On 19 Mar 2004 at 21:39, Terry Smith wrote:
> I took my drive shaft to be balanced. When I took it to the
> specialist shop, I had the arrows on the shaft and flange sides lined
> up like they were supposed to be. When I got the shaft back, the
> arrows were no longer lined up
I didn't follow this thread closely until I saw this note. Now, I
may be wrong about this (I spend a lot of my life wrong), but I
thought the point of lining up the flanges between the two ends of a
double-u-jointed shaft wasn't for balance. Rather, it was because a
classic u-joint (i.e. the non-CV type) doesn't produce a constant
rate of turn on the driven side (i.e. w.r.t. the driving side) if the
angle wasn't absolutely straight. If you have any angle in the joint
(which after all is the point of a u-joint in the first place), the
driven side will accelerate and decellerate as the driving side
rotates at a constant rate through half a revolution. But if the
other end of the shaft has a u-joint with the same angle (more or
less) and the two u-joints are aligned, the acceleration of the shaft
caused by the angle at one end will be given up by the angle at the
other, producing a more constant rotation at the far end. For a
gewarbox/driveshaft/diff combo, this means the diff is driven at more
or less the same speed as the gearbox, even if the driveshaft itself
accelerates and decellerates as it spins. If this is the real reason
for aligning the flanges between the ends, that shaft won't work as
well as it ought. On the other hand, perhaps this is such a small
effect that it doesn't matter. I'm sure RY or JC or someone can
expostulate on this matter further.
Gentlemen?
--
Jim Muller
jimmuller@pop.rcn.com
'80 Spitfire, '70 GT6+
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