Rock Krawler or Poly Performace Long Arm - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 56 Old 11-28-2013, 06:46 PM Thread Starter
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Rock Krawler or Poly Performace Long Arm

I know both Rock Krawler and Poly Performance make quality products and have good customer service. My question is about the design of their long arm kits.

Both kits use the factory mounting location on the front axle but the frame side front mounts are much different.

The Rock Krawler front frame side bracket seems to have less separation but the upper arm mount is back farther allowing a longer upper arm.



The Poly Performance kit and most other kits moves the lower link lower and the upper link forward compared to the Rock Krawler kit.



Seems like a drastic difference in design.
Has anyone driven both systems? Other than exhaust modification with the Rock Krawler kit what are the advantages and disadvantages of each system?
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post #2 of 56 Old 11-28-2013, 06:58 PM
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I have no experience with either as I have a Teraflex Longarm. Had it on my TJ and served me well. However, both of the aforementioned kits are very nice. You would likely be satisfied with either. I nearly went with the Poly because of the praise it gets on this site. It also is bolt on and it is adjustable without having to remove the arm to adjust the joint. Great selling point in my opinion. However it is a pricey kit and that is why elected to go its old faithful. Once dialed in correctly overall performance of either will likely satisfy your needs. Best of luck. I am sure others will tune in to this thread.
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post #3 of 56 Old 12-02-2013, 01:41 PM
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I have spent over a year researching and trying to decide which lift I wanted for our '13 JKUR. I just ordered the 2.5" X-Factor Long Arm Kit from Rock Krawler.

From an engineering standpoint, I think the RK configuration is a much better design. Having the chassis pivot point close together should create much better geometry through the entire range of suspension flex.

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post #4 of 56 Old 12-02-2013, 03:05 PM
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Quote:
Originally Posted by stanman View Post
From an engineering standpoint, I think the RK configuration is a much better design. Having the chassis pivot point close together should create much better geometry through the entire range of suspension flex.
Your analysis isn't quite complete.....
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post #5 of 56 Old 12-02-2013, 03:09 PM
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post #6 of 56 Old 12-02-2013, 04:41 PM
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Your analysis isn't quite complete.....
It's not even worth it
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post #7 of 56 Old 12-02-2013, 05:58 PM
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I have Synergy - it is a nice setup that is easily adjusted.

That being said, I wheel the hard trails and the Synergy mounts hang down low - so the arms and the mounts take a beating.

Next year I am probably going to swap out the Synergy stuff so I can stretch the WB forward 3-4 inches. I'll probably use the RK mounts and custom arms.



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post #8 of 56 Old 12-02-2013, 06:19 PM
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Flip a coin.
You would do better to just build your own custom 3 link.

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post #9 of 56 Old 12-02-2013, 08:02 PM Thread Starter
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Quote:
Originally Posted by thedirtman View Post
Flip a coin.
You would do better to just build your own custom 3 link.
I was thinking of doing a 3 link using Clayton's crossmember.



and Artec's inner frame link mount

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post #10 of 56 Old 12-02-2013, 09:59 PM
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Quote:
Originally Posted by thedirtman View Post
Flip a coin.
You would do better to just build your own custom 3 link.
Been tossing around this idea recently, RK recommended against running their 8" stretch with a short arm up front. So looking into building my own links and purchasing the mounts to save some cash, just need to do much more research.

Quote:
Originally Posted by JustinJK View Post
I was thinking of doing a 3 link using Clayton's crossmember.



and Artec's inner frame link mount

Are you doing a three link out back as well? If so what will you be using for mounts? Making your own links?

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post #11 of 56 Old 12-03-2013, 04:46 AM Thread Starter
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Quote:
Originally Posted by Thisguyhasadd42 View Post
Been tossing around this idea recently, RK recommended against running their 8" stretch with a short arm up front. So looking into building my own links and purchasing the mounts to save some cash, just need to do much more research.



Are you doing a three link out back as well? If so what will you be using for mounts? Making your own links?
I was thinking dom tube for the links using Rock Krawlers new joints.

For the rear I was planing on doing a 3 link using Artec's rear truss



And these mounts on the outside of the frame and trim the rear body mount as needed.



By the time you add everything up and add in your time I don't think you would save much money over buying a kit.

I am going to wait and see what Rock Krawler's new pro kit looks like before I do anything, just trying to get ideas.
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post #12 of 56 Old 12-03-2013, 05:49 AM
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Originally Posted by JustinJK View Post
I was thinking dom tube for the links using Rock Krawlers new joints.

By the time you add everything up and add in your time I don't think you would save much money over buying a kit.

I am going to wait and see what Rock Krawler's new pro kit looks like before I do anything, just trying to get ideas.
Ya that's what I am starting to realize, I just like the idea of building my own. Didn't know RK had a new kit coming out, I'll have to look out for it. The only problem I see with buy a kit is paying for parts I already have.

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post #13 of 56 Old 12-03-2013, 08:40 AM
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Quote:
Originally Posted by JustinJK View Post
I know both Rock Krawler and Poly Performance make quality products and have good customer service. My question is about the design of their long arm kits.

Both kits use the factory mounting location on the front axle but the frame side front mounts are much different.

The Rock Krawler front frame side bracket seems to have less separation but the upper arm mount is back farther allowing a longer upper arm.



The Poly Performance kit and most other kits moves the lower link lower and the upper link forward compared to the Rock Krawler kit.



Seems like a drastic difference in design.
Has anyone driven both systems? Other than exhaust modification with the Rock Krawler kit what are the advantages and disadvantages of each system?
We have increased the separate by 1.5" at the frame for the front arms to account for a little better "go fast" geometry and have not seen any negatives as far as articulation or crawling. We feel it actually helped when it comes to climbing steep vertical faces. We can guarantee no system moves as smoothly as our long arm systems do, nor do they offer the cross over angles we do. They are really tough systems to beatÖ

For those of you that already have components you want to keep, we can certainly build custom BOM's for your builds to utilize what you have as best as possible.

Good luck with your builds!

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post #14 of 56 Old 12-03-2013, 09:01 AM
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I'm currently installing the new configuration (more separation) front long arm brackets in my 4-Door.
I'm excited to compare it to the previous (less separation) system that is in my big 2-door. Both Jeeps on Kingpin one tons and 40+" tires. So should be a fair assessment.

I'm not sure how you can beat the RK system. I watch so many people get defeated by obstacles because of low hanging control arm mounts. All it takes is a little bit of contact on a sharp rock/edge and you're done. Just doesn't make sense to me. RK tucks that shit up in the belly and they follow the general rules of suspension design.

Also, pay attention to control arm lengths on other systems. The upper arms should be about 80% in length of the lower arms. A lot of systems out there run shorter upper arms. I just watched ANOTHER Teraflex system tear the upper rear mount off the frame 2 weeks ago. It was a good friend of mine, and he attributed it to his massive horsepower. I just chuckled because it's a design flaw that has failed numerous times. Short upper arms.
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post #15 of 56 Old 12-03-2013, 07:39 PM
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Quote:
Originally Posted by JustinJK View Post
I was thinking dom tube for the links using Rock Krawlers new joints.

For the rear I was planing on doing a 3 link using Artec's rear truss

[URL=http://s1303.photobucket.com/user/justinschmehl/media/Jeep%20JK/image_zps3aac9091.jpg.html]
And these mounts on the outside of the frame and trim the rear body mount as needed.

[URL=http://s1303.photobucket.com/user/justinschmehl/media/Jeep%20JK/image_zps4a74e8f7.jpg.html]
By the time you add everything up and add in your time I don't think you would save much money over buying a kit.

I am going to wait and see what Rock Krawler's new pro kit looks like before I do anything, just trying to get ideas.

Just asking why you would choose the new RK joints over another brand?

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post #16 of 56 Old 12-04-2013, 01:00 PM Thread Starter
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Quote:
Originally Posted by thedirtman View Post
Just asking why you would choose the new RK joints over another brand?
I am currently using the old style joints and have had no issues with them. I would think the newer style joint would be as good or better.
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post #17 of 56 Old 12-04-2013, 03:39 PM
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They are better in every way shape or formÖ Thanks for the support.

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post #18 of 56 Old 12-04-2013, 07:50 PM
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Recommended control arm lengths for the front long arms

Synergy
25" upper
31 5/8 lower
Got really close to the 80% "rule of thumb"

Rock Krawler
36 1/4 upper
34.125 lower
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post #19 of 56 Old 12-05-2013, 07:02 AM
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I would agree that Poly got the geometry right. Just don't like how their lower mounts hang so low.
What are their rear arm lengths?
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post #20 of 56 Old 12-05-2013, 09:52 AM
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Quote:
Originally Posted by Co4Lo View Post
I'm currently installing the new configuration (more separation) front long arm brackets in my 4-Door.
I'm excited to compare it to the previous (less separation) system that is in my big 2-door. Both Jeeps on Kingpin one tons and 40+" tires. So should be a fair assessment.

I'm not sure how you can beat the RK system. I watch so many people get defeated by obstacles because of low hanging control arm mounts. All it takes is a little bit of contact on a sharp rock/edge and you're done. Just doesn't make sense to me. RK tucks that shit up in the belly and they follow the general rules of suspension design.

Also, pay attention to control arm lengths on other systems. The upper arms should be about 80% in length of the lower arms. A lot of systems out there run shorter upper arms. I just watched ANOTHER Teraflex system tear the upper rear mount off the frame 2 weeks ago. It was a good friend of mine, and he attributed it to his massive horsepower. I just chuckled because it's a design flaw that has failed numerous times. Short upper arms.
I have yet to see or hear of a TF long arm tearing the upper mount loose from the frame if their reinforcement plate is installed.


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post #21 of 56 Old 12-05-2013, 10:02 AM
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Quote:
Originally Posted by da20captain View Post
I have no experience with either as I have a Teraflex Longarm. Had it on my TJ and served me well. However, both of the aforementioned kits are very nice. You would likely be satisfied with either. I nearly went with the Poly because of the praise it gets on this site. It also is bolt on and it is adjustable without having to remove the arm to adjust the joint. Great selling point in my opinion. However it is a pricey kit and that is why elected to go its old faithful. Once dialed in correctly overall performance of either will likely satisfy your needs. Best of luck. I am sure others will tune in to this thread.
I also have the TF long arm, which has been outstanding. Whichever kit you choose going long arm is a wise move. I did not expect how much more stable and capable the rig would be with this upgrade. Had I known I'd have installed one from the start. You do get what you pay for.

Would add that some friends did a Poly LA kit and rave about it. Meanwhile one of our club members is likewise bullish re his RK long arm. The common barrier is simply the time and skill needed to cut off the stock brackets, prep the frame and install the new ones, weld on or bolt on. After that the setup is fairly straight forward.


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post #22 of 56 Old 12-05-2013, 10:11 AM
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Quote:
Originally Posted by SoK66 View Post
I have yet to see or hear of a TF long arm tearing the upper mount loose from the frame if their reinforcement plate is installed.


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I's happening. I've personally seen 2 of them. And a couple on the interwebz as well. Not sure about the reinforcement plate, but I know the last one was pretty well integrated into the frame.

There is obviously some serious stress at that mounting point in the TF system if tears the mount off the frame.

The interesting thing is, RK's lower long arm mounts weld to the side of the frame in a very similar configuration/location as the TF upper mounts. There is no reinforcing plate, just simple mounts welded to the side of the frame. And I've never seen an RK mount tear off the frame. Wonder why.
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post #23 of 56 Old 12-05-2013, 11:20 AM Thread Starter
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Quote:
Originally Posted by HeloJeff View Post
Recommended control arm lengths for the front long arms

Synergy
25" upper
31 5/8 lower
Got really close to the 80% "rule of thumb"

Rock Krawler
36 1/4 upper
34.125 lower
So how does this effect how the suspension works? Is one way better on the street and one better at climbing steep ledges off road?

I would think the differences would have an effect on how the suspension works in different situations.

Last edited by JustinJK; 12-05-2013 at 11:24 AM.
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post #24 of 56 Old 12-05-2013, 11:27 AM
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Yes it does make a difference on what you are wanting to get out of your suspension. A go fast on pavement will be vastly different then a rock crawler.
Location of control arm brackets will also have an affect as well as coil rates and shock valving. There are books out there on suspension theory and how one thing affects others.

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post #25 of 56 Old 12-05-2013, 12:06 PM
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Quote:
Originally Posted by Co4Lo View Post
I's happening. I've personally seen 2 of them. And a couple on the interwebz as well. Not sure about the reinforcement plate, but I know the last one was pretty well integrated into the frame.

There is obviously some serious stress at that mounting point in the TF system if tears the mount off the frame.

The interesting thing is, RK's lower long arm mounts weld to the side of the frame in a very similar configuration/location as the TF upper mounts. There is no reinforcing plate, just simple mounts welded to the side of the frame. And I've never seen an RK mount tear off the frame. Wonder why.
There is also a guy on JKfreaks (Lucas I believe) who has torn off both front UCA frame mounts on his teraflex long arm.

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2007 2dr X, 6sp, 35's on D44's, 2" lift, cage, hydro, etc.
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