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cj7 caster angle - what should it be?

56K views 40 replies 16 participants last post by  2001WJv8 
#1 ·
I just finished building my cj7 and I feel like it's wandering and not returning to zero like it should. Everything is tight. I have rear factory yj springs up front with a soa lift. I welded the perches parallel to the ones on the bottom. The upper ball joint is a little behind the lower like its supposed to, but what should the angle be? I'm running 35" tires. I was thinking about making some taller spring mounts to get some more angle, plus get a little more height that i need in the front. Has anyone ever done it this way? What are your opinions?

I know I'm having a bump-steer issue too. Im running a factory pitman arm with an offset drag link. Everything runs under the springs. Could this be causing all of the problems? I know a ton of people have done this before so I'm hoping someone on here can help me out...
 
#3 ·
Do you know what your caster angle is? You should aim for 5* to 8* positive caster.

Also, an offset draglink doesn't help with bump steer. It's really only for clearing components, which is what you need with your setup anyway. A drop pitman arm (or high steer knuckles) will help the bump steer issue.
 
#4 ·
hey, thanks for the reply. i measured it a lil while ago. its about two degrees. i'm thinking seriously about welding on some taller spring mounts for the fixed end.

and yea i know that about the offset drag link. i need to do something different there too. i think im going to tackle the caster issue first.
 
#11 ·
OK thanks. I asked because my Haynes doesn't give specs, it only explains what caster/camber is and the alignment tools required are out of reach of what a "home mechanic" would have. Just seems to me that 6 is a preference and not a factory specification. Once you get away from the factory spec other things like pinion angle should also be factored in. 80cj's is nice and low (I like that setup), but once you start going twice the factory caster spec and then add a big lift you will be getting into pinion angle problems.
 
#14 ·
It's not surprising that a '76 model required less caster... for the same reason most Scout axles have 0* caster.

Unlike Europe and Japan, American tire makers stayed with bias ply tires well into the '70s. Because of how a bias ply tire behaves, the contact patch actually moved backward at speed and required less caster.
 
#19 ·
If you search for "rotate" in CJ Tech, you'll probably find the ones where this has been discussed. People have linked to writeups in them

Its quite a biotch, as it is a labor-intensive process to grind through the welds from the tube to the knuckle yoke. Having the axle out of the vehicle so you can turn it while grinding will be helpful, but you'll need to have it back in the vehicle and able to be under load before performing the final welds. (Estimate and turn the yokes, tack them, set the vehicle down, measure, possibly adjust, etc.)
 
#20 ·
The way I get inner knuckles to turn is this.
1) Grind the welds between the tube and the C (inner knuckle) with a grinding wheel till it is almost gone. You have to be careful to not grind into the tube.
2) Switch to a flat cutter wheel to grind down the side of the knuckle and along the tube to get the last part of the weld. I try to make a 90 degree angle at the joint between the tube and knuckle at this point.
3) Once I think I have the weld ground out (it won't be) I take two hammers (about 3 lb) and bang on both sides of the C so as to try to knock it off the end of the tube. This generally makes a tiny crack show somewhere along the joint between the tube and knuckle. The crack will be so thin that is is not easy to even notice. I'm talking width of a hair thin. Once you get a crack you can see where else you need to grind to get all the weld out.
4) Then you can knock off the C with the two hammers hitting the C on both sides toward the outside of the tube at the same time. Once you have the Cs off you can put them on at your desired angle.
5) Note that you do not want any difference in caster angle from one side to the other so spend whatever time it takes to get the angles as exactly the same as you can otherwise your steering will pull to one side when you put it back together.
6) Jeephammer says don't hammer on the cast Cs but I've done it 3 times with no problem and I can't find any other way to do this job with the limited tools I have in my garage. I have seen pictures of people actually turning a C while still on the tube but you would need a lot of force and a way to hold the axle to do this. The ones I have had were always on too tight to even think about turning them.
7) note that you have to set caster, pinion angle and spring perches all at the same time with respect to each other to get the geometry you really want. If you think about it a minute that will make sense.
 
#22 ·
#26 ·
#28 ·
I've had 4°, NAPA bought, shims in my front axles for over 20 years and it has never been a problem but has been one hell of an improvement when 33" tires went on. Steering returns to center when completing a turn and it goes nice and straight down the road no matter how many ruts and grooves there might be. I installed them back on the front axle now that I have rebuilt the entire Jeep and switched to 32" tires instead. Didn't want to discard a good thing when I had it and will always keep them because of the improvement they made. The only thing I bought was new centering bolts of longer length so the wedges stay bolted to the spring packs of the new Black Diamond lift kit.
 
#29 ·
I purchased 4* shims for my 76 CJ5. Haven't installed them yet but eager to give em a try. I have a brand new 4" lift kit in which the center pin is 3/8"dia and about 5/16" long on both sides for mounting on the perch/springplate. I hear people mention a leaf spring stud replacement. My new leafs dont have a bolted stud holding the spring pack together. Is it necessary?
 
#30 ·
You won't find anyone offering the opinion that shims won't "work". They'll certainly change your caster. That's what blinds people about this. They take the shortcut and play a Jedi Mind trick on themselves, thinking that since it worked it must be okay. (Think low-hanging fruit.) The proper way to make this kind of adjustment on the front axle of a vehicle already modified, lifted, and with increased forces acting everywhere in the suspension is to do it permanently and without adding any additional parts between your perches and springs by way of rotating and re-welding your knuckle yokes. Shims are fine on non-steering axles.



Take another look at your center pin. I believe you will find that one end of it has a round head and the other is threaded. It is a bolt.

If your center pin doesn't go all the way though your leaf pack with a nut on the other end, please post a picture and identify what brand the leaf packs are. I'd like to see that.
 
#31 ·
They are already installed so I guess I didn't take a really close look at it. You are probably right. The jeep is only going to be driven ocasionally on sunny days, so I am not too concerned about durability of the shims. I have not installed degree shims before and would appreciate any direction? Do I purchase longer bolts and bolt the shim to the leaf springs? Would welding the shims to the perches be stronger and more secure?
 
#33 ·
I believe you meant rotate the perch forward on the tube, but the question was understood.

While easier than rotating the knuckle yoke, that will also rotate your pinion down by the same amount.
 
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