Driveline alignment

[Mike Grace <mgrace@domain.elided>]

I've been chasing down a drive line vibration problem for about a year now,
and with help from Tom Sahines, I think I may have stumbled onto something.
It seems that my drive line donut is under tension created by the drive
line center bearing mount and the motor/transmission mounts. Tom suggests
that the resulting distortion of the donut ~6mm must be eliminated via shim
washers on the donut bolts or other means and I'm hoping that this will
solve my vibration. Before dropping the drive line again to extract the
donut (it's a pain with no lift and only two arms), I loosened the motor
mounts at the cross member and the tranny support cross member and pushed
the motor as far rearward as it will go (this bought maybe 1mm). Then, as I
dreaded removing the donut again to add shims, I started wondering how the
experts out there deal with the general problem of aligning the motor and
drive line after a rebuild (assuming all new motor/tranny mounts), since
there is some slop in the mounting points and since it does seem to be
fairly critical to get things lined up and happy. What sequence have others
used? Has anybody else dealt with this particular problem before?

Mike Grace
74 GTV
Santa Barbara

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