Author: Mike

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ZJ Ring and Pinion swap

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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Diagnosing Jeep Front Axle Noise

Diagnosing Jeep Front Axle Noise

Jennifer’s Jeep has been making a horrible grinding noise in the front lately. We tried putting it on jack stands and running it but we really could not tell where the noise was coming from.

There was some end play evident in the pinion so, since there has been a rash of pinion bearing failures around my shop lately we looked into that as a cause. I tried tightening the pinion nut but that did not help at all.

I finally pulled the front drive shaft and then removed both front axels from the housing. I replaced then with two wheel drive stub shafts. This eliminated the drive shaft, front U joints and differential bearings as potential sources of the noise.

The noise is still there. She has to live without 4wd for a bit while we wait for the new wheel bearing to arrive. While both wheel bearings feel fine when rotated by hand, one must be making noise when the weight of the Jeep is on it.

She also noticed that sometimes in hard right turns the noise will suddenly go away. This is another indication that a wheel bearing is the cause of the noise.
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Trail and Jeep Maintenance

Trail Maintenance and a broken U Joint

The last wind storm put a few trees down across the trails on my farm. The creek crossing spot has multiples angles that you can attack if from but they were all blocked by two large trees.

I finally got to use the new Chainsaw my dad gave me for Christmas. I took it out of the box for the first time. I was out of fuel so I stole a gallon from the ZJ that I have been working on. I hooked up my fuel pressure tester and jumpered the fuel pump relay and pumped a gallon into my small gas can.

I mixed in the little bottle of 2 stroke oil that came with the saw and filled the tank. Next I added chain oil to the reservoir. I also managed to spill oil all over the new saw and the floor. This oil is very sticky and hard to clean up, I might add.

It took me a moment to figure out how to switch on the ignition. The instructions say to flip the switch them pull the choke. Well before I broke the switch, I realized there was an interlock that causes the switch to flip as you pulled out the choke. I don’t see any other way to flip the switch on.

I pushed the primer bulb a few times and pulled the rope a few times. I was very happy that my new saw roared to life. I made a test cut and I was ready to go to work.

By that time it had started to rain lightly. Janice, Jennifer and I donned our rain gear and headed down the hill. I cut the trees into sections small enough for the girls to haul off the trail.

The first tree was easy, but the second one spanned the creek. Walking across the log was the only way to cross the creek with out getting wet. I walked across the log and found a way to cut the log loose from the stump and let it fall in the water so I could still walk on it.

I hiked back up the hill and got Jenny’s Jeep to help haul away the logs. I drove down in the creek and hooked a strap to the first long section. I drug it down the creek to a place out of the way. When I tried to back up, I got hung up in the mud and started to slide sideways against a tree the overhangs the creek.

I thought I could go forward and climb the bank further down. However the steady rain made the bank too slick to climb from that angle. I tried to drive on down the creek but I got wedged between a rock and the other bank in a narrow and deep section.

I finally was able to walk one front tire up the rock and do a rear dig to bring the back into the right angle to back up the creek. Then I was able to get the proper angle to climb up the creek bank.

One the drama of being stuck was over, I backed back into the creek and lined up to pull the remaining stump. The stump proved too heavy to drag down the creek. The Jeep just dug in and would not move forward. I did manage to get the stump clear of one of the paths across the creek and dislodged form the creek bank. I hoped that soon the creek would rise and move the stump out of the way.

The trail up the hill to the house was already getting very slick as we made our way back up. I had to use much more throttle than normal to climb it. Right at the top we heard a loud pop, but could not figure out what it was.

The next day, the overnight rains had completely flooded the bottom land and the creek bed looked like a lake. The stump was no where to be seen. It will be interesting to see where it ended up when the water recedes.

As I was hiking the trail, I noticed a U joint cap near the spot where we had heard the pop. I crawled under the Jeep and began checking all the U joints. I found the missing cap belonged on the driver’s side axle. Luckily we keep a spare around.

Twenty minutes later we had the spare shaft installed and she was ready to go again. Looks like the C clip twisted out then the cap worked loose. Another argument for welding the caps I suppose. I still have not tried welding the caps.

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Promoting Interest in Safety

Promoting Interest in Safety

One of the common subjects in any safety reference is how to get people interested in safety. Apparently, not getting hurt is not enough motivation for people to be interested in safety. Personally, I prefer to avoid getting injured whenever possible so working safely is just part of my work ethic.

Looking at a 1964 issue of the National Safety Council handbook, they suggest using “a pretty girl” to promote interest in industrial situations. They also recommend “a shaggy dog.” I guess there were not as many women working in industry back in 1964 as there are today.

The 5th edition of the Accident Prevention Manual suggests Using Pretty Girls to promote safety.

I notice that from internet search data that promoting safety is still a big concern for managers. Safety slogans and other safety promotional ideas still rank very highly.

However, it is my observation that all such safety promotions are basically useless. Unless you change the fundamental culture of the workplace, accidents will continue to happen and people will continue to get hurt no matter how many pretty girls hold up safety banners.

In order to create a safe working culture, we first need to consider why people get injured at work. Often injuries are caused by inattention to the job or by taking short cuts. Next we must consider why people take chances with their own safety either by not paying attention or by taking shortcuts.

I often see managers who perceive those who get hurt on the job as being lazy or who are otherwise not trying to do a good job. Often, however, the exact opposite is true. These people want to do a good job but due to their own lack of skill or understanding of mechanical principles, they take unnecessary risks. They may not realize how much danger they are facing; they are simply trying to do the best job they can with minimal effort on their part.

People who get injured may also be unconsciously punishing themselves. It the work environment is oppressive and devoid of positive reinforcement, they may injure them selves in an unconscious effort to prove that they are working as hard as they can.

In order to create a safe working environment, we can begin by placing clear expectations on the work that is to be preformed. By providing clear and detail work instructions that describe the safe and effective way of doing the job, employees will be less inclined to experiment with potentially unsafe methods. Supervision can play a huge role in insuring workers follow the safe work procedures by observing the work. If the procedures need to be changed to match current practice, then the revisions need to be investigated and implemented without delay. Employees should not be allowed to deviate from the prescribed safe and effective work instructions.

Care must be taken by supervisors not to reward unsafe procedures either by actively supporting unsafe practices or by ignoring them. If safety shortcuts are allowed to become part of the routine, a safety culture cannot be established.

For more information on creating a safe and effective working environment, see my other articles. Safety promotions become unnecessary once a safe and effective work environment has been established.

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100 Acre Wood rally

Trip to the 100 Acre Wood

I was once again given the job as Steward for the Rally America 100 Acre Wood Rally. It was held in Salem Missouri, the last weekend of February.

I headed out on Thursday and after driving through some huge thunder storms arrived in time to observe registration and Tech inspection. Both were held at the Dent County fire Station which shows the kind of support they get form the community there.

It was fun to connect with some rally people that I have not seen in a couple of years. I found out that the former organizer of the even Kim Demotte was driving his old Datsun 510 in the event. It as fun to see Kim behind the wheel and in a very well prepared old Datsun.

I caught up with my fellow stewards and we made a plan for the weekend. I went back to my room at the holiday inn and studied the maps and route books. I sat in on the Novice driver class and part of the worker training meeting.

The first day of the rally started in Potosi which is about a two hour drive from Salem. I plotted a route that would take me past a couple of the stages that were to be used later in the day so I could check them out.

I enjoyed the delicious Holiday Inn Express cinnamon rolls while I chatted with the other stewards and other people from Rally America. I looked out and saw that it had snowed overnight. Eventually I headed out to Potosi.

I turned off on TT to check out stage 6. I was quickly met by Road Closed signs and after driving past them, I saw the cause. One of the many low water crossings was flooded by the huge storms that had passed through the area the day before.

In this part of Missouri, they don’t build bridges much. They just pave the bottom of the creek beds. Sometimes they build a small elevated concrete platform to with some culverts so that some of the water can flow under and the rest flows over when it rains. Due to the heavy rains, the creeks were very deep.

I made my way to the start of the stage and was able to get through. The stage road was fine but I then became trapped by the high water again. I had to reverse my course and find another way out.

I met up with the Safety Steward who was looking at the spectator area on stage 5. We both found that we could not follow our proposed route due to very high water on one of the longer crossings. We had to plot a different course that took us out of the way but generally toward Potosi.

I made it to the Parc Expose in Potosi just as cars were starting to arrive and helped set up the first MTC and the start of the Super Special Stage. The Super Special was a rally cross like course around the fair grounds there.

There was a big puddle of water on the inside of the final turn right at the finish line. It was fun to watch the cars splash through. The finish control workers eventually decided to move to the other side of the road to give the competitors more room.

After watching a few cars run the Super Special, I headed out to the first forest stage. Due to some flooding o the transit, the rally master rerouted the course. I observed to make sure every thing was handled correctly and it was. We received a report that Travis Pastrana had crashed on the stage. After the stage was run, I followed the sweep team and helped them drag what was left of Travis’s car to a safe place off the road.

Travis’s Navigator remembered me when he saw me. I had towed his car back to service in one of the Cherokee Trails rallies.

Near the end of the stage I came across one of the participants in our rookie school from the night before. His car had a coolant leak and the engine computer had shut it down on low water. I gave him a jug of anti freeze from my Jeep and some bottles of water. He filled it up and drove to the end of the stage.

I stayed at the finish and watched the second pass through the stage. It was much less eventful than the first.

After that I headed to Steelville to check out service. Along the way, I saw one of the competitors disabled along the transit. I picked them up and gave them a ride to service.

After service in Steelville, I checked on the control checking crews out and then headed back to Salem. I was dark and late when I got back. The stewards met with the Rally Chairman to make adjustments to the procedures for the next day.

Saturday started early with a 7:30 am stewards meeting. I enjoyed the delicious Holiday Inn Cinnamon rolls again. Then I headed to the downtown Parc Expose. I wandered up and down the street looking at the cars and talking with the competitors.

After Parc Expose, I headed out to observe the start of the stages. This stage was repeated directly and I was concerned that they would not get it cleared in time. However, the Rally Master had prepared well and the stage was restated on time.

However after just a few cars started, one crashed blocking the stage road. The remaining cars were turned around and sent to the next stage. I transited the stage and ended up assisting the sweep jeeps with moving the car and a a huge rock that the car had moved into the road.

Luckily then Jeeps were equipped with winches and we were able to easily winch the car off the road and then move the big rock out of the road as well. Moving the rock was a bigger challenge than moving the car but with some simple rigging of a strap and a snatch block, we were able to get it clear of the road.

I then moved down to stage nine to make sure that the lack of transit times had not caused too much trouble for the control workers. After the stage I decided to follow the sweep vehicles again to see if they were doing their job correctly. Just a short way into the stage, there was a Honda stuck just off the road. The fast sweep had stopped to give them a chance to get back in the rally. I Pulled off the road well behind all the sweep vehicles and assisted in the recovery as well as checking on the competitors.

When it was all cleaned up, I walked back to my Jeep and noticed that the door would not open. I looked closer and realized that the Sweep truck had backed into my fender pushing it into the door. I had to dig in the back to find a pry bar to move the fender so I could get in. I caught up with them later and asked the guy about hitting my Jeep. He tried to deny he had hit it but them I showed him the matching scrape on the side of his truck.

I drove on to Viburnum to check on service there. After service, I headed up to Stages 12 and 14 which was a turn around stage. I assisted in setting up the finish control where the start had been. The control workers offered me a sandwich. I guess I looked hungry and I was.

I worked my way back to Salem in time for the champagne spray for the winners. They can’t use real champagne due to Salem’s laws about open containers of alcohol so they use sparkling grape juice.

The awards party at the eagles lodge lasted well into the morning. I made it back to my room and fell asleep around two am.

The drive home on Sunday was pleasant with much better weather than the trip out. I missed a turn. I ended up north of my intended route but found an interesting mining museum. It was not open but I took time to explore outside the fence and found it very interesting. It did not say what they mined there, but since the towns have names like Steelville, Iron Town and the like I assume they mined iron ore.

I crossed the Mississippi at Cape Gerardo. The Mississippi river was much higher than it had been on the trip out.