Strange vibration

[uberdrah]

Firstly thanks to everyone who has replied to my previous posts, you've been a great help while i was working on the car.

Now the car is back in one piece and have I installed a new clutch, pilot bearing and the dough nut behind the gear box, changed the open diff for an LSD and replaced the springs, dampers and top mounts.

The car drives brilliantly except when i am between 2 and 2.5 thousand revs with out any feet on any pedals (engine breaking down hill or slowing down) there is a strange vibration.

Can anyone give me any ideas what may be causing this?

[uberdrah]

BUMP

[kuSt]

mine does the same...

i'm not a mechanic, but for me i'm suspecting my drivers side wheel bearing or flywheel bearing, or both. (Auto Bavaria newcastle reckoned my timing belt was too tight).

have a listen over your engine and tweak the throttle, see if you can hear a mid-pitched whine coming from the flywheel area.

hope you get it sorted, i'll be watching the thread for any info.

[uberdrah]

I've always have the whining since i bought the car with as far as i can remember no other noticable effects.

I did think that as i have replaced most off the drive train bearings and linkages which has effective tighten up the drive train that the wear in the prop bear is now apparent and that i never noticed it before?

At the moment i'm super sensitive to every rattle because i have taken so much appart. If no one can point to one specific area i think i will wait for it to get worse as i'm enjoying driving it to much to have it off the road again.

If i find out what it is i'll let you know.

[uberdrah]

I've just driven home from work and while driving down the dual carriage i took my foot of the accelerator and between 2 and 2.5 thousands revs there was a vibration. However when i dipped the clutch the vibration went, let the clutch out and the vibration is back. Anymore ideas would be appreciated, thanks.

[kuSt]

with the car idling, dip the clutch and then let it out. if there is a slight metallic grumbling that disappears when you dip the clutch, and appears when the clutch is released it may be the layshaft bearing.

[uberdrah]

excuse my ignorance but what is the layshaft bearing?

[kuSt]

this was my question uber:

there's a very light, but still quite noisy, grinding sound that you can hear from inside the car. it disappears when you put the clutch in. the clutch doesn't feel like its worn, biting point is still pretty good.

any info here'd be great.

cheers.

Layshaft bearing.

Common on most E30s not a problem.

i took this to mean a bearing in the clutch.

[uberdrah]

KuSt,

Thanks for the reply, from what you have described the bearing you are referring to i would call the release bearing. I changed this and the bear that the end of the gear box drive shaft sits in when i replaced the clutch as this bear was my original problem.

If you or anyone else have anyother ideas they would be gratefully appreciated.

[Martinaston]

Slacken off the prop center coupling and make sure the other ends are firmly seated onto the diff and gearbox, rotate the prop a few times so it settles at its correct length and then tighten the center joint.
After that make sure you pre-load the center bearing by pushing it forward by 5-10mm before fully tightening the securing bolts.
If you still have the problem after that the only other thing i can think of is the prop is slightly out of balance, did you spilt the prop while you were replacing the parts you mentioned ?

[uberdrah]

Thanks Martin, i'll give that a go.