E30 Transmission Vibration

["Spataro, Mike" <spatarom@xxxxxxxxxxxxxxxxxxx>]

My 85 318i 5speed creates a lot of vibration at low rpm, mainly when
accelerating.
I have checked various driveline components, and cannot find anything which
I suspect would cause this problem.

The symptoms are:
1st gear-  ok.
2nd gear- under acceleration, 1300 to 1500 rpm, noticeable harshness /
vibration.
3rd gear-  under acceleration, 1300 to 1500 rpm, bad vibrations.
            -  when slowing down (in gear), 1300-1500 rpm, slight vibration.
4th and 5th gears-  similar to 3rd, but the vibes are worse.  The whole car
seems to shake.  You do not want to open the throttle at these revs.  I
can't tell if the source of vibes is from the front or rear of the car.

My inspections included:
     - engine and gearbox mountings - ok
     - flexible coupling between gbox and driveshaft (guibo or rubber donut
- - it has a few names) - ok - a few small cracks in the rubber
     - centring guide between gbox and driveshaft ( inside the flexible
coupling ) - not checked
     - center bearing - ok - I adjusted the preload from 0 mm to 5 mm, no
difference
     - universal joints - ok
     - sliding coupling (between the two driveshaft sections) - ok - tiny
bit of radial play, but no more than a few 1/1000 inch
     - driveshaft alignment - not measured, but looks ok (difficult to check
without removing the exhaust)
     - final drive mounting - ok
     - final drive input shaft play - ok
     - final drive output flanges - clear movement on both of them, both
radial and axial. Does not look good, but I dont think this is my problem
     - CV joints - ok
    
I think the problem would be close to the gearbox (gbox output shaft or
flexible coupling), given that the vibrations occur in a particular narrow
rev range, but it is difficult to say.
I would appreciate any thoughts on this matter.

Thanks,
Mike.

+++++++++++++++++
Mike Spataro, 
'85 318i 5 spd 2 dr, 100K miles.
'68 1750 Alfa Romeo GTV coupe (dead)
+++++++++++++++++

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End of bmw-digest V9 #1101
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