Plasticman

History: Lowered the rear of my 87 Z-52 700-R4 coupe (currently 103K miles) by 1" several years ago (certainly not extreme and the half shafts look pretty level). Rear end was realigned, and tire wear is outstanding. Vehicle handles like new.

Have had a U-joint noise (cycling noise that really does not change with driveline load) ever since, but mostly only when I have a passenger, and only after a few miles (will not make any noise immediately upon start up).

I replaced the half shaft U-joints a few years back thinking that it would solve the noise issue. It did not, although the U-joints certainly needed to be replaced.

The rear bearing are original, and have some play, but do not make any noise that I would attribute to "bearing" issues. The driveshaft U-joints have not been replaced, and have no play, and I doubt that they would cause this type of noise (noise appears to be cycling at tire speed, not trans output speed).

The rear end (3.07) was resealed about 6 years ago (probably 20K miles ago), and new Amsoil synthetic lube installed. No wear was seen at that time, and the posi acts just like it should (2 black stripes when required, and no noise/clunks at anytime).

The tires are older BF Goodrich Comp T/As that have about 60K on them (and are due for replacement pretty soon - but not needed just yet). I discount it being the tires, since I rotate the tires front/rear every 6K miles, and no change in the noise, and the fact that it does not make the noise immediately.

Comments or ideas?

Thanks,
Plasticman

C4boy

Not sure if I can be much help on this, but I did come across an interesting thread a few days ago http://forums.corvetteforum.com/show...ght=half+shaft

Can you be more specific on the sound you're hearing or isolate where it's coming from? i.e., wheel, pumpkin, shafts?

polo91cnvt

Plasticman,

It sounds like your rear bearing(s) are starting to go. I replaced mine at 107,000, after the right rear bearing broke and took out the ABS sensor. Up until the bearing broke it made noise but the bearing felt just fine, a tell tail is red rust in the wheel hub. I would replace the bearings, it sounds like it is time anyways.

Good Luck Polo

Plasticman

Sound is coming from the rear (below the trunk/storage area), but very hard to tell exactly. Could be anywhere in the rear driveline area (pumpkin to the tires). It is a whirring sound that goes up and down in pitch with wheel rotation (or maybe twice a wheel rotation) which sounds to me like U-joints, but they have already been replaced (and made no difference!). It does not change with driveline load, so it is not the rear end gears.

Thanks for the link to the thread. I will be sure to get the teflon coated washers and coat the splines when I do the bearings.

It is interesting that they talk about clinks. I have diagnosed a clink that is coming from the OEM replacement Delco/Bilstein shocks (both sides). I can disconnect them, and the clink goes away. The bushings are like new, and no broken pieces, etc. The clink is coming from internally to the shocks. They operate great, just the irritating little clink. Did find another click that was a loose bushing for the rear anti-sway bar link.

Thanks,
Plasticman

Plasticman

I agree completely that the bearings are due for a change and will do that next. I'll look for the rust signs! I'll probably change the U-joints (again), since I know I did not use Spicers last time.

Thanks,
Plasticman

Casethecorvetteman

Yeah mate, do the bearings, clean the spindles where they go through the bearings while youre at it.