Vibration from 10-25mph

[trry96]

I've almost finished my 87' 325is project!

I buttoned it up and drove it down my street today. From 15-25mph there is a serious vibration and thumping/squeeking noise. After I hit 25 or so, it stops and the car runs perfectly fine. I tried putting the car in neutral and it still had the same problem.

The car is an automatic, and before I began the project it hadn't been started/driven in 5 years. Tranny fluid was changed.

It seems to me the problem has to be something with the driveline, but that wouldn't explain the symptoms stopping at 25mph, or only in neutral. Perhaps there is a suspension problem that would "fix" itself once a certain amount of force was applied at higher speed?

I am thoroughly stumped!

[trry96]

forgot to say it happens more around turns, and appears to be coming from either the tranny tunnel or passenger side suspension...really hard to tell which.

[Mike325]

I think it could be eaither the flex disk or the center bearing. You said it only happens when turning? Or even going strait? If it is only while turning, I would look at the diff, as any front end suspension problems really should not just go away like that. What was done/changed on the car?

[trry96]

Happens when in a straight line also.

I guess I should have stated. I do my research, but as far as hands on stuff, I'm fairly new to car repair. The entire engine was replaced. So, pretty much every driveline component was removed. I did preload the CSB.

However, the PO took out the driveshaft and didn't mark it. So I installed it without lining it up. Could this cause such an intense vibration at low speed?

TIA.

[HST]

However, the PO took out the driveshaft and didn't mark it. So I installed it without lining it up. Could this cause such an intense vibration at low speed?

TIA.

Yes this could cause issues with the drive shaft being out of balance. With it not being driven for that log you should also consider replacing the diff fluid.