Thanks for the info old skool luvr.

After many attempts to pull the c-clips I was able to get them out. Here is what the problem was - since the limited slip differential has nowhere for the c-clips to fall off because of the parts in behind them, they need to be pulled out.

However, it isn't simple to do because due to the limited visibility through the space available to access them and the fact that the opening faces somewhat upwards, it's next to impossible to know when the c-clips are aligned properly to come out. Complicating the matter is the fact that the little suckers keep rotating on their own when you try to line them up with the opening away from the point where you intend to grab and pull. Once I got them out I noticed that they were scratched from the grab and slip action of trying to pull them out on one side and not in the middle of the curve - so in effect I was trying to pull them sideways due to doing it blindly. So it takes much perseverence and pain to eventually get them out. I don't know of a different way to do it. I got them out with the needle nose pliers.

Once I got them out, I pulled the axle shafts and examined the bearings and oil seals. They look good to me on both sides. The bearing rollers appear to be nice and round and well lubricated although the grease appears to be rather thin. The oil seals look sound with no cuts. I am tempted to just put everything back!

However the noise I was hearing before would still be there! Any ideas where to go from here?

Thanks.

 

If the axle does not move up & down when in place and if the rollers and axle look shiny & smooth. (no pitting or discoloration) you should be good to put it back together. Don't use the old seals as they are not expensive and even if the old ones are not leaking they get harder & less flexable with age. Just don't drag the splines on the seal and try not to let the axle drag on it either. Put a light coat of grease on the seal which will help protect the seal from damage if the axle contacts it on the way in. It won't hurt to put a light coat of grease on the bearing also so it will be lubed until the gear lube works it's way out there.
Clean the housing where the seal goes and if the seal does not have a rubber coating on the outside put a light coat of gasket sealer in the housing and on the seal as metal to metal contact between the seal & housing can result in a leak.
Differential noises are hard to trouble shoot. You may have a pinion or carrier bearing that is noisy. But this can often go a long time as long as it is full of lube. Synthetic gear lube would give you some extra protection and if the posi unit is working add some GM limited slip lube. It comes in a small bottle. 4 oz or something like that.

 

Thanks bud. The problem I have is that before opening up the differential I had all the brake gear off and put the two rear tires on held on just with two tightened nuts on opposing studs so my son could spin the wheels while I went underneath with a stethescope to listen for any noises. I heard nothing from the differential but could hear noises emanating from the axle near the left wheel. Then I took the whole thing apart and, after much blood sweat and tears, the bearing looks good! Weird stuff. The noise was very loud, to the point that people walking down the street would turn their heads when I drove by! I have to fix that noise. So, no matter how tempted I am to just put everything back, I am wondering if perhaps I have to take the bearings off and clean them thoroughly to see the damage (there has to be some). Or, should I just replace them anyways (they're not that expensive) now that I got this far?

Thanks for all the good points. I appreciate all that since I've never done one of these before, and realize that sometimes just one little thing done incorrectly can cause big problems.

With regards to the synthetic gear oil, I believe that's what our friend TBB suggested too, but when I look in the owner's manual it recommends only SAE 80W90 for both regular differentials and locking differentials, so shouldn't I follow that? It even says "do not add friction modifier" under locking differentials !!! I know that some differntials even call for additives (Chrysler ones I believe) but this one seems to not need them!

 

Differential noise can fool you as to where it is coming from. From what you have said I would replace the left bearing. You don't want to put it all back together and then wonder if the noise would be gone if you had replaced the bearing. You can do a better job of inspecting it if you remove the bearing but if you go that far I would replace the bearing as you will need a slide hammer to get the bearing out and you might damage it anyway. Since you have done all this work it might be best to put both bearings in and if the noise is gone GREAT. If it is not you won't be wondering if it was a wheel bearing.
The SAE 80w90 is just the weight (viscosity). Absolutly no harm in using synthetic. I am surprised that the owner's manual says not to use friction modifier in a locking unit. Are you sure it is not saying to simply add it to existing so you don't have too much? I don't recall seeing GM say not to add modifier on a drain and re-fill. Some aftermarket fluids say no modifier needed. Just read the bottle. If you do not use the modifier and you don't get any clicking or popping from the differential when going around corners all is well. If it clicks or pops the fix is to then add the modifier.

 

Yes, terry s, the words I quoted above are verbatim from the capacities table in the owner's manual.

The differential takes 1.9 liters of fluid. I have actually purchased a pair of bottles of Castrol HYPOY C SAE 80W-90 gear oil (as per the owner's manual spec) which is formulated for limited slip performance. Each contains 946 ml which is the correct amount. Once I put the full contents of both bottles in the differential, I suppose I'd have to siphon out some to put in any modifier (if I found it was needed as you indicate).

I know that synthetic is supposed to be better, but if the manufacturers recommends this, I think it's wise to follow their recommendation.

FYI, I was involved with an additives business at one time, and found that most additives do nothing (usually not good or bad, although some containing teflon (as an example) actually do harm - i.e. have you ever considered what happens to the teflon that gets scraped off pots and pans - you guessed it, it ends up in your stomach - if you put that in your engine it breaks down the same way contributing to the dirt in the oil possibly causing damage to the cylinders and pistons)! Some manufacturers even void the warranties if they find out you've been using additives!

So, based on the warranty issue (which no longer applies to this vehicle), and my past experience, I am reluctant to use any additives. Even if they do no harm, they are typically a waste of money!

As far as the bearings go, I think I will pick up two bearings and two oil seals and a can of brake cleaner to clean up the differential and replace those old bearings and seals and get this vehicle back on the road. Hopefully the noises will be history. The auto parts store will loan me the tools to pull and re-install the bearings. Hopefully this will go smoother from now to the finish.

 

i left you a mssg. quick, but i guess i missed you (probably under the truck when i called).
here's some info for you, according to two different techs i know (one is a GM service manager, the other owns a transmission shop). they said not to put any in additive in the diff, you truck has a redesigned locking diff in it, and doesn't require it.
as for running synthetic gear oil, there's nothing wrong with using a 75W90 synthetic gear oil in it. the diff will actually run cooler, and it helps to free up your power being put down by the rear wheels. go get the front diff done as well. if you still want to run regular gear oil, that's fine, it's not gonna hurt it. and the Castrol HYPOY C SAE 80W-90 is a good oil to use (it's formulated for the higher demanding limited slip diff's).

 

I won't argue with GM as they should know what is best for their vehicles. They have used the friction modifier in their locking differentials for decades and they still use it today. If yours does not require it I would not add it either. I agree with old skool in that the Castrol you have is good.

I agree that there a lot of snake oil additives out there making big claims that I would not use. I was only referring to using the GM additive when recomended by GM.

Have the vehicle level and the correct amount is to have it at or just below the bottom of the fill hole. Put your index or little finger in the hole and bend the first joint. If you get fluid on the tip of your finger you are good to go as the fluid level will come up slightly when the diff, gets hot. To much fluid can be forced out the seals.

While you are under there make sure the vent on top of the axle housing is open. It looks like a 5/16" or so diameter tube pointing straight up. It should have either a hose on it or a cap on top to keep dirt out. This vents pressure as the diff. gets hot. If it is plugged up it will force fluid out of the seals.

You should be on the downhill side of this project and hopefully it will be easy from here on out.

 

In order to inform those that helped here and to hopefully help others that may be facing the same or similar issue as I did, here is how I finished this job.

I completed the job yesterday.

I borrowed the bearing and oil seal extractor tool set from my parts supplier, (valued at close to $300!) the day before yesterday. I also bought all the parts I needed from that supplier - two bearings and two oil seals for the shafts and a gasket to go with the differential cover for the 7.5 inch gear in my Jimmy. I had previously bought a tube of RTV, a spray can of brake cleaner, and two bottles of gear oil matching the manufacturer' recommended grade formulated for limited slip differentials, so I just used that rather than switching it for the synthetic variety which I considered (I couldn't be bothered to do that, lol). I did not use any additives for this differential as per manufacturers' warning. I had some blue thread locker and some grease in the garage from previous jobs. I also had a scraping blade, rags and sandpaper and other goodies around the house.

So with the tools and parts on hand I started the job early in the afternoon. I am not the fastest mechanic in the land, so it took me about five hours to complete the job with a little help from my son to hold the light and hand me parts and tools for part of that time.

I started by pulling the right oil seal using the seal puller in the tool set I had borrowed. That came out easily using the hammer. Next came the bearing. That was a little bit of a problem at first and I popped two bearing rollers from the old bearing because it was rather tricky to place the edges of the adapter on the bearing race. The kit came with three "adjustable" adapters, none of which fit my shaft exactly so I had to use the hammer on it with the adapter end angled. So it's tricky to keep the adapter angled and not let it slip up onto the rollers, but with added care and my son holding the light right at the end of the shaft I was able to pull the entire bearing out without popping more rollers (projectiles) out in the process. At the start I was turning the end of the bearing puller in the unscrewing direction without giving much thought to it and the adapter shot into the shaft, so I had to fish it out with a wire! From that point on I made sure to only rotate it in the screwing direction while hammering, lol. It was tough and time consuming getting it out because it fit so tight. Then I repeated the process on the left side. As I pulled out the seal from the left side I noticed what appeared to be a piece of thread! On closer inspection I saw it was the spring O-ring that had come off the seal. BINGO - the cause of the noise I was trying to fix. The darn thing had broken and the ends of it were rubbing on the bearing rollers as the vehicle moved! The bearing then came off, still with difficulty but without shooting rollers out like bullets as I used the bearing puller on it. Alas, the old seals and bearings were gone. The bearings themselves were fine but since I had bought new ones and ruined the one on the right pulling it out, I threw both out and installed the new ones. This allowed me to clean out the shafts anyways.

Next, I sprayed a bit of brake cleaner on the axles and wiped them with a clean rag. Then I took a clean cloth and placed it over the differential gears to keep dirt out. Then I took a scraping blade and cleaned off the surfaces of the differential and cover to remove any residue left behind from the old gasket. I then used some sandpaper to sand off any left over residue and rust both from the differential and the cover. Then I removed the rag and sprayed most of the remaining brake cleaner into the differential to thoroughly clean all the parts and let it drip into a pail underneath it. While it was dripping, I took a lint-free long rag and wrapped it around a long stick and while grabbing one end with my hand so I wouldn't lose it in the shaft, pushed and pulled and turned it to clean out all the crud from each of the shafts. Then I went in the house for a coffee and to warm up (it was only about 50 degrees F, 10 degrees C in my neck of the woods), while the brake cleaner finished evaporating from the gears.

A bit later I went back to it. I started by installing the new bearings. They were really tough to push in. I used the heavy hammer handle (weight) and a mallet to bang them in. About 50 strikes later I could see the groove in the shaft that lines up with the outer edge of the bearing race, so it was in place and time to install the seal. I wanted to avoid damaging the seal with the axle spline so I applied a couple of blobs of grease onto the seal rubber part and then placed the seal over the axle first and slid it back about half way, then inserted the axle in the shaft so the seal was roughly in place. I then applied a thin coat of RTV to the outer metal surface of the seal (note that if you place the RTV on the shaft end it will get pushed into the bearings, by placing it on the seal surface any excess amount gets pushed out). I got my son to hold the axle horizontal while I lined up the seal and gently tapped it into place using a small block of wood and my mallet around the axle until the surface of the seal was flush with the shaft. Then I pushed in the axle gently to engage the spline into place; just before pushing it in all the way I rubbed a bit of grease with my finger tip all around the area the seal rubber comes in contact with the axle. The right side was done. I repeated the same procedure on the left side, except I rubbed a drop of engine oil with my finger tip on the end of the shaft to reduce friction, which made installation of the left bearing slightly easier than the one on the right.

Now it was time to get back under the vehicle. I took a clean rag and cleaned out any brake cleaner from the bottom inside part of the differential housing. With both axles pushed all the way in, I inserted the c-clips back on the axle ends. I had a locking pair of tweezers which made the job of putting the clips back a breeze. I wish it had been that easy to get them out, lol. Then I pulled out on the both axles and inserted the pinion shaft lining up the hole through it for the locking bolt. Took a tube of blue thread locker and dabbed some around the threads, then tightened it up. I was ready to cover it all back up.

I then applied a thin coat of RTV all around the differential housing where the gasket goes making sure to go around all bolt holes and placed the gasket on it. I then applied a thin coat of RTV on the cleaned differential cover, again making sure to go around all bolt holes and placed the cover with all bolt holes lined up to fit over the gears (with the big bulge to the left). Then I replaced all bolts with a ratchet as tight as I could (no torque wrench here!) making sure to attach the brake line brackets back on with two of the bolts. One of the bolts was underneath the brake line and I had to tighten it an open end wrench. Next came the gear oil refill.

I realized I could only get about half of the bottle's contents out by squeezing the bottles underneath the vehicle, so I devised a hose/funnel set up I had seen on the net. I took an old washer hose that I had sitting around and cut off the brass connections on the ends. One end fit beautifully and snug into the differential fill hole and I inserted a small funnel into the other end,then used some masking tape to secure the hose to the side of the vehicle. No squeezing required now! I took the complete cap off the bottles and poured the contents slowly into the funnel. When all the oil had been poured, a very small amount leaked out the fill hole into a waiting pail below. I took the fill plug and re-installed that as tight as I could. The little that leaked out may have been caused by the vehicle being raised up on stands, but it was so little I doubt it will make any difference. I then checked the vent tube coming up from the differential which winds around and ends up behind the U-frame behind and near the top of the left tire. It's impossible to see the end without taking off the clips securing it in place so I just felt the end and found the the cap to be loose, so I left it as is.

So with the bearings and seals replaced and the differential serviced, it was time to put back all the brake gear and wheels, clean up, and take the vehicle for a test drive, hoping it is running smoothly now.

Went to start it and it wouldn't start! We had one day inadvertently left the vehicle in neutral (some lights come on in neutral) for a few hours when turning the gears to expose the c-clips, but I wouldn't think that would have been enough to drain the battery. Since the battery light came on in the dash, I'll have to give it a boost and take it for a fairly long drive to see if it recharges or if that is my next job!

I hope this detailed account of my experience helps others doing this job with somewhat more ease than I have gone through. I have tried deliberately to be as detailed as possible for those that may be doing this for the first time; sorry if that bored some of you to tears! I found the experience very educational, very dirty, smelly, and challenging. I can only imagine how much a garage would have charged me for all this or if they would have done as thorough a job! But I know it cost me about 100 Canuck bucks, which isn't much. I wouldn't call this an easy job, but it is doable by many backyard mechanics. Unfortunately the instructions I found online (that I followed) left out many details, as is usually the case with all things auto mechanics. The assistance of all of you that contributed to my endeavor was of great help and I thank you all.

Cheers,

quickcurrent

 

glad to be of help quickcurrent. sorry my schedule got all screwed up, preventing me from getting down there, but at least you have my # now. hope all the noise is history. be sure to give us an update after your run down.

 

Glad you got it done. Very detailed write up.