SoSlow1

I posted this in the tech section and got one response so decided to post up here to see if I can get more feedback..

I guess I should've worded that differently but I'm looking for some input on this problem. I've done a search and have read just about every thread there was started on this and it seems to be a common problem.

A little about what happened. I installed this rear end in the car at the end of last year. Its a 3.42 3 rib Z06 rear end . It had about 20,000 miles on it when installed and after I got it back the rear made no noises at all. I've put about 10 passes on the car since the install and had no problems. This past weekend we went to our local track and after the 2nd pass it started whining. I have a DTE brace on it and the car didn't wheel hop which I've heard will cause it to whine or have other major problems.

The car on the accel side and the decell side is dead quiet. But once in the cruise area it has a distinct gear wine. I did drain the fluid once home and really nothing was found in the bottom of the drain pan once it settled. The rear has no leaks and it wasn't low. I did go with a little higher viscosity oil and it is a little quieter but the whine is still there. Between 65-70 is about the worse and the faster you go it does kind of subside somewhat. We did check the wheel bearings and they are both good.

I have the original 3.15 rear that I know is good and could reinstall it but my question is how many people just put up with the whine ? I've also been told if its just a gear lash problem I should be able to drive the car and just put up with the whine. Any help will be greatly appreciated..
Thanks

easyvette

I had a whine once... And when the rear was disassembled we found some of the main gear teeth were cracked. The good thing is I removed it had it taken care of before it had the chance to totally come apart and possibly destroy the case. I guess the car could survive with the whine, how long? I think reguardless you need to have it looked at.

ragtopws6

The diff whines due to too much backlash. When the dimensions stay the same and the backlash increases, that means the gears are eating itself. Most of the times when you drain the fluid, all or most of the metal debris is caught by the magnet. Have you seen a magnet that looked like a dome? The whine will only get worse. Better to have someone replace the gears than destroy the bearing/diff. Good luck.

SoSlow1

Thanks ragtopws6 ..The car is going in Monday morning to put the original 3.15's back in because we know that rear is dead quiet. The same shop is going to take the 3 rib apart to see just waht happened to it..

Chris Stewart

The symptoms sound familiar. Does it sound like this video? Mine was cured with a new polished ring & pinion from RPM.

SoSlow1

Same exact sound Chris. What I don't understand is how a rear that went in quiet and with only a handfull of passes at the track all of a sudden has a lash problem ?? Although the only good thing about this whole deal is I can get the 3 rib freshened up and have a good spare..

dogboy

dogboy

That sounded just like mine also. It looked real bad when the oil was changed per my mechanic. I started getting a lot of clunking also as if a universal joint was bad. ( I know we don't have those in C5's). New RPM unit in now & quiet as a mouse.

4DRUSH

That don't make sense. Have the 3:42 (3 rib) re-build while the car is apart & put in back in. Only takes a hour for the re-build.
Why put the old one back in and eventually pay to have it swapped out again.

SoSlow1

Beleive me 4DRUSH I thought the same thing but I don't trust anyone in our small town to attempt setting up or even rebuilding the rear. The shop that does my tranny work even though they are great transmission rebuilders aren't setup to rebuild rears. Plus they do cut me good deals and look forward to getting my car in their shop because its the only performance car in the area they work on.

The wife and I have a few roads trips to make coming up and the 3.15's are dead quiet since being reinstalled in the car..
Thanks