b5rider

Quick history: Automatic Sahara Unlimited. Regeared to 5.13. Month later had to replace the rear driveshaft to a double cardan. I have the OME 618 and 619 springs which are supposed to net 2-3 inches max, 35" tires, and adjustable front lower CAs. I have a slight harmonic vibration starting around 60 to 65mph and continues to 75, but I'm not going any faster in the Jeep. I also have mild wandering and bump-steer
Questions:
I tried to measure the pinion angle and got beween a 1 degree to 2.5 degree difference from the DS to the different spots I was measuring on the pumpkin. How much difference is enough to warrant a set of upper CAs to set the angle to zero? Where do you take an accurate angle measurement?

I'm having the front caster set to 4.5 degrees on Monday. Where, and how, do I take an accurate caster measurement?



Any info would be helpful, thanks

rinkishJK

The most accurate spot according to Dynatrac is the pinion flange with driveshaft removed.

river2c

Adjustable rear upper control arms are required when adding an aftermarket double cardan drive shaft. There is no other way to adjust the pinion angle. The pinion angle needs to be as close to zero under torque as possible (this may be a few degrees shy of zero at rest). To just add an aftermarket drive shaft and hope the pinion angle is "close enough" is asking for trouble. In the front, if you set your caster to 4.5 with adjustable lower control arms, you should be good to go. Although you can measure caster from the bottom of the knuckles or top of the ball joints, the best way to accurately measure caster is to get an alignment done.

b5rider

Thanks for the responses. I hope it drives better after Monday. I really don't want the vibration to grenade the transfer case