Another Vibration Under Acceleration Thread

[michael325e]

I know there are a bunch of threads on this subject. The problem is that most of them never proceed to resolution. So here is my story.

I got my 84 325e about a month and a half ago. After I bought it I found it had a nasty vibration that was only evident under hard acceleration in 2nd gear at 35-40 mph. The PO had installed a new CSB, but that is all I know about the history. The vibration was through the seat, not the shifter, and seemed to slightly favor the right side as a location. I took it to the local bimmer mechanic and he said driveshaft most likely. So I asked him if he had any opinions on putting in a used one. He thought it might work and happened to have one that looked and felt like it had tight and smooth u-joints and a good CSB. So I had him install it. The old driveshaft seemed to have tight u-joints, but the rear one was somewhat catchy in one direction.

Unfortunately, this did not solve the problem. It changed the nature of the vibration somewhat, but now I can get it in 1st and 2nd under hard acceleration, and in 3rd if going up a hill while applying throttle. Except for 1st gear it is still chiefly in the 35-40 mph area.

Further background, the guibo, transmission and differential mounts appear to be in excellent condition. The mechanic said the rear subframe bushings look ok. The half shafts do not have torn or leaky boots and seem to be tight. The differential is, I believe, a 2.79 LSD.

Here are my questions, the BMW tech manual goes into great length in describing how to align the entire drivetrain. How likely is a misalignment to cause my symptoms? It also says to check the runout on the differential input and the transmission output. How likely? Are the outputs from the differential possibly involved?

I am pretty sure the consensus opinion will be that it is the driveshaft. I would rather spend that money for winter tires though, so I thought I would see if more experienced than I E30 people have found any other sources of this sort of vibration.

Thanks

[Ether-D]

Sounds like csb or driveshaft to me also. Good luck.

[michael325e]

I'm in no position to disagree with you, from either an experience or a technical perspective, and more or less resigned to getting a rebuilt driveshaft.

I am curious though why the BMW repair manual under the heading of troubleshooting vibration at 25-30 mph mentions first drivetrain alignment and then spends two pages and two special tools describing alignment. I don't remember seeing this mentioned in any of the many threads I've read while searching for info here on this subject. Perhaps they are talking about a vibration of a completely different character or magnitude, but like I said, I'm curious.

[jlevie]

A drive shaft with a "catchy u-joint" is a bad drive shaft. The first action should be to replace what is in the car now with a new or quality reman.

[NJ2.5rser]

Try motor mounts if nothing else works sometimes it is hard to see if they are bad. I had a very similar issue and that fixed it.

[amarino]

Are you sure the driveshaft was properly balanced/aligned before it was installed. I am having the exact same issues that you describe in 1st, 2nd, and 3rd but I already know my problems are the guibo. I plan on replacing it this weekend.