2000 Z28 with M6 trans. What is happening is when I turn more than say 45 degrees, the drivetrain is making a pretty audible groan. Sound is worse turning left, but does happen when turning right. Mods that might be applicable are UMI adj torque arm with transmission relocation bracket, BMR springs (1" lower), UMI adj lower control arms, LCA reloc brackets, UMI adj panhard. I've only just noticed it recently, but nothing has been changed within the past year (except for the addition of headers and y-pipe).

Is it just the torque arm relocation bracket and stiffer bushing that's causing it? Any suggestions?

Thanks!

 

does this only happen when turning? If so check tie rod's , ball joints ect.....

 

The noise is coming more from the middle of the car, not the front, which is why I think it is not steering related. I have to check out a brake squeal, so I will check the front end too, but I'm not expecting to find anything there.

 

I'm having the EXACT same issue on my 2001 WS6. Very similar suspension mods as yours also. I'd be very interested in hearing if you locate the problem. I have spent A LOT of time under the car trying to figure this one out. Nothing yet.

 

I checked my tie rods, ball joints and the like this past weekend, didn't notice anything out of the ordinary. I did notice that all my ps fluid was gone (again, that's been happening for a LONG time), so filled that up, and haven't noticed any noise while moving and turning.

My noise seems to happen mostly at slow speeds, like doing a tight turn in a parking lot. My mechanic had told me that he'd noticed these cars make a lot more noise once they are lowered, and with the torque arm relocation mount. I have noticed a slight increase in rear end noise, but nothing major, and certainly nowhere near the groan when turning. My guess is the stiffer bushing for the torque arm and the more solid tranny mount is where the problem lies, but I don't have the resources or time to figure it out.

My wife thinks it is the wheel rubbing against the inner fender, but there are zero signs of the tire rubbing. Maybe with the stock engine mounts there is some twisting? I'd like to get a new K-member too, and that would test that theory!

Maybe with the tax refund I'll get it checked out. But of course, it's one of those things that doesn't happen consistently.

 

My 93 made that same noise when the differential was about to take a ****. Not the ring/pinion.. the diff itself.
Only when turning at low speeds.
FWIW I did notice it more after I lowered the car for whatever reason. Maybe slightly different pinion angle made it worse.
It had an Auburn.. replaced it with a stock SLP piece for $100.

 

My diff went about 2 years ago, replaced with an Auburn Pro unit. I certainly hope that's not it! That was a $650 part (Cdn funds). If that ended up it, I'd probably just replace the entire rear as I'm still on the stock unit (except for diff).

 

My noise is not the diff. I'm fairly confident it has to do with the lowering and other non-stock suspension parts. I suspected my Power Steering pump but that wasn't it either.

 

That is what I suspect also. I have an adjustable torque arm, and it was set by my mechanic (who deals with a lot of performance vehicles), and the bolts are all tight, so the pinion angle should be good. Maybe I should have them check the panhard bar? Maybe the rear isn't centred anymore?

 

I have an adjustable panhard bar that hasn't been touched in 20K miles or more. Hmmmm...

 

After a little research on the internet, it seems these symptoms generally refer to the diff and changing the fluid and putting in the proper additive fixes the problem. I just had my rearend gears changed out about 3K miles ago. The guys who serviced it said nothing about changing the fluid after break-in. Does anyone know if it is common procedure to put fresh diff fluid in shortly after break-in?

 

Not sure about that but it does need some kind of additive for limited slip

EDIT: After reading some I guess most syn fluids have limited slip additives already in them.

 

Hmmm.....my diff was changed about 2 years ago, and about 2-3 months after it was changed, the fluid was changed and the additive added. Maybe just a diff fluid change is in order?

 

I've heard different stories from different people on this one. I just put Richmond 4:10 gears in mine and the guy who did the work said as long as I broke it in the right way (2 or 3 full heat cycles) I shouldn't have to change the fluid for a long time. I have noticed that a lot of others say that you should change the diff fluid within 1000 miles of a new ring and pinion change because that is when the majority of wear occurs during break-in so you should get fresh gear oil and additive in there soon.

I guess it's an easy enough procedure to just do it whether it needs it or not and see if it makes any difference with the groaning.