Loose Control Arm Play = Caster Adjustment

[Kevin32199]

I just installed a Quadratec 2.5" lift (Skyjacker springs and their proprietary shocks per Quadratec) on my 18 2-door Sport S. While researching on this site I noted that at least one degree of negative caster is expected. My idea was that there MUST be some relatively easy play to work with once the control arms are loose, the track bar is disconnected, and shocks and sway bar links are removed--to regain a measly ONE degree of caster. I did the following with the front wheels off and the front axle on jack stands carrying full weight (with safety stands wedged under frame). Using a pry bar, I was able to twist the front axle back and forth, so the play was there. After some experimentation, I ended up using a 3 foot pipe wrench clamped on the section of axle to the right of the gear housing, and pulled up and propped up on a large socket out front of the Jeep. This took out all the slack in the direction I wanted. I smacked all the control arms with a hammer to make sure they were all being compliant, then tightened all the control arm bolts. When the lift was complete, I used the Clinometer app. My caster was in the high 5's, 5.8 to 6 (L-R) before the lift, and after it is right about 6 on BOTH sides, almost more than when I started. My conclusion is that if you install a lift kit without doing this, you are leaving your final caster result to whatever random position your control arms happen to be in. There's adjustment there--not much--but its there. Worth a shot before getting adjustable or longer control arms. Of course, your result may vary. Hope this helps someone.

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[Headbarcode]

Control arms don't get torqued until the jeep is fully assembled with all 4 tires on the ground. This ensures that the control arm bushings are in a neutral state while at normal ride height. It will also pull everything taut and square.

 

[Kevin32199]

Control arms don't get torqued until the jeep is fully assembled with all 4 tires on the ground. This ensures that the control arm bushings are in a neutral state while at normal ride height. It will also pull everything taut and square.

Thanks for the info. You are correct. On perfectly flat and level surface, with a full tank of gas, with the factory recommended tire pressure, using a recently officially calibrated torque wrench, at a temperature of 62-77"F, and sandbags in all the seats and luggage compartment, with the exact weight of yourself and everyone and everything you will carry 90% of the time. If you mostly drive on the highway then you should also simulate front end lift by the oncoming air. Then there is the real world where some of us use measuring tapes, guesstimating ride height on jack stands, eyeing out alignments and wheel centering, and air tools, because we would like to complete the lift we are doing in the dirt under a shade tree (because you could) sometime this century LOL. To each their own. I drive a Jeep, not a formula one race car--that's my take on it as someone who has worked on cars professionally and privately for 40 years. There's plenty of forgiveness in those bushings, otherwise they'd be tearing apart all the time. If they wear out I can replace them. There's nothing wrong with doing it the way you say, I just think its overkill and am not willing to waste my time doing it. Although if you wanted to do the procedure I recommend with the wheels on the ground, it could be done that way. Remember, adjustable arms force the front end to do what you want as well as what I did. "Taught" = tight. "Square" = the adjustment I force the front end to do--in this case 6 deg caster on each side. There is built in adjustment, or play. I say use it to your advantage. Why let the front end naturally fall where it may and make itself lopsided, then buy special control arms to fix it? We are only talking about 1 degree of caster. Why buy special control arms if you dont have to? Its only a measly 2.5 inch lift. It worked for me.

 

[Glamisfan]

I noticed the slack when I changed out my lower control arms. I had the weight of the vehicle on the ground and I used a jack I think on the front side of the front diff to preloaded with as much caster as possible.
And then after I put 2 inch springs on it, I loosened all the suspension bolts to re center all the bushings and when I loosened the front uppers I noticed the axle tilt back even more.

 

[Headbarcode]

 

[Glamisfan]

What is in the twilight zone? Is it common knowledge that there’s slack between the bolts and mounts enabling an extra 1/2 degree or so of caster? Or ?

 

[Headbarcode]

Someone?....... anyone?........................ please?

 

[hoag4147]

IMO you are placing undue stress on joints and creating a binding effect doing this way. Sitting on ground, cycle suspension with a few good ups and downs on bumper should settle in natural position and then torque everything. Could be wrong but have read a ton of folks/vendors recommend

 

[word302]

Someone?....... anyone?........................ please?

I’m sorry, I just can’t with this one.

 

[Headbarcode]

I’m sorry, I just can’t with this one.

 

[Speed331]

Six months later.....

When control arm bushings begin to go bad on your vehicle, likely the first symptom you will notice is increased vibrations often felt in the steering wheel. Usually the vibrations will intensify when accelerating, which can quickly become annoying. This is due to wobbly wheels because of excess play in the system.

Intentionally giving yourself a death wobble....

 

[Speed331]

BTW...70 bucks gets you the (slightly) longer mopar lca's...

 

[XJfanatic]

I am with the op if there is slack use it as long as you aren’t binding the bushings. The front lca axle end holes are squares anyway.

 

[Kevin32199]

I am with the op if there is slack use it as long as you aren’t binding the bushings. The front lca axle end holes are squares anyway.

 

[Kevin32199]

The bushings arent binding. They only bind if the position you bolt them in differs greatly from the position they are in most of the time, eg tightening them with wheels in the air vs on the ground with weight on the vehicle. Thats a twisting motion, that never allows the bushings to relax. A caster adjustment, whether using a hole thats larger than the bolt, an elongated hole with cams, or longer adjustable LCAs doesnt apply here as long as the height of the vehicle above the axle is the same as it would naturally be with the vehicle parked.

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