Proper drive shaft phasing reduces the stress/strain on the U-joints and reduces vibration. It mitigates 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 well over $1,000. (BMW part 26112325746)

Your drive shaft could end up looking like this:

And your ride home could look something like this:

Properly phasing a drive shaft is simple. When sliding the two halves of the drive shaft together, line up the U-joints at each end so that they are on the same plane.

Align these to be on the same plane

 

When you put the two halves of the BMW drive shaft together to align them, you'll notice that they are about one half of a spline tooth from being able to be perfectly aligned. The front half of the drive shaft has some rubber around its splines that insulates the drive splines. Join the two halves of the drive shaft so that when that rubber flexes under load while accelerating that the U-joints will be aligned.

Rubber in front half of drive shaft:

Before reinstalling the front half of the drive shaft on the transmission, put some paint or whatever on the rear face of the front half's splines and the rear U-joint. This will allow you to properly phase the drive shaft when reinstalling the final drive.

Only Removing Final Drive:

If you are only removing the final drive and want the front and rear splines to remain in the same alignment then place some tape or a mark on the rear brake rotor before removing the final drive and then have the brake rotor in the same rotational position when you reinstall the final drive. Do not spin the brake rotor when the final drive is removed.

 

Learn About Drive Shaft Phasing:

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