another note, if you're using your disc/drum CJ-7 master cylinder, make sure there is no residual valve on the rear brake hydraulic circuit. Otherwise, the rear brake pads will drag on the rotors with the pedal released, causing quick pad wear, brake fade or even wheel lockup. This step is often overlooked on rear disc conversions. I've opened a new "topic" on this important safety subject. See this discussion begin at http://www.4wdmechanix.com/forums/index.php/topic/110-rear-disc-brake-conversions-master-cylinder-needs-and-the-drum-brake-residual-pressure-valves/. I'm taking photos of the brake pressure test equipment and will post at the tools forum...4x4 owners who work on their vehicles and professional techs will appreciate this diagnostic tool. Have a safe, fun 4th of July holiday. Looking forward to the update on your Jeep CJ-7 four-wheel disc brakes. Moses

The exchange with Megatron around his 48RE shudder at take-off reminded me of installation of oversized tires on our Ram 3500 4WD truck. Prior to installing the 4" lift and oversized tires, the truck had achieved great fuel mileage as a stone stock vehicle. I was thrilled with the Ram's fuel mileage and performance from new (October 2004) until the summer of 2011. Then it was time to bring the truck to the standard that readers and sponsors like—lifted, accessorized and sporting oversize tires! (See the Ram truck build up at the magazine: http://www.4wdmechanix.com/2005-Dodge-Ram-3500-Major-Makeover.html.) Stock gearing was 3.73:1, and with a Cummins 5.9L ISB engine, that meant cruising between 1,600 and 1,900 rpm most of the time. This worked perfectly for fuel efficiency, much to Chrysler's engineering credit. My expectation, considering the extraordinary low-end torque of the H.O. diesel, was that oversized tires would have little impact on the fuel mileage—in fact, I even speculated that the mileage would improve, since the engine could stay in the 1,600 to 1,700 rpm range at interstate speeds! Peak torque for this engine is at 1,600 rpm, optimal for fuel efficiency. Boy, was I in for a surprise! Trips to Chico, CA for the Transfer Flow fuel tank installation and the subsequent run to the 2011 Off-Road Expo at Pomona gave a hint. Mileage seemed stagnant and, if anything, off its usual peaks. I attributed the unimpressive mileage to mountainous roads and higher cruising speeds, but the true problem reared itself when I towed a 7,500# toy hauler trailer to the 2012 King of the Hammers Race at Johnson Valley, CA. The trip was to film the races and interview celebrities like Shannon Campbell that week. (You'll find this coverage and more at the 4WD Rock Crawling & Racing Channel on the magazine website.) Trailer in tow to places like Moab, UT, the truck had achieved 17 mpg at interstate speeds and 6% grades with the stock diameter tires (under 32" diameter). Now, with 35" tires, the mileage with the same weight trailer in tow, adhering to California's trailering speed of 55 mph, the mileage plummeted to 12-13 mpg! Before all of the modifications and weighty accessories, at 55 mph with the stock tires and gearing, trailer towing would have netted 19-20 mpg! Oversized tires with stock gearing creates an additional "overdriving effect". Sometimes this is advantageous, but in the case of our '05 Dodge Ram 3500 4x4 Quad Cab, the combination of 1,350 pounds of new accessories and auxiliary fuel, plus the 35" tires, made the stock 3.73:1 gearing unacceptable. The change to 4.56:1 gearing has bumped fuel efficiency back to a peak of 21-23 mpg (unloaded, full fuel capacity, no trailer in tow)—if I keep speed at or below 65 mph in overdrive. While a direct correction for the tire size and axle gearing would have been 4.10:1, I knew that the added weight of accessories and auxiliary fuel, plus the increased drag from the lift, would make "stock" gearing no longer practical. With the 4.56:1 gears, I do "pay for it" in extra fuel consumption when driving above 65 mph. It acts like a linear thing: The fuel mileage drops with each mph increase in speed! Had I planned on driving over 65 in overdrive most of the time, without a trailer in tow, I would have opted for the 4.10:1 gears. We do plan to pull trailers with a GVWR under 10,000#, so the 4.56:1 gears are optimal, and mileage is good—if I keep my foot out of the throttle! If you own a Ram 2500 or 3500 HD 4WD pickup like ours, a suspension lift and oversized tires will likely demand ring-and-pinion gear changes. I cover the 11.5" and 9.25" AAM axle re-gearing at the magazine site: http://www.4wdmechanix.com/How-to-AAM-11.5-Axle-Rebuild.html [detailed article with how-to steps in color photos] http://www.4wdmechanix.com/HD-Video-How-to-AAM-9.25-Axle-Rebuild.html [an overview that works in conjunction with the 11.5" AAM axle rebuild article] Moses

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.4wdmechanix.com/Survival-Upgrades-for-Jeep-and-Dodge-Ram-Automatic-Transmissions.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: 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. Moses

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. Moses