Driveline vibration?

[E30FourLife]

I have a 3.73 LSD in my 90 325i. When I'm going 20-26mph in any gear I get a pretty decent vibration coming from the back end of the car under accel, decel or just coasting with clutch in, feels like a drive shaft vibrating possibly? Then just recently I noticed I feel the passenger seat vibrate (kinda feels like the rear end maybe?) between 40-55ish mph only on accel, if I let off the gas it goes away completely.

Any ideas?

[e30rapidic]

check your driveshaft center bearing

[Adrian_Visser]

Word to the wise from someone who has been through this though: the CSB goes bad because the drive shaft u-joints are seizing up, and it is the rubber mount for the csb which lets go. You might as well source a good used driveshaft before you replace the csb and still have a vibration. Albeit the vibration will be less until the new csb gets pounded out well you're in there it is a good time to do the guibo disc and maybe if you feel ambitious the shifter bushings too.

[SpecM]

^ agreed... at the very least, carefully inspect the joints for binding or slack

[accident]

Last time i replaced a CSB it was fine for a year. The only reason it went out of service again was because the car was wrecked. :p

[genocide98]

When my driveshaft was bad I would only get vibrations when I had the car in gear under harder acceleration.

I had another vibration, which was a rear wheel bearing, would vibrate from the get, but it would get really bad above 30mph.

Make sure your exhaust isn't rubbing, all your engine+tranny+diff mounts and exhaust hangers are good.

From there, check your wheel bearings.. pretty easy, just jack up the rear and grab the top of the tire, if there is any play when you push/pull the wheel bearing is going bad.

If that all checks out, look at your axles, driveshaft and differential.

If you remove the driveshaft you should be able to play with the joints. If they catch, click, or pop when you're turning them, your universal joints are bad and you will need to replace the driveshaft. typically you can't service these BMW driveshafts without a lot of effort, and a new shaft is the best idea. You can buy a rebuilt, serviceable driveshaft from www.driveshafts.com , which is the driveline service of portland. Excellent guys, know what they're doing, and their driveshafts are about the same, if not cheaper, than a new replacement.

Drivetrain problems on these cars are synergistic. If you have bad mounts, it wears your CSB, if you have a bad CSB, it wears your drive shaft, etc.

Typically the only thing that will wear/damage a part of this system is non-action. So as long as you take care of the problem quickly it'll help keep the rest of the system in check.

TL;DR

Check the entire drivetrain out before you take action. Start with the easy stuff such as bushings and hangers, then move on to externally serviceable parts, and if you still haven't found the problem get under the car and check the driveshaft, CSB and guibo itself.

[E30FourLife]

Thanks for the advice. I'll look into it.

[midnightslyr22]

check your guibo....

[midnightslyr22]

if for some reason you need an actual drive shaft. let me know because i have a spare.

[red325i]

midnightlyr22-- pm'd

[scottinAZ]

ok, not to start a pissing contest, but what is it about the u-joints that makes it non-replaceable, is it an odd size, held in there by a strange means?? Ive done loads of u-joints and while some are a real pain in the ass, they have all been replaceable. Even the freaking chevy units with the injection molded plastic retainers were do-able with enough force, and the right tools.

[ZombiE30]

also CV axles can give this vibration. in my case it is only at 3k rpm or higher and hard acceleration (so far......).
these can be tested by driving backwards slowly and turning really hard to the right and the left. if one of those yields a CLUNK CLUNK sound, that CV needs to be replaced.