I just lifted my wifes JK Unlimited with a 3.5" Rock Krawler lift. For now we just bought the basic kit that has shocks, springs, and adjustable front and rear track bars. We will add on adjustable arms as soon as we can. It has MT 35x12.50x17 MTZ's. It is wandering quite a bit, and I assumed that caster is probably the cause. The dealer did an alignment today, and fixed the toe-in, but the caster is 2.7 drivers side, and 2.3 passenger side....the sheet has the factory acceptable numbers as 3.7-4.7.

Is the number off that much to make it wander so much? Should I be looking for something else? As far as control arms, which is going to be the best fix?

Thanks in advance

 

this is a great question and I would love to hear some feedback.

 

I would start there. Adjustable upper arms are usually recommended. Lower arms can be used, but they will stretch your wheelbase a little, possibly causing the front tires to rub your front bumper (if you have one). You will actually get used to how it handles somewhat, so it's not like it's an emergency to change them...

 

Jeep/Mopar has cam bolts for the lower control arms IIRC. If you look at the lower control arms on the frame side you will see knock outs for the CamBolts you can purchase directly from Mopar (and others) to fix camber.

I purchased adjustable front lower control arms because of this assuming that if Jeep/Mopar does it this way I should as well.

Not to mention the adjustable lower control arms I purchased are stronger then stock. Since I rock craw from time to time it was a side benefit.

All comments welcome.

 

From the factory, your caster should be set at +4.2°. If you are now at +2.5°ish, you are basically flat and that would cause your wandering. I have my JK set at +7° and it drives straight as an arrow. Now, I wouldn't advise getting cam bolts to correct this problem as it is limited as to how much adjustment it can make (remember, they are not intended for a tall lift) and once you knock out those tabs, there is no turning back. In my experience, cam bolts tend to come loose and cause all kinds of problems. Your best bet is to get a set of adjustable upper control arms to set your caster. On a side note, why did your dealer adjust your toe-in? Due to the new steering design of the JK, your toe-in should not have changed at all. Now, if you had a TJ, this would have been a must.

 

I started another thread about my jeep wandering before finding this one. I seem to find conflicting info regarding control arms and caster angle. Some say upper arms will fix it and others say lower arms as does this one. Can you only change one and if so which one should I do. Here is the link to my other thread https://www.jk-forum.com/forums/show...d=1#post138602

 

On a solid front axle setup like the JK, changing the castor is just a matter of rotating the axle about it's long axis. With the suspension setup that we have, you can do this by adjusting either the lower arms, the upper arms or both. For example, if you lengthen the lower arms and keep the upper arms the same length, it has the effect of rotating the axle in a clockwise direction if you're looking at it from the driver's side. This increases the castor.

Similarly, if you leave the bottom arms alone and shorten the top arms, it has the same effect of increasing the castor.

There is one other effect. If you lengthen the bottom arms and leave the top ones alone, it not only increases the castor but it pushes the whole axle forward a little. And, if you shorten the tops and leave the bottoms alone, it increases the castor and pulls the whole axle back a bit.

If you wanted the axle to stay in exactly the same location and you also wanted to adjust the castor, you'd have to lengthen one set of arms and shorten the other set. In practice, I think this is rarely done and most setups just include adjustable links at either the top or bottom but not both. The amount the axle moves is usually pretty small.

 

In addition to your caster issue I would like to know what your TIRE PREASURE is set at? When I did my lift my tire shop put 40 psi in my tires. when they were hot I'm sure it was 45. I dropped it to 26 as per my chalk test and the majority of my wandering went away. I adjusted caster also and now it's puuurrrrrrfect.

 

If the stock arms are not adjustable how is this done?

 

how did you adjust the caster?