++> I have a '67 Spitfire Mk II that I've had a lot of trouble getting the
++> driveshaft (OK, propeller shaft) balanced. I've taken it to two different
++> Does anyone have any experience with this problem or any advice?
I'll admit it, I'm a balance freak. I don't know why, but vibrations
really seem to bother me. I've fought with a few driveshafts. First off, why
have you pinned this vibration on your driveshaft? They usually are pretty
trouble free, as long as the u-joints are in good shape.
More to the point, can you now assume it is balanced properly? (do you
think the last guys did a good job) You can try to balance it yourself using
the old hose clamp method. I think Haynes manuals describe it. Basically you
put a hose clamp on the shaft and the screw portion acts like a weight. After
several iterations of moving it around, you can home in the right postion YMMV.
If it is balanced pretty well then you need to look upstream and downstream of
the prop shaft. Are your transmission and differential mounts in good shape?
Also, is the face of transmission output flange parallel to the differential
input flange? Poor alignment here can be caused by a number of things,
including bad engine mounts. If they aren't parallel, the u-joints will wear
out quickly and can cause a vibration. Does the vibration change under load?
(If it does, it is probably a bad u-joint somewhere) Check for excessive play
in the transmission output and the differential input flanges.
The Spit driveshaft is so small that I doubt it would cause a
horrible vibration without being obviously bent, or having obviously bad
u-joints.
Your driveshaft shop would have told you if that was the case.
--
William Woodruff woodruff@caen.engin.umich.edu
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