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There you go, Moses! It's going to be my first attempt at an engine rebuild... Starting the tear down. This Jeep spent most of its driving life on a tow bar being towed to NY for the hunting season. The engine has very low actual miles on it.
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So I am in the process of a total restoration on my 67 CJ5 v6 225 and have reached the transmission rebuild. I found a damaged first/reverse sliding gear and cluster gear. Question is should I pay the high cost of the t86 gears ( cluster $ 220.00 / first gear $ 125.00 ) or do I find t-90 parts and convert it? The first gear is almost impossible to find, I only found one after a week of searching. I would have to find used T-90 parts to make it cost effective but then there are no guarantees I will spend less to convert than to just get the t-86 parts. I do not plan on abusing the jeep off road when done. Also can I get away with grinding the teeth of the first sliding gear ( bottom photo ) a bit to dress them up rather than replacing ? The other side of gear not shown is good. Thoughts ? Damaged parts: -
Hi, I'm getting a noise from my YJ 3-speed TF999 transmission. It starts when the transmission shifts to 2nd gear, then it comes louder and faster when shifts to 3rd gear. When I release the gas pedal it will be more noticeable as the Engine sound is not at the background. I've removed the tunnel cover plate and recorded this video to see if anyone of you can help me out to identify which will be a possible source of that noise. I'm thinking it can be the planetary gears. There is also another noise that I think it can be coming from the Transmission Oil Pump. Let me know what can be causing that pump to emit that noise if you know. Any comment is wellcome. Thanks. IMG_3531.MOV -
We recently received a recall notice for my wife's '06 Libby. The problem is that the fuel tank could leak during a rear-end collision (ya think?!), and the fix is to install a trailer hitch. I thought that was an interesting fix, but I sure won't complain about a free OEM hitch! It also noted that parts are not currently available, but that we'll receive another notice when they are. Can you imagine how many hitches Chrysler will need for all the '02-'07 KJs on the road?? -
I have a 95 YJ 4 litre let's running extra rich. It will foul out the spark plugs with carbon fouling within a few minutes. Let me start at the beginning, I bought this Jeep running terrible. I was told it had a dead battery while jump starting they hooked up the cables backwards. I thought this was probably true due to the fact that both alternator fuses were blown. I drove it nine miles home and went through over 4 gallons of gas. Most of that ran out the tailpipe or was dumped into the crankcase. The number 5 and 6 injectors we're running fuel anytime the key was in the run position. I diagnose that problem to a burnt PCM. The PCM was sent out to a repair facility and upon return was installed and no start. the light on the dashboard would not even light up. I was told by the repair facility that that was their fault send it back and I would get a replacement. Upon installing the replacement PCM, the engine would start but still running very rich. The injectors no longer run when they're not supposed to. I started doing test procedures according to the Chrysler service manual. Cylinder leak down test shows all cylinders between 12 and 10% leakage. All cylinders 125 to 130 psi compression. Cam position sensor checks out ok crank sensor okay distributor cap rotor wires and plugs all new. timing ok per the book. ignition coil showed a low ohm reading on the primary side so I replaced it. spark is OK MAP sensor is OK idle air control solenoid was sticky so I replaced. Sprayed carburetor cleaner all around intake and didn't show any vacuum leaks. Manifold vacuum on my gauge reads low. About 5 inches at idle and up to 12 to 15 inches when rev up. Pulled the o2 sensor and plugged in a pressure gauge to do back pressure. Shows 1 pound pressure. Doesn't go up when engine revved so catalytic converter doesn't seem to be clogged. Running rich enough that in the three weeks I have been trying to figure this out, the new spark plugs were fouled enough to make hard starting. Since then I have installed fresh spark plugs. It will start and run but terribly rich. It acts like its not timed right, but all that is controlled through the PCM. Every check I do seems to point to the PCM still not being right. I am now one step away from doing the 5 gallons of gas and a match procedure. What in the heck am I missing? -
I've owned a 2004 TJ Wrangler Sport for a couple of years now and it has been stalling in 2nd gear the last few weeks. I gave the car to Berwick jeep service centre and all they tell me is that their computer doesn't show them what's causing it and that there is no problem. Has anyone had this issue? i know its not my driving!!! -
So, you're considering a Jeep FSJ restoration, maybe a multipurpose, family-oriented vehicle? While the quintessential off-pavement build is a 2-door, full-size Cherokee from the AMC/Jeep era, the Wagoneer finds begin with the 1968 models. The first Buick 350 V-8 offering, loaded with accessories and power option content, epitomized the true "luxury class" Wagoneer. In fairness, we could push that date back to the AMC 327 Vigilante V-8 models of the mid-'sixties, certainly the groundbreaking Super Wagoneer. Despite the truck-based ranching culture of Carson Valley, I remember Super Wagoneers on the showroom floor at C.O.D. Garage, Minden, Nevada, when I was a high school student. The Super Wagoneer looked impressive at the Carson Valley Country Club parking lot in those years...Paradoxical that this advanced design, luxurious 4WD vehicle sold alongside F-head four-cylinder CJ-5 and CJ-6 models in 1965! The last, traditional Willys-style Pickup and Station Wagon had recently rolled off the assembly line, replaced by the modern Gladiator J-trucks and Wagoneer. If you know Jeep technology, the Willys era models could trace their design origins to the 1941 Model MB. By contrast, the Wagoneer led the industry in new 4WD technology. Imagine the Jeep Corporation assembly lines and drawing boards of the 1962-65 era! AMC's acquisition of Jeep Corporation took the Wagoneer to the next level, eventually evolving into the Grand Wagoneer. This cult classic has been a regular movie star, appearing in motion pictures from its inception. The Grand Wagoneer became the middle- to upper-middle class icon of American 4WD transportation, popular in Hollywood's depiction of suburban and upscale country life...Pay attention to the movies and television, count the number of Grand Wagoneer stars and props! That brings me to one of our family's favorite vehicles. Just prior to the unsettled shift in American culture to a post-9/11 mindset, we stumbled onto our 1987 Jeep Grand Wagoneer. Dark blue, wood-trimmed and glistening in the morning sunlight at a Carson City supermarket parking lot, the 4x4 sported a "For Sale" sign with phone number. I combed the Jeep topside and bottom, confirming that the vehicle was a truly original, well-maintained J-model. It took two minutes to decide that a phone call was warranted, and by that afternoon, we were the happy owners at a purchase price of $6200. A two-owner, documented Jeep Grand Wagoneer, the vehicle ran and handled flawlessly. With it came the famous ride quality with the factory sway bar and compliant spring rates. Donna immediately seized on the vehicle's agility, a bona fide J-truck chassis with a wide wheel track for stability, a shortened wheelbase, all adding up to a superb ride: Some dimensions—1987 Grand Wagoneer overall length is 186.4 inches, width 74.8 inches, wheelbase of 108.7 inches. 37.1 inches of front headroom, 36.8 inches of rear headroom, 40.5 inches of front legroom and 37 inches of rear legroom. Curb weight around 6,200 pounds—hefty! Your wife, like Donna, would be enchanted with the Grand Wagoneer. Step on the gas, the 360 V-8 and 727 Torqueflite respond immediately. Brakes are larger power disc/drum, 1/2-ton J-truck grade, outstanding stopping power. Wide, Dana 44 axles front and rear, open knuckle front with 5-degrees positive caster for a tight turning radius and ease of parking. Solid, easy entry and exit from the four doors, a tailgate with power window, generous leather upholstered seats, power everything for the era, what's not to like? Behind the scenes, I did the PM (preventive maintenance) on this Grand. AMC made sure there were inherent weaknesses and quirks, like the embrittlement-prone nylon window lift tracks, touchy tailgate window mechanism and the vacuum shifting mechanism for the 229 transfer case. While Donna enjoyed the driving time, I kept the AMC issues at bay: changing the oil pump gears to a high volume kit (timing cover/oil pump housing was still functional, most unusual); rolled in new rod and main bearings while changing out the leaking rear main seal; restored the tired emission controls, changed the A/C system over to R134a (system virtually 'spit out ice cubes' following the recharge, amazing York compressor!); rebuilt the 2150 series Motorcraft carburetor. My "blueprint" rebuild of the 2150 and careful adjustment of its altitude device produced extraordinary results! This engine started like an EFI motor, accelerated likewise, and performed flawlessly year 'round, even with sub-freezing starts when parked in winter. The fundamental simplicity of the 2100/2150 Motorcraft carburetor is a joy, and if you simply remember to depress the accelerator to set the choke and provide a small shot of fuel to the cold engine, this wonderful carburetor and the conventional Motorcraft distributor perform much like EFI. The Grand Wagoneer retained Motorcraft 2150 carburetion and a conventional distributor though the last, 1991 model built. I watched the front track bar frame attachment point carefully, as many Grand Wagoneers have broken these brackets loose, but our '87 stayed intact. The A727 transmission and even the 229 transfer case worked flawlessly—well past the century mark on the odometer. When we purchased a new 2002 Liberty, our mistaken notion was that the era of the Grand Wagoneer had passed. We imagined that consistent 14-15 highway mpg was no longer sustainable at "foreign oil" fuel prices, and we talked ourselves into selling the Grand Wagoneer...What a mistake. I tolerated the Liberty and its best-ever 19 mpg for two years, lamenting the whole time about the loss of the 'Grand. Donna was a bit kinder about the Liberty than I was, although she wasn't the one to change spark plugs on the 3.7L V-6—using a piece of fuel hose to carefully hold and work the new plugs into their out of reach spark plug positions—and start them into the soft, aluminum cylinder head spark plug threads...Curious about the fuel hose trick? Post the question, I'll reply! When asked about her favorite vehicle, Donna still responds promptly, "My favorite car ever was the Grand Wagoneer..." Funny that she still insists it was a "car". Motorheads know the Jeep Grand Wagoneer as the most rugged SUV truck ever built...That's the mystique of the Jeep FSJ models, especially the now classic Grand Wagoneer... Moses -
AMC/Jeep® always leaned forward in both car and utility vehicle designs. By the mid-'80s, the CJ needed a contemporary replacement, a vehicle with wider track for handling and a better highway ride package. The Wrangler emerged just as AMC sold to Chrysler, and the Wrangler and XJ Cherokee were the profit items Mopar wanted! The Wrangler four- and inline six era represents huge growth in the 4WD/SUV market overall, and there are huge numbers of enthusiasts, owners and buyers who can build a "community" at this forum! —Moses Ludel At left is an '87 YJ Wrangler, leaf springs articulating on the rocks! Middle is the Quadra-Coil™-suspension TJ Wrangler Rubicion edition, the engineering and off-road pinnacle of the Wrangler inline four- and six-cylinder era! At right, Moses Ludel's Jeep Owner's Bible, 3rd Edition, covers models through the Wrangler YJ and TJ...
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I've been a Jeep enthusiast since 1997. My first Jeep was a 1982 CJ8 Scrambler. One YJ and 4 TJs, the current one being a 2004 Rubicon with 52,000 original miles and trail modified. I have been experiencing the famous P0301 trouble code very intermittently unless it was cold outside, then it was steady. Rain or shine didn't seem to change anything. I live in Minnesota where winters are cold. Started with the obvious tune-up, copper plugs and the coil rail. Battery connections, grounds, injector cleaning and replacement, throttle body cleaning. The works. Could not isolate the misfire. Started chasing wires. No luck. Many live data scanners, no luck. Compression tests and leak down well within spec. Valves also seating and rotating well. Became very frustrating. Pulled the alternator, tested good. The battery tested good ( the first time). Wasn't sure what to do. Finally, the other morning it was -17 degrees F. The Jeep just didn't have the juice to start. Thought that was strange. Rain or shine it always started. Jumped it and went to auto parts store. Dead cell in battery. Thinking back first good freeze, we experienced this and had the same test done. I overlooked the issue and accepted its first passing test. No one on any of these forums makes mention of voltage or battery replacement or testing. Well I replaced the battery. Not a single misfire in a month. I've wasted countless hours diagnosing this misfire, and it ended up being my battery. Turns out they're pretty sensitive to low voltage. Thx for all the info on your site! -
Is there a manual transmission that can handle an 800 horsepower racing Jeep 4.0L stroker engine? I need a 2- or 3-speed only transmission. -
In this video discussion, I describe the symptoms of hydraulic clutch linkage leaks in 1987-95 Jeep YJ Wrangler models. Originally part of the Q&A Vlog at the magazine, the viewer's question refers to hard shifting and loss of hydraulic fluid. I share what causes these troubles in this how-to HD video on troubleshooting: Moses
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Aisin AX15 manual 5-speed transmissions are popular and found in 1989-99 Jeep vehicles, Dodge Dakota pickups and some GM/Isuzu and Toyota light trucks. Highly detailed, this close up step-by-step instructional HD video rental is available only at vimeo.com/ondemand/ax15rebuild. Included is the information necessary for performing a complete restoration and professional level rebuild of the AX15 transmission. The AX15 transmission rebuilding process involves complex disassembly and assembly sequences. This is a precision gearbox, and every teardown and assembly step is equally important. Knowing which new parts your transmission requires is also valuable. This HD video rental includes two sections. Part 1 is teardown and inspection to establish your needed parts list. Part 2 is the assembly work. Both Part 1 and Part 2 are included in this 94-minute instructional HD video! Whether you have a shop specializing in light truck and 4x4 work or have a one-time 'DIY' project for your personal Jeep, light truck or SUV, this 30-day HD video rental can save you considerable time and money. For the cost of an AX15 shift cover boot, the rental will pay for itself many times over! The magazine's most popular technical articles and how-to videos have been reformatted and painstakingly edited as Vimeo On Demand productions. The latest feature is this in depth instructional how-to covering the rebuild of the popular Aisin AX15 transmission. Access the 94-minute Vimeo On Demand feature at: http://www.vimeo.com/ondemand/ax15rebuild
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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! mb.
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In 1984, AMC/Jeep® took its unitized body and 4x4 technology into the XJ Cherokee platform. This breakthrough compact SUV became the best selling model of its era and made the AMC sale to Chrysler profitable. These models and the subsequent Jeep ZJ and WJ Grand Cherokees feature beam axles front and rear, two-speed transfer cases and rugged engine packages, making them candidates for off-road upgrades and 4x4 trail use...Welcome to the XJ Cherokee and ZJ/WJ Grand Cherokee community at 4WD Mechanix Magazine!—Moses Ludel At left is a ZJ Grand Cherokee equipped to tackle the Moab Area BFE course! Reno Off-Road Motorsports Expo (center) is one more place to see the owner enthusiasm for the XJ Cherokee! At right, the magazine's 1999 XJ Cherokee multi-tasks, pulling the Caravan trailer and our XR350R Honda dirt motorcycle!
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After watching your videos I decided to look at a 1998 Jeep TJ Wrangler. My concern since i have no knowledge of the vehicle is how to scrutinize and assure it is a sound vehicle. Background on the vehicle: 1) The Jeep has a new 2.5 4-cylinder in it, not sure what that means, whether a rebuild or remanufactured? 2) Has 138,000 miles, 5 speed manual no mention in ad of new transmission parts. 3) 1998 black Jeep Wrangler TJ 2.5 with a 5 speed manual with 3,000 miles on the new motor. New motor put in over the summer (has receipts). 4) 4-inch suspension lift, 1.25 inch JKS body lift+ 1 inch motor mount lift 5) Swing out tire carrier bumper 6) Aftermarket stereo and speakers 7) Aftermarket rims and 31x 10.5 inch tires+ full size spare 8) Aftermarket adjustable track bar 9) Newer shocks and steering stabilizer 10) Aftermarket sway bar links 11) Heavy duty lower front control arms 12) Cold air intake 13) Windshield mounted fog lights 14) Bumper fog lights 15) Custom differential guard 16) Full skid plates 17) Custom lockable center console 18) Tinted turn signals and tail lights (to legal specs.) 19) New water pump, spark plugs, hoses, coolant flush and all new gaskets and seals put in with new motor 20) Hardtop with tint 21) Undercoated frame (prevents rust) 22) Clean title! 23) Paint on hood is chipping a bit but mechanically everything works great. My last question: What aftermarket products are critical to inspect for damage? I noticed a MOAB sticker on back window and I'm not very astute or have much knowledge on what to look for! Any guidance would be greatly appreciated! Papaobewon -
I have a 1996 Jeep Cherokee 1996 stroker six with these specification: - High compression pistons - CompCams camshaft #68-239-4 with lifters, valve springs, retainers, etc. - Three-into-one header Currently, I have a Hypertech program with a Unichip rev limiter module on the way. I want the most powerful computer and am considering these options: Superchips - SCT Computer - Jet Performance Stage 2 module Which is the strongest module?
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Took the Eight out for a ride Sunday and all systems worked flawless. This is upper ledge Steve's Loop near Pyramid Lake, NV Near the top are some interesting 'wind caves' to explore. Access trail has a short section with slick rock like bedrock, but it was sprinkled with ball bearing-like dirt and sure enough, i slid sideways about 4' enough to pinch seat covers. compound winching was the fix along with a front dig thanks to the twin stick dana 300. Whew! short video. winching fun at the end Jeff's classic Commando is a real trail beast. The helper winch line was from Al Lockett, and for added leverage, went to top of the family roll cage. i then made the hard left pull. It is really steep there and video/photos do not convey the sense of oh my god sidehill action. you can see how the uphill pulling helped level it all out. Also having twin stick abilities really helped get the nose straight-- otherwise it just wanted to plow forward and gravity pulling into the deep abyss.
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This topic is new member Sparky1's question...I moved the discussion here, as this is a Jeep XJ Cherokee topic that will be of interest to many...Thanks for participating at the forums, Sparky1, we look forward to your involvement! In response to Sparky1's original question (in the next post), I haven't done this swap, but here's what I do know...The later model Jeep vehicles feature a security/anti-theft interlock system that ties the steering column/key functions to the powertrain management system. This matches the vehicle's VIN to the key lock mechanism, actually useful. When I toyed with the idea of a Liberty diesel engine swap into our 1999 XJ Cherokee (like your XJ), informed sources at Chrysler shared that this could only be done with a PCM match to the steering column. The standard route was to install the recycled engine, its PCM and the steering column from the same donor vehicle. So, I would suspect that the JK Wrangler steering column has ties to its PCM, and the PCM for a JK would drive a 3.8L or 3.6L V-6, not your inline 4.0L Jeep six. That's what I do know, others may have more insight here... As a footnote, I also know that the late JK Wrangler steering wheel is very cool! Moses
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Hello out there! I found this forum recently and decided that I would like to do some work on a 1984 CJ 7. I will need tons of help. To begin with I have a hard time shifting from 2H to 4H to 4L and all in between. Most likely due to the fact that the Jeep is 30 years old, and likely no one has looked at the oil level in the transfer case! I have posted a couple of pictures to ask for help in identifying the transfer case on my CJ. I think it is a Dana 300? To be specific I would like to know if I could read or watch some recommended videos on the removal and proper way to rebuild this transfer case. What tools would be required to complete the rebuild properly, and what should I look for when opening up the transfer case. I want to do it right but don't want to exceed my skills. I would be willing to take and post photos along the way. -
Just picked up this 55 CJ5 minus motor for next to nothing. Going to build a rotisserie and try to rescue the tub for my 67 restoration. Going to be a challenge but hate the thought of an aftermarket tub. Everything else is for sale. Just not sure what anything is worth yet. hood fenders two grills tailgate t-90 transmission dana 18 transfer case bell housing for F head two oil pans heater box air cleaner windshield frame ( rough ) axles frame rear draw bar
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I wanted a wider,stronger less over hang flare for my 86 CJ7 widetrack with 35" tires on 10" rims. I did not want a 6" or 7" flare. So I went with a 5" flat flare from Xenon.
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Hello All: I have a 2003 Wrangler Rubicon SWB with many mods for wheeling - (6" Full Traction LA suspension/new wheels/35"Toyo MT etc.etc). She is very heavy. I am the original owner and try to keep my truck mint, although I do occasionally wheel it aggressively. She has 35,000 miles on the odometer and since I am very safety aware, I think it is time for new brakes. (The brakes on this truck are the original factory brakes/pads etc.) She doesn't seem to stop as well as she used to - there is too much fade - although the pedal is strong and I had everything checked out (bleed lines etc.) by my dealer in December. I'm just not comfortable on the Highway at 55 mph or so with the thought of a quick stop with a 4600lb brick that doesn't stop like she used to. So I am thinking of doing a full replacement with EBC rotors and pads. What else do I need to replace if I go this route? Remember everything is factory original and never replaced! Many thanks for your thoughts and suggestions, Joe Mac -
I am looking at used jeeps and I will be a first time jeep owner. I am interested in CJs or YJs. I want the jeep mostly for hunting and putt-ing around town. As far as engines go, do you think a 4 cyl would be okay for what I want and not get me in trouble in the mountains, or should I just look at the 6 or an 8 cyl? If a 4 would work, what transmission, axle gearing and tire size would you recommend? I have already found the forums to very informative. Thanks. Rich -
I've got a 1986 CJ7 258 Weber carb, factory Dana 44 rear (re-geared to 3:73's with Lockright locker) narrowed down Scout Dana 44 front with 3:73 gears, Spartan locker, old-style 6 bolt wheel hubs, stock factory front discs, Jeep T18 4 speed to a Scout/Dana 30 transfer case, power steering cooler, AMC Concord A/C now, onboard air with a tank, 35" BFG muds on 10" rims. I recently added Ford 8.8 rear discs to the Dana 44 rear. I had to have the bolt pattern redrilled to 5 on 5 1/2 and cut out the middle hole bigger for the flange. I had to elongate the mounting holes and bracket holes, mounted everything up and discovered the rotors set out 1/4" too far on the hat of the rotor. I added a 1/4" spacer, and everything bolted up. I hooked up the calipers and bled the lines. Had front brakes but little to no rear brakes. Went to the local u pick it junkyard and got an '05 TJ Rubicon proportioning valve. I checked all the lines and installed the proportioning valve. It seemed worse! Questions: 1) Should the proportioning valve be up near the master like the Rubicon, or is it okay to have it in the CJ7 location on the frame? 2) Should I still get an adjustable pro valve and keep the Rubicon proportioning valve, or 3) should I go back to the CJ7 proportioning valve and add the adjustable valve near the master? Or should I upgrade the master? -
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
