Driveshaft vibration

Sat May 06, 2006 5:55 am

I've just had the front driveshaft coupling replaced on a 325i Sport, now I have a vibration/banging when acclerating off the line. Comes in about 4k rpm and feels like the driveshaft is actually hitting the floor plan, makes no noise if driven gently. Any ideas? Cheers.

Sat May 06, 2006 8:40 am

What condition is your prop centre bearing? this can cause vibration/banging if it's faulty

Sat May 06, 2006 9:25 am

I sincerely hope your garage hasn't done what a local garage did to mine, pulled the prop out without marking the position of the 2 halves first.

The 2 part prop is balanced as one piece and if it isn't kept in alignment at the splined joint it'll vibrate like hell.

My E30 had the same symptoms as you, above 40mph it felt like the prop would come through the floor pan.

I took mine back to the garage 3 times but they were clueless so I spent a whole weekend removing it/turning it one spline at a time/testing it/repeating the whole process etc until I got it right. I thought initially that the universal joints orientation must match up with each other but that wasn't the case.

That's the problem with modern private garages, most only know front wheel drive and have no idea about propshaft alignment

Best of luck to you mate,

Iain T

Sat May 06, 2006 9:45 am

They are BM specialists, so hopefully they know what they're doing with regards to putting it back together, although on current evidence, maybe not? Everything was sweet until it went in for this work, only seems to happen under hard acceleration, no issues at up to 70-75mph. I hope it's not misaligned splines, I don't have the patience for that. . . .

Sat May 06, 2006 9:47 am

If it vibrates when you first pull away i'd guess the centre bearing is not pre-loaded, loosen the two bolts holding it in place and slide the mount towards the front of the car to load it.
Give that a go before you start pulling the prop apart.

Sat May 06, 2006 9:54 am

While your under it slacken the join in the middle of the prop and then re-tighten it, if the new guibo you had put on is a bit stiffer than the old one the prop will be a bit too long (fraction of a mm) but enough to force it out of alignment and cause it to knock.

Mon May 08, 2006 1:09 am

Cheers guys, nice diagnosis from 12,000 miles. Centre bearing is the culprit. Tried increasing pre load, but much the same, so I understand it will need to be replaced. It's the original one, so I guess after 176,000 miles, I shouldn't complain.