325i vibration after propshaft centre bearing changed

[connoisseur]

not sure whether the two are linked but I picked up the car after having a new propshaft centre bearing and doughnut put in. Under acceleration, and particularly noticeable in second gear, there is a vibration/ thrumming coming from the rear.

Not very loud - I think I can still hear slightly it in the background when driving normally.

All suggestions welcome before I take it back tomorrow and ask them to look at it.

1990 325i saloon

Thanks in advance

C

[fuzzy]

its possible they fitted it back to front as its set slightly off centre on the carrier.or it could be something unconnected like a rear wheel bearing or failing to preload the prop on refitting.

[Brianmoooore]

Propshaft has to be split to put a new centre bearing on, and it is important that it is reassembled exactly as it came apart, otherwise it will not be balanced.
Failure to do this would be the most obvious potential cause of your problem.

[connoisseur]

Thanks both for your responses. I'll see what they say in the morning.

C

[snoops]

funnily enough I have the same problem after changing propshaft

[Simon13]

as i said to you at gaydon the prop is out of balance!

[koos]

sounds like they did not line up the yokes, even a spline out will cause a vibration.

[mrLEE30]

not preloading the centre bearing causes same vibrations... check this first,

loosen the centre bearing mounts let it find its natural position, and slide the bearing 5mm toward the gearbox and tighten the mounting bolts thus pre-loading the bearing, this may clear the vibration, if not then as brian says the prop is out of balance....

bodge fix is to use a metal jublee clamp fixed around the prop.... experiment by rotating the clamp using the nut as a balance weight until you find the position where the vibration is less or gone.

[fuzzy]

having your prop professional rebalanced is pretty cheap. i payed just under a hundred quid to have half a cossie prop custom made then welded to half an e30 prop and balanced. just a rebalance would probably only cost about £20-£30 id guess and that would eliminate that from the equation for sure.

[koos]

I've never heard of pre-loading a centre bearing? Why should it be done and what does it do to the bearing? Just wondering.

[fuzzy]

I've never heard of pre-loading a centre bearing? Why should it be done and what does it do to the bearing? Just wondering.

ive heard it mentioned a few times in threads but never understood what it meant or how it was done but its pretty clear now.as a result i didnt pre load mine the last time it was apart so that could be the cause of the very slight vibration i have through my car.its coming of soon again so i can remove the rear subframe so i can replace the subframe bushes/prop centre bearing/fuel tank all at the same time as my set up is a nightmare and needs the driveshafts and diff removed to able me to remove my prop

[koos]

I've done loads of prop centre bearings on trucks and never heard of it and never had any probs with them afterwards. I gotta do my centre bearing aswell, will do it when I swop the engine over. Will be on a hoist so makes life a bit easier:)

[mrLEE30]

dunno what is does, the bearing housing can move due to its slotted mounting holes, and the bearing is held in a rubber housing, so it too can move, i guess pre-loading the bearing helps it to centre better.... its also in the bentley manual and they are normally quite good.


and all i know is my old sport had vibration after changing the bearing, then read up on it, preloaded the centre bearing and vibration gone (but then the UV joint packed in anyway..unrelated i might add)

mrlee

[connoisseur]

Thanks for the help guys but sadly vibration is stil lthere. The mechanic pre-loaded the bearing but said that the vibration got worse when he did that so he let it find its own position.

Driving it more the vibration is more apparent on take off/initial acceleration, which might suggest a problem with the donut?

Not sure what to try next. Perhaps I just need to take it to a place that knows the E30 inside out. I guess most places won't know much of the detail needed.

Cheers

C