Rear End Noise Aahhh

[98gpking]

i got a 1996 trans am WS6. i just bought it like 2 months ago. im not sure what all the guy did to the car but i know he has some work done to it. anyways i was pulling into a parking lot today and i kinda went to fast not knowing the entrance had a bump there. my rear end sounded like it smashed to the ground(maybe just my struts maxing out) now whenever i take my foot off the gas rather im going 2mph or 100 it makes like a loud grinding noise. it only makes the noise when i let off the gas. i dont know what it is, my granfather thinks its the front bearing because it only happens when i let off the gas. im wondering if my gears are just stripped the car still pulls hard and seems to be ok its just the grinding noise...who knows maybe its normal for these cars and i just never noticed it now im being parenoid(but i dont think thats the case) so what should i do. should i buy a whole rear end off ebay and rebuold it with 3.73 gears making it posi. or just try and fix this rear end. lemmi know what you guys think is wrong with it. oh yea i just replaced the rear end fluid in it after it happened. thanks

vince

[FormulaForce]

I'm no expert but I wonder if you twisted or bent the whole rear axle in it's mountings if the bottom of the differential case hit the bump. That would throw your driveshaft/rear-axle u-joint out of alignment in an up/down way, and put strain on the bearings. These cars are very sensitive to driveline alignment and balance issues. My 95 gets that "let off the gas" vibration at high speed even with a carbon driveshaft. That would be my guess if there are no dents in the differential housing that would affect the ring and pinion gears. As a WS6 your car should already have a limited-slip rear axle, so getting a used one wouldn't make any difference unless your housing is really damaged. You can get different gears for about $200 new (parts only), but they need to be installed by someone with experience or you risk bad gear meshing and whining. If you put in new differential fluid, you need to include limited-slip additive as well. Just my 2 cents worth, good luck.

[gmack221]

Sure hope you put in the limited slip additive, or you just took years off the diff case life, but if you did you should double check your fluid level, if all is well there put the rear axle on jack stands and remove the drive shaft, see what kind of slop you have between where the driveshaft mounts & the rear tire (hold tire with foot & turn driveshaft flange). Should have a little slop there but not too much. Take a look at your u-joints on the drive shaft, move them around and make sure they are free (I had some dry out and rust up, they were tight but made a squeaking noise, got a lot of rust out of each cap, wouldn't have been long and the bearings would have been bad and I could have broken a u-joint & did damage to the vehicle when the driveshaft came off).

A front bearing will make a noise when it you reach a certain speed, when you turn it will get worse or better based on which way you turn.