Hey, I have a 1980 corvette with rear problems. I just re-installed the rear differential and I double checked everything so I’m pretty sure my problem is not caused by the installation. When I put the car in gear (it’s an automatic) it feels and sounds like something in the rear driver side is snapping into place. Once I start driving the “snap” goes away until I come to a stop then it happens again when I drive away. Other than that the car feels fine. I haven’t had a chance to look at the car so it could be something simple; I just want to have an idea of what’s going on before I tear it apart again. Thank a lot.

 

Did you add a bottle of positraction additive to the gear oil ? If not, that could be your problem.

 

The dealer didn’t have it so I just figured I’d put it in when it came in. The snap is pretty aggressive; could it really just be that? I hope it is. Thanks.

 

Either that or you didn't get a u-joint back together right. Your local autoparts store should have some posi additive. I got mine in a blue bottle from advance auto. Put the whole thing in and it works fine no clattering at all. I think you can rip apart your clutch packs if you don't run additive.

 

Thanks I'm gonna put some in as soon as I get home.

 

Tough to diagnose sounds on the net. Why don't you take a peek at the car and let us know what you find.

 

Thats going to be your problem. You can buy it at any auto parts store. Shouldn't run it without it.

 

Hey, I put in the additive and drove around, but it's still making the snapping noise. It's not as aggressive but I hear it more frequently while I'm driving. Before, I only heard it when I put it into gear, but now I hear it every time I punch it. Any other ideas? Thanks!

 

Could be a u joint. When i put mine back together one of the clips wasn't put in all of the way and somehow cause a clunking noise. Took me forever to figure it out.

 

U joints was my next guess. Ima take the driver side half shaft out this weekend and replace both u joints.

 

Get the ones that don't have to be greased if your parts store has them. You will know because they won't have any zerks on them and should be labeled as lifetime or something. Just makes life that much easier.

 

I battled a snapping sound coming from my right rear for several months this summer. It would occur as I let the clutch out and started to accelerate. It would go away once I got rolling. It got louder / worse the more I drove it, so heat made it worse.

I thought posi additive, but I knew I had two bottles of the GM additive in the rear. Next I suspected loose or worn u-joints. Thought it was kind of unusual since they were only a year old and only had about 300miles on them. I replaced them anyway, same problem.

I went over the whole suspension with a fine tooth comb checking everything was tight. Found nothing loose.

I had my daughter stand next to the car as I pulled away and she consistently said that the noise was coming from the hub area.

I then suspected something in the emergency brake had come loose. I removed the rotor (didn't want to since they were riveted on) but found the e-brake components intact.

Along the way I had called the company that rebuilt the trailing arms in 2006 (about 500 miles were put on them since the rebuilt). They were very helpful in trying to diagnose it over the phone, but ultimately could offer no solutions. We decided that since I had the trailing arm off that I return it to them for inspection of the bearings. When they got the arms back they went through them and could find nothing wrong. The bearings were fine. I had them put new bearings in. They reassembled it, put the rotor back on and sent it back to me. They even went so far as to cut me a break on the cost so that I pretty much just paid for the parts and shipping. Plus they turned it around in two days so I could have it back for the weekend!

Put the trailing arm back on and success! No more noise!

So what was the problem? I really can't say for sure, but I would suspect that there was something binding up in one of the bearings. I really can't say for sure. All I know is I spent a lot of time and effort tracing down this problem only to not know what it was!

Good luck finding the problem.

Tom

 

Ok.... So i finally came home and had some time to look at the car. I drove it around and it seemed more aggressive now,[ I hear the snap when the car downshifts coming to a stop. I lifted the car, and everything looks fine so I decided to put the car in gear and let the tires role to see if i noticed something different; I heard nothing. When the car is in the air with no weight on it theirs no snap. Does anybody know why this is? Any help is appreciated. Thanks!!!

 

Check that the yokes are not making contact with the differential. If the strut rods aren't set right it will give you enough play for this to happen. Check your leaf spring. Does it look intact? how do the ends look? It sounds like a u joint though. U joints usually sound like a clunk. Does it happen when you put in reverse also?

 

It could be the front differential mount.
Zip calls it PINION SNUBBER CUSHIONS
Product Number:SU-390

 

Sounds like a ujoint to me-especially taking weight off of rear and not hearing it.Take out the shafts and check for a ujoint thats loose you will no it when you see it-if they all look fine and none are extremely tight to move put them back and let us no.When you have the car up in the air both sides push the tire back and forth hard to see if their is excessive play in the bearings.

 

[QUOTE=corvette744;1568336905]...Take out the shafts and check for a ujoint thats loose.../QUOTE]


its funny how easy that sounds on paper

 

Thanks for the responses. The car does not make the noise in reverse.

 

Never turn the rear wheels if they are not supported.
Don't let them hang and run the car!
Sly

 

Based on the information you have given, I would check the pinion snubber cushion too. According to your information the noise occures when you put it in grear, when you step on the gas, when the tranny down shifts..... All of this equates to torque trying to rotate the rear end. Check all the components that are trying to abate this.