Driveline Possibly Out?

[brutus87]

I noticed today that when i'm in low speeds, or taking off from a standstill, you can hear a thumping sound coming from below the car. All of the gears shift smoothly. I can't hear it above 25 miles per hour, maybe because its too loud outside? Anyways, has anyone encountered this type of thing? What was it? Any help is greatly appreciated, thank you.

[brutus87]

Car: 1988 325is, 5 speed swapped from a donor car.

[jclar]

Can you feel it at all? mid car, rear, front?

[reelizmpro]

Could be many things like a center bearing going out, u joints, axles, worn diff. Hard to tell without actually being there. Maybe you should have a shop look at it before something happens. I went to a meet 30 miles away from home when my center support bearing broke. I knew it was going out but I didn't think it would break on me (I was taking it easy). Needless to say, I didn't make the meet and it was not the way to spend a friday night.

[Cronopoulos]

With the "thumping sound" my money is on the CSB...

[accident]

Sounds exactly like the symptoms I had when the CSB went bad. Replace the guibo at the same time.

[jlevie]

A thumping from under the car in the lowest gears that gets worse when accelerating briskly will usually be from a failed center support bearing. And failure of the center support bearing will almost always be caused by binding u-joints in the drive shaft.Meaning that the only long term fix is to replace both the CSB and the drive shaft.

[brutus87]

So I replaced the driveline and CSB. Noise still there. I think it may be a noisy throw out bearing or tranny.

[Cronopoulos]

So I replaced the driveline and CSB. Noise still there. I think it may be a noisy throw out bearing or tranny.

Stock tranny mounts?

[brutus87]

No, they're new. I replaced the oil on the tranny, it had barely anything. Im thinking the tranny is fried because of that :(

[DrLeadFoot]

Is this common?

A thumping from under the car in the lowest gears that gets worse when accelerating briskly will usually be from a failed center support bearing. And failure of the center support bearing will almost always be caused by binding u-joints in the drive shaft.Meaning that the only long term fix is to replace both the CSB and the drive shaft.

[brutus87]

Whats common?