juddering at the back @ full boost

[A80Avant]

I emailed Javad yesterday about the juddering i get after mounting the rear diff alloy mount.
What i get is as soon as i go WOT and full acceleration,you get a feeling as if the rear wheels are spinning,although they are not.You are feeling a juddering at the back while accelerating.

Javad mentioned that i should only feel the whining of the diff while driving and not any juddering.He mentioned that maybe my driveshaft might not be alignhed properly or something.
Now by driveshaft i suppose he means the propshaft.We did have this out to replace the bearing and i know it has weights in it and it is balanced.

How can one check if that is mounted properly?Is there an easy way?
Also if that is ok,what else could it be?
The rear has new bushes(OEM) and only the subframe bushes have stayed the same,as they werent all that bad in condition.

[A80Avant]

anyone else that is using the BMW center support bearing and having this problem as well?
maybe i should concider getting the proper bearing fitted....

[Error404]

i think it needs aligning carefully with spacers to make it sit at the right height away from the body - it might need some tweaking?

[A80Avant]

do you think that by getting the proper support bearing fitted,this may go away?
i could go to Rob(GT500) to have it fixed,although i waited as the BMW unit is still holding on.,..

[Error404]

IIRC the workshop manual specs various sized spacers for the centre bearing alignment, and there is a special VAG tool for aligning the prop, so i think you will have to do the sajme with the OEM bearing anyway. Not sure how to align the prop, but there was some scans of the workshop manual posted on here with info

[A80Avant]

i didnt have any problems with the propshaft before taking it out to replace the support bearing.
I also read that taking the shaft out to do that job is not a big deal as to how you should mount it again.So im guessing my mechanic didnt mess the alligment,its only the BMW part that is causing the issue.
Ill contact Rob to get together to replace it with the new part i have.

[s2driveruk]

did you get this sorted in the end - i have the same issue (with febi/bmw part and I think the prop is out of alignment somehow. I'm fairly sure it is to do with the washers used as they are probably the same as the ones used with the OEM centre bearing, however the cross member is a different thickness so it might be out of alignment high wise?

[A80Avant]

yes i had this sorted with Rob,apparently it was not only the proshaft but also the rear apicol diff mount that i used which transferred a lot of juddering in the car when on boost.

when i replaced that with the OEM unit,and a slight modification i did,everything went back to normal and the feel is much better

[Lloyd]

Hi Vasilis,

What was the other modifcation? I'm curious as I'm not getting the boost symptoms you described when running the Apikol mount.

Cheers,

Lloyd

[A80Avant]

well i was getting mostly from the back of the car a judder AS IF the rear wheels were spinning, and that happened on 5th and 6th gear pulls with 2bar of boost and around 3500rpm and above.

when i replaced that with the original rear diff mount and an addition of a thick rubber between the OEM rubber,which came from exhaust mount rubber, everything went back to normal and still better than OEM.I dont get that unusual sit in the back that much BUT i also dont get the judder.

So it was the rear diff apicol unit causing this for me as after Rob's magic and realignment i still had it big time

[Bram]

I have the same judder with the upgraded rear diff mount from 034MS, but the more I smash my car the judder slowly starts to become less noticable. Maybe the blue rubber get's worked in or something?

[A80Avant]

i had it for almost 9 months or so.I couldnt bear it.It just made the car seem to have a problem all the time. Besides now you get that kick in the back much more when you get that boost up,so its nicer!

[Bram]

Any pic from your extra rubber mod?

[A80Avant]

here you go!

[Bram]

Are you mad?

did you tape it or something?