Proper drive shaft phasing
reduces the stress and strain on the U-joints and reduces
vibration. This also reduces the chances of one of the
U-joints "exploding" and crippling the bike when you're out
riding. This is worth doing because a new replacement
drive shaft from BMW costs over $1,000.
Your drive shaft could end up
looking like this:
And your ride home could look
something like this:
If you line up the two halves of the drive shaft,
you'll notice they are about one half tooth from being able
to be perfectly aligned. This is because the front half of
the drive shaft has some rubber that insulates the front and
rear parts of the drive shaft. Phase the two halves of the
drive shaft so that when that rubber flexes under load while
accelerating that the U-joints will be aligned.
Before reassembling it helps if
you put some paint or whatever on the rear face of the front
half's splines and the rear U-joint.
© 2013 Drake Smith - Please do
not use or reproduce this elsewhere. Feel free to link
to it though.