Driveline Vibration revisited

[shiftbmw]

So, I've got some interesting driveline vibration that I'm trying to figure out.

I have the usual vibration between 2-3k rpms in first and second. Probably(hopefully) just the guibo/csb starting to go as opposed to the u-joints etc. This vibration is very slight...someone who didn't drive my car as often as I do would most likely not even notice it.

From 3k-6k, there is really no detectable vibration.

Where it gets strange is that the vibration becomes MUCH more vigorous at 6k rpm WOT in first. I haven't felt it second. It sounds like a knocking coming from my tranny tunnel right under my right kidney bolster on the drivers seat.

Has anybody experienced a driveline vibration in the upper rpms like this? I have an autocross coming up so if I have a serious safety concern or anything I obviously want to address it beforehand.

Any insight appreciated.

[AlarmedBread]

Inspect your drive line obviously somethings wrong. If it isn't the ujoints, it will be soon if you keep driving it like that. Just because you don't feel/hear it doesn't mean the vibrations went away, just a higher frequency.

If you don't think its safe to autocross why would you drive it out of the garage?

[Dirtsquirt]

CSB usually shows itself on acceleration.

[shiftbmw]

Yeah, I need to climb under the car and see what's going on. Sadly I don't currently have a jack or a place to do it. I'm going to try to chase one down tomorrow though.

Regarding safety, if I thought I was in danger, I wouldn't be driving the car. I was more referring to safety of surrounding parts.

[Nlando]

Sorry for the stupid question, but what is CSB?

CSB usually shows itself on acceleration.

[aschmidt]

Sorry for the stupid question, but what is CSB?

Center support bearing.

[StereoInstaller1]

So, I've got some interesting driveline vibration that I'm trying to figure out.

This is kind of odd. I sat down to R3V for a moment to post about this exact same issue!

By "interesting", you mean an annoying pain in the ass, right?

I have the usual vibration between 2-3k rpms in first and second. Probably(hopefully) just the guibo/csb starting to go as opposed to the u-joints etc. This vibration is very slight...someone who didn't drive my car as often as I do would most likely not even notice it.

The "usual" vibration? This is a BMW, I expect no vibration from the driveline...and for 99.999% of the 4 years I have owned this car, I have had none. Mine is a slight shudder/shimmy feeling, really annoying when I am used to feeling just throbbing raw M20B25 power (teehee). Last night I installed a new CSB and guibo, both being pretty damned thrashed.

I used OE stuff from the stealer. The Guibo is beefier than the Febi that was on there, and WAY huge improvement on the CSB. See my thread here. Somehow, it feels "firmer" when driving. I will never buy aftermarket again! I also like that this guibo has arrows indicating what bolts go where.

From 3k-6k, there is really no detectable vibration.

Just exactly like my car...I am gonna find this damn vibration no matter what!

Where it gets strange is that the vibration becomes MUCH more vigorous at 6k rpm WOT in first. I haven't felt it second. It sounds like a knocking coming from my tranny tunnel right under my right kidney bolster on the drivers seat.

I had this too. Mine was more like a mettalic knocking under the passenger seat. Pretty damn bad, but controllable through careful throttle application.

With the new CSB/Guibo, no more robot hammering at all...but the vibration is STILL THERE!

When I had the driveshaft on the bench, I checked the U-Joints. The front was perfect, no slop or crunchiness or binding during movement at all. The rear joint had a tiny bit of binding/crunchiness on one phase of travel, like the earliest phase of failure.

The binding is so slight that I really have a hard time believing that it is the problem. I am talking hard to feel with bare hands and driveline on the bench.

Has anybody experienced a driveline vibration in the upper rpms like this? I have an autocross coming up so if I have a serious safety concern or anything I obviously want to address it beforehand.

I have replaced the driveline before. The old one was so freaking shot that there were no bearings in the caps of the u-joints at all...just a pin and a cup. That was 3 or so years ago and I just do not remember what the hell I dealt with.

Anyone who tells you that pot doesn't damage your memory is full of shit.

Today I am hopefully going to swap drive axels out to see if that is the issue. Every time I drive my car I am annoyed...I will keep posting in this thread as I find stuff. Hopefully we can both find the issue.

GL!
Luke

[shiftbmw]

Stereoinstaller - Sounds like we have identical issues.

First, yes by "interesting", I mean an annoying pain in the ass. Second, the "usual" vibration is only usual when you know your csb/guibo are on their way out.

As for the 6k vibration, a metallic knocking is a good way to describe it. I'm going to jack the car up today and see what I can find. At least tke a look at the guibo and see if it's beat.

When you replaced your csb/guibo and say no more hammering but vibration is there, you mean the vibrations are just less intense at 6k or are we talking about a different vibration?

[StereoInstaller1]

The high RPM vibration stuff and the knocking is gone 100%.

The "shimmy" on acceleration between 2K and 4K RPM are still there, unchanged.

Luke

[shiftbmw]

So, hopped under the car to find that my guibo looked gorgeous. Stunning in fact.

Didn't have time to remove the cat shielding so I didn't have the ability to check out my center support bearing, although my guess is that it needs some help.