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[Boyracer]

I've got a 87 535i (e28) that has a strange vibration when you decelerate. Let's say you down shift from 3rd gear to 2nd, as soon as you release the clutch, there is a violent vibration that shakes the whole car. This happens in all gears, only when downshifting. I've checked the rear end cv joints and u joint thinking it was back there, but all looks ok. any ideas? Car has 109k miles.

[edjack]

Check your Guibo joint (at the read of the tranny). It's a big rubber donut, that takes the place of a U-joint.

If it's never been replaced, chances are about 98% it's got one or more cracks in it. You may even be shocked at how many crackes it has!

You'll need to drop your exhaust system to replace it. Get a LARGE hose clamp that will go around it, so that you can compress it enough to remove the 6 bolts that go through it.

[echobelly]

Have you checked your Rear Differential mount?

[sailingphotag]

Hey, ive had a couple that had bad center bearings do this, is the steering wheel deflecting?? if not jack it up jack stands cause Earnharts dead and take off the heat sheild and exaust now you can tealy look at the drive shaft..shake twist and spin it any and i meen any clunking ticking or grinding and you will have most likly found the problem. if the steering wheel is deflecting well then its frount end time let us know what fixes it cause it will help others ...also post again if you have any questions or problems...jeff

[Boyracer]

UPDATE!

It was the rubber u joint that connects the transmission flange to the driveshaft flange.
The original unit had a cup that surrounded the rubber joint. The cup itself was bolted to the trans flange, and is there to prevent the joint from completly disentrigating. The cause of the vibration was that the bolts of the driveshaft flange were rubbing or resting on the lips of the cup due to the rubber joint failure.
The "Haynes" manual stated that the exhaust and the driveshaft needed to be removed to replace the rubber joint, in my case this was not true. Removing the 6 nuts that hold the heat shield enabled me to slide it far enough back that it exposed the center bearing nuts. Removing the center bearing nuts allowed the driveshaft to drop and rest on the exhaust. This allowed just enough room to pull the driveshaft off of the centering pin on the transmission flange. The whole operation took less than 40 min to complete.
The 535i now drives just like new!
Thanks to all who replied!

[edjack]

Yep, that's known as a Guibo joint.