From the start....
My M Reg 300tdi auto developed an odd vibration when under acceleration which gradually got worse. Definately drive train related.
Sooo... I ordered a UJ set and a new rubber donut. As I assumed the vibration was been caused by a bad UJ or the donut.

When I pulled the disco on to the ramp at work (Im a mechanic) to find the bad UJ it was glaringly obvious that the play was in the transfer box out put bearings.

The transfer box was leaking oil blah blah blah so I located a second hand transfer box from a friend for £100.

Removed the props.

Removed the transfer box.

Replaced the out put shaft from the gear box as the splines were 3/4 worn.

Fitted a "known to be good" transfer box with no spline wear

Replaced all the UJs in the props while they were off, greased them off the car so all 4 bearings got a good amount of grease, and refitted the props them with a new donut. on the rear.

And at first it seemed to be ok.....BUT....The vibration has come back!!!

Its an odd rhytmic vibration which stops instantly if you let the vehicle coast.


So I have checked....

• Prop shaft UJs (even though they were new) - No play
• Donut (even though that was new) - No play/as new condition
• Transfer box - No play
• All wheel bearings - No play & plenty of grease
• Diffs with props off (11o'clock to 1 o'clock's worth of slack....so pretty good)
• Wheel balancing (As good as it gets with MT's)

Then.....the plot thickens.....

2 nights ago when going around a round about the whole drive train went "tight" for a split second half way around the round about.

Its been fine since (apart from the vibration); until it went tight again going around the same round about tonight. Except this time there was a slight noise which sounded like "miss meshed splines" and its now fine again.

I couldnt pin point the noise as it was very brief...so I went aroundthe roundabout 15million times to try and replicate the problem and it wouldnt do it!!!

The vibration is relative to the speed I am travelling.

I now cant think of anything else to check, and I am getting really cheesed off to say the least!!

Sorry its a long post but I figured that for anybody to shed some light on this annoying saga they would need the full story.

PLEEEASE HELP!!!

yu in difflock?

nope, definately not in difflock.

did you check front props aligned properly and ujs arent tight removed each prop in turn and drive it in difflock

I will remove props individually tomorrow and drive in difflock.

After fitting the transfer box it seemed perfect for 2/3 days until it (settled down) and the vibration has slowly crept back

hows things on the gearbox ????

The gearbox seems to be good pal.

Gear changes are silky smooth, no clunks, kick down is perfect and ATF is a nice cherry red and at the correct level.

It was clunky on the over run and when selecting D or R until i fitted a replacement out put shaft. The clunkyness (if thats even a word) was down to spline wear.

Wouldnt be your propshafts needing balanced would it.

Well.....had look at it today and the front out put on transfer box was f**ked. Tonnes and tonnes of play in the bearing.

So pulled it off and put another 1 in....a spare I had aquired; and this has made the issue a million times better.

There is still a dull vibration coming through the floor of the car. There was a tiny bit of play in the front prop splines. So going to get another prop and keep my fingers crossed.

Broke my record today....transfer box swap from start to finish (driving in to driving out) 3hours!!!

Not a lot to say about the vehicle but you sound like a diamond geezer anyhow.

Hello