sykotic

Well I just purchased a 2001 NBM Trans Am last wednesday, it was making some noise in the rear when I bought it and it didn't sound like it was going out or anything from me or my friends experience the sound didn't sound bad and you couldn't feel it. So, I took it to a few performance shops in town, let them drive it and they said its not a whine or a howl, they figured probably bearings. So, this weekend I pull the cover off and checked things, the gears are OK, everything looked pretty normal(without pulling anything apart of course). So I tried some royal purple 75w90 w/ some gm LSD additive. While we had it up on jack stands I inspected the rear brakes because of a horrid noise I was hearing when coming to a complete stop and ended up getting new rear pads and rear rotors.

Now when driving, going straight it has a sort of grainy, kind of grinding noise, what it really sounds like is the drive shaft rubbing rubbing on the floor pan or something metal but I don't think that's the case. If there is a right hand curve in the road and I am turning with it, the noise completely goes away. It goes away at certain speeds in certain gears(or it may be the exhaust drowning it out). The car used to vibrate @ 60 in 5th gear but I didn't notice it last night after changing the brakes(rotors were warped). I did notice a point on the driveshaft where the welds of my catback(borla) were making a ring around the driveshaft, I am not sure if it still hits not or if it just did at one point but it is near the end of the driveshaft by the rear end. My buddy seems to think it is either that or a pinion bearing, but I can't see how turning right would affect a pinion bearing, the exhaust is a possibility in my mind if the exhaust swings or the driveshaft sways one way with the transmission. What about the u-joint?

I know little to nothing about a rear wheel drive car, up until this car everything i've had has been a FWD import. If anyone has anything I can look at or test to try to narrow this down please post it up, I need to figure this out cause it's really bugging me, I can get bearings replaced for free but if I don't have to put money into this rear end, I don't want to. I will eventually be replacing it with a 9" so if I can just get by with this until that point, i'd like to. Anyway, thanks for any input.

YoMommasTA

iTrader: (1)

bad pinion bearings make a whirring sound starting at very low speeds.carrier bearing problem is what you are discribing.the noise will start @ about 20+mph get worse the faster you go and in turns COULD go away because the axles load_unload the carrier bearings in a turn.if you 're turning to the right the LEFT carrier bearing is unloaded...turning the left the right bearing in unloaded.that exhaust rubbing could cause the noise too.be sure to eliminate that posisblity 1st!

sykotic

I'll make sure and find out this week if it is the exhaust, but if it turns out to be a carrier bearing, how difficult are they to replace? Is there an article on here that I can use to replace them myself or is this something i'm going to have to take somewhere to get done, me and my friends are very mechanically inclined and have quite a bit under our belts, just not experienced with a rear end. Does the gear assembly have to come out to replace the carrier bearings? Maybe a diagram/picture of the rear end would help me see what you're talkin about, thank you very much for your input.

YoMommasTA

iTrader: (1)

if you don't mind getting a little smelly and dirty.have access to a press,you can easily change them.plus if you buy the same brand bearings you pull out you shouldn't need to change the bearing preload.look online there are plenty of articles on changing fbody 10 bolt carrier bearings.i would do a cpmplete tear down and inspect everything while you're in there.i would not touch the pinion or pinion bears as long as they feel-check ok.unfortuneatly the 10 bolts carrier bearings are too small to take the constant pounding an ls1 engine can serve up.seems to me to be a very common trouble in ls1 cars.everyone i've taken apart has worn carrier bearings.

Travis99LS1

iTrader: (2)

hey man...i might be missing something, but wouldnt it be the other way around?? If your turning to the right, the left carrier bearing should be loaded, not unloaded. When turning left, the left bearing would be unloaded, while the right side would be loaded. Please correct me if i'm wrong on this.

YoMommasTA

iTrader: (1)

nope,the car tries to continue straight as you turn right causing the LEFT side axle to apply force to the carrier.applying force from the left axle loads the right carrier bearing.


axle bearings might have something to do with the noise too.

Travis99LS1

iTrader: (2)

okay that makes sense...thanks for clearing that up for me!

carado1984

i had a noice similar to yours that i suspected was coming from the rear bc it increased the faster i went.. this was in my old 99 A4 TA, it didnt seem to be getting any worse, but i babied it.. eventually i found myself on a straight away and being the smart person i am, decided to see what would happen if i just mashed it.. 60... louder.. 70.. louder.. 80.. even louder.. 90.. 100... BOOM.... sounded like the back half of my car got hit by a missile.. and then i smelled that awful 80-90 gear oil burning from hitting the exhaust.. a mile later i was at my house, i looked under the car and there was a hole i could fit a marble through in the bottom of the diff. housing.. i dont know what broke but i got a good deal on another 10bolt.. about 300 from a guy who put in a 9", so i put it in and traded it in... i recommend taking it to a quality gm dealer and having them look at it.. i know some places rip you off, some arent bad... sorry i didnt really help you, but, hopefully this doesnt happen to you.. oh and this was all on 245 kumhos, not sticky at all