Sorry, I tried to be as brief as possible and appreciate any comments/recommendations.

I installed the HD OME coils (~3" of lift ) on my Unlimited with JKS Trackbars and JKS Discos not too long ago. It drove good but felt a little flighty at times and figured a set of Currie Upper CAs would do the trick. I made them 1/4" shorter, due to research from previous threads, than my stock ones and put them on. I bought a cheap angle finder from Harbor Freight and it read ~5 degrees on both passenger and drive side knuckles after CA installation. I also measured my garage floor and it was at 0 degrees.

After this, the jeep drove like crap. It was scary going above 50mph. It had flighty steering and when I hit bumps I felt like it was harder to control. Being frustrated and pressed for time I took it to a reputable alignment shop that deals with many lifted vehicles. I requested them to set my caster to 5 degrees and check my toe. I went to pick it up and they proceeded to tell my they couldn't adjust the caster unless I had cam bolts and in fact jeeps like to be at about 3 degrees of caster. They also said I should throw out the stock steering damper and get a better one. From experience and reading this forum this advice does not seem right.

Ultimately the toe was off, so they gave me 1/8" toe in (this is fine) but I am concerned about the caster. It drives much better now but for some reason still feels more flighty than when I had my stock control arms on.

Any suggestions? Am I looking for too much of an improvement with upper CAs?

 

You're should be fine with just uppers. It's a trial and error process to get it dialed in for 'your' vehicle. (No one else can tell you the magic number that is right for you or your jeep, since there are so many preferences and variables in the equation.)

Most shops read the factory specs, and assume that 3.xx deg caster is fine even when lifted. Start with the numbers from the alignment write-up and adjust from there. I believe it suggests 6-7 deg? (I also saw a post from one of the TeraFlex folks saying his caster is at 2.9deg. Still trying to figure that one out, as mine drove like crap at that setting...)

 

Try adding more caster. I was flighty for awhile and ended up getting the TF adj. lower control arms and setting mine at 7 degrees. You should be able to do that with the uppers you have. You would be surprised at what 2 degrees can do. Also check your tire pressure and make sure one of the shops didnt air you up to like 35psi. I run my 35" Cooper STTs at 25psi and you would be amazed at how it helps drivability!!

 

First, you cannot measure caster with an angle finder. Because of SAI(steering axis inclination), the caster angle is an arc and angle finders can only measure straight angles. So, your angle finder can only be used to adjust both sides equally, NOT to find the caster angle. Try shortening the upper arms by 1/2" at the time until you acheive the desired feel in the steering.

 

Thanks for all the input and ideas. I have my next gameplan.

 

Get a set of front lower adj. control arms.

 

You should have went with lowers first... IMO you can get better adjustment

 

Dave at Northridge actually suggested I go with the uppers if I don't plan on doing any hard wheeling. The uppers were cheaper and since I don't need the strength of the lowers (at this time) the uppers will accomplish the same task.

When do you guys think I should be concerned with pinion angles? I don't want any driveline vibes/issues.

 

I usually agree with David but I much prefer lowers in this use; regardless of how you wheel. Spending the extra few dollars is worth it. Making the adjustments with the lowers preserves your wheelbase rather than shortening it. You need to be concerned with pinion angles when you go to an aftermarket driveshaft. Having said that, even then you are more concerned about caster as when on the road at speed your front driveshaft is unpowered and coasting.

 

Hi MPBoxer,

I installed the OME LT kit from David also. This included the adjustable upper control arms.

I struggled trying to understand how best to balance the caster versus the driveline angle.

I adjusted the uppers shorter. I did some quick calculations that I thought would give me over 5 degrees of caster. I agree with RedNeckJeep that you can only get a relative measurement on the caster using an angle finder. I took mine to an alignment shop to confirm the change that I made. As it turned out, shortening the uppers only brought the caster back to OEM spec. (I can go back through my notes if you are interested to tell you exactly how short I made them.)

At 4.1 L and 4.2 R (OEM spec is 4.2 +/- .5 degrees) my JK drives/rides with absolutely no problems. I'm going to hedge my statement a little because I am running the stock 32" tires, and I understand that larger tires may affect the stability more than the stock shoes.

As Chuck pointed out, the driveshaft vibration issue caused by too much caster may not be a problem for most at highway speeds; but, you should keep in mind that setting the caster angle may cause more vibration in your front driveline.

Good Luck

Jeff