Dealer blaming rear dif noise on lowering of car.

[Dion_1969]

I have this grinding noise only when pulling a u-turn and accelerating fairly hard. The first time I took it in they couldn't reproduce it and couldn't find any bulletins themselves. They actually told me they couldn't change out the fluid because the exhaust was in the way. I have an after market cat-back exhaust with clamps at the axle back. I knew there was a TSP so I found it and took it back. I had to explain that my exhaust would be easier to deal with than stock. They still couldn't reproduce but I had my dealer do the fluid change and additive per tsp. They added a note about my car being lowered. Now I have called again because the noise is still there. The service department is telling me that because it is lowered they most likely won't be able to help me.

So will lowering cause any problems with the differential? CV joint?

This actually started before I lowered it but they have no record of me telling them. I told them but at that point It had only happened 2 times and I wasn't sure exactly what the noise was associated with. They service guy told me to figure out exactly when it happened and bring it back.

[The Stig]

Find a new dealer. Lowering wouldn't cause that.

[V1c1ous]

I am having same issue. I did take it to the dealer last fall. I made over 100 laps around the lot and couldnt get it to reproduce, and this was before I lowered it. It seems like its getting worse now and have an appt for next week. And I agree, lowering has no effect in the rear end.Nor the shifter, CAI or painted engine cover that I installed. I will post up when I get her back from the dealer.

[Robert91RS]

Possi diffs make some noise guys. Are you sure what you are hearing isn't your diff doing its job?

[V1c1ous]

I did find this on the forum.

[Robert91RS]

Very similar to the TSB for the corvette diff. Just the sound of a properly operating clutch type posi trying to make both tires spin at the same rpm while your steering wheel is forcing them to do the opposite.

[Dion_1969]

Originally Posted by V1c1ous

I did find this on the forum.

Thanks for that but I took this in and they did they fluid change and additive. It has not helped. I'm worried that there may be some permanent damage. Guess I'll put in new gears when it breaks

[Dion_1969]

Originally Posted by Robert91RS

Possi diffs make some noise guys. Are you sure what you are hearing isn't your diff doing its job?

Originally Posted by Robert91RS

Very similar to the TSB for the corvette diff. Just the sound of a properly operating clutch type posi trying to make both tires spin at the same rpm while your steering wheel is forcing them to do the opposite.

Guess I'll have to live with it for now. Thanks for the reply! maybe a new gear ratio is in my future.

[Toyaholic]

They did he same sh*t to me with my truck. I put a 6" lift on it and they blamed the front driveshaft noise on the lift. They canceled my drivetrain warranty! I had them change the fluid and the noise went away. They still won't say they will honor future drivetrain issues.

Know your dealer! That's the best advise.

[V1c1ous]

Also its like Robert91 said. If you are doing a U turn and mashing the loud pedal the rear end is doing what its supposed to. Its slipping on the "inside" axle ( depending on what direction your steering wheel is) so some thing doesnt break. Probably shouldnt do that with this set up, you might end up with a "one tire fryer" !?

[My 5th]

Did you put urethane diff bushings in? With harder differential bushings the rear end will make more noise when turning. Mine howls like a banshee on turns since I put the Pedders street bushings in mine. I lowered it first with Xa coilovers and it didn't make noise until I added the bushings later. Changing the fluid didn't help. Next, I'm trying another fluid change, but add more additive to see if that helps.

[Dion_1969]

Originally Posted by V1c1ous

Also its like Robert91 said. If you are doing a U turn and mashing the loud pedal the rear end is doing what its supposed to. Its slipping on the "inside" axle ( depending on what direction your steering wheel is) so some thing doesnt break. Probably shouldnt do that with this set up, you might end up with a "one tire fryer" !?

That is exactly what i'm doing. It makes since that a limited slip dif would do this I was just not expecting it to grind. Since several people have made this same comment I'll go with it.
Thanks

Originally Posted by My 5th

Did you put urethane diff bushings in? With harder differential bushings the rear end will make more noise when turning. Mine howls like a banshee on turns since I put the Pedders street bushings in mine. I lowered it first with Xa coilovers and it didn't make noise until I added the bushings later. Changing the fluid didn't help. Next, I'm trying another fluid change, but add more additive to see if that helps.

No I haven't but I am glad you mentioned it. I was going to do this sooner or later. Now I may reconsider.

[Dion_1969]

Originally Posted by Toyaholic

They did he same sh*t to me with my truck. I put a 6" lift on it and they blamed the front driveshaft noise on the lift. They canceled my drivetrain warranty! I had them change the fluid and the noise went away. They still won't say they will honor future drivetrain issues.

Know your dealer! That's the best advise.

Good Point!

Anyone know a mod friendly dealer in the Tampa Bay Area- Pasco, Pinellas, Hilsborough?

[Chevrolet Customer Svc]

Originally Posted by Toyaholic

They did he same sh*t to me with my truck. I put a 6" lift on it and they blamed the front driveshaft noise on the lift. They canceled my drivetrain warranty! I had them change the fluid and the noise went away. They still won't say they will honor future drivetrain issues.

Know your dealer! That's the best advise.

Good advice Toyaholic. Also I am sorry to hear that your powertrain warranty was voided over this issue. It's another good piece of advice to consult your dealership before going through with modifications if you have a newer model year vehicle like the Camaro or apparently like your truck in your situation. Hopefully we'll be able to be of more help in the future.

Jeff Morris, Chevrolet Customer Service