Hi Everyone,

Ever since a trip to Colorado last summer, and then a winter of the JK sitting in the garage, there is a problem with a wobble in the front end.

For background, the lift is an OME long travel lift purchased from Northridge. At the time I purchased that lift, the package was being sold with adjustable upper front control arms.

The problem that I am experiencing mainly occurs at around 45 mph +/-5 mph. The first time it happened in January it was really serious.

The tires have been rotated/balanced, and I have even installed a different set of tires (also balanced). The problem was better, although still noticable.

I also had the toe adjusted to 1/8".

I believe the caster is right about 4 degrees. I know that many posters suggest 4.5 degrees, so I am planning on adjusting the upper control arms.

I have read the write-up for the OME lift install; but, I was hoping someone could give me some advice on just the steps necessary to adjust the front control arms. I am thinking that putting jack stands under the frame, jacking up the front axle, removing the wheels and then lowereing the axle would be the starting point.

Which suspension components should be loosened?

Is it necessary to drop the track bar first?

Would it be better to remove the bolts at the rear of the control arms and adjust from that end?

From what I remember of the install, there is very little adjustment left for shortening the control arms. (I'm hoping for a little.) If I don't have enough adjustment, I suppose my options are to remove the control arms and have the screwed shaft on each one cut/shortened or to buy adjustable lower control arms. Being that I am selling the JK I would prefer to not being buying new parts.

Or, would more toe-in be a better choice?

Any advice will be appreciated. (I remember how tight it was getting those control arms installed. I just want to make sure I do this the right way.)

Thanks

Jeff

 

if i adjust front uppers, i usually remove the axle end and screw the arm which ever way is needed.. its easier imo.. just loosen the jam nuts first..if u want more caster u have to shorten the uppers. i would set the caster closer to 6 with an angle finder, which should put you around 5.5 positive caster.. at least thats what ive found.

 

Hi Guys,

Thanks for the advice.

I had a heck of a time getting the control arms to seat into the axle brackets when I first installed it. Maybe I'll get lucky this time.

As far as the caster goes... if I can get 4.5 out of it, I'll be grateful. There just isn't much adjustment left. (There are probably 6 or 8 threads showing; but, the problem was with the female threaded components.)

I'll give it a try and see what happens.

Thanks

Jeff

 

6 or 8 threads is MORE than enough to get you whatever you want. I was surprised, but if I remember correctly, 1/2 turn was about 1/2 degree. I am not positive about that, but my point is that you have plenty to work with.

 

Hi,

The problem is with the female threads on the inside of the control arm... the male portion of the threaded rod is binding up inside the arm... that's the reason I can't run it in further.

Thanks for the information on the turns/caster angle. I'm hoping to get a full turn out of both sides and then have the alignment checked again.

Thanks

Jeff

 

spray some pb on the threads. run the rod out, spray and try and run it in... also u could use a screw driver through the mounting hole for more leverage... maybe some dirt is in there... what brand are these arms??? the arms should def be able to bottom out on the male end.

 

Hi Guys,

Thanks for the input.

The JK is sitting with the front end on jack stands in the driveway. I found that I was able to shorten both shafts by screwing them together. I remember how tough it was when it was first installed. Maybe I expected a fight this time. Before I put it back together, I wanted to ask a few opinions.

The adjustable control arms are Currie.

I screwed both sides together (shortening each) by two full turns. (And I think there is room to go further.)

The alignment I had done 2 months ago showed a caster of 4.1 (left) and 4.0 (right).

By shortening the uppers by two turns each, is there a way to calculate the change in caster? JEP THNG said that it should be about 1/2 a degree for 1/2 turn. In this case the caster may be as great as 6. Is that a good place to start until I can have the alignment checked again? Or, is that too much?

Also, the toe is at 1/8 in. Does that sound reasonable? (Although won't the toe change with a change in caster?)

Thanks for your input.

Jeff

 

Hi Again,

I have been doing a little more searching and just thought I'd state a few things I read to make sure I am understanding them correctly.

1. Planman suggests a caster of 4.5 to 4.7, with a greater caster on the passenger side.

2. jlarso states that for every 1/8" the upper control arms are shortened, the caster changes by 1 degree.

That leads me to a couple more questions:

1. How much difference is desired for the caster on the passenger side versus the driver side?

2. What is the spec on the thread used by Currie on their control arms. I'll measure it tomorrow; but, I just thought I would see if anyone knows tonight.

If the 1/8" control arm distance relationship to 1 degree of caster angle holds true, all I really need to do is double the distance between threads (to account for the two turns of the control arm end) and that will tell me how much I shortened the control arm, and I can then calculate the change in the caster.

Any input would be appreciated.

Thanks

Jeff

 

Goto home depot and pick up an angle finder and see what it says. U place it on the flat spots on the bottom C. Also the truck will pull to the side with lowest caster setting, and u want them set pretty close to each other... I.e..5.0 driver,5.2 pass..

thunderbolt on tapatalk

 

Hi,

Thanks for the reply.

I used an agle finder when I first set up the JK. To get you kind of in the ballpark, I guess it's okay. I just find that between the basic design of the angle finder and the mounting surface, it's tough to think that a precise measurement is possible. I thought it would be better to try to calculate based on the known starting point and the specifics of the control arm adjustment.

Thanks,

Jeff