Car repair – Page 48 – The Jeep Guru

March 15, 2011March 16, 2011

Dana 35 Pinion Bearing Replacement

Janice’s Jeep was making a roaring noise from the rear end. After just a short test drive, the pinion on her Dana 35 was much warmer than the rest of the axle. Listening with a stethoscope confirmed that the pinion bearing was noisy.

I tried just changing the outer bearing and seal but since the race was worn was well, I had to disassemble the differential and change both the pinion bearings.

I ordered a Pinion bearing kit from Crown Automotive. This kit came with bearings, a new crush sleeve, shims and a reusable gasket.

I removed the wheels, and brake drums. Then I removed the cover and drained the fluid. Next I removed the carrier. I was careful to keep the bearing races and shims in the proper order. I noticed that the bearing caps were marked with and X to keep them on the correct sides. One X was vertical and one was on its side.

I dropped the drive shaft and removed the pinion nut. I used a dead blow hammer to knock the pinion out of the front bearing. I then used a pry bar to remove the pinion seal.

I used a chisel to tap out the two bearing races. I used a soft punch to drive the in the new bearing races. I used a bearing separator and hydraulic press to remove the inner bearing from the pinion. I ended up breaking the bearing race while pulling it off, so I was glad I was not trying to reuse it. I reused the shim under the bearing. I used my heat gun to warm the bearing and then slipped it onto the pinion shaft.

I installed the new crush sleeve on the pinion as well. Next, I cooled the pinion in the freezer for a while before slipping it in to the housing and placing a warmed outer bearing on the shaft.

I installed the seal and yoke and then tightened the pinion nut until the preload on the bearing was about 15 inch pounds. To check the preload, I had to use several adapters to get from the ¼ inch drive of my torque wrench to the ½ inch drive of the socket.

With the preload set, I reinstalled the carrier. I used a dead blow hammer to tap the bearings into place. I reinstalled the caps making sure they were turned the right way round and they were on the correct sides.

I slipper the axle shafts back in place and re secured the C clips. I then reinstalled the center pin set screw.

I put the cover back in place using the reusable gasket from the kit. I put some silicone on the cover to glue the gasket to it and cleaned the housing well. I put the bolts back in and tightened them evenly. I filled the housing with gear oil and the Limited Slip friction modifier compound.

I reinstalled the brake drums and wheels before taking it for a test drive. It was much quieter and the pinion did not heat up as before.

The pinion bearings are also available from Advance Auto:

March 14, 2011March 14, 2011

Jeep Dana 35 Wheel Bearing

A few weeks ago I replaced the wheel bearing and seal on Janice’s Jeep Cherokee. Her Jeep has a Dana 35 rear axle with anti lock brakes and the Trac Loc limited slip.

Not long after, the rear was making a roaring noise worse than before. I noticed a lot of heat in the pinion after a short drive so I replaced the pinion bearings.

I also replaced the axle shaft due to some checking in the bearing race area. I used a ZJ shaft as a replacement. This meant that I had to swap the anti lock tone rings as they are different. I used an acetylene torch to heat the ring and allow it to fall off the shaft. To reinstall, I used my electric heat gun to warm the ring and then tapped it into place with a hammer.

The noise continued to grow and there was noticeable sloppiness in the brakes. This was followed a few days later by a leak in the wheel bearing seal.

I pulled the wheel and brake drum to inspect and found that the new bearing was extremely worn. There was noticeable slop in the axle and the brake drum had been dragging causing a lot of heat.

I pulled the cover, removed the C clip and pulled the axle. The axle looked fine. I extracted the bearing and found it very worn. I installed a new bearing and seal.

Upon closer inspection of the bearing, I noticed that the race was cracked. I suspect that I got it twisted while installing it in the axle tube. I had used a punch to install the bearing since I did not have the correct size bearing driver available at the time.

This time I turned down one of the bearing driver I have using my mini lathe to make it fit. The bearing went in with a satisfying thunk. Hopefully this one will last.
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March 14, 2011March 14, 2011

Jeep Front Wheel Bearing Hubs

The noise in Jennifer Jeep was traced to a wheel bearing hub. The bearings are not normally serviceable. The whole hub is replaced as a unit.

To swap the hub, begin by removing the wheel and tire. Her 33” Dick Cepeks are very heavy.

Next, remove the brake caliper and rotor. There are two bolts holding the caliper in place. The old AMC Jeeps use a 7mm hex key while the Mopar built Jeeps use a standard 13mm bolt. For some odd reason, one side on Jennifer’s Jeep has 12mm head on the bolts.

Remove the cotter key and the keeper. Then using a 36MM socket, remove the center nut. An impact wrench works great for this. If you are using a breaker bar and need a way to keep the wheel from turning, you can remount a wheel with the center cap removed and use the weight of the vehicle to hold the shaft.

Remove the three bolts that hold the hub to the knuckle. These have 12 point 13mm heads. If the hub is stuck in the knuckle as it often is, I have three sacrificial bolts that have the same thread. I screw them into the hub and use a hammer on the bolt heads to drive the hub out of the knuckle. Do not hit the wheel mounting flange as this will damage the bearings.

Slip the hub and brake shield off the knuckle. You can leave the axle shaft in the axle to prevent loss of gear oil.

To replace; slip the new hub into the brake shield and then into the knuckle. If your Jeep is only for off road use, you may choose to delete the brake shield as it tends to catch rocks and debris and does not help cooling at low speed.

Tighten the hub to knuckle bolts. Place the washer and nut on the end of the axle shaft and torque to 170 foot pounds. I used a pry bar through the U joint to hold the axle while torquing it. It is possible to damage the seals on the U joint using this method, so be careful how you place the pry bar in the yoke if you choose to do it this way. The proper preload torque is important to making the bearings last. Replace the keeper and cotter key.

Mount the rotor and brake caliper. Be careful not to over torque the small brake caliper bolts after getting used to working with the larger bolts.

Remount the wheel and tire. Torque the lugs nuts and give it a test run. Jenny’s Jeep was much quieter after the bearing swap.
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March 11, 2011March 14, 2011

Jeep 8.25 Differential Cover

Jeep 8.25 Differential Cover by Blue Torch

A few years ago, I backed into a stump and dented my rear differential cover. I thought it was not a bad dent until I pulled the cover off for an oil change. That is when I saw the groove that the ring gear had cut in the cover. I hammered out the dent and reinstalled the cover for more wheeling. I began shopping for a stronger cover.

I found very few choices for a replacement cover for the 8.25.

I finally found the one I wanted at Blue Torch Fab Works. But I did not want to pay the $140 price. Later, they offered the same cover in a weld it your self kit. Jennifer also has an 8.25 and when she found she could buy two covers for less than the price of one, she got two under the condition that I weld up both of them.

I was not sure my welding skills were up to the task so I asked my Dad for advice. He suggested that I simply have him weld them. That sounded like an excellent plan; so I took him up on the offer.

While I mostly use a wire feed MIG, he prefers his stick welder. Our welder is an old Hobart with a four cylinder Continental flat head engine just like used in the Willys Jeeps. It had not been run in years. So, my first task was to get the old welder running.

Some cleaning on the distributor cap and a bit of ether in the carb and the old motor roared to life. This welder is really loud when it runs; but it welds really nice. Dad showed up with a hand full of rods and after we figured out how to assemble the pieces, he started welding. I did the finish grinding and touched up some spots with the wire feed. I used a flap disk on the grinder to make a very smooth finish on the welds.

Next, I filled them both with water and let them set to test for leaks. Finding none, I sanded them again and painted them with Rustoleum Red paint.

Several of the bolt holes have very little clearance between the weld fillet and the hole so I elected to use hex bit Allen head screws instated of the normal hex head. I got these at Fastenal.

I removed the old dented cover and drained the fluid. It looked a bit contaminated with water, so I discarded it. I cleaned the mounting surface. I applied an even coat of black RTV on the cover and installed it using the Allen head bolts. I tightened them in a crisscross fashion.

After letting it set a bit, I added fresh gear oil. The Blue Torch Cover uses a nice big screw in plug for the filler. The cover also holds quite a bit more fluid than the stock one. I think I put in almost three quarts. I then coated the threads of the plug with pipe sealant and screwed it in place. Since I did not have the right sized hex bit, I made a tool using a 3/8 bolt and a couple of nuts jammed together.

The Blue torch cover looks really nice and is very strong. I think the axle would break before this cover dents. I think it will add strength to the axle housing as well.

March 10, 2011March 11, 2011

ZJ Ring and Pinion swap

I have been working on a 96 Jeep Grand Cherokee (ZJ) that came to me with 3.73 gears in the front and 3.55 gears in the rear. Obviously this did not work well with the Quadratrac full time four wheel system. So the previous owner had removed the rear drive shaft and was running around with front wheel drive. This solution worked surprisingly well except for the trouble with the back of the transfer case not being sealed.

The owner obtained a set of 3.73 gears for me to install. I decided to try to make use of as many of the existing parts as possible to reduce the overall expense. I also decided to use this as an experiment to learn how to change differential gears.

I was surprised to find that my automotive advisors: my dad and my millwright friend; had never set up differential gears before. They both knew the concept, but had never actually performed the task.

I began by removing the wheels and the brake calipers. Next I pulled the cover and drained the fluid. I pulled the pin retainer screw and then slid the center pin half way out so that I could release the C clips without dropping the spider gears. I slipped the axles out of the way. I then reinstalled the center pin and the retaining screw. Again this was to hold the spider gears in place.

I noticed that the bearing caps were marked with an H on each one. However one side had the H on its side. There was a matching mark on the housing flange to help keep track of the caps.

Since I do not have a housing spreader, I chose to use the “pry it out” method. It took a lot of force on the pry bar to get it to move the first time. And even when it was “loose” it still would not come out. I finally noticed that one of the axle shafts was not pulled far enough out and was catching the edge of the bearing. Once I slid it out, the carrier came out.

I was very careful to make sure the shims on each side stayed with the bearing races. I laid every thing out to make sure I kept them in order.

I put the carrier in the vise and loosened the retaining bolts. I then carefully tapped the old ring off. The new ring did not slip on at first. I decided to heat it to make it slip on easier. I also realized that if the bolts did not line up, I would have to hammer the new ring back off so I made some alignment pins to go in a couple of the bolt holes. I threaded some 5/16 rod to match the bolts holes in the ring and screwed them in two opposite holes.

As I set the ring up to test the alignment, it slipped right into place and stayed there. I guess the heat of handling it expanded it just enough to let it slip on. I put the bolts in and torqued them to 55 foot pounds.

I then removed the yoke and knocked the pinion out. The new pinion had a new bearing on it already so I decided to give it a try. I put the pinion in and crushed the sleeve to get 15 inch pounds preload on the pinion bearing. I then reinstalled the carrier using the original shims.

I put some Prussian Blue on the gears and rotated it around. I could not see any kind of pattern what so ever. I tried several times. I had read where there needed to be some resistance on the gears to make a mark, so I tried driving a wooden wedge between the gear the housing. I still did not see a mark in the dye.

I tried several more times and I noticed that the pinion was transferring marks to the unpainted teeth. The marks appeared on the toe of the gear. According to the manual, this meant that I needed to remove a shim form under the pinion. The trouble was, there were no shims under the pinion.

I checked the backlash using a dial indicator. The spec is 7 to 9 and I was reading not quite 10 so I decided it was close enough.

I waited until the next day and buttoned it all back up and took it for a test drive. As you might expect, it whined horribly. It only took a quarter of a mile test drive to realize this was not going to work.

I set the Jeep aside for a few days as more pressing projects to the service bay. Later, I put it back to try again.

I pulled the cover and axles again. I cleaned up the gear with brake cleaner and it was obvious where the pattern was. It was not on the toe as I had thought; it was very much on the heel. Well that was good news as I knew I could add pinion shims easily enough.

I pulled the carrier and the pinion shaft. I pressed the bearing off using my Dad’s press and my Harbor Freight bearing separator. I looked at the old pinion and saw there was a shim under the bearing. I tried pressing that bearing off but it refused to budge. I looked around and found another old pinion that had a shim on it.

I had no idea if it was the right one our not, but since it was the only one I had, I decided to give it a try. I slipped it on the pinion, heated the bearing and dropped it n place.

I slipped it in place with out the crush sleeve to check the gear pattern. I snugged up the yoke to take out the end play and then reinstalled the carrier.

I found that mixing the Prussian Blue with some of the gear oil and brake cleaner, I could make a mixture that smeared easily. I also found that by working the pinion back and forth across the due I could wipe off a spot. The clean spot looked just like the desired wipe in the manual so I decided to call it good.

I pulled the carrier and pinion again and installed the crush sleeve. I then set the preload to 15 inch pounds again. I put the carrier back in and tightened the bearing caps to 57 foot pounds.

I put the C clips back on the axles and glued the cover back with Black RTV. My tube of RTV is getting hard so I had to punch a new hole in the side of the tube to get to the good stuff.

I let it dry overnight before refilling it with oil. I am looking forward to test driving to see if it worked this time.

UPDATE: I filled it with gear oil and mounted the wheels and tires. A quick drive up the road let me know the rear is nice and quiet now.

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