I think that my rear end is shot and I was looking to get the best approach to fixing it. For the last year or so there is a VERY loud hum/whine coming from the rear of the car ( a 1996 RS 3.8 w/Y87). I thought it was a result from the car sitting for about 8 months and the tires getting hard and maybe a flat spot. Today I jacked it up and took the tires out of the equation. Put the car in drive and the noise was still there. I had a leaky seal in the rear end which I found before it ran out of fluid, but the level did get low.

So is this rear end shot? I've tried changing the fluid and adding the slip addy... but nothing seems to be helping. I called Chevy and they said it would cost me about $2k to fix. I looked up the parts and they aren't that expensive. Is this job a pain in the ****? The only thing that worries me is setting the backlash and pre load.

Anyone know what would be a good setup for a daily driver car? Also does anyone sell a pre assembled 3rd member?

Thanks for any possible help


Also found this how to link
http://www.chevyhiperformance.com/te...148_0207_bolt/

 

Sounds like it could just be a shot bearing. It's possible that it could be something else, but it would be best if you take the cover off and take the axle shafts out and inspect everything before you spend a lot of money... unless you just want to get it overwith and do a gear swap.

If you're not that familiar with how to do it it's probably best if you had it professionally done, because then you'll be getting a guarantee that everything is going to work. Just make sure you shop around for a good price, I've heard 2-300 is a decent asking price for labor. I did my gears myself but it definitely wasn't a fun job. Now if you have access to a lift, a press and some air tools the job gets significantly easier.

 

I've replaced the axle bearings and had the cover off of the pumpkin. I didn't see anything obvious no huge chunks of metal. When I put gear oil in it and added the additive I didn't use any thing special as far as brand... I know that it wasn't LSD fluid.. I thought I didn't need it due to the additive. Was I wrong to do this, does the oil make that big of an impact? As lound as it hums I wouldn't think that fluid would get rid of it.

If I was to only replace my bearings in there (as the noise does sound like a bearing) is this something that I could remove myself and have them pressed off/on? Does this mean I would still have to set the backlash? Sorry for the noobie questions.. never messed with rear end.

 

Well, usually bad gears or ones that are improperly adjusted will make a whining noise, while bad bearings make more of a humming noise. Do you have a repair manual at all? It will make it easier on you for directions. If you take the cover off and the caps off you can inspect the diff side bearings, but you have to take the axles out to check the wheel bearings, and the pinion for the pinion bearings as well.

No, you won't have to set backlash if you replace the bearings. But I would recommend you either get/borrow a dial indicator w/ magnetic base and check the backlash while you're in there, as well as using some gear marking compound to ensure there isn't a problem with your gears. Setting backlash is rather easy, actually. There are shims on both sides of the differential side bearing caps. If you take one out of the left side and put it on the right, you just moved the differential and the ring gear away from the pinion, and increased the backlash.

Pinion depth is a lot more of a PITA, especially since adjusting it requires pounding the pinion back out and removing bearings. But you won't need to do that, the shims are already there. Now you'll need either a brass hammer or punch to get the pinion out, you don't want to use steel on it or you'll damage the threads on the end. The bearing closest to the teeth either needs to be pressed off or you can try cutting it off if you think you're good enough to not damage it. Leave the shims on there and then install the new bearing. I used a pipe from Home Depot, it fit almost perfectly on the race, I can't remember the diameter though. Or you can have it pressed on at a machine shop as well. When you reinstall the pinion you need to set the pinion bearing preload, which is the amount of torque required to turn everything (I think it's everything, I did mine with diff & axles installed anyway). I think with new bearings it should be between 15-30 in lbs.- you'll need a dial or beam type torque wrench, of course. It may take quite a bit of force to get that pinion nut tight enough- it took an impact wrench in my case, that bearing just didn't want to move. Oh, I almost forgot, the crush sleeve in between the pinion bearings needs replaced, it's there for preload, if you overtighten the pinion nut (and preload is too high) you're supposed to start over with a new crush sleeve, so try to be careful and take it slow on that part. I got lucky, it was at 20 in lbs my first try.

So to sum it up, here's what I would recommend:

Inspect gears
Pinion front & rear bearings
Diff side bearings (will need pressed off as well, you can install yourself if you're careful)
Wheel bearings
Pinion seal & wheel bearing seals (the old ones will be worthless when you pry them out)

Well, I hope you understood all that, I know it's a bit much if you've never worked on a rear end before, especially without a diagram.

 

Thanks for the lengthy reply GreenDemon.

How do I check for a worn bearing? Does it become loose or sloppy? I seem to remeber when I found my seal leaking in the rear that the oil smelled burned but atleast I had fluid in there. Would this be from a burned bearing?

I will be picking up the repair manual and all the other parts soon (if needed). Can anyone suggest where I can find these parts. I know there is a lot of places to get them from and a lot different brands. For my application I don't need anything that can take a lot of abuse. My RS is just a daily driver, not planning on any mods. Basically I would need:

1. Rebuild kit (bearings, seals, bolts, and crush sleave)
2. New Ring and Pinion
3. Fluid and additive (do i need LSD gear oil or regular plus the addy??)

I have the Y87 package so I know that I have 3.42 gears back there. Will this be enough info for ordering or do I need to know the number of teeth or size in inches??


Thanks Again

 

Is this your only car? If not I would definitely recommend doing a thorough inspection (some of the things of which I mentioned above) before spending a bunch of money. Especially since you can't really get any more performance by swapping gears 3.42s w/ lsd on a sixer A4 is about as good as it gets, I should know I used to have one- on that note a 3k rpm stall would be cool though . Anyway, inspecting bearings is easy. I assume you've pulled bearings out of the box before, they should look very close to that. Disoloration, distortion, scratches or other wierd marks are bad, and the cage should hold the individual rollers without a lot of slop- you don't want them popping out and tearing everything up. To re-emphasize you really need to see what's wrong with it before you spend the cash (at least I would) to replace everything, or in otherwords, if it ain't broke don't fix it. If you don't feel confident a shop should be able to tell you what's wrong. There's plenty of knowledgeable people on here that can walk you through it if you need help, the inspection is the easy part afterall.
BTW if you still feel like ordering all the stuff you can get it from most performance places (check the supporting vendors section), also summit racing. I got my Motive 4.11s on ebay for 145 shipped, that's where I'd recommend getting them, just look for gears that say they fit late model Camaros, S10s, etc (7.625 or 7&5/8" ring gear).
You just need regular gear oil 80-90 weight (GL-5 spec, which is almost everything now), plus LSD additive, I get mine from Advance Auto, it's in a blue bottle, says Posi something or other on it, says it meets the GM part # specs you'll find in the manual. Put half in with the gear oil and put it in there, save the other half for later. Also there is no LSD gear oil, it may say it's for use in LSD diffs or that it doesn't need an additive but that doesn't mean you couldn't use it in an open diff, all the additives do is change the oils' properties so the clutches/cones don't make noise.
Hope this helps, got more questions, I'll answer the best I can.

 

Brought the bow tie into my mechanic and he put it on a lift and told me that the driveshaft center support bearing was shot... I guess he used the old screwdriver trick to locate the vibration. So I will be picking this up and starting there... didn't even think about that as the problem. We shall wait and see. Any good deals on a one piece shaft?

 

Ebay or http://www.tacreationsusa.com/other_rear_parts.htm

It's a good thing you took it in and got it checked out first, eh?

 

Ummm.. Have I lost my f'ing mind or do they not make a replacement bearing for the ds? I have been on a few different sites and my searches come up empty. And if I was to go with a used one piece is there any special years I need to look for? Also a good idea to change U joints while its out?

 

If you want to reuse the same driveshaft, you'll probably have to pick up that bearing from a dealership, not all V6 cars came with 2 piece driveshafts so it's an item that's probably been overlooked. Otherwise a one piece would be suggested, although I'm not sure about torque arm compatibility, you may have to get a torque arm compatible as well, although you can tell better than I if there are any fitment issues. And yes, it's a good idea to change U-joints, whether you keep the original or get a different driveshaft (anything not new). You'll probably need to take it to a shop to do that, it usually takes a hydraulic press to get those suckers off the yoke.

Oh almost forgot.. any fourth gen driveshaft will work, I think third gen ones work as well. Just check the overall length (yoke and shaft combined), the variance between the two you see doesn't matter as far as I know, although maybe GM had a reason for doing that... they all FIT anyways.