JK Wandering on highway
01-09-2015, 05:49 PM
#32
JK Jedi Master
Join Date: Jan 2008
Location: Austin <--> Colorado Springs
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so if I'm on a budget, should I get front Lower or Upper adjustable control arms?
They are a bit harder to install since you need to cut a bolt off (or spend some time prying the exhaust out the way). They are adjusted shorter than stock to raise the caster, so with taller lifts they may not go short enough to get the caster where you want it. (this will not be an issue at your 2.5" height, but is worth mentioning).
Front lowers are generally more expensive, they are adjusted longer than stock so have a better range of adjustability, and are beefier than stock arms so should handle rocks better.
On a budget, at your lift height, either will work fine. Or you could even look at drop brackets.
01-09-2015, 06:00 PM
#33
JK Newbie
Join Date: Oct 2012
Location: Yuma AZ
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thanks for the info. One thing I didn't mention, I added a leveling kit, so I probably have a total of 3 1/2 of lift in the front. I went ahead and ordered Synergy adjustable front lower control arm since they will be easier to install. Also, do you know what factory specs for to in is? I know camber is not adjustable and caster should be around 4.2.
06-16-2019, 06:09 AM
#34
I'll try one more time to explain.
Assume the frame of the Jeep has a straight line running through it back to front. During an alignment there are 3 toe specs that are produced for front and rear: left toe, right toe, total toe. So, each value is relative to the straight line. Let's say right front is -.1 and left front is -.12, total is -.22. What it is also saying is that relative to the straight line, right front is pointed in .10 degrees and left is pointed in .12 degrees. The difference between the two doesn't matter in the front (assuming small values like in this example). When you drive straight, they are equal. When you adjust the tie rod, you adjust TOTAL toe.
Let's now say that the rear axle has a total toe of 0 degrees. That means that the wheels both point straight ahead (perfectly parallel to the imaginary line we drew). When you add adjustable rear arms, you have the ability to inadvertently push or pull one side more than the other. Let's say I accidentally set the upper and lower driver rear arms one turn longer. The result would be an axle that is no longer perpendicular to the imaginary line. How is that measured? Rear toe. It's like pinion angle vs. caster, it's a zero sum relationship, but an important one. If the toe of the driver rear is .10, then the passenger rear is -.10. The total toe can't be changed, but the individual toe can be.
You'd never visually be able to tell if the axle is pointing straight ahead. Toe is how you measure the angle of the rear tires going straight ahead. I can almost guarantee that most people never check it and is almost definitely off a little.
If this still doesn't make sense, look at an alignment sheet printout and stare at the rear toe readout until it makes sense.
Assume the frame of the Jeep has a straight line running through it back to front. During an alignment there are 3 toe specs that are produced for front and rear: left toe, right toe, total toe. So, each value is relative to the straight line. Let's say right front is -.1 and left front is -.12, total is -.22. What it is also saying is that relative to the straight line, right front is pointed in .10 degrees and left is pointed in .12 degrees. The difference between the two doesn't matter in the front (assuming small values like in this example). When you drive straight, they are equal. When you adjust the tie rod, you adjust TOTAL toe.
Let's now say that the rear axle has a total toe of 0 degrees. That means that the wheels both point straight ahead (perfectly parallel to the imaginary line we drew). When you add adjustable rear arms, you have the ability to inadvertently push or pull one side more than the other. Let's say I accidentally set the upper and lower driver rear arms one turn longer. The result would be an axle that is no longer perpendicular to the imaginary line. How is that measured? Rear toe. It's like pinion angle vs. caster, it's a zero sum relationship, but an important one. If the toe of the driver rear is .10, then the passenger rear is -.10. The total toe can't be changed, but the individual toe can be.
You'd never visually be able to tell if the axle is pointing straight ahead. Toe is how you measure the angle of the rear tires going straight ahead. I can almost guarantee that most people never check it and is almost definitely off a little.
If this still doesn't make sense, look at an alignment sheet printout and stare at the rear toe readout until it makes sense.
This is called thrust angle, not toe.