Engine Vibration After Clutch Install

Hey guys, I own an 01 LSB with 144k on it, and I recently ordered the clutch kit from TMS which included the OEM clutch, PP, and throwout bearing.

Other than the car slipping, the car ran fine.

I got the clutch replaced by the head mechanic of my local BMW at his house, he does a lot of work on the side.

After he was done, he called me and said it went good, but while test driving it he felt a vibration, which he noted seemed like a driveshaft vibration? I thought this was weird, considering I had no vibration beforehand. I asked him about my flywheel, which he said looked great, just had some burn spots on it.

As I picked my baby up and headed home, I noticed the vibration he was talking about. It's only between 1k-2k (roughly) and if I rev it up while in neutral (moving or standing still) the motor sounds much louder. At first I was thinking it may have been an exhaust leak; maybe he didn't bolt the manifold back up or something.

There are no CEL's.

I work at a dealership, and some of the guys here said it seems off-balance, most likely the flywheel.

With my wallet in mind, I'm hoping it's only the manifold, or the motor or transmission mounts, but with my baby at heart, I'm open to all possibilities.
If there are any things I forgot to touch on please ask.

(I just picked it up yesterday, and haven't gotten a chance to ask the BMW mechanic yet, I am going to ask him to look at it for free to determine if it was a problem he created.)

Flex disc (a.k.a. Guibo) on the back of the transmission? Only other thing I can think of.

is it only while you are driving and not if you are just reving it up?

he might not have marked the drive shaft and put it back different than it was before.

That is a myth.

The shaft is balanced independent of the transmission. Otherwise, when you changed transmissions, you would need to change the driveshaft too (which you don't have to do, I know, I have done it). Also, if it was a balance problem, it would most likely get worse the faster everything spun, like an out of balance wheel. But that does not sound like the case as it is a low RPM problem, so it sounds more like a harmonic issue.

Originally Posted by dcf

That is a myth.

The shaft is balanced independent of the transmission. Otherwise, when you changed transmissions, you would need to change the driveshaft too (which you don't have to do, I know, I have done it). Also, if it was a balance problem, it would most likely get worse the faster everything spun, like an out of balance wheel. But that does not sound like the case as it is a low RPM problem, so it sounds more like a harmonic issue.

maybe maybe not...when it didn't vibrate before it shouldn't in the future. It's very cheap insurance.

When I had a ltw flywheel mine have a vibration when reving around 1500-1800rpms so i went back to oem flywheel.

Yes it vibrates and sounds louder both while driving (still in the 1k-2.5k range) and while sitting still. I understand that it most likely still vibrates past 2.5k, I guess it just isn't noticible because of how fast it is at that point.

Most people are saying it's harmonics, most likely the flywheel. Maybe it's because I'm not as mechanically inclined yet, but I don't understand why the flywheel would cause vibration now when it didn't before...

Would it have to do with the old pp and flywheel growing unbalanced together? So when the new pp is added, it doesn't sync with the flywheel?

Could be a new part isn't properly balanced. Could be things weren't properly aligned during re-assembly. Could be the motor mounts were on their last legs and damaged during the clutch replacement. Less likely but not impossible are problems with the flywheel, harmonic damper, or drive shaft components.

Originally Posted by Tysis

Yes it vibrates and sounds louder both while driving (still in the 1k-2.5k range) and while sitting still. I understand that it most likely still vibrates past 2.5k, I guess it just isn't noticible because of how fast it is at that point.

Most people are saying it's harmonics, most likely the flywheel. Maybe it's because I'm not as mechanically inclined yet, but I don't understand why the flywheel would cause vibration now when it didn't before...

Would it have to do with the old pp and flywheel growing unbalanced together? So when the new pp is added, it doesn't sync with the flywheel?

the dual mass flywheels acts as sort of a damper for radial oscillatory-caused loadings... when you reduce the weight of the part, the less it will dampen these vibrations as the part is now easier to 'shove' around by oscillations.

if the flywheel weighed next to nothing, i don't even think the engine would run without a high idle...less rotary mass and momentum to keep it running

Never had this issue but could it be a break in of some sort? I doubt it though because I've never had that on a clutch replacement.

Did he make sure your guibo is okay? Give it a few hundred miles, maybe the clutch just needs to be broken in. Or maybe he didn't torque a bold right or something.

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