So I changed the CSB and flex disc...

[Sean]

My dad recently purchased a 1989 325is, black on black, 155,000 miles. Lets just say, he spent too much on it.

Anyway, it had a major vibration issue from 2 grand up until 4 or 5. I knew right off the bat that it was the flex disc - looking under the car, that was confirmed. (chunks were missing).

Well, anyway, while I was down there, I did a couple of things:
- Rebuilt the linkage, used UUC shift carrier delrin bushings, and rebuilt all linkage except a new shift lever)
- Had a driveline place in town install a new center support bearing (after I seperated both halves of the driveshaft (marked both sides))
- Installed a new flex disc
- Removed the huge ass harmonic balancer

For one, this driveshaft was different - it had "headless" bolts - I had to pound them out - to remove the harmonic balancer. I thought nothing off it - since it wasn't needed. Come time to put everything back together, I pounded the headless bolts back in, and screwed the flex disc on.

I put everything back together, and all was well, however, there are some issues I didn't have with my car when I did the same work. To start with, the driveshaft makes a nice sqeaking noise depending on how fast I'm moving. It's only heard when the car is at a crawl - usually coasting down the driveway, or coasting in a parking lot. It's a constant, repetitive sound - it's not random. It gets faster or slower dependong on my speed. Eventually, once to get faster than a crawl, you no longer hear it.

The other thing is, the car still vibrates a little between 2 and 3 grand. It's mostly felt in 1st and 2nd gear. In 1st gear, when WOT, there's a fairly loud vibration felt for a split second at around 5500 rpm. Only at full throttle is it felt though.

Basically, my dad bought this car thinking he could fix the problems it has. So far, I've done all the work. And, since it's not my car, these issues piss me off even more than they would on my own car. he says he doesn't care, but I know he does.

Any insight on this?

Thanks!

[Old'n'Slow]

OK. BMW driveshafts seem to last roughly 100K miles before the u-joints start to seize up and cause vibrations. These vibrations can tear up your CSB, and cause accelerated wear on the guibo.

Here's the test. If your u-joints aren't buttery-smooth with no stiff spots AT ALL, then it's OK. Once the u-joints develop a notch the driveshaft no longer spin on its axis, but oscillates, causing the vibrations you described.

Also, you're probably due for motor and trans mounts at this point as well.

Your squeak could be due to several things...

1. Bad CSB install (not preloaded properly)
2. DS making contact with exhaust heat shieldind due to sagging motor or trans mounts
3. Giubo contacting the shifter rod

Does the squeak follow the driveshaft rotation? During coast or drive?

My eta was a money pit for a while, but I still love it!

[Sean]

And, when you say preloaded, you're talking sort of pushing the rubber on the CSB forward a bit, like the bentley mentions? Cause, I don't think I did that.

Motor and tranny mounts are fine, none are drooping or anything. Guibo isn't hittin anything at all, I checked for clearance. It's probably the preloading issue...

ORR - It could very well be the U-Joints, cause when I was moving it around a little, the front one (in relation to where the driveshaft is usually) was a bit stiff at some areas. I bet that would do it, wouldn't it?

Well, I'm back at college now, so I won't be touching my dad's car until Late May, and he won't be able to fix it. I have another driveshaft in the garage though.


The squeaking I mentioned is definately following the driveshaft rotation. You can only hear it when it's cold, and if you're below about 5 mph. Otherwise, you can't hear it. I can be driving or coasting, as long as I'm below the above mentioned speed.

I'll probably end up pulling everything apart again to check things out when I get home in May. I didn't read my bentley when working on the car, thinking I knew what to do, and completely forgot about the preloading. So, I'm guessin that's causing the squeak.

Thanks for the assistance! :)

[BimmerHeadBri]

CSB sound like it needs to be replaced

Sean,

I had this same thing happen to me. the actual metal frame of the CSB cracked, then broke. The rubber and bearing were still ok, so they were supporting the driveshaft, but at low speeds, it would squeal (and later thump) like crazy. Once you got into 2nd, the driveshaft would spin enough that it kind of levelled out.

This was a brand new CSB too. But I did NOT preload it when I put it on initially (also, I hadn't lined up the 2 pieces of the driveshaft - so I think it was out of balance too).

I found the driveshaft marks to line the splines up properly and installed another new CSB and everything is better than new.

Hope this helps.

Brian

[Sean]

Thanks, I'll have to check that out.