That's my point though. You need the readout from an actual alignment to see where you really are, then you can just adjust in the garage using your angle finder as a baseline.

I meant to say "a bit more peace of mind for when we run Holy Cross on the next trip!"

 

For the vibration check the new flange to ensure it is tight on the TC. Friend years ago had this issue on his 78 F150 when it was near new.

 

good point. When I had the drive shaft installed, it had the vibration(very slight). I went to Moab and the drive shaft actually became really loose. I guess the installer forgot to locktight the bolts. The shop in Moab didn't do anything to the flange as far as I know.

 

Well, I just shortened my UCA's by 1 revolution and changed the angle by 1* (at the flat spot on the diff). Test drove the jeep and the steering is better (less wander), but the rumble appears to be a little more noticable. Going to pull the DS at next opportunity.

 

Sure, I’ll park and record you doing it, then probably drive you back to your Dad’s place in my still working Jeep.
Man my iPad hates this site anymore, multiple resets , slow loading, and very slow typing response.

 

i thought 3 degrees of caster was the sweet spot after a lift? The factory setup should have 4 degrees of caster built in when the pinion flange is at 90 degrees. Rotating the pinion up 1 degree leaves you with 3 degrees of caster. If you’re at more than 4 degrees, wouldn’t your pinion flange be less than 90, potentially causing a vibration?

The real question I guess is what driveshaft do you have now? That would determine what your pinion angle should ideally be, then you can play the caster game some more to find the mix of drive ability versus happy angles

 

Correct me if I'm wrong, but shortening the UCA should increase the caster since it would move the pinion down. For a 3 1/2" lift, the sweet spot should be 5* to 6*? Metalcloak calls for 5* on their lift install directions.

 

You're on the right track, but there is a 6* separation between Caster and Pinion, not 4.

Caster 7* = Pinion 1* dn
Caster 6* = Pinion 0*
Caster 5* = Pinion 1* up
Caster 4* = Pinion 2* up
Caster 3* = Pinion 3* up

This is am image from the Dynatrac PR44 FAQ that has been floating around for years now. Gives a decent illustration of how rotating the housing will affect caster and pinion angles.

 

Correct. Shortening the uppers (or lengthening the lowers) would rotate the pinion down while raising the caster.

Better to use posted numbers as starting points, not hard fact. The 'best' caster/pinion angles will depend on lift height, type of driveshaft joints, usage, etc.

 

Ah, that’s right, I swear I’m dyslexic and I look at the 96 degrees and always think 4 degrees of caster. I love this picture but always have to check it before I do my math!