Heavy vibration under acceleration but not CSB or driveshaft!! Thoughts???

[skatingzooyork]

So I got the usual vibration while accelerating and from searching on here everyone said it was the CSB which was caused by your driveshaft.

Bought those parts, went to install them and noticed that my tranny mounts were trashed. So I replaced those first w/ some solid mounts and problem was still there. So then I replaced the CSB and driveshaft and the problem is still here!!!

I thought the exhaust might be rubbing the body but I can't seem to find any likely spots...


Any ideas???? The guibo feels stiff/strong and doesn't have too many cracks on it, so I doubt that is the problem. And the motor mounts "seem" ok but I know that doesn't mean they are...

I'm a little lost at this point...

[E30Nova]

So you put in a new/rebuilt driveshaft? Or another used one?

And when is the vibration happening? Off idle, a specific rpm range, or all the time?

And by solid transmission mounts, do you mean aftermarket ones? Solid transmission mounts will cause the car to vibrate more from idle to around 1500-2000 rpms, just an FYI.

Matt

[skatingzooyork]

Used but came from a good running car, new csb.

It happens under hard accel. If I'm cruising in 4th-5th gear it's fine but if I push it a little too hard it does it.

And yeah I feel the vibration from the new mounts but it's definitely not that. It's a lot worse, u can even hear the vibration from outside!

[///digitalme]

um...check your axles and diff, and diff mount...but does sound like youre describing a bad u joint type of deal...i had a similar problem changed the driveshaft flex disc and no more issues other than the diff mount

[skatingzooyork]

I was wondering about the diff mount - it doesn't look too bad but definitely not great! The axles seem fine and I still have to change the diff fluid but I didn't think that could cause such a reaction.

[///digitalme]

i bet its the diff mount...long time ago my old e30 had a bad diff mount everytime i would step on it it would vibrate and make a thump sound...i changed the diff mount and fixed the problem...now i need to do that to my current one

[skatingzooyork]

i bet its the diff mount...long time ago my old e30 had a bad diff mount everytime i would step on it it would vibrate and make a thump sound...i changed the diff mount and fixed the problem...now i need to do that to my current one

Ok I will give that a shot next! Thanks!

[u3b3rg33k]

Sounds like mine when the subframe & diff bushings failed, and the subframe cracked. look for rubbing on the DS where the subframe could touch.

[QUKBMER]

The only time in any of my bimmers i had that problem was my centersupport or the u-joint stiffend up. I have either put in a reman or new with no problems. The diff mount or subframe only when i put it into gear then it made a slight thump. Do you have a vibration around 15/20 mph to 30/35 mph and if feels like it is under the car in the middle?

[87e30]

The only time in any of my bimmers i had that problem was my centersupport or the u-joint stiffend up. I have either put in a reman or new with no problems. The diff mount or subframe only when i put it into gear then it made a slight thump. Do you have a vibration around 15/20 mph to 30/35 mph and if feels like it is under the car in the middle?

That's a good point. If it's your driveshaft/csb you can kind of feel it right in the middle of the car.

[skatingzooyork]

Yeah it definitely is in the middle of the car but I just found out a couple things!

The CSB I bought brand new, my buddy (that helped me install it) said that the rubber was ripped across 30-40% of the bottom, under the bearing AND we didn't preload it either... I completely forgot about preloading and didn't see the rip. :(

So my CSB is STILL shot and causing the problem I guess. But honestly I would think that after a new DS and a slightly better csb it would feel a little better but I guess not.... FML!!!

[hotghias]

The only time in any of my bimmers i had that problem was my centersupport OR THE U-JOINT STIFFEND UP. I have either put in a reman or new with no problems. The diff mount or subframe only when i put it into gear then it made a slight thump. Do you have a vibration around 15/20 mph to 30/35 mph and if feels like it is under the car in the middle?

(edit: sorry to threadjack, but this is related)

Could someone explain the "U-joint stiffened up" thing to me? I only replaced the shot CSB in my e30 because my u-joint didn't have any noticable play (I've seen a u-joint with massive play before on my old subie)... but when I got the DS out, the u-joint did seem a little "stiff" when I rotated it through its range of motion. Is that a problem? And is that why there is still a little vibration under acceleration for me? What causes the u-joint to get stiff instead of loose?

Thanks.

[jlevie]

CSB failure is almost always the result of binding (stiff) u-joints in the drive shaft. Replacement of just the CSB may provide temporary relief, but the new CSB will have a short life and there may still be vibrations from the drive shaft. The only real fix is replacement of the CSB and drive shaft.