Vibration: What else could it be?

[Martin323i]

Currently there's a war raging between the mechanic and the propshaft guy. Why?

Well, since I got a recon'd propshaft in car May '05 I've had BAAAD vibrations. This led to another recon being put in, and another, and another (Yes! four since May).

I finally accepted the vibration as something internal to the gearbox or maybe the diff and accepted it as part of my car.

My autobox crapped the other day. Another was put in. Same fcuking vibration. So... let's change the diff then. Another diff in... same FCUKING vibration.

Now the mechanic thinks the propshaft guy doesn't know what he's doing and propshaft guy keeps telling mechanic to change this and that and theother. All the while costing me a crapload of money.

Vibration: Above 60km/h, gets worse as speed increases.

So any ideas guys/gals?

[Steviec]

Have you had the wheels balanced? Tracking checked?

Might be worth a look.

[Martin323i]

Mechanic had the sideshafts off diff and 'drove' the car on a ramp. So must be between engine and diff.

BUT mechanic also took off prop at gearbox output shaft and drove. No vibration.

Conclusion: Vibration must be coming from between flex coupling (had this changed for new as well) and diff.

[Martinaston]

When the centre bearing is fitted you have to push it forwards (or backwards, can't remember) to pre-load it before fully tightening the bolts. Is the guy doing that or just bolting it straight on ?
And as an after thought is the engine sitting straight ?

[MONSPORT42]

It's not as simple as the rubber donut thingy is it? Seem to remember when I had vibrations on my auto 323i we (Bexleys) discovered that these were not fitted to the earlier cars but were added to later models.

[Martin323i]

Martinaston: He did just bolt it on initially. I saw in my Bentley last night that the center bearing should be preloaded 4 - 6 mm to the front. Took car in today. Had that done, mild improvement. The propshaft guy had the car a whole day last week and one of the things he did was to make sure the alignment was good.

MONSPORT42: My car was initially an '88 320i. The coupling was there to begin with. Do you think I should remove it and see what happens?

[Martinaston]

Was the prop shaft seperated into two when fitted ?
If so then you may as well give up with it because they are balanced as one piece and should stay on the exact same splines or you throw out the original setup.

The only other thing i can think of is the difference between the early and late centre bearings having slightly different mounting positions, so if you have the wrong one for the year of the chassie then it may be sitting off centre.

[MONSPORT42]

I would go with Martinaston first, but it would certainly be worth a try.

[Martin323i]

see my previous post.

Nope, prop wasn't split in two. Balanced and installed in one piece.

[Martinaston]

Do you have the centering sleeve fitted ? (part number 1)

http://www.realoem.com/bmw/showparts.do ... g=26&fg=10


and is it a new one ? If it's an old one they can get damaged if the prop is pulled downwards when removing it rather than undoing the centre nut and sliding the front section into the rear.
It may be worth getting part number three as well to help balance it out (only normally on the 325i)

[Martin323i]

Hmmm... don't know about the centering sleeve. Will have it checked.

Thanks for your help guys.

[Martin323i]

Nope, apparently not the centering sleeve. This comes with the recon propshaft.

Ouch! Part no.3 is expensive. Maybe I'll get one at a scrapyard.

[Brianmoooore]

Nope, apparently not the centering sleeve. This comes with the recon propshaft.

Ouch! Part no.3 is expensive. Maybe I'll get one at a scrapyard.

Part 3 is commonly removed from E30s anyway - gets in the way of short shift conversions.

[Martin323i]

Had the mechanic push the center bearing forward 2 mm more. The vibration is gone. *Touch wood*

At 140 km/h there is another vibration but this one comes from the front. The dash shakes a lot. It gets a bit better as I increase speed further to 150 km/h. Haven't tried more than that yet. Traffic cops here seem to be on a mission these days.

Any ideas on this one?

[MONSPORT42]

That's good news. Dash vibration usually means rear wheels out of balance.

[Martin323i]

Thanks MONSPORT42. Will have it checked.