Please help with some advice

Once upon a time I noted grinding sound from right wheel when cornering. I went to repair shop and they tell me that it was because of axle endplay and endplay caused by dead diff. So they took off diff cover and remove my POSI ( G80 GU5). The gears inside diff were worn in some places. Then they took another such diff and made one out from two, but said that I required a new one. After this grinding sound went away !
Yesterday I received it. It was Zexel Torsen POSI. I just dont understand the PN is YP PGM7.6ZT3-28. What does it mean ? After installation the sound came back from right wheel added same sound from left wheel Just to note that they also tried to install new ring&pinion kit, but failed to place the bearing on gear and had to install the old set.

So, the questions are:

1. What can cause that sound when cornering ? It starts when I turn steering wheel above certain point. The sharper the turn - sound starts earlier.
2. How can I eliminate axle endplay ? If for example C-clips are gone, what I should I replace it with ? What should C-Clip thickness to get rid of endplay?
3. Why the grinding sound disappeared after used diff install and came back after installation of new diff?
4. Its probable that they did some mistakes during diff and axle installation. Can any mistakes did the problem?

Any help very appreciated

PS: Car is 91' 350 Formula with rear disks 10-bolt, POSI, 28-spline axles, Posilube added to rear end oil.

 

I had a similar issue with my 91 Z28. Basically the C-Clips in the axles will have some play. The noise you are probally hearing is the Rotor hitting the brake carrier. That was happening with mine during tight turns. I used thin washers to space the carrier out a little better and the problem is gone. The way i found this is to jack the car up, remove the tires, remove the caliper, put a lug back on the hold the rotor tight against the axle, and then push and pull the rotor and see if it hits the carrier. Mine would hit the carrier when the axle was pushed in.

The only thing i can come up with is that the axles that are being used are slightly longer than the originals. I am talking about 1/16th - 1/8th of inch at most. I also have the rear disc 10 bolt rear. Hopes this helps.

Steve

 

What kind of noise is it? If it's a clicking noise, that's normal from the zexel torsion because it is 100% gear type. No clutches are involved. You also do not need the friction modifier, but I'm not sure if that will hurt anything since it's already in there.

If it's a high pitched whining noise, it could also be the axle bearings worn out. That will get worse on a turn as well because one wheel is turning faster than the other. Replace those along with the races and see if it fixes it.

I'm also alittle unclear on what happened with your rear.

Is it a brand new unit, or one pieced together from two old ones? If it's pieced together from two old ones, the wear pattern won't match up and that will give you a high pitched whining noise during differencial action.

Good luck, and maybe someone else can chime in on the friction modifier with the torsion rear.

 

Thanks for replies, I'd like to clear some things...
The POSI is brand new, this is why I am conused that I hear that noise again. Its not whining, but looks like Steve described. Tomorrow I'll try to check his assumption.

 

Today I visited repair shop. We took off rear tyres, lift them up, started engine, placed tranny into drive position. Then we applied brake to one wheel and 'sound ' could be listened !
So I think that this sound made by diff working ?
The endplay is about 1 mm on one wheel and 1,5 on another.

Who can tell is it normal for Zexel Torsen to produce such sound taking into consideration written above ?

Also, how can I be sure that it works properly ? Please dont suggest to burn the tyres