rubi takeoff suspension vs. LCA

txj2go

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I have the Rubicon takeoff parts and I've been doing research on the installation. What I don't understand is why the LCA needs to change if you only change springs and shocks. I understand what caster is and I understand how the geometry changes when you lift the suspensioni, but what I don't understand is how the Rubicon gets away with the same LCA as the sport when it is effectively lifted the same amount. IOW why doesn't the Rubicon require a different LCA with its stock springs and shocks? Take them off of one frame, put them on an identical frame without the decal on the hood, and the geometry is different? Is there a difference in the mounting points on the axle that makes the difference?





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daveprice7

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My understanding is that Rubicon caster is on the low side from the factory, but "in the acceptable range"... Plus, folks tend to try and find springs for a heavier configuration to use in the swap, which gives more lift and lowers the caster more than a factory Rubicon.

I put 4dr Rubicon springs on my 2dr Sport, and while they were one or two steps lower than the tallest Rubicon springs, I got about 1.75" of lift from it (maybe a bit more than that in the back, as my Sport was low in the back before and now rides a bit high in the back). I can't really tell the difference in caster after the swap, so I'm in no rush to change the LCAs. Maybe some people are just more sensitive to it than me, or it's more obvious at speeds I don't usually drive.
 

Headbarcode

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I have the Rubicon takeoff parts and I've been doing research on the installation. What I don't understand is why the LCA needs to change if you only change springs and shocks. I understand what caster is and I understand how the geometry changes when you lift the suspensioni, but what I don't understand is how the Rubicon gets away with the same LCA as the sport when it is effectively lifted the same amount. IOW why doesn't the Rubicon require a different LCA with its stock springs and shocks? Take them off of one frame, put them on an identical frame without the decal on the hood, and the geometry is different? Is there a difference in the mounting points on the axle that makes the difference?
The lca's and their frame and axle mounting points are identical in all models. They get the caster right in the comfort zone on the Sports and Saharas, but are barely toe nailing the minimum range on the Rubicons. Many stock height Rubicon owners have switched to the .25" longer lca's from the Mopar lift, to get their caster into the comfort zone. Proper caster eliminates wandering.

The more parts that cross over, the less cost is involved in providing different models.
 
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txj2go

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I was thinking that all of the parts were identical except the springs/shocks. As I wrote my first post I realized that the AXLE is different and if all of the details were followed through with during design they could have designed the Rubicon axle to have slightly different mounting points for the control arms to use the same control arms but get the right caster. Apparently they didn't do that so now I understand the situation.
 

limeade

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Like @Headbarcode stated, get yourself a pair of the Mopar lift LCA's when you install the Rubicon suspension. Your caster will be very similar to what your Sport has now.
 

entropy

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I understand what caster is and I understand how the geometry changes when you lift the suspensioni, but what I don't understand is how the Rubicon gets away with the same LCA as the sport when it is effectively lifted the same amount.
It doesn't get away with it. Rubicons have shitty caster from the factory. If you don't install the longer LCA you will have the same shitty caster rubicons have. If you install longer LCA, you'd have better caster.
 

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