Driveshaft Woes and Wonders???????????

[jahnaboi]

If at all possible could anyone help me identify/discuss the problem I am having? Here is the link to the original thread. I did the 24v swap which is why it is here and thought I'd personally ask 24v swap savvys.

http://r3vlimited.com/board/showthread.php?t=146343

-Jasper

[e30this]

Have you checked your rear axels?

[jahnaboi]

Axles are 100% fine. I checked as much as possible. To eliminate probable causes these have been changed/checked.

- Differential bushing - Good (no rips or wear)
- Subframe bushing - IE race poly bushings
- RTAB - IE poly Bushings
- RSMB - Ground Control Polys/reinforced Bushings
- Transmission Mounts - E21 mounts (no rips or tears bought 9 months ago)
- Motor mounts - E28 m5/535i mounts (same as above)

God I wish it was as easy as I hoped.

[hugh jass]

my guess is its at the guibo. i had the same vibration problem but for completely different reasons (wrong driveshaft for the transmission i was using). the simplest thing you can do at this point is replace the guibo and see what happens.

[e30polak]

The diff carrier bolts like to back out if they haven't been tightened nicely with lock-tite. It probably isn't the problem, but I had this happen to me, with very similar symptons that you have. It caused the driveshaft to rub against the lower part of the diff carrier.

[jahnaboi]

Honestly, I've taken it off and inspected it and flexed it and there is no tears/wear on the guibo.

[bmw320e21]

Same issue i had when my diff was going out on my e21 and my ae86. Vibration in rear end only under load. It was slight at first but it became more and more pronounced. I would try another diff if you have one laying around.

[dude8383]

The diff carrier bolts like to back out if they haven't been tightened nicely with lock-tite. It probably isn't the problem, but I had this happen to me, with very similar symptons that you have. It caused the driveshaft to rub against the lower part of the diff carrier.

dude same thing happened to me, one of the bolts was completely missing!

[rThor432]

I noticed that you said in the other thread that it is only in second gear under WOT. Could your rear end be compressing the arches into the tires? That would make sense if it lessens with each upshift.

I would think that is something that you would have noticed, but I thought I'd mention it because mine did that when I first got the engine buttoned up in the car. Never had a problem with the old eta motor putting my 225's into the arches, but the S52 is a little bit more powerful across the board. Mine also was worse as the RPM rose.

[jahnaboi]

The diff carrier bolts like to back out if they haven't been tightened nicely with lock-tite. It probably isn't the problem, but I had this happen to me, with very similar symptons that you have. It caused the driveshaft to rub against the lower part of the diff carrier.

I wish it was this problem. I was aligning the differential with the tranny/motor, so I've checked these bolts and they are not loose.

Same issue i had when my diff was going out on my e21 and my ae86. Vibration in rear end only under load. It was slight at first but it became more and more pronounced. I would try another diff if you have one laying around.

This could be a possibility. Sadly enough I have no extra differential. Was sold a while back. Only thing is, how would a differential cause vibration under WOT other than the bushing/bolts being bad?

I noticed that you said in the other thread that it is only in second gear under WOT. Could your rear end be compressing the arches into the tires? That would make sense if it lessens with each upshift.

I would think that is something that you would have noticed, but I thought I'd mention it because mine did that when I first got the engine buttoned up in the car. Never had a problem with the old eta motor putting my 225's into the arches, but the S52 is a little bit more powerful across the board. Mine also was worse as the RPM rose.

I have 205s in the rear. They wouldn't rub even with a full car load. I could feel the vibration through my shift nob more than anything which is why I know I have vibrations coming from the driveshaft. Was silky smooth for 10 months and now no more. =/

Lol this is so annoying... I can't enjoy my car anymore because I can't floor it...

Thanks for the suggestions so far. I've looked at your suggestions and they are ruled out. Usually problems are because of the smallest details but in this case, I think its going to be something else. I've lifted and taken off my whole exhaust system, heatshield, and drive shaft at least 3 times to no avail...

[dude8383]

could it be the tranny? could it be the shift linkage?

[jahnaboi]

Transmission no. Unless the output shaft was messed up it wouldn't vibrate. Shift linkage is not a probable cause as there is no load thrust upon it. Please keep in mind, there was nothing for 9 months before the torn CSB. The torn CSB probably happened because the old driveshaft's u-joints which is why I replaced it and had my new one balanced. More suggestions welcomed. Thanks so far.

EDIT: going to be taking everything out the fourth time around... this is so gay.

[Jason89i]

check to make sure the driveshaft is aligned / straight.

not sure with the e36 driveshafts..... but..... some older e30 / e30 m3 driveshafts used a different csb and had the u joints on the opposite halves of the shafts. intermixing the older driveshaft with the newer chassis can reak havoc. the old csb's did not fit the newer chassis, and some of the older driveshafts have ujoints on the rear half. when installing the newer style (87+) csb on some of the older e30m3 driveshafts, you have to flip the csb backwards or the driveshaft will not line up correctly. it seems really odd, but you have to flip the csb (thus cannot install the dust shield) for the driveshaft to be straight.

just a thought. cheers, jason

[bmw320e21]

This could be a possibility. Sadly enough I have no extra differential. Was sold a while back. Only thing is, how would a differential cause vibration under WOT other than the bushing/bolts being bad?

Possible clearance issues with ring and pinion. Id check for any play in the diff. You can take out your rear seat bottom and have someone try to listen to the diff during acceleration there will be apparent noise if it is bad. By what your saying everything else in the drive train HAS been ruled out except the diff. Id try to get a hold of someone and see if they have one laying around.

[jahnaboi]

Possible clearance issues with ring and pinion. Id check for any play in the diff. You can take out your rear seat bottom and have someone try to listen to the diff during acceleration there will be apparent noise if it is bad. By what your saying everything else in the drive train HAS been ruled out except the diff. Id try to get a hold of someone and see if they have one laying around.

I will try that. I have my doubts though. =/ Didn't really get to work on my car today like I planned. Was working on my cousins 3sgte swap into his 88 alltrac.