Front LCAs on 2 door with 2.5" spring lift. Castor is good, still needed?
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JK Enthusiast
Joined: Dec 2013
Posts: 130
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From: SLC, UT
Front LCAs on 2 door with 2.5" spring lift. Castor is good, still needed?
I installed a 2.5" TF spring lift with shock extenders almost a month ago on my '13 2 door sport. Its been awesome, it drives well, isn't too stiff or soft and is the perfect height for me. I had initially planned on adding an adjustable track bar, front lower control arms, and longer shocks as money became available. I picked up a track bar yesterday and was trying to figure out if I really needed control arms. I had an alignment done ten days ago and my castor is at 3.5 degrees which on the print out shows as being within specs.
What else does the front lower control arm do other than correct castor? Visually, my wheels seem to be centered in the wheel well. How much do I need to replace them, if at all? When I search for info people say they need to be upgraded but don't explain why other than for castor adjustment. I'm just trying to understand the why-s before I throw money at the Jeep. There are plenty of other things I'd like to spend the $300+ on but if its something that is a documented need I'm willing to buy them.
(Running rubi take off wheels/tires now and am very happy with them. In the future I *may* go up to 35's but do much more dirt road exploring than crawling and will probably stay close to where I am now.)
What else does the front lower control arm do other than correct castor? Visually, my wheels seem to be centered in the wheel well. How much do I need to replace them, if at all? When I search for info people say they need to be upgraded but don't explain why other than for castor adjustment. I'm just trying to understand the why-s before I throw money at the Jeep. There are plenty of other things I'd like to spend the $300+ on but if its something that is a documented need I'm willing to buy them.
(Running rubi take off wheels/tires now and am very happy with them. In the future I *may* go up to 35's but do much more dirt road exploring than crawling and will probably stay close to where I am now.)
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
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From: Austin <--> Colorado Springs
Stock caster is around 4 degrees. As you lift higher, the housing tilts, bringing the pinion up, which lowers the caster at the same time. Adding a set of adj ca's (either upper or lower, they do the same thing, just backwards of each other) allows you to adjust the caster/pinion. (Raise the caster, which lowers the pinion. Or lower the caster, which raises the pinion.) Add a second set of ca's, and you can move the entire axle forward/backward in the wheel well, as well as having more options for fine tuning the caster/pinion.
If you are happy with the lower caster, don't worry about it. If you decide that you do want to raise the caster, then add arms (or brackets) later. Completely up to you.
One note - Aftermarket driveshafts/joints like different angles than the stock driveshafts. So if you ever get around to replacing one, you will want the ability to adjust the pinion. (which, as noted above, will also adjust the caster for the front end)
If you are happy with the lower caster, don't worry about it. If you decide that you do want to raise the caster, then add arms (or brackets) later. Completely up to you.
One note - Aftermarket driveshafts/joints like different angles than the stock driveshafts. So if you ever get around to replacing one, you will want the ability to adjust the pinion. (which, as noted above, will also adjust the caster for the front end)
Last edited by nthinuf; Mar 13, 2014 at 01:17 PM.