E30 Drivetrain noise

[Leonstt]

Hi guys,

I notice when I was driving down a highway, I heard some sewing-machine like noises coming from somewhere in the driveshaft/diff area of my car. The noise sounds like a rotating part touching something and only noticeable when doing 40mph and above and gets worst when the road is bumpy. And dissappear as I slow down. Anyone has any idea what is going on with my Drivetrain?

[Leonstt]

https://streamable.com/az28vg

here's a video showing how it sounds

[tomstin]

You need to get under the car, my guess is the flex disk (rear of the transmission) (which you can see without removing anything) or the center support bearing which you need to pull the rear exhaust and shields to inspect. Also, the rear universal joint at the rear of the driveshaft which you can also inspect without removing anything.

[Leonstt]

You need to get under the car, my guess is the flex disk (rear of the transmission) (which you can see without removing anything) or the center support bearing which you need to pull the rear exhaust and shields to inspect. Also, the rear universal joint at the rear of the driveshaft which you can also inspect without removing anything.

Thanks for the reply

Would failures of any of the parts you mention cause vibrations? I don't feel any vibrations at all. Just the noise

[tomstin]

I would expect the universal joints to make more noise than vibrate. The flex disk and center support bearing tend to vibrate. Of course then you have the half shafts on the rear axle, the wheel bearings and the rear gear itself. Running it on a lift may be helpful but then the suspension is hanging and all the geometry is different. But under the car, with that noise, I doubt if the noise will be hard to locate.