[Supras] Vibration

[berniek at technicaldevelop.com]

Bob:

    One other possibility for vibration are incorrect U-joint phasing 
and angles.  I forgot about it after these many years, but in a '59 
Chevy I had, I once reassembled the two piece driveshaft with the joints 
out of phase, and had vibration with frequency which varied with speed 
as a result.  There was one other instance I had where U-joint angles 
were not complementary, also with vibration, though not severe.


    In any event, although its a long shot maybe this link will help:


    http://www.drivetrain.com/driveline_angle_problem.html


    The new '65 GTO which followed the Chevy began to develop a 
driveline vibration at about 40K miles, which got worse with time.  
After changing U-joints to no avail I took the shaft to a specialist who 
did the following:


1.  Installed it on a machine with rollers to support it, and rotated it 
at 400 RPM.  Why 400 RPM?  He did not know.  The rollers were supported 
on some sort of floating mount each of which was connected to a sensor 
for a strobe light.


2.  He removed the factory spot welded balance weights.


3.  The next move was to bring one spot on the shaft to red heat with a 
torch and let it cool.


4.  The shaft was then declared to be balanced.  After reinstalling it, 
the vibration was worse then ever.  I ordered a new shaft complete with 
U-joints and yoke (it was one piece) and it solved the problem.  Cost 
then (1967) was $35 from a Jeff Watson GM counterpart. 


       Bernie