What's the right way to set caster on a Jeep?

[TerryMason]

I'm trying to set the caster on my TJ, and have a few questions. Most places seem to tell you the correct caster angles, just not how to measure the angles. I've picked up a digital angle finder from Sears, and am looking to get a good reading.

How's this process:

1. park on level ground
2. attach the angle finder to the frame of the Jeep and 0 it out
3. attach the angle finder to the bottom of the steering knuckle and measure.

Is this all there is to it?

 

[SteelHeadz]

Excellent question Terry, i'm stumped:???:. I've never tried doing an alignment without using an actual computerized alignment machine. One thing though that came into my thoughts , the measurement of the Caster is also measured during the Steering Axis Inclination Angle(SAI) measurement so i thought this two came hand in hand while the computer is reading all the current values and comparing it to the stored factory specs. in the machine. Since the Caster is the forward or rearward tilt of the steering knuckle from vertical, i think the idea of placing the angle meter on the axle is correct, the question is, how would you know what the current setting is on the caster to know if it's out of spec.?. From my observation , training and experience, these values are derived from the steering turn angle, camber and toe measurements. I'm now officially insane in my way of thinking this through. I'm curious if that's possible to do to attain the correct angle. On the other hand, If you zero out the angle meter on a true flat surface then install it on the axle, theoretically speaking, that should be an accurate reading of the axle tilt granted that all 4 wheels are perfectly leveled. I dont know Terry, i'm sorry but this has got me left with more questions in my head:twisted:..

 

[Sid1966]

hope this helps Jeep caster adjustment on TJ Wrangler w/wo adjustable control arms | SavageSunJeep | SavageSun Engineering

 

[Bounty__Hunter]

If you're on level ground, I would zero out the gauge to the ground and not the frame. You can measure across either upper or lower balljoint to get a pretty accurate reading.

 

[yo momma yj]

I had a wild thought. in the old days we'd eyeball a vertical thumb and throw the dice, but in this age of little cameras and zoom computer screens, the picture you take is just as good as the b&w picture in the service manual... take it to where you can see it... after you stir your coffee, maybe slap the protractor on the screen.

<I would zero out the gauge to the ground and not the frame.

in a picture, rotate by angle, center of axles front to rear as your level reference (same diameter/air right fr/rr).
you should be able to double-check trail against caster pretty close too.