Front Control arms

J

jeeperstrudie

New member
Hello everyone, I apologize if this is duplicated or somewhere else in the forum..... i've searched high/low and am struggling.... 2008 JKU, i've put teraflex alpine adjustable control arms on my jeep.

I'm on 4" teraflex springs and measure around 4" of lift. I wanted to re-center my front axle and get my pinion and caster back within spec. I've had the lower control arms in for about a month not realizing that I should have done the uppers first.

LCA's set at 23 3/8" with axle pretty close to centered on bumpstops.
UCA's D.S. at 19 1/4" P.S. Shorter (it's raining so I can't confirm right now)

I need to reconfirm my pinion angle but I believe i'm at 6.5 Deg currently (I'm assuming I'm shooting for 4.2 deg) so I'm sure I have more adjustment to do on the uppers.....

here is my dilemma / question:

1. When I went to put the P.S. UCA on, at 19 1/4" it was about 1/2" +/- off. Do I need to hold the 19 1/4" on both D.S. and P.S.?
2. what pinion angle should I be shooting for? I also struggle getting my angle finder to sit on top of the C due to grease fitting so i'm not confident on that reading.
 
jeeperstrudie said:
Hello everyone, I apologize if this is duplicated or somewhere else in the forum..... i've searched high/low and am struggling.... 2008 JKU, i've put teraflex alpine adjustable control arms on my jeep.

I'm on 4" teraflex springs and measure around 4" of lift. I wanted to re-center my front axle and get my pinion and caster back within spec. I've had the lower control arms in for about a month not realizing that I should have done the uppers first.

LCA's set at 23 3/8" with axle pretty close to centered on bumpstops.
UCA's D.S. at 19 1/4" P.S. Shorter (it's raining so I can't confirm right now)

I need to reconfirm my pinion angle but I believe i'm at 6.5 Deg currently (I'm assuming I'm shooting for 4.2 deg) so I'm sure I have more adjustment to do on the uppers.....

here is my dilemma / question:

1. When I went to put the P.S. UCA on, at 19 1/4" it was about 1/2" +/- off. Do I need to hold the 19 1/4" on both D.S. and P.S.?
2. what pinion angle should I be shooting for? I also struggle getting my angle finder to sit on top of the C due to grease fitting so i'm not confident on that reading.
Click to expand...
First off, factory front lower control arms measure 22-5/8". If you're really 23-3/8", you've got them set way too long. What you don't seem to realize is that your axles travel in an arc and while your axle may "look" centered to you at ride height, it will be way off centered at a full bump. This can lead to other issues as well such as your track bar making contact with your differential cover, spring bow, etc. AT MOST, you should only need to set them to about 1/4" - 3/8" longer than stock to help with the "look".

That said, there is no specified measurement that you need to set your front upper arms. You just need to set their length to give you about +4° of caster. Any more than that and you run the risk of getting drive line vibrations especially if you're running an aftermarket u-joint style double cardan drive shaft and a higher gear ratio. Pinion angle is only a concern on the rear and again, only with an aftermarket u-joint style double cardan drive shaft. For that, you just want it to be in line with the pinion.
 
This link will help you to find your caster angle.
wayalife.com

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