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post #1 of 51 Old 11-26-2013, 02:45 AM Thread Starter
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Radius arms

anyone runnin a radius arm setup? how much wheel travel are you getting? How long are your bushings lasting and what bushings are you running?
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post #2 of 51 Old 11-26-2013, 03:24 AM
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The only partial (front only) radius system I would run was Clayton's with JJ's. Way too many story's of bushing failure with others.


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post #3 of 51 Old 11-26-2013, 03:47 AM Thread Starter
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I was thinking of having the driver side the radius arm and the passenger lower a standard arm. The axle mounts would be from poly and I would use artecs rk 3 link truss and for bushings metalcloaks or jj.
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post #4 of 51 Old 11-26-2013, 05:17 AM
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I was thinking of having the driver side the radius arm and the passenger lower a standard arm. The axle mounts would be from poly and I would use artecs rk 3 link truss and for bushings metalcloaks or jj.
If you are going to build it why not run an actual 3link?
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post #5 of 51 Old 11-26-2013, 05:48 AM
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I was thinking of having the driver side the radius arm and the passenger lower a standard arm. The axle mounts would be from poly and I would use artecs rk 3 link truss and for bushings metalcloaks or jj.
If you don't go with a three link up front and end up using a kit with radius arms, they will be on both the driver and passenger side.

I don't personally have experience with MC but they have a solid reputation. I would say if you are looking at getting a long arm kit to look at Clayton, Rock Krawler or Metalcloak. All three have proven kits that you just don't hear bad reviews about.

We have installed many Rock Krawler lifts and they perform extremely well. Their long arm kits are pretty sweet. As far as flex joints, on my own rig I run johnny joints as they are my preferred flex joint.

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Originally Posted by van7559
I can bury my pinky in the rear, and just barley feel it, the front is a little easier, but still seems low to me!

I fist fuck life with a nuclear powered pneumatic fuck hammer for 60, 70 hrs a week...
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post #6 of 51 Old 11-26-2013, 09:31 AM
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Two locals here run the Clayton front radius arm. Both had issues with bind around the 10" travel mark with the factory clevite UCA bushing. Both replaced with JJ's (either the currie kit or poly kit, I can't remeber) and have had no issues since. One of them run 14" coilovers and uses every inch of travel.

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post #7 of 51 Old 11-26-2013, 09:35 AM Thread Starter
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If you are going to build it why not run an actual 3link?
More than anything just curious as to how well it would work. By getting rid of the passenger side radius arm seems to me that you would take a lot of the torsional stress out of the housing and axle mounting brackets which might be easier on the joints as welll. I have not seen a setup like this so I am assuming there are problems with it that im unaware of.
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post #8 of 51 Old 11-26-2013, 09:35 AM
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Two locals here run the Clayton front radius arm. Both had issues with bind around the 10" travel mark with the factory clevite UCA bushing. Both replaced with JJ's (either the currie kit or poly kit, I can't remeber) and have had no issues since. One of them run 14" coilovers and uses every inch of travel.

Currie kit = Poly kit I believe. I need to order those joints [2x drivers side], mine are just mush at this point.

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post #9 of 51 Old 11-26-2013, 09:38 AM
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Currie kit = Poly kit I believe. I need to order those joints [2x drivers side], mine are just mush at this point.
For the driver side, yes they are pretty much identical. The pass side is different IIRC. Currie's uses the factory box tower and welds into it, poly's is a complete replacement.

I could be confusing it with the poly prorock replacement....

-Mike
2007 2dr X, 6sp, 35's on D44's, 2" lift, cage, hydro, etc.
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post #10 of 51 Old 11-26-2013, 09:47 AM Thread Starter
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Two locals here run the Clayton front radius arm. Both had issues with bind around the 10" travel mark with the factory clevite UCA bushing. Both replaced with JJ's (either the currie kit or poly kit, I can't remeber) and have had no issues since. One of them run 14" coilovers and uses every inch of travel.
Thanks! Do you know if they use their rig as a DD?
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post #11 of 51 Old 11-26-2013, 09:52 AM
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Thanks! Do you know if they use their rig as a DD?
Yes I know for sure one does, but I believe both of them do.

-Mike
2007 2dr X, 6sp, 35's on D44's, 2" lift, cage, hydro, etc.
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post #12 of 51 Old 11-26-2013, 10:18 AM
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glad this came up. I have been looking into the clayton kit, seems like a great concept but a lot of stress on that lower frame side joint. especially for a bolt on trans crossmember.
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post #13 of 51 Old 11-26-2013, 10:35 AM
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Okay, the Poly kit and the Currie kit are exactly the same on the driver side (diff housing jj joint just presses in) but they do vary on the pass side. Currie, as was pointed out above, has you cut the existing mount down slightly at an angle then slide the new tower assembly inside the existing mount and weld it up (you also drill out a couple holes for some plug welds too).

Where these two really differ depends on how your gonna run your front axle. If you are gonna truss it with say an Artec truss kit, I highly recommend the Currie kit as it has less of a gap around the tower if you install it per the instructions, however, you can always cut the existing tower a little higher so that the truss wraps it tightly.

The Poly kit has a much narrower tower and the gussets provide the lateral support. In a situation where you use an Artec truss it leaves a huge gap to fill, plus you are spending a little more money for some gussets that you wouldn't need if you use a truss.

I refer to the Artec truss only cause I think it's really the best setup for our axles and the most complete kit I have used so far.

And further, yes...the jj's really allow a shit ton of flex. I get no bind whatsoever with them and I always recommend that the front housing kit be done when adding a truss or even just doing a simple gusset addition. It free's up the front end so much and things feel very smooth.

If someone were to order a Clayton lift I would only get it with jj's. Clayton and RK both have good flex joints, I'm just partial to Currie jj's myself is all. I have had no issues with the older style RK flex joints and haven't had enough of the newer joints out there to judge them yet. I'm sure they will be fine though based on my experiences with RK.

Also on a side note, I suggest you disassemble the jj and weld it up without the guts so you don't melt your bushings. They are very susceptible to melting even with just a little heat. You will be adding a few tacks to the backside of the driver side joint and of course your putting a lot of heat on the tower to get it all set up properly. Not only that but then you can see for yourself how easy it is to rebuild the joint when and if that time comes for you........

Originally Posted by van7559
I can bury my pinky in the rear, and just barley feel it, the front is a little easier, but still seems low to me!

I fist fuck life with a nuclear powered pneumatic fuck hammer for 60, 70 hrs a week...
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post #14 of 51 Old 11-26-2013, 10:42 AM Thread Starter
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I stumbled upon this idea because I need a bit more lift and I wanted longer, adjustable arms but I want to piece it all together because in a little weird. After seeing rough countrys long arm upgrade kit for $1200 it seemed like a good starting point untill I decided I want to do a 3 link in the rear and I would have to swap out all the bushings. So now I think I can get the front axle done for around $600 in materials. I havent seen radius arm set ups like this and figured there has to be a reason why so im really looking for someone to poke holes in my idea
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post #15 of 51 Old 11-26-2013, 10:46 AM
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Steer clear of RC if you are able. I too have a bit of a Frankenstein lift but it all works very well together. I don't have a long arm though as I really don't find the need for it the way I drive and I do get out there and ride mine pretty hard.

RC has some great customer service and they have some great warranty policies so I can't knock them for that but I just prefer to stick with the guys I know hold up to the type of wheeling I personally do. Others opinions may vary on this.

Originally Posted by van7559
I can bury my pinky in the rear, and just barley feel it, the front is a little easier, but still seems low to me!

I fist fuck life with a nuclear powered pneumatic fuck hammer for 60, 70 hrs a week...
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post #16 of 51 Old 11-26-2013, 10:57 AM
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M&M, thanks for clearing up the poly/currie differences. Agreed, take apart the guts before welding or weld slow, and the currie kit works perfectly with a flush cut on the artec truss

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From my understanding of link geometry, a radius arm in the rear has terrible anti squat characteristics, that would steer me clear of Rubicon Express. That said I don't have experience with it, so take it fwiw.


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post #17 of 51 Old 11-26-2013, 11:00 AM
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Steer clear of RC if you are able. I too have a bit of a Frankenstein lift but it all works very well together. I don't have a long arm though as I really don't find the need for it the way I drive and I do get out there and ride mine pretty hard.

RC has some great customer service and they have some great warranty policies so I can't knock them for that but I just prefer to stick with the guys I know hold up to the type of wheeling I personally do. Others opinions may vary on this.
Oh God of Gods Murray is correct on this. Take it from me, I was one of those that immediately pulled the trigger on the RC route. But slowly and painfully been emptying my wallet to improve the quality whether it'd be on the steering or the sagging springs, stiff shocks, crappy bushings etc.

As far as him riding it hard, tis a fact he rides everything hard. Just ask lambchop!

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post #18 of 51 Old 11-26-2013, 11:10 AM
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If you understand how a radius arm suspension works, then you'll understand why it's very undesirable when shock travel is a priority. It can work OK on the road (it's still not ideal) but once you start articulating the suspension, the axle housing is treated as a torsion bar. The links are literally attempting to twist the tubes out of the housing. The instant center location generally results in a front end that reacts heavily to weight transfer, ie it unloads when climbing and dives when braking.

When it comes to bushing requirements, you cannot use a spherical joint at every end. The wrist connection between the "upper" and lower links requires a complex movement that a spherical joint cannot provide. This connection must use a standard Clevite-style bushing.

Both of these characteristics of radius arms are very undesirable--the housing is put under immense stress when articulating and it forces the use of bushings with less misalignment capability and, thus, less durability. Radius arms rely on binding and, thus, don't make sense in a vehicle with a healthy amount of shock travel.

If you're planning on building a front suspension, radius arms don't make any sense at all. A more conventional link setup--3 or 4 control arms--is easy to setup and package assuming the installer has a high school-level understanding of the mechanics involved. The axle housing will never be under torsional loads, there will be no inherent binding (3 link) and spherical joints or high quality bushings (MC) can be used.

The "radius arm under a Jeep" idea has been around since the early days of the TJ. It packages and installs very easily but that's where the positives stop. Any manufacturer attempting to put this design into good light needs to either re-examine their understanding of the subject or quit lying to their customers.

Last edited by Imped; 11-26-2013 at 11:14 AM.
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post #19 of 51 Old 11-26-2013, 11:24 AM Thread Starter
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If you understand how a radius arm suspension works, then you'll understand why it's very undesirable when shock travel is a priority. It can work OK on the road (it's still not ideal) but once you start articulating the suspension, the axle housing is treated as a torsion bar. The links are literally attempting to twist the tubes out of the housing. The instant center location generally results in a front end that reacts heavily to weight transfer, ie it unloads when climbing and dives when braking.

When it comes to bushing requirements, you cannot use a spherical joint at every end. The wrist connection between the "upper" and lower links requires a complex movement that a spherical joint cannot provide. This connection must use a standard Clevite-style bushing.

Both of these characteristics of radius arms are very undesirable--the housing is put under immense stress when articulating and it forces the use of bushings with less misalignment capability and, thus, less durability. Radius arms rely on binding and, thus, don't make sense in a vehicle with a healthy amount of shock travel.

If you're planning on building a front suspension, radius arms don't make any sense at all. A more conventional link setup--3 or 4 control arms--is easy to setup and package assuming the installer has a high school-level understanding of the mechanics involved. The axle housing will never be under torsional loads, there will be no inherent binding (3 link) and spherical joints or high quality bushings (MC) can be used.

The "radius arm under a Jeep" idea has been around since the early days of the TJ. It packages and installs very easily but that's where the positives stop. Any manufacturer attempting to put this design into good light needs to either re-examine their understanding of the subject or quit lying to their customers.
Ive read many threads about radius arm but I have not seen anyone use a conventional lower control arm on the passenger side to eliminate the torsional force on the housing. It sounds like with the clayton kit and the right bushings travel is not an issue. My main concern is if the drivers side upper mount would support the extra stress. Im gonna be using 2" dom with 1/4" wall thickness for the controll arms and metalcloak ends and a jj on the upper driver side mount

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post #20 of 51 Old 11-26-2013, 11:35 AM
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Ive read many threads about radius arm but I have not seen anyone use a conventional lower control arm on the passenger side to eliminate the torsional force on the housing. It sounds like with the clayton kit and the right bushings travel is not an issue. My main concern is if the drivers side upper mount would support the extra stress. Im gonna be using 2" dom with 1/4" wall thickness
What is a "conventional lower control arm" to you? Not using a wristed upper link?

Regardless of who built the parts and what bushings/joints are being used, the physics behind it isn't changing. Travel is and will always be an issue since the torsional loads acting on the housing will increase as the angle of the housing to the horizontal increases. The more travel you use, the more often you'll wear out the wrist connection bushings. Even in brand-new form, there is quite a bit of movement/deflection due to the design relying on bind to constrain the rotational axis of the housing.

If you're really dead set on using this type of suspension, there's nothing I can say other than I highly recommend against it. The performance sucks and you won't be happy with it long-term if you actually wheel.
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post #21 of 51 Old 11-26-2013, 11:42 AM
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The driver side UCA joint is cast into the differential. It significantly stonger than the passenger side stock-to-stock comparison. A trussed passenger side is, however, stonger IMO.

Imped and I share the same concerns with a radius arms... however I have seen the clayton setup travel the full range of a 14" coilover without bind (this is with springs removed and shocks uncharged, cycling the suspension to check mount position and clearances).

-Mike
2007 2dr X, 6sp, 35's on D44's, 2" lift, cage, hydro, etc.
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post #22 of 51 Old 11-26-2013, 11:43 AM Thread Starter
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I would use a radius arm for the drivers side and just a lower control arm on the passenger side without a link to the upper mount. I figure if this doesnt work out its easy enough to just switch over to a 3 link.
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post #23 of 51 Old 11-26-2013, 12:01 PM
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Imped and I share the same concerns with a radius arms... however I have seen the clayton setup travel the full range of a 14" coilover without bind (this is with springs removed and shocks uncharged, cycling the suspension to check mount position and clearances).
Let's say we make a bet on the existence of bind when one side is at full bump and the other at full droop with 14" travel shocks. You say there's no bind and I say prove it--we install a spherical joint in the wrist connection so that there's room for you to put your finger between the joint housing and the mount tab. Would you bet your finger that there's no (or very little) bind at in that situation?

Point: Just because the axle is able to articulate doesn't mean there's not a huge amount of force built up in the joints/bushings. You'd come out of that test with a completely flattened finger, I'm afraid.
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I would use a radius arm for the drivers side and just a lower control arm on the passenger side without a link to the upper mount. I figure if this doesnt work out its easy enough to just switch over to a 3 link.
Housing wrap would be a concern and you'd still have a very unfavorable instant center location. But you're correct in that binding would be much alleviated.
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post #24 of 51 Old 11-26-2013, 12:15 PM
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Given the opportunity this is where we install radius arms...lol



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Originally Posted by van7559
I can bury my pinky in the rear, and just barley feel it, the front is a little easier, but still seems low to me!

I fist fuck life with a nuclear powered pneumatic fuck hammer for 60, 70 hrs a week...
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post #25 of 51 Old 11-26-2013, 12:26 PM
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Originally Posted by Imped View Post
Let's say we make a bet on the existence of bind when one side is at full bump and the other at full droop with 14" travel shocks. You say there's no bind and I say prove it--we install a spherical joint in the wrist connection so that there's room for you to put your finger between the joint housing and the mount tab. Would you bet your finger that there's no (or very little) bind at in that situation?

Point: Just because the axle is able to articulate doesn't mean there's not a huge amount of force built up in the joints/bushings. You'd come out of that test with a completely flattened finger, I'm afraid.
Like I said before, I share the same concerns (especially housing torsion), and I see your point.

The clayton arms use a JJ at the frame (not really relevant), a clevite at the LCA bracket of the arm, a JJ at the knuckle of the arm, and the factory clevite in the UCA joints. Thinking about it some more, I would suspect with stock UCA bushings, the bind (relistically deflection in the bushing) is shared between the UCA bushings and the LCA axle bracket end of the arm. Like you said before, the celvite handle the deflection better, but does not work as well as a sherical joint in terms of articulation. So potentially adding the JJ in the UCA bushings (which aleviated bind in my friends setups) aids in less articulation resistance. But if there is excess bushing load at 14" of travel, which I don't disagree on, that would leave the Axle LCA bracket bushing as the only joint soft enough to take the remainder of the deflection.

So realistically, the axle LCA end of the arm should begin to wear significantly over time. I'm not saying that the JJ's wont take a little of the deflection, but the majority would be taken by the "softest" joint, no?

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