Drivetrain vibration

[Hypr5]

Hello all,

In my other e34, I've had a driveshaft vibration (failed center bearing due to trans. mounts) and I replaced it, all was well.

Now in this one, I feel a VERY similar vibration, but it will only do it in one gear. The transmission had failed, it is now rebuilt and reinstalled and the same vibration is there. In my past experience, the driveshaft caused the vibration in every gear at the same RPM.

Could this still be a driveshaft issue? I'd hate to throw money at the wrong part. The guibo LOOKS ok, has minor minor cracks, but thought the driveshaft would be RPM specific, but independant of the gear.

Any ideas / advice?

Thanks!

[genphreak]

Depends on the load against the engine at the time, as well as speed and gear. Problem with this is hills, gs and traffic (all variables making your judgement on load hard). Ideally, at the same loading and accelleration gear should make no difference- I expect you could go off the economy gauge to most accurately measure drivetrain loading, are you sure its only one gear? Is that 2nd you are talking about? If it is only first gear you might want to test a bit more... if 2nd it could be the tranny, the 2nd gear band is often the first to go... but that said a new centre bearing is too cheap to argue with... especially if the guibo needs replacement. Sounds like time to pull the exhaust and see... when my bearing went all 3 (RPM, gear and load) all contributed to making the noise (or avoiding it...)

[Hypr5]

Well thanks for that reply.

It IS second gear that it vibrates in, but the transmission is freshly rebuilt and it did this before the rebuild as well. I noticed it the second I drove off with the rebuilt installed. Interesting. This has me a bit worried...

edit: which car are you talking about has the common second gear band failure? The one equipped with 4hp22 or the one equipped with 4l30e??

[632 Regal]

driveshaft could be slightly bent or off balance, it could also be out of phase since it was removed a couple times.

[Scott H]

depending on how long the center bearing was bad and wobbling. The u-joint could be worn a bit. The d/s on my 535iT creates a small vibe at 40mph....it's a bit out of balance.....the same thing happened in the 535im that the same d/s was in.

driveshaft could be slightly bent or off balance, it could also be out of phase since it was removed a couple times.

[Hypr5]

Thanks again guys,

I took her out for another test because I got worried, it does the shimmy slightly in 1st gear at approx 2600 - 3000 RPM and in second stronger at 2200ish RPM.

Also, in "M" and "D" at the same time, from a stop, should the car move? I always thought that being in "D" overrides the manual mode. Am I wrong?

Thanks again I guess I'll work with the driveshaft and update. Hopefully thats what it is!!

Keep the suggestions / ideas coming if anyone has one.

[Hypr5]

Depends on the load against the engine at the time, as well as speed and gear. Problem with this is hills, gs and traffic (all variables making your judgement on load hard). Ideally, at the same loading and accelleration gear should make no difference- I expect you could go off the economy gauge to most accurately measure drivetrain loading, are you sure its only one gear? Is that 2nd you are talking about? If it is only first gear you might want to test a bit more... if 2nd it could be the tranny, the 2nd gear band is often the first to go... but that said a new centre bearing is too cheap to argue with... especially if the guibo needs replacement. Sounds like time to pull the exhaust and see... when my bearing went all 3 (RPM, gear and load) all contributed to making the noise (or avoiding it...)

Driving super lightly, I can avoid the shudder. How can I check to see if it is the transmission? Or would it do it no matter how I drive it in 2nd gear??

[632 Regal]

to give you an idea of how fast the driveshaft is spinning at any speed, shift int the last gear befory the final gear, dont have to gas it or lug it, thats the driveshaft speed at 1:1. Inspect the shaft for any play at all, push it side to side and up and down and watch/feel the universal joints. Any play is real bad.

[genphreak]

Thanks again guys,

I took her out for another test because I got worried, it does the shimmy slightly in 1st gear at approx 2600 - 3000 RPM and in second stronger at 2200ish RPM.

Also, in "M" and "D" at the same time, from a stop, should the car move? I always thought that being in "D" overrides the manual mode. Am I wrong?

Thanks again I guess I'll work with the driveshaft and update. Hopefully thats what it is!!

Keep the suggestions / ideas coming if anyone has one.

Hey Hypr5, in D (and manual mode) D is equal to 3rd or 4th (I can't remember if it will go into 4th or not in M mode). S lower the shift points and prevent 4th from happening (I still don't get why, something to do with not needing spirited throttle response at 120+ MPH??)). If you use M mode, 1=1 2=2 3=3 D=3 (or maybe 4) and that's it. You really want to get that exhaust off and jiggle the shaft as Jeff said. The bearing itself is suspended in a rubber diaphragm (something he might not know a lot about), both of which can deteriorate with age (something he really would not know about) allowing the shaft to bend under load causing the 'wooping'. Under more load it may hit the edges of the outer casing (which is no longer suspending the diaphragm and bearing within it) which is when most people notice it as it bangs loudly and stresses the spot-weld zones of the casing near where it mounts to the body. The thing is so crumbily made (they built it out of 1.6mm thick tin foil) that it seemingly has no failsafe (?). Once this happens it looks ot me like the shaft can actually pop out if you are stupid or unlucky, so I would be careful testing- though I haven't heard of it before, you might be better off replacing it straight out as a hole in your e34's floor would not be too good for the wallet... Nick

[Hypr5]

Thank you.
I'll go ahead and check for play at the end of the week when I have some time. On my red car, there was the slightest notchiness in the u-joints, but new trans. mounts and a center bearing cured that, so is some notchiness ok?? I'm not sure if since this is a different car, it will be affected differently.

Is the guibo pretty much ruled out with only having minor cracks on the surface? Does this sound like it's basically going to be the u-joints or the center support bearing??

Thanks again.