why is my new guibo already shredded?

[87-325ic]

alright so,, i found out why it sounds like im running over bricks when i accelerate...

we got it up on the lift, and Wow, where is my guibo?

I replaced the flex disc (guibo) and the CSB myself only a few months ago (as well as tranny seals and shifter stuff..)
plus the 20 yr old one i took out looked better than what i saw yesterday.

the thing was shredded, two bolts did not even connect to the rubber... it was like it got caught in a garbage disposal...

the CSB still seemed intact (from what we could see with mirrors since the heatshield and exhaust was still there..)


The tech advised it was probably the u-joints causing vibrations..
soo.... in goes a new driveshaft..



What i am asking of you all is.... Why would these go out in the way they did?
and is there any way vibration from the rear tires ( bearings or half shafts) could telescope through the driveshaft..?



Thanks folks..

[winstontj]

Do yourself a favor and do this right. Go to Home Depot and buy yourself a section of 48" black pipe. Hang it below the driveshaft in paralell with zip ties or with wire. Next use a slug, caliper, socket, etc. as a slug and MAKE SURE the driveshaft is straight. I'd assume that when you put in your CSB it cocked the middle of the driveshaft which is overflexing the flex disc.

Another thing you can do to adjust is install the flex disc to the gearbox but leave the three bolts out of the driveshaft. Put the gearbox in neutral and rotate the dshaft. Watch to see where the dshaft seperates from the disc or pushes it a little. You'll be able to shim the CSB as well as possibly the trans mount to get it perfectly in line. I'd also suggest to put the car up on the trailing arms in the rear rather than on the frame. You want to make sure that when the rear suspension settles in (the car is weighted back down on the road) that the rear doesn't settle in and move the driveshaft again.

Hope that makes sense.

OH and can you FEEL the vibration? When you drive can you put your hand on the hump behind the parking brake & feel a vibration or is it only on acceleration?

PS how are your motor & trans mounts? if your motor & trans flex a lot & move around it'll only help in the giubo shredding efforts.

[87-325ic]

thanks...

the motor and trans mounts are all good.

How could the driveshaft not be straight, with new mounts, flex disc, and CSB?
also, if its not perfectly straight, arent the u-joints there for this reason?




and speaking of vibrations, id be suprised if the car next to me with the windows up and stereo at full volume didnt hear it.. it sounds like i literally am running over piles of bricks.

[winstontj]

Dunno why that center joint is in there but I do know that if you read your manuals it's supposed to be PERFECTLY straight. I'd imagine that over time things (CSB) sag and when you replaced new they went into different positions. Now that is causing vibrations & driveline issues.

Good luck & get it fixed cause that's dangerous!!!

[fretburnr]

i had the same issue. insane loud vibration on acceleration, shredded guibo.

turns out the driveshaft had notched the ujoints, and they were torquing the driveshaft off center once every revolution; it tore up the CSB and guibo, and sounded like someone was punching the back of the trans tunnel every half second or so.

new driveshaft, new guibo, new csb, and all is good. expensive fix, but now i know that it can take whatever I dish at it.

[jlevie]

A failure of the center bearing rubber mount is almost always as a result of bad driveshaft u-joints. So if you had to replace the center bearing and quibo and didn't also replace the driveshaft you are just asking for the new parts to fail quickly.

[winstontj]

A failure of the center bearing rubber mount is almost always as a result of bad driveshaft u-joints. So if you had to replace the center bearing and quibo and didn't also replace the driveshaft you are just asking for the new parts to fail quickly.

I agree. Take your dshaft to a shop and have the ujoints replaced (or buy a new BMW one) Make sure when you seperate the sections you mark them so they go back the way they were balanced.

I'd get on it ASAP cause what you have is a ticking time bomb

[Mike325]

I agree. Take your dshaft to a shop and have the ujoints replaced (or buy a new BMW one) Make sure when you seperate the sections you mark them so they go back the way they were balanced.

I'd get on it ASAP cause what you have is a ticking time bomb

The two halfs of the drive shaft are ballanced seperatly. The reason you mark them is for the phasing of the u-joints. If the u-joints are not in the same position, this will couse a vibration.

[winstontj]

The two halfs of the drive shaft are ballanced seperatly.

are you sure about that? I've never done anything to an e30 but i know that e28 and 2002 ones must be balanced together on a special machine. It's hard to find a shop that has the ability to balance a two part driveshaft. There are a few in North Carolina that I know of though.

[4bimmers]

You have to mount the guibo in the right fashion. There should be arrows molded into the rubber. The guibo should be put on so that these arrows point to the mounting arms of the drive-shaft. I know this from experience. I put on a new guibo on an e28 and it was "backwards". The thing didn't last 100 miles and it basically flew apart.