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Discussion Starter #1
So interesting development in my lift install has me a bit stumped.

Set my LCAs as per RK instructions (which I know may need to be adjusted) but when I went for an alignment today my caster came in at 6.5 degrees. The one good thing was that in confirmed my fancy 'measure the pinion with the iPhone level' trick was relatively close.

So I came home tonight and took them back apart with the intent to shorten them up. When I ran out of stroke, I got a bit concerned as my iphone was still showing 0-1 degrees on the pinion. As a last ditch I put the stockers back on and low and behold that put me somewhere between 2 and 3 on the pinion.

A quick test drive did not reveal any problems. Steering was a little sloppier but nowhere near anything I'd call 'flighty' and the wheel returns to center no problem. Tomorrow's commute will help confirm this, but question is:

Is there any reason I should worry about running stock front LCAs on this kit? Is it common for things to work out this way?

I do like the idea of less maintenance on the stock arms, but I was just a bit surprised.

In the same vein I checked the rear end and there appears to be a 6 degree differential between rear shaft and pinion. This seems a kind of high. I do have rear uppers I can put on though to straighten things out.
 

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What RK kit do you have?

2dr or 4dr?
 

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Discussion Starter #3
RK 2.5" Max Travel

4 door

 

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kjeeper will know better, but IIRC RK's CAs are longer than stock even when fully shortened which may be part of the issue without adjustable uppers.

The only issue I can think of would be drive shaft related if your pinon angle is off. Any noticeable vibrations?
 

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Discussion Starter #5
I didn't measure them all the way closed, but from what I saw I'd guess there's probably 3/4" between RK arms closed up and stock. I probably need to be somewhere in that area ideally.

But yeah the driveshaft is what scared me about the 6.5 degree caster. I've read too much about tearing the boot at the transfer case at such a severe angle, and that much caster really doesn't provide any benefit. No vibes persay, but the CV joint coming out of the transfer case sure looked pretty severe.
 

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There is no reason to worry about using stock CAs on any 2.5" lift. Having adjustable control arms is not a hard requirement. There are so many variables from to Jeep to Jeep that it is impossible to predict the Caster angle after you install the lift. In addition, every owners sensitivity to steering and handling is different. When you couple these things together some cases require adjustable CAs and others do not.

Sometimes the geometry correction brackets force the axle to rotate just enough by lowering the CAs and that is all you need. If your steering does not feel flighty and you pinion angle is not off you are just which is one of the benefits of moderate amounts of lift.

I had a 3.5" with no CAs for a while and it was "OK" but I knew it would be a lot better with the CAs and added them shortly after. Suspension flex more than anything else will determine if you have interference on the driveshaft.
 

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Over 6° is too much caster. You're driveshaft would be running at a pretty extreme angle. It should be noted in the instructions. Settings vary and the numbers listed might be different based on application. How many turns were you able to turn them back ?

In the rear the 6° doesn't apply. With the max travel rear lowers (shorter or the 2 sets offered ) they should be set close to stock. On a 4 door, pinion is not crucial anyways unless running a aftermarket DS.
 

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Op, I see you posted on WAL. Do not take ther advice.
First of all .. Only the X-factor REAR arms are +1"
The max travel rears are stock in length.
What they DONT know because they like to slam RK and are just ignorant. RK now offers a shorter rear upper to work with the max travel lower.
If further research was done .. RK has said over and over they will custom cut any length for nothing. All you have to do is call.

With that being said. I'm not sure what the front arm lengths are, I just know they are not 1".
If the alignment was correct to begin with, you might have been blessed with higher caster #'s stock. Together with a shorter lift and slightly longer arms = high caster.

+1/4 inch on most front lowers is common because it will give a acceptable range in caster at different lift heights.

Keep us posted on this.
 

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Discussion Starter #11
Heh I knew somebody was going to call me out for the cross posting. Just looking for as much input as possible. I'll draw my own conclusions. No drama.

So yeah everything you said on the tears makes sense. The upper rears I bought in an effort to be extra prepared were RK02028. I haven't taken them out of the box yet because I ran out of time this weekend so I'll have to investigate whether they'll even work with my max travel lowers.

In the front I was able to turn the lowers in about 5 full rotations from the 23 1/8" I started at. That only looked to buy me about a degree max in pinion angle.

When I measured compared to stock the front lowers appear to be somewhere around 1/2 longer. I think my stockers measured about 22 1/2?

Anyways, yeah I'm guessing an extra 1/4" in length would be about perfect to get me in that 4.5 range. Good to hear that I may just be on of the lucky ones that don't need adjustables.

I'll post and update tonight after some more commuting. Have over 100 mi to drive today so should get a good feel.
 

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Discussion Starter #12
Btooth sorry for the highjack but what tires are those? Are you running spacers with the stock rims?
They're Duratracs. 315/70R17 on the stock rubicon rims. I used spidertrax 1.5" spacers and had to find a shop that'd mount them on rims that were 1/2" narrower than spec.

Came out great I think!
 

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Haha .. Cross posting is fine. I just want you to get the right er unbiased info.

The uppers won't work. You have a few options
- if you can return and swap for the shorter arms
- sell the lowers and buy the x-factor lowers
- cut them down yourself.

As far as the fronts .. Curious what RK gives you for lengths. Agree .. You might have gotten lucky,

Stock front lowers = 22 5/8
 

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I am actually waiting for a full set of X factor control arms. I've requested the rear arms to be shortened. I just did not want to move the axle back that far.

The shorter rear poppers I mentioned are brand-new. I'm expecting a new product release memo any day now. Assuming the new part number will be on there.
 

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So interesting development in my lift install has me a bit stumped.

Set my LCAs as per RK instructions (which I know may need to be adjusted) but when I went for an alignment today my caster came in at 6.5 degrees. The one good thing was that in confirmed my fancy 'measure the pinion with the iPhone level' trick was relatively close.

So I came home tonight and took them back apart with the intent to shorten them up. When I ran out of stroke, I got a bit concerned as my iphone was still showing 0-1 degrees on the pinion. As a last ditch I put the stockers back on and low and behold that put me somewhere between 2 and 3 on the pinion.

A quick test drive did not reveal any problems. Steering was a little sloppier but nowhere near anything I'd call 'flighty' and the wheel returns to center no problem. Tomorrow's commute will help confirm this, but question is:

Is there any reason I should worry about running stock front LCAs on this kit? Is it common for things to work out this way?

I do like the idea of less maintenance on the stock arms, but I was just a bit surprised.

In the same vein I checked the rear end and there appears to be a 6 degree differential between rear shaft and pinion. This seems a kind of high. I do have rear uppers I can put on though to straighten things out.
Thats pretty high on caster for a 2.5" kit, can you grab us some measurements of the arms center to center completely collapsed?

RK
 

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Discussion Starter #16
Thats pretty high on caster for a 2.5" kit, can you grab us some measurements of the arms center to center completely collapsed?

RK
I measure 22-15/16" fully collapsed
 

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Discussion Starter #17
So after 120 mi of highway driving today, at which one point I got it up to 90 mph (didn't know Jeeps went that fast!) I have one conclusion: This kit rides absolutely awesome.

Its pulling left a little bit again so I'm wondering if my caster adjustment didnt throw the toe out again. Might just get it aligned one more time out of curiosity anyways to see where the caster comes in with stock arms.

I can safely say there's no 'flighty' steering though.

These coils are seriously awesome though guys. Nice job. Can't wait to get it off road Saturday.
 

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Discussion Starter #18
How much lift btw ? Are you sure they're not the 1.5" coils ? I thought the RK front arms adjusted stock or close to it.

what rear uppers do you have RK ? Unless custom the only available on the site are to long. They are meant to work with the x-factor lowers
Just saw your diagram, missed it this morning on my phone.

I'm measuring 13.75" from the bottom perch to up inside the top perch. 13" even from bottom perch to where the spring rests in the top.

What's the reference point supposed to be at the top?

Either way I think I'm in the neighborhood of 2.5", right?
 

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Discussion Starter #20
Two reference points not directly in line makes it a bit hard to measure.

I'm between 12-5/8" and 12-3/4"
 
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