With my JE Reel drive shaft I have to set the pinion angle at 5° or less otherwise I get excessive drive line vibration.
Driveshaft Angle: 10.1º
Pinion Angle: 4.5º
This gives me a caster of around 1.5°. It drives pretty good, a little light but not bad at all. I started at around 4º caster and it drove great, but there was a lot of drive line vibration. I also went down to 0º caster, but the steering was scary light and dangerous.
If I increase caster the steering gets more positive, but I start to introduce driveline vibration. If I improve the pinion angle then the steering gets too light.
With factory driveshafts you will get more caster without any drive line vibration.
I'm running ones with the OE flanges, and I know about the problem with the OE flanges being out of true. That doesn't seem to be causing me a problem and I've ran a dial across the flanges and calipered their thickness and mine seem to be good. I believe it t is the elliptical path of the axle end UJ that seems to be causing the vibration when the pinion angle gets too far off.What drivelines are you guys running? The ones with the bolt on flanges or the ones with replacement yokes?