E36 drivetrain shatter on clutch engage

[makaveli1996]

hi fellas,
evertime i get fast load changes into my drivetrain like pressing the clutch while accelerating, or bouncing on the gas pedal i get a klunk klong klung swinging noise from arround the transmission.

it sounds like damaged engine mounts (brandnew),metallic like a hammer bouncing forth and back a few times.Iam pretty sure it is my clutch disk and its springs (brandnew clutch,pilotbearing and throwout bearing).
ive read a LUK (clutch manufacturer) documentation over clutch damping and i found out that there are 2 reasons for a clutch disk to get an erratic movement.First it could be selfinducted by differences in clamping and friction forces,second it can be inducted by external components like engine mounts or transmission mounts,flex disk and so on that lead frequencies to the pressure plate disturbing it to engage or disengage smoothly.

nevertheless i asked myself if my carrierbearing/middlebearing is to soft as i can move the driveshaft in the rubbersection quiet a bit.
here i found 2 videos showing my exact problem.,
by the way - i dont have a dual mass flywheel!my flexdisk seems tobe new or recently exchanged.

Merc:
http://www.youtube.com/watch?v=Oc7B0GVsgVg
BMW:
http://www.youtube.com/watch?v=LxPp-M8TN-4

[mmkale]

dual mass flywheel springs worn out. I have a similar problem.

[Beeker1972]

My wife's 95 325i does that it has 274,000 miles on it so I wouldn't be surprised the dual-mass flywheel springs are worn out haha

[RouteZeroDesign]

I had this same problem after installing a lightweight flywheel and M3 clutch on my M44.
The problem in my case appeared to a combination of worn out gearbox mounts and broken exhaust bracket that braces between the gearbox and the section of exhaust just after the catalytic converter.

I too thought that it was my center bearing or flex disc but it would appear that the issue is caused, at least in my case, when moving a slow speeds, slipping the clutch and the drivetrain torquing in its mounts.
Whereas before when I had the dual mass flywheel, both the flex disc and worn out clutch were acting as torsional dampers for the drivetrain, with the lightweight flywheel and M3 clutch, not only is the damping effect of the dual mass flywheel gone but the engagement of the clutch is a lot harsher and can apply a lot more torque to twist the drivetrain. The flex disc is now the only effective torque dampener and with its rubber having quite a high Youngs modulus, it wants to spring back as the clutch slips.
Imagine twisting in a screw with two screwdrivers, one with a shaft made of gum, the other made from an eraser. Now imagine that you're wearing very slippy gloves, the reduced spring back in the gum will allow for a much smoother screw engagement than the eraser material which constantly wants to unbind.

The net result of this (again, I can only speak from my own experience) is that with a combination of worn gearbox and engine mounts, the engine is free to torque in its mounts and when slipping the clutch the drivetrain goes through a cycle of binding and unbinding causing the differential, prop-shaft, gearbox and engine to shake violently. This in turn shakes the exhaust system around, knocking the center or rear boxes against the underside of the body or against the tunnel and in my case eventually braking the gearbox to exhaust bracket, allowing it to shake even further.
This can cause the noise to be very difficult to locate and make tracking down the root cause severely frustrating; I changed my differential fluid fearing that it was on the way out and that I would at least hear a change in tone.

Anyway, I hope that helps. Again, this is purely from my own experiences and your issue could be something entirely different.