Author Topic: Flex disk and drive shaft questions (Read 3265 times)

shiver · « **on:** July 10, 2006, 09:13:36 PM »

my flex disk just died- causing some vibrations upon acceleration. i am obviously going to replace it.

here is the question. i spoke with the PO of my car and apparently the flex disk was replaced within the last 10k km. shouldn't the flex disk last longer than that? this means that:

A) the disk was not actually replaced.

OR

B) the drive shaft is somehow out of balance causing the flex disk to wear/break prematurely---> can anyone confirm this?

C) what else could cause it to break so soon?

edit: the flex disk was replaced a couple of months ago, so what could have caused it to break so soon??

TIA

M42boy · « **Reply #1 on:** July 10, 2006, 10:00:46 PM »

^^
Scenario B is a likely explanation.

I'm buying a rebuild prop shaft this week to replace my bad one. I just hope my driving the car with a bad shaft didn't chew up my new guibo. FYI, if you have to replace your guibo, supposedly an E34 M5 guibo fits the stock location and is made of a much more solid (durable) rubber.

shiver · « **Reply #2 on:** July 10, 2006, 11:10:52 PM »

well, i've put more thought into it, and the flex disk could have been faulty. also, the installation may not have been done properly. if not, it is probably something that has to do with the drive shaft-:mad:

should i just replace the disk and wait and see if it breaks again- then fix the drive shaft as well? how can i tell if its the DS that giving me problems?

thanks

M42boy · « **Reply #3 on:** July 11, 2006, 09:10:58 AM »

Quote from: shiver

well, i've put more thought into it, and the flex disk could have been faulty. also, the installation may not have been done properly. if not, it is probably something that has to do with the drive shaft-:mad:

should i just replace the disk and wait and see if it breaks again- then fix the drive shaft as well? how can i tell if its the DS that giving me problems?

thanks

That's the cheapest thing... But my question is, how do you screw up installing a guibo??

bmwman91 · « **Reply #4 on:** July 11, 2006, 10:26:46 AM »

Check the center support bearing. The rubber bushing surrounding it is thin and prone to breaking. If that is shot, then it most likely caused the excess wear & tear on your guibo. The out of balance part...the shaft is 2 pieces. They are balanced as one, and are ONLY in balance in one orientation relative to eachother. There are like 15 splines at the intersection between the 2, and it is easy to misorient the 2 when not paying attention.

Pull the shaft and look for 2 white dots on the yokes/neck of the shafts where they meet. Use an old toothbrush and some warm soapy water to gently scrub the dirt off revealing them (rather than scrubbing them off). They should be exactly in-line with oneanother. I found this out the hard way on my first car...I had the 2 halves off by like 80 degrees! THAT was some rough driving for the 5 minutes I drove ti!

sheepdog · « **Reply #5 on:** July 11, 2006, 11:50:05 AM »

Couple things could be the cuplrit. Most are easily fixed.

First off, plan on replacing the center bearing. It is probably trashed.

Second, I doubt the driveshaft is out of balance. Look up how to properly align the driveshaft. If the u-joints are out of phase, it will lead to guibo destruction. They have to sit in a certain alignment.

Third, replace every nut (and bolt) attaching the guibo. They are self locking nuts that use a cruch method to hold, this method is typically only good for one use. I re-used mine and one fell out, destroying my guibo, luckily it was an old one.

D. Clay · « **Reply #6 on:** July 11, 2006, 12:35:36 PM »

Maybe it was replaced a long time ago or as you said, was damaged during installation or was a used part. Or they just put a new guibo in and didn't look for any other cause. Just assumed "it" was the problem. By now everything in there has taken a beating.

shiver · « **Reply #7 on:** July 11, 2006, 07:26:06 PM »

it is a possibility that they might not have been torqued properly. i'll make a note on getting the new bolts. my CSB was replaced not too long ago (6-7 months~), do you think it might have been damaged because the guibo was causing excessive vibration? anyways, ordered in a new disk and am changing it on thursday. i'll have a good look at things while i'm underneath.

thanks