E36 vibration problem

sballard · 06-21-2008, 05:50 PM

I had a previous post documenting my replacement of my rear lower control arms. It required quite a bit of wiggling and wrestling my rear drive around. I finally got it done but now I have a vibration in the drive train that is really noticeable when I accelerate but not otherwise. I didn't disconnect either the driveshaft or the rear half shafts when I did the work. I suspect that I may have accidentally damaged the CV joints or perhaps the driveshaft center support bearing. Anyone have any ideas?

coolbear1 · 06-22-2008, 12:24 AM

It sounds like the Guibo coupling, but, if you didn't unbolt your differential from the frame, I don't see how you could cause harm to the drive center support bearing, or the Guibo coupling. Did you have to disturb the differential much?

Did you have to remove the CV joints or unbolt the flanges?
If so did you match mark them and return them to there original orentation?
Also you didn't over bend the CV and the one of the balls get out of place maybe?

sballard · 06-23-2008, 04:26 AM

I did not unbolt the driveshaft or the half shafts from the rear drive. I just unbolted the rear drive and carrier from each other and the body and wiggled them around to get the inner bolts out of the lower rear control arms. I only hear the noise, a low-pitched growl and vibration, when I accelerate, which is strange. My instincts tell me that I could have damaged one of the CV joints, but I put the car up on stands and started it up and put it into gear. I could not detect any unusual noise at either rear wheel. That's is why I was wondering about the center support bearing or guibo. I never opened up the rear drive case, but I wacked the case a couple of times with a hammer to align it with the bolt holes. I can't imagine that did any harm. I want to have some reasoning and logic for replacing parts as this could get expensive fast.

Jeron · Jeron's Garage

How far down did you drop the diff? Do you think you put any pressure on the center support bearing? I highly doubt you damaged the guibo and if you did it would be visible.

sballard · 06-23-2008, 06:27 PM

The differential was essentially suspended from the drive shaft and the half shafts during this repair. Plus, I was pushing and pulling the differential around quite a bit. I suspect that I did put pressure on the center support bearing.

Jeron · Jeron's Garage

The diff is very heavy and letting it hang from the drive shaft was probably not a good idea. Take a look and see what you think was taking the weight of the diff while it was hanging.

You are going to be pretty close to getting the drive shaft out when you change the center support bearing. If you can take the whole drive shaft to a axle shop and have the balance tested, it may be bent.

sballard · 06-24-2008, 11:59 AM

Thanks for the reply Jeron. I had no idea that a driveshaft could be that fragile. I'll hope for the center support bearing. Any way that I can determine if the bearing is damaged before I replace it?

Jeron · Jeron's Garage

I wouldn't expect it to be that fragile either but the diff is heavy and the shaft was only designed to take twisting forces not support any load.

I didn't replace my center support when I did my clutch. The bearing spun without noise. I would expect the bearing to make a noise long before it would cause vibration. When you pull the center support bearing I imagine you will be able to tell if it is damaged or the bearing is bad.

You could be right about the half shafts or CV joints but the drive shaft seems more likely to me. Ultimately only you know where you put the most stress.