driveline vibes

["Watry, Andrew" <Andrew.Watry@domain.elided>]

Re Mike Grace's GTV driveshaft problems:

	My own experience on numerous 105/115 cars has shown these common
problems, listed in order of cause of problem in my cars:

	1. Bent/out of balance driveshaft, esp. the rear piece.  Solution is
to straighten and balance.
	2. Non-OEM u-joints, whether properly or improperly installed, can
cause vibes.
	3. Broken, deteriorating donut causes vibes.
	4. Way, way worn out motor mounts or rear trans rubber mount.

	My own experience has been overwhelmingly that the straightness and
balance of the driveshaft itself has been the main concern, and the quality
and installation of the u-joint kits has been a distant second.  On my old
Giulia TI, replacing totally worn out motor and trans mounts made no
difference to the vibration.

	In terms of misalignment, what 5mm or 6mm spacers are people
referring to? I've never seen these on a 105/115 car.  I have seen them on
750 and 101 cars, and a transaxle car would be a whole different story.  But
I thought the 105/115 rear trans mount bolted solidly up to the body by way
of its four 8mm bolts.

Andrew Watry
Berlina Register
Berkeley, CA

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