Vette 460

my '02 Z06 has a whine from the driveline when driving at highway speeds in 6th gear, I thought it was the differential, it gets louder if I ease off the throttle, and it seems to be getting louder in the past few weeks, especially around 75-85 mph. If I push in the clutch it stops. Does anyone know what would cause this?

Bobbo76

I might have some unfortunate input on this one based on experience. Depending on power output and driving style you maybe facing what I went through and it's not completely uncommon.
I might not have this completely correct but you'll get the jest. There is a tapered roller bearing at the rear of the trans supporting the main shaft. When that bearing fails all hell breaks loose... literally.
Mine had similar symptoms and what ended up happening was after a spirited pull (694whp) I got a trans high oil temp warning. I pulled over and had no reverse and reeked of hot trans oil. I was able to limp the car to safety.
Please don't take what I'm telling you as what is going on with yours but some of your symptoms are the same as mine. You would be wise to get an oil sample tested for more info.
Here's what my trans looked like after we managed to get it apart.

This is where the tapered bearing "was". You can see where the gears cut into the back of the trans case.


There are magnets on the bottom/rear of the trans case. This is all of the accumulated ferrous material. JUNK.

I wish you more luck than I had.

Vette 460

Thanks for your quick response.
Did the whine stop if you pushed in the clutch? The transmission would still be in gear when freewheeling?
I will get the trans oil tested. maybe I should get it changed too.

Bobbo76

Regretfully I don't have a good answer for that. My diff was making so much noise at the same time that locating the noise (on top of engine noise and supercharger noise) wasn't really an option.
The more I think it seems less likely your issue was the same as mine.
Here's another suggestion... Do you have access to a hoist? If so put the car up, and with the car running induce the noise. While the car is making the noise use a stethoscope or the screw driver trick touch the torque tube, trans, bell housing and see if you can locate it.
It may just be a bearing going in the torque tube. You'll still be dropping everything from the bell housing back but the repair cost would be substantially less.
Let us know what you learn! Best of luck!

norcalace

If the sound is coming from the differential, which I would suspect first, the reason the whine goes away with the clutch in is, as the car is now coasting it is receiving no forward pull from the engine and basically no engine braking when decelerating. So when coasting there is no force applied to the diff and whether it’s gear mesh, bearings etc internal to the diff it will not exhibit any whine. Changing the gear oil in the diff as well as the trans fluid is a good start to look for foreign material. Good luck.

Vette 460

Thanks, I will change and inspect the fluids in the trans and the differential.

Bobbo76

Given that clarification and I literally just had mine rebuilt (put the rebuilt diff in yesterday) I learned that the pinion spacer/bushing can compress taking the ring/pinion lash out of spec.
If you do find that you're going the route of rebuilding the diff there are lots of good parts available HOWEVER the trick is the special tools required. If you're going to do it yourself here is an AMAZING wright up:
Rear-gear Swap/Differential Rebuild How-To - CorvetteForum - Chevrolet Corvette Forum Discussion

acroy

Only in 6th, and only when coasting, and only when in gear?
The more details you can provide the better.

Vette 460

That's exactly what it sounds like. I don't think I'm equipped for a DIY rebuild. but thanks for the info, I'll study it.

Vette 460

I think it was louder in 6th but it's in all the gears. My other Vettes have the same whine, just not as loud. When coasting with just a little throttle it is the most prevalent. When you put the clutch in it stops most of the time.
The car has 46K miles.