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CA and caster q's


NAXJA Forum User
Mid Missouri
Anyone know what the length of RE's fixed length control arms are for their drop bracket kit?

Also, what is the relationship between arm length and caster?
(What I mean is for every ___" of LCA extension or UCA shortening, you move the caster angle by ____*).

I put in new to me 6.5" springs and have a contact issue between one of my springs and the sway bar. I figure it has to do with running a negative 5* caster or so (Yes I mean tipped the "wrong way" but just a guess, will measure it tomorrow, but my pinion angle is great :D ). Need to find a good middle ground between caster and pinion angle for 6.5* of lift.

Bones :skull1:
They only have one set for all the set-ups.The lower's are 16" and my upper was set at 15.5".
What's wrong with negative Castor? Just drive around in revearse ;)

Here's a chart that should get you in the ball park (YMMV)

Lift = Change (delta)
1" = -0.78°
2" = -1.56° (-0.78)
3" = -2.32° (-0.76)
4" = -3.10° (-0.78)
5" = -3.89° (-0.79)
6" = -4.70° (-0.81)
7" = -5.57° (-0.87)
8" = -6.50° (-0.93)

As you can see, it's roughly 3/4 per inch of lift, increasing slightly the higher you go. Don't forget to factor in the 4" brackets if you're using them.
Ok, I think I figured out the stuff I was looking for. Instead of trial and error under the Jeep trying different control arm lengths to set my caster (it was -3* BTW) I decided to use my brain.

After bottle or two of aspirin to control the pain :wow: I was able to do a mock up of the front control arm and axle set up in cross section. I then adjusted the "arms" length and was able to measure the change in caster.

It appears that caster is changed roughly 4-4.5* for every .5" of control arm change (4 for the lower and 4.5 for the upper). For some reason it appears there is a mild penalty built in if moving both arms at the same time (even opposite of one another).

I plan to extend my lower arms .5" and my upper ones .25" and figure on a caster change from -3* to a positive 3.25* give or take. If I pick up front vibes again I'll just start unhooking the driveshaft on long runs.

Bones :skull1: