Stephen68

Hello everyone, i have a very strange vibrating/howling in my car at speeds over 45 to 50 mph. The inside of the car is noisy almost like tire noise and on decel or steady cruising with the cruise set on 70 i have a sound that almost sounds like a vibration until i get back down to a speed under 45 or so. i raised the car and checked the rear and front u joints as well as the aluminum drive shaft but there is no play nor leaks. like i said, its mainly like a vibration noise at steady speeds above 50 mph and on decel....The car is a 1998 TA with the T56 and around 180k miles. i just got it so i am not sure what has or hasn't been done to it but it looks all stock. looks and runs great other than the dang howling/vibrating/sound...what or where should i start my trouble shooting?..

gaedbo

You may want to consider pulling the driveshaft and having it rebalanced at a specialty shop. They can evaluate the balance and the u joints for you. It is not that expensive to have done if you pull the driveshaft yourself. You would eliminate a potential issue without spending a lot of $

Stephen68

i really appreciate the info gaedbo, after taking it to the garage today and lifting the car the mechanic determined that the problem is my flywheel. we have decided to drop the tranny and install a new kit with new clutch, pressure plate and flywheel. someone before me had already replaced the drive shaft and all u joints.

gaedbo

Really glad you got it figured out. Hopefully that is the end of your woes, and now you can enjoy your 98 Trans AM.

Stephen68

Well, after taking it to a 2nd mechanic today for another opinion, i was told that the noise is a bearing going out in my rear differential...Also said it would cost me $800 to rebuild it. This mechanic actually took my car out and drove it after i insisted. Can anyone tell me a procedure that i can do to verify if i n fact i do have a bearing in the diff. going out before i tear down something that may not need to be? Thanks!

gaedbo

Two different mechanics with 2 different opinions. I haven't been involved with this problem ever, but am wondering if the driveshaft was disconnected to isolate the 2 suspected areas and then some type of inspection or testing can be done to confirm either one of the opinions.

Hopefully others with experience will jump in to help you out.

Chimera96

I would confirm your drive line angles are correct.

Is there aftermarket rear suspension mods?

Do you have lower rear gears than stock?

Lower rear gears can bring drive shaft speeds up and cause vibrations. A better balanced wider aftermarket DS would resolve. You could try and get the stock shaft re-balanced....is there any sign on the DS that it was hit/bent causing the vibration?

Regarding the mechanic that said flywheel...they really don't go "out of balance"..

Injuneer

If its an accurate diagnosis, seems excessively expensive. Complete rebuild kit will cost about $100-125. Labor should be $250-350