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Discussion Starter #1 (Edited)
I called Metal Cloak yesterday and they said my 2.5" lift kit should ship today. Unfortunately, they ship their kits with the control arms and track bars set at length for the 3.5" lift. Kinda shitty but what can you do. What I want to do is see if I can adjust them pre-install for 2.5". Since these parts aren't completely vertical I can't just crank them in one inch. So I came up with the following formula. I think it will not only get me in the ballpark but actually onto the pitchers mound.

(MC length - stock length) *.71 + stock length = 2.5" length.

MC length minus stock length gets me how much MC had to extend the arms from stock to get 3.5" length. I then multiply that difference by .71 as that is the ratio of 2.5" to 3.5". I then add that new extension difference to the stock length to get the 2.5" length.

For example, the lower front control arms from MC are set at 23 1/16" and the factory arms are 22 5/8" for a difference of 7/16". 7/16" times .71 is .31". So adding .31" to the stock 22 5/8" is 22.94" or 22 15/16". :bounce:

Edit: Oh and I need the lengths from center of mounting point to center of mounting point.

If your an engineer or mathematician and see a flaw in this logic please advise.

The MC instructions provide all the data I need for my calculations EXCEPT stock front and rear track bar lengths. That is why I am asking this fine JK community for their help. Thanks. :)
 

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Engineer aside, the biggest flaw I see in this is the assumption that you will get 2.5" of lift out of this kit. The weight of your vehicle, resulting from bumpers, armor, gear, etc, will alter the actual lift heigh you get. The lengths of all your components will be determined by the final lift height you get from the springs.... just my opinion.
 

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This really is over complicating something very simple. You what if you get 2.76" of lift? 2.4"? Oh no! Now what?

MC's lengths are also baselines, they will ALL need to be adjusted to center the axle under frame. If you're still looking for -baseline- numbers, Rock Krawlers instructions will probably have -baseline- track bar lengths for their 2.5" kit.

It'd be easier to make a right triangle out of the track bar and just calculate the difference in height [short side, long side wont change] and just pythagorean theorem the length..But it's still a baseline.

I'd take the stock track bar out once lifted. Center the frame with a ratchet strap, measure hole to hole and set it to that length...Much better use of your time.
 

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Discussion Starter #4
I know it's just a baseline. I just wanted to get close. I know the only difference in the 2.5 vs 3.5 MC kit is the shocks and springs. But I was afraid if I put 2.5 shocks and springs in but left at arms at 3.5 the springs could fall out at or near full flex.
 

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Discussion Starter #5
It'd be easier to make a right triangle out of the track bar and just calculate the difference in height [short side, long side wont change] and just pythagorean theorem the length..But it's still a baseline.
that's a good idea. A2+B2=C2. I like it.
 

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Discussion Starter #6
Engineer aside, the biggest flaw I see in this is the assumption that you will get 2.5" of lift out of this kit. The weight of your vehicle, resulting from bumpers, armor, gear, etc, will alter the actual lift heigh you get. The lengths of all your components will be determined by the final lift height you get from the springs.... just my opinion.
Then how can they preset for 3.5"?
 

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Then how can they preset for 3.5"?
Baselines, like goody said.

And your spring is not going to fall out due to arm lengths, only if your shocks are too long and you don't have retainers.

Control arms and track bars locate the axles, align them, and provide their arc of travel. Springs carry weight and set ride height, shock dampen. Shocks are usually used as the down travel limiting factor (tho it should ideally be a limiting strap) and bump stops limit up travel (before the shock bottoms out). Springs, especially a dual rate like MC, usually have a longer free length than shocks do travel, so they wont unseat.


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Discussion Starter #8
Thanks. Good to know. I'm sure I will have to tweak (measure, strap, adjust) the track bars but was hoping the control arms would be close enough since you have to unbolt each one to adjust. Sorry but I'm new to all this.
 

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Discussion Starter #10
My stock rear track bar measures 32 7/16".

I'm 99% sure it's the rear because I only have one and the front has been off the JK longer than the rear so I'm sure it's long gone by now.
MC front track bar is 33" and the rear is 40 1/8" so it is prob the front. Thanks I'll pop that in my spreadsheet.
 

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Then how can they preset for 3.5"?
It's an estimation.

If you had astock Jeep with their 3.5" springs or two 100# bumpers, 100# winch, 90# sliders, 150# cage...isn't that one going to sit lower? Won't that effect the track bar length even though the spring rate is the same between them? F=kx for spring displacement. You're increasing F, k stays the same [spring rate] therefore increasing X as well when F is higher.

So everything that is adjustable within suspension is going to have a baseline measurement you can use to run off of. Its the same as if they told you to set it to 40" +/- 1/4". So it can be 40", 39.75" or 40.25". Manufacturing tolerances or variables will make almost -nothing- set in stone when it comes to suspension.

Also the notation for Pythagorean theorem would be A^2+B^2=C^2 or (A^2+B^2)^0.5 =C for what you were looking for.

A2+B2=C2 would be = (2*A) + (2*B) = (2*C) which is /= A^2+B^2=C^2
 

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Discussion Starter #12
Thanks goody. I knew the theorem just didn't know how to type it. I was just trying to get close but I guess the consensus is to just install everything, measure, and then adjust. Got it.
 

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For what it's worth, my MC control arms did not arrive adjusted to a particular length. In fact, they were all at different lengths.
 

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Ok dude. Make this as easy on yourself as possible.

Install your lift per the supplied instructions. Leave the trackbar off. Use a ratchet strap to center the axle to the frame at the new ride height.

Shake the hell out of the jeep, bounce up and down, back and forth, etc.. Check center again, adjust if necessary, measure center to center then adjust the new track bar and install.

Install all your bolts tight enough to hold everything together but don't torque them down. Drive back and forth in the driveway a few times then get back on level ground, check axle centers again. If out, adjust again. If good, torque everything down and recheck in about a week or around 500 miles.

Best thing to do with this is to ask for a little help from some local guys who have done it before. They will help guide you through it and make the whole process much easier.

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I just look

I called Metal Cloak yesterday and they said my 2.5" lift kit should ship today. Unfortunately, they ship their kits with the control arms and track bars set at length for the 3.5" lift. Kinda shitty but what can you do. What I want to do is see if I can adjust them pre-install for 2.5". Since these parts aren't completely vertical I can't just crank them in one inch. So I came up with the following formula. I think it will not only get me in the ballpark but actually onto the pitchers mound.

(MC length - stock length) *.71 + stock length = 2.5" length.

MC length minus stock length gets me how much MC had to extend the arms from stock to get 3.5" length. I then multiply that difference by .71 as that is the ratio of 2.5" to 3.5". I then add that new extension difference to the stock length to get the 2.5" length.

For example, the lower front control arms from MC are set at 23 1/16" and the factory arms are 22 5/8" for a difference of 7/16". 7/16" times .71 is .31". So adding .31" to the stock 22 5/8" is 22.94" or 22 15/16". :bounce:

Edit: Oh and I need the lengths from center of mounting point to center of mounting point.

If your an engineer or mathematician and see a flaw in this logic please advise.

The MC instructions provide all the data I need for my calculations EXCEPT stock front and rear track bar lengths. That is why I am asking this fine JK community for their help. Thanks. :)
I just look to see if my wheels are centered under the jeep.... and adjust as needed to achieve that. :dunno:
 

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Discussion Starter #16
Ok dude. Make this as easy on yourself as possible.

Install your lift per the supplied instructions. Leave the trackbar off. Use a ratchet strap to center the axle to the frame at the new ride height.

Shake the hell out of the jeep, bounce up and down, back and forth, etc.. Check center again, adjust if necessary, measure center to center then adjust the new track bar and install.

Install all your bolts tight enough to hold everything together but don't torque them down. Drive back and forth in the driveway a few times then get back on level ground, check axle centers again. If out, adjust again. If good, torque everything down and recheck in about a week or around 500 miles.

Best thing to do with this is to ask for a little help from some local guys who have done it before. They will help guide you through it and make the whole process much easier.

Sent from AutoGuide.com Free App
Yup that's how I'll do it. I don't think the instructions tell you how to measure and adjust the control arms. I'll just look that up.
 

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Discussion Starter #17
I just look to see if my wheels are centered under the jeep.... and adjust as needed to achieve that. :dunno:
Yeah the track bar seems easy. It's the control arms that I need to learn about setting up properly.
 

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calculations

I called Metal Cloak yesterday and they said my 2.5" lift kit should ship today. Unfortunately, they ship their kits with the control arms and track bars set at length for the 3.5" lift. Kinda shitty but what can you do. What I want to do is see if I can adjust them pre-install for 2.5". Since these parts aren't completely vertical I can't just crank them in one inch. So I came up with the following formula. I think it will not only get me in the ballpark but actually onto the pitchers mound.

(MC length - stock length) *.71 + stock length = 2.5" length.

MC length minus stock length gets me how much MC had to extend the arms from stock to get 3.5" length. I then multiply that difference by .71 as that is the ratio of 2.5" to 3.5". I then add that new extension difference to the stock length to get the 2.5" length.

For example, the lower front control arms from MC are set at 23 1/16" and the factory arms are 22 5/8" for a difference of 7/16". 7/16" times .71 is .31". So adding .31" to the stock 22 5/8" is 22.94" or 22 15/16". :bounce:

Edit: Oh and I need the lengths from center of mounting point to center of mounting point.

If your an engineer or mathematician and see a flaw in this logic please advise.

The MC instructions provide all the data I need for my calculations EXCEPT stock front and rear track bar lengths. That is why I am asking this fine JK community for their help. Thanks. :)
Of course you may need to use this math formula if you end up with death wobble after the upgrade.... ;)
 

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Discussion Starter #19
For what it's worth, my MC control arms did not arrive adjusted to a particular length. In fact, they were all at different lengths.
Really?! The instructions say that everything is preset for a 3.5" baseline. When I talked to MC yesterday I asked if they had a 2.5" baseline yet. He said they are working on it and it should be on their site soon.
 
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