Can you adjust caster on one side?

Hi gang,
Here's the scoop;
Put in the 4.5" springs and adjustable uca's and lca's. I tried to achieve a decently symmetrical wheelbase by adjusting the lca's and then used Gojeeps site to work on my alignment.
Well, I ran out of decent weather and also plain got sick of crawling under that damn rig!
So I took it in for an alignment and got these numbers;

Front _______ Left _______ Right
Camber _____ -0.43 _____ -0.63
Caster _______4.87 _____ 5.30
Toe ______________ .22
Set Back ________ -0.06
They also gave me a printout on stock specs For 90 to 94 Cherokee that showed:
Camber: 0.00 preferred, (-0.75 to .50)
Caster: 6.00 preferred, (5.00 to 9.00)


I had not known that they gave a number for Set Back. The guy at the shop told me that the number meant the drivers side is 6/100 degree further back than the passenger side. I don't know about the figure, but it definitely is further from the sway bar mount on that side.
So, I am thinking that I need to shorten the passenger side lca a bit to bring that side of the axle back some.
Also I need to shorten both uca's to achieve a bit more caster. This I am getting from the numbers and from the fact that the steering doesn't return to center much at all.
I guess my big question is;
Can I shorten one uca more than the other to get both of the caster readings closer than the .44 difference between them?
It doesn't really seem possible to me, not without physically twisting the axle.
Any thoughts would be appreciated.
Todd

I would think that you might be able to get the caster split between the two sides a little tighter than what it is by either shortening the passenger side lca or lengthening the driver side lca.

Thinking two-dimensionally, yes it seems that getting the caster split closer than the .44degrees difference isn't possible without twisting the axle, but when you consider ALL dimensions involved, it is. I would suspect that one side of the vehicle (in the front) is *SLIGHTLY* lower than the other one due to the difference; by adjusting the lca's to correct the split, it should partially correct this (I say partially b/c typically, if I recall correctly, there is always a slight difference between the front height from side to side due to the way the spring perches are mounted on the axle.)

Good luck with it, and let us know what happens.

trekker said:

Hi gang,

So, I am thinking that I need to shorten the passenger side lca a bit to bring that side of the axle back some.
Also I need to shorten both uca's to achieve a bit more caster. This I am getting from the numbers and from the fact that the steering doesn't return to center much at all.
I guess my big question is;
Can I shorten one uca more than the other to get both of the caster readings closer than the .44 difference between them?
It doesn't really seem possible to me, not without physically twisting the axle.
Any thoughts would be appreciated.
Todd

Click to expand...

Doesn't really matter. You're less than half a degree off, it wouldn't come from the factory with tolerances closer than that. Just adjust your arms to where you want them and don't worry about it.

Before you shorten the pass side and the two uppers, you might try lengthening the drivers side lower first, and see what you get. We've found that anywhere from 3* to 9* of castor will work fine, so it's mostly your own personal preference and if you have any vibrations or wobble.

Have fun,

Thanks for the replies.
I have been trying to picture in my head how changes in ca length will impact overall caster, and I think you are right MightyXJ.
As for just lengthening the drivers lca, I think you are right Goatman that it would give me the caster I am looking for.
The problem is that the wheelbase is plenty long as it is, considering full stuff pushing the tires forward.
Therefore I really think I have to shorten the passenger side. I just don't know if I should shorten both uca's the same amount or not.
Oh well, trial and error I guess. And some $$$.
Thanks again,
Todd

You shorten the first control arm the amount that you want, then you adjust the second arm to match the hole.

BTW, you will never twist that axle, and the "multi-dimension" thing is meaningless, really. If you try to force the position of the axle housing with CA lengths exactly what you want, all you'll do is make them very hard to connect and the bushings will be deflected......but you're not going to twist that housing.

Bottom line....don't worry about it.

If you are within a 1/2 degree of spec and it drives fine leave it. My old front axle was off by 2 degrees of caster from one side to the other because I twisted the housing. The alignment tech was impressed since it still was in the factory allowed of 5 to 7 degrees of caster I think I drove a little over a year with teh front housing twisted with no real ill effects other than having a twisted housing. A trussed HP Dana 44 solved the spun housing issues.

AARON

Goatman said:

If you try to force the position of the axle housing with CA lengths exactly what you want, all you'll do is make them very hard to connect and the bushings will be deflected......but you're not going to twist that housing.

Click to expand...

I was gonna say...with a SFA housing, the caster on each side is set in relation to each other, and you won't be able to change that really.

The thing that can throw that caster angle off on the aligment measurement center is if the axle isn't completely square to the rear one, so if it's really worth it to ya, take a tape measure to both axles and compare left and right side.

vetteboy said:

I was gonna say...with a SFA housing, the caster on each side is set in relation to each other, and you won't be able to change that really.

The thing that can throw that caster angle off on the aligment measurement center is if the axle isn't completely square to the rear one, so if it's really worth it to ya, take a tape measure to both axles and compare left and right side.

Click to expand...

Thats total "BS",castor has nothing to do with it!

Thanks again for all the replies/suggestions. Hopefully it will be done "correctly" tomorrow.

Another question for you. The jeep seems to really dart side to side when I go over uneven surfaces. Likely culprit?

trekker said:

Thanks again for all the replies/suggestions. Hopefully it will be done "correctly" tomorrow.

Another question for you. The jeep seems to really dart side to side when I go over uneven surfaces. Likely culprit?

Click to expand...

Sorry, can't seem to edit this out. I believe correct track bar alignment/torque, as well as a decent alignment should take care of this as much as possible.

Again, thanks.