96 Impala SS Rear Axle Noise

Hello to all...I have a 1996 Impala SS with 51K. the car is flawless. I just bought it off of a friend who had it since new. The car from day one has had a rear axle noise. The cover gasket was replaced in about 1998 with the one with the proper lubrication features. The noise is a cross between a rushing sound and a little bit of a howling sound. The oil has been changed a couple of times and the posi additive added. Each time the oil showed no contamination. I have read that some of these axles were mis shimmed from the factory. Does anybody know if this is true and if they are shimmed tight or loose? Also does anybody know what is involved in reshimming them? Can it be done with the gears in the axle or do they have to be removed? Any help would be appreciated. Thanks for your time.

Is it real loud? If it is a minor whining then let it go. Even Richmond gear will not guarantee their gears to be quiet anymore when setup properly. the whine is likely from the Pinion being off by as little as .002" from where it is supposed to be. I setup lots of gears and even when they are right on, they make a little noise. Most don't but some do. you say that they look good and no metal was in the housing? that is good, I really wouldn't wory about it unless the noise bugs you. If it does then I suggest replacing the gears cause these have 51k miles on them of being run incorrectly setup and there is no hope in resetting them now. I have tried that and they will likely just make a different whine. maybe even louder.

Since you said any help, i had a guess. I would think that noisy gears would be more of a function of backlash, then side to side play, as i guess the shims would take up the play. If it were me i would call around to a few transmission shops at there non peek times and ask them. I think there is other components too in there besides gears, like for limited slip, posi traction...etc.. Sorry never had to work on a differental. Went from Motorcycles to front wheel drive.

Some posi units tend to be a little noisier than stock rears. Is the noise fairly constant? If you have a decent auto manual it should have a section on diagnosing differential noises. They will make different noises under different conditions if something is truly amiss. Hunt around online and I'm sure you'll find a helpful chart. Just follow the chart, like coasting, hard acceleration, etc. If the noise is constant all the time and the fluid is free of metal and other debris, you're probably ok.

If you have the rear cover off, look at the wear pattern on the ring gear, that will tell you if the pinion is too deep or too shallow. A good gear chart will have a few pictures of those as well.

Bob

I don't know much about rear axles, but you should get on the ISSCA forum for impala's. Most helpful forum for our model cars I have ever been on. Some of the people on there know a lot and certainly answer your question if you have not already become a member.

Funny thing about the issca page..many people there dont know s$%t!!!