Rear end noise - bearings perhaps?

[chevyaddict]

HI all;
My 81 Corvette has this strange clunking/clinking noise in the rear end. I just had the entire rear end rebuilt by a very reputable place so I don't suspect it is in the internal workings of the member itself. I also replaced the u-joints when I put the rear end back in. I was curious what it sounds like if the rear wheel bearings are going out. Will it sound like a bad u-joint? It is pretty loud (when it makes noise) and I think it is in more of the right rear but can't be sure. It tends to make the noise more when I make left hand turns. When I am going straight it comes and goes. However, I also notice it alot when shifting from park to reverse than into drive. I realize it could be the member itself but I was wanting to see if there was a sure way to determine if it was the wheel bearings instead (FIRST). I am sure they have never been replaced. When the noise comes though it is pretty loud. Any ideas? I know this is vague. Is there a good way to test if it is the bearings? The problem is when I raise the car up and the weight is taken off the tires the noise goes away and I have no way to test it under a "load". Any advice?
Thanks
Dawn

 

[wishuwerehere82]

Dawn,
If the bearings are severely worn, when you jack the rear end up, the wheels will have some play in the axle shaft, and you will be able to wiggle the wheel top to bottom.
The tolerances are very tight in the rear bearings and if you have any play at all, they are probably wearing.
There are also parts inside the emergency brake that could be making the noise.
I know you said that you replaced the U-joints, did you replace all of them or just the driveshaft? There are 4 more of them on the halfshafts. They will click /clunk if they are bad.
I you have a freind that trusts you well, they can get under the car and listen to where the sound is coming from when you shift from forward to reverse and back again. That may give you a better idea of the area that is involved.

 

[C3RVETTE]

I just replaced all my u-joints,and my wheel bearings.I have a clunk when I take hard turns only.I also have to wait for the rpm's to come down to shift the auto tranny into reverse,or I get another loud clunk as it engages.I have also replaced the "snubber" with a poly one.I have a '79.

 

[chevyaddict]

Thanks wishyou...
Actually, I replaced all u-joints EXCEPT the main drive shaft; I don't know why now come to think of it. I have had some underneath it to listen but when their is no load on the tires it doesn't make the noise. I don't recall alot of play in the rear wheels but I'll jack it up and try again. The car has been sitting for eight months because I didn't want to drive it but I have to run it through emissions this month so thought I would take another stab at it. The emergency brake cable is interesting - I never thought of that. I'll check that out too!!
Dawn

 

[wishuwerehere82]

Hey Dawn,

Did you ever solve the problem?

 

[C3RVETTE]

Thanks wishyou...
Actually, I replaced all u-joints EXCEPT the main drive shaft; I don't know why now come to think of it. I have had some underneath it to listen but when their is no load on the tires it doesn't make the noise. I don't recall alot of play in the rear wheels but I'll jack it up and try again. The car has been sitting for eight months because I didn't want to drive it but I have to run it through emissions this month so thought I would take another stab at it. The emergency brake cable is interesting - I never thought of that. I'll check that out too!!
Dawn

I havent taken the time yet to track down my problem yet.Mostly because it doesnt sound bad unless I dont follow the "procdures" I mentioned earlier,and because I dont drive my 79 alot.But I'll get to it.Dawn,I read your homepage profile and am quite impressed and like what your doing concerning the environment. Plus,your a Camaro,Corvette,etc.freak,too! Hey,wanna sell one of your Caminos?:confused :cool

 

[chevyaddict]

Heck no! No selling here!! I don't know what that word means! Yes; I'm very passionate about my environmentalism - hope using science as a means will be more fruitful than tying myself to trees and bombing fishing boats.

Its funny I get two posts today about this because I am working on cars as we speak! Dually brakes, 81 power steering leak and new front right caliper, 68 Camaro starter, 71 camaro starter, 84 Dually leaky rear wheel cylinder and 84 corvette front end rebuild. Have all but the last two completed. As soon as I get done with that I am going to jack up the 81 once again tosee if I can see anything visually. If I can't then I'm just going to have to take it to the rear end shop (I hate having other people 'round my cars) but I have no way to test it under "load" with the wheels down and they can so perhaps they can at least identify it. I'll definitely keep you posted. I took it through emissions couple weeks ago and the noise was really loud and "clunky". Yikes - didn't like it at all. You would think with all that noise it would be obvious! I'll definitely let you guys know if I find anything!

 

[C3RVETTE]

"Yes; I'm very passionate about my environmentalism - hope using science as a means will be more fruitful than tying myself to trees and bombing fishing boats."
Yea,I tend to believe that would be a big waste of time...a little counterproductive,eh? It definately sounds like your more "handy" around cars than I am,plus I dont really have a place to work on them anyway.Good luck on your repairs,and do fill me in on the Corvette noise when you get there.

 

[crause]

Before you go crazy, let me offer a very easy solution to your problem. First, mine did the same thing when I bought it and the key to determining the problem is the left turn issue. I sounds to me like it is a rearend fluid issue. Do you know if the shop put in the GM additive that is required for our corvettes? If they did, what type of diff. lube did they put in? The first time I did mine I sucked out all the old lube and put in a tube of the additive but for some stupid reason I bought some "Slick 50" gear oil and put that in there. What a mistake, it still made the noise you described but just not as bad. I posted here and was told that the Slick 50 was the problem because our rearends are very particular about their fluids. My solution was to suck all of the stuff back out and I went to my local Chevrolet dealers parts counter and bought GM differential fluid (yes I paid a little more) and another tube of the GM additive. Outcome: not another peep out of my rearend, I forgot I even had the problem it runs so quiet. Good luck.
Andy

 

[C3RVETTE]

Before you go crazy, let me offer a very easy solution to your problem. First, mine did the same thing when I bought it and the key to determining the problem is the left turn issue. I sounds to me like it is a rearend fluid issue. Do you know if the shop put in the GM additive that is required for our corvettes? If they did, what type of diff. lube did they put in? The first time I did mine I sucked out all the old lube and put in a tube of the additive but for some stupid reason I bought some "Slick 50" gear oil and put that in there. What a mistake, it still made the noise you described but just not as bad. I posted here and was told that the Slick 50 was the problem because our rearends are very particular about their fluids. My solution was to suck all of the stuff back out and I went to my local Chevrolet dealers parts counter and bought GM differential fluid (yes I paid a little more) and another tube of the GM additive. Outcome: not another peep out of my rearend, I forgot I even had the problem it runs so quiet. Good luck.
Andy

I recently drained all mine and put Amsoil synthetic in that contained posi additive,plus added some GM additive with that.And yes,I'm crazy..thats why I have a Corvette

 

[chevyaddict]

Well, I'm about 90% positive I added the proper stuff. Yesterday though the noise clunked REALLY LOUD shifting from drive to reverse. So I still think it is a u-joint issue - perhaps one oft he joints I put in was bad from the factory. Having said that, your suggestion just may be an easy fix so just for giggles I am going to go rebuy the proper additive and lube and put it in there. Can't hurt. At least I can be absolutely certain that isn't the culprit!

Thanks muchas!
Dawn

 

[C3RVETTE]

Well, I'm about 90% positive I added the proper stuff. Yesterday though the noise clunked REALLY LOUD shifting from drive to reverse. So I still think it is a u-joint issue - perhaps one oft he joints I put in was bad from the factory. Having said that, your suggestion just may be an easy fix so just for giggles I am going to go rebuy the proper additive and lube and put it in there. Can't hurt. At least I can be absolutely certain that isn't the culprit!

Thanks muchas!
Dawn

Dawn,I replaced ALL my u-joints..whats that-6?...& I bought Spicers...and I still have the loud clunk at higher rpm's going into reverse,unless I wait until the revs come down.Theres just a small clunk taking hard rights or lefts sometimes.

 

[chevyaddict]

Well, that gives me some hope then. What concerns me is that I didn't have any clunking whatsoever until I had the rearend rebuilt. Like I said way earlier in these posts - it is a very reputable shop so I just don't wnat to believe they messed something up AND I also don't want to believe that because I don't want to tear the darn thing back OUT again! I'll try the lube and keep y'all posted.
Dawn

 

[C3RVETTE]

Well, that gives me some hope then. What concerns me is that I didn't have any clunking whatsoever until I had the rearend rebuilt. Like I said way earlier in these posts - it is a very reputable shop so I just don't wnat to believe they messed something up AND I also don't want to believe that because I don't want to tear the darn thing back OUT again! I'll try the lube and keep y'all posted.
Dawn

I've had suggestions that its possibly tranny or diff. mounts,too.

 

[Bob Chadwick]

That clunking from first to reverse and back could be the front differential bushing. If it were me I would pull the diveshaft, re do those u-joints and replace that front bushing.

 

[C3RVETTE]

That clunking from first to reverse and back could be the front differential bushing. If it were me I would pull the diveshaft, re do those u-joints and replace that front bushing.

If you're referring to the bushing sometimes called the "snubber",I replaced that also,with the poly version.

 

[Bob Chadwick]

I was. The poly unit changes the angle on the drive shaft slightly. If you didn't replace those u-joints it's possible that the change is stressing them.

 

[C3RVETTE]

I was. The poly unit changes the angle on the drive shaft slightly. If you didn't replace those u-joints it's possible that the change is stressing them.

To try & fix the "clunk",I replaced the "snubber"...no change.Then I replaced all 6 u-joints when I had the rear wheels bearings replaced...no change(At least concerning the "clunk").What is next on the list thats least expensive? I just got laid off :cry

 

[wishuwerehere82]

Welcome to the unemployed Corvette owners club. I wonder how many more of us there are?

From my experience, waxing and cleaning are the two cheapest ways to spend your time. Any time you get the urge to get parts...STOP.
Good luck in finding a new job.

Pete.

 

[C3RVETTE]

Welcome to the unemployed Corvette owners club. I wonder how many more of us there are?

From my experience, waxing and cleaning are the two cheapest ways to spend your time. Any time you get the urge to get parts...STOP.
Good luck in finding a new job.

Pete.

Great! Thanks for cheering me up AND solving my problems,too! You know we only work to support our vettes anyway,rite:confused