Guibo or Center support bearing?

[Laldog]

Finally got my car back on the road...but as is custom, a new problem has developed.

Upon acceleration (most often in 1st gear) a vibration/thumping can be felt from under the car.

I'm quite sure its the drive shaft, and I'm also guessing it's either the center support bearing or the rubber flex disc. Both have been recently replaced, and I admit the "preloading" sequence of the center support bearing may not have performed to factory specifications.

Any thoughts or suggestions would be greatly appreciated before I crawl under the thing this weekend.

Thanks in advance.

 

[Stevehose]

Hard to say without going under, if the vibration feels farther back from the tranny then maybe it's the center bearing which tends to shudder upon starting from a stop. Rotate the drive shaft and look carefully also at the guibo for a crack, often they are cracked on inside and not all the way through to see.

 

[Stan]

I just had the center support bearing replaced. Same Symptoms. Start in first gear and whump whump whump until you get to about 10 mph then everything smooths out. When I got under my car the rubber was obviously torn. I was able to drive it up to VSR in Bow NH and they had it fixed quickly.

 

[inovermyhead]

Is it a 5 speed box?
I'm having the same problem on take off in 1st with only modest throttle opening and it's looking more likely that the rotational forces acting on the engine mounts cause the engine and gearbox to 'twist' expanding the left mount whilst compressing the right. A solution 'maybe' to fit stronger billet mounts, still yet to go there, but a possible cure.

Cheers. John

 

[inovermyhead]

Check out Vibra techniques M30 mounts

 

[Stan]

If your center bearing looks like this it needs to be replaced

 

[Stevehose]

Also make sure the drive shaft is aligned to the guibo with no lateral or axial movement:

From the 2002 FAQ (and Rob S.):

http://www.bmw2002faq.com/blogs/ent...alignment-from-hell-or-it-just-doesnt-matter/

I aligned mine by cutting a slot into the hole side of the CSB carrier so it could be adjusted laterally, and added some washers to drop it a little lower so when the driveshaft is turned there is no play between the guibo and the driveshaft flange (measured by loosening the bolts a little to check the play).

If it's not aligned it wont take long for it to destroy itself.

Both have been recently replaced

 

[lloyd]

Finally got my car back on the road...but as is custom, a new problem has developed.

Upon acceleration (most often in 1st gear) a vibration/thumping can be felt from under the car.

I'm quite sure its the drive shaft, and I'm also guessing it's either the center support bearing or the rubber flex disc. Both have been recently replaced, and I admit the "preloading" sequence of the center support bearing may not have performed to factory specifications.

Given your symptoms, sight unseen, I would point to the center support bearing. It can be torn, distorted, poorly installed on the driveshaft, installed backward and even unintentionally left loose where it attaches to the chassis. In my experience, the suggested preload of 2mm is not critical, especially considering the amount of flex designed in the rubber carrier.

That said, there are other possible contributing factors. Some "tramping" or drive line shudder upon acceleration can occur if the rubber transmission cross member mount is torn, broken, or super soft. However, more likely than not, you would feel the shudder through the shift platform as the transmission is moving too. Motor mounts too, if bad (soft/loose) can cause anomalous drive line behavior.

Much much further down the list is the drive shaft itself. Among other things, the threaded coupling of the two-piece drive shaft (near the splines) can be inadvertently left loose. There are other oops situations too, e.g., a flex joint that wasn't properly tightened. I had one where the installer only torqued the nylon lock nuts finger-tight which resulted in strange clinking and clunking sounds along with vibrations at different speeds.