D30 caster......

is it positive or negative? My XJ is about 4* positive. I think I need to change the upper control arms to match the lowers.

Should be 6-7 degrees negative. Meaning the upper ball joint is behind (towards the rear of the vehicle) the lower ball joint when viewed from directly above.


Bob

There are caster shims in the lowr arm/frame rail brackets.

Rock Yacht said:

Should be 6-7 degrees negative. Meaning the upper ball joint is behind (towards the rear of the vehicle) the lower ball joint when viewed from directly above.


Bob

Click to expand...

Strange;... I have as we speak 2" of lift, Rusty's LCAs for a 3" lift and the original OEM UCA's. The LCA's are shimmed all the way forward as far as they could go and yet the caster reads only 2*... top of axle rearward. There is something here that I do not know. The LCAs in use are longer than the OEM units that I replaced.
I would thing that using longer control arms on the bottom and the OEM units on the top that the reading would be way off but in the other direction to be corrected only by replacing the top OEM units with units manufactured for the same lift as the ones on the bottom.
I need to refer back to the laws of geometric arc once again. Then again there are so many things that I am yet to understand regarding the XJ.

Note: the measurement was taken across the head of the two center bolts on the pumpkin using an angle finder I bought from Home Depot.
The diff pinion is definately looking down like I expect it would only not as much as I expect it to.

i think that you are measuring wrong, take a look for Go-jeeps website here http://www.go.jeep-xj.info/