I've been noticing a vibration that coincided with road speed (not engine speed) but the frequency was higher than tires/wheels/brakes would normally produce. I had been running the original driveshaft for the time being, so I decided it was time to replace it with all new parts. No dice.
I started looking into driveline angles and it turned out that my factory setup was pretty bad. All of the u-joint angles were around 2.5deg (reasonable), but the arrangement of the angles was not ideal. After some measuring, drawing, and calculating, I ordered 1/2" worth of transmission mount spacers, 4deg axle shims, and some new axle u-bolts (because I had cut my existing ones to exactly the right length). The results were very satisfying! That vibration is gone and I can ride easy now knowing my u-joints aren't aching.
