noise from center of car, driveshaft ?

[Jordan325iC]

I had this noise pop up during an autocross. After the autocross, I jacked up the car to figure out what was making the noise, couldn't find it, put it back on the ground and it stopped making the noise. It was quiet for a few weeks, then it came back with a vengance a week ago.

Car: '88 325is, 250k miles, lowered w/ LSD.

The noise:
-Sounds like the wheel from "wheel of fortune".
- Correlates to wheel rotation, not RPM.
- Really loud, undrivable.
- Pretty much constant, happens loud under braking, intermittent during turning.

According to the GF outside car:
Comes from underneath the cabin, equally loud on both sides. Like it's coming from the driveshaft tunnel.

When I jacked up the rear of the car and turned the wheels, there was a slight noise coming from the driveshaft underneath the exhaust.

Does anybody have any ideas?

[ColdAccord]

check the center support bearing

[mattdk318i]

Csb

[Dibo718]

When i first bought my car i had a similar problem, same sounds and everything... it was the U joint.

[Jordan325iC]

As of now, I know the CSB is completely gone, and the driveshaft was dragging on the heatshield. I'm going to replace the CSB and see if that helps.

[jlevie]

If the rubber mount around the center bearing is gone simply replacing the CSB will be at best a short term fix. The usual cause of the mount failure is binding drive shaft u-joints tha place unusual loads on the CSB. Replace both at the same time.

[HST]

also do the guibo (sp) when the CSB goes out it weakens the guibo.

[Jordan325iC]

I ordered the CSB with mount, I believe. I ordered this:

Correct?

The guibo looks ok, no shredding or anything. I've got a rallycross tommorow which I can't miss, so I'll just have to hope everything works out.

[thectrlguy]

Any other symptoms? Clutch shudder/disengagement issues? Have you removed the driveshaft / transmission?

[Jordan325iC]

Clutch works fine. It became a little light after I left it sitting for a while, but I think that's because air is in the system. The whole car has a shudder, but I noticed that my tranny mounts were broken in half, so that might be contributing, and I've got two new ones to install to see if that helps. I haven't completely removed the tranny, but the driveshaft is out. I'm in the process of installing the new CSB right now.

[thectrlguy]

According to the BMW TIS, thing to verify/check

a) Propeller shaft not aligned precisely
b) Runout on centring spigot, transmission flanges or final drive flanges
c) Center mount damaged
d) Universal joint worn or seized
e) Engine/Transmission suspension not OK
f) Joint-disk rubber damaged
g) Centre mount not perpendicular to propeller shaft, not at all or insufficiently preloaded

Clutch works fine. It became a little light after I left it sitting for a while, but I think that's because air is in the system. The whole car has a shudder, but I noticed that my tranny mounts were broken in half, so that might be contributing, and I've got two new ones to install to see if that helps. I haven't completely removed the tranny, but the driveshaft is out. I'm in the process of installing the new CSB right now.

[Jordan325iC]

I forgot the order of things when I took off the old CSB. When you are banging on the new CSB, does it go:

#1 dustshield - csb - dustshield - circlip
OR
#2 dustshield - csb - circlip - dustshield

#1 would make more sense to me, but I can't seem to get the new bearing on far enough for that to happen, it seems like it's as far as it can go.

[thectrlguy]

http://ee1394.com/bmw/docs/factory/repair/en/index1.htm

[Jordan325iC]

That site doesn't explain where the circlip should go.

[thectrlguy]

Sure it does,

Dust cap > bearing > dust cap > circlip