Long arm materials

[Israel]

I've spent the past few days searching up information on building a set of radius arms for the Jeep and would like a critique of my plans before I go and buy materials.

I want to use 2", 1/4" thick DOM for the lowers.
1.5", 1/4" thick DOM for the uppers.
Stock style rubber bushings for the axle ends of the upper and lower arms.
Big RE Flex joints for the axle end of the lowers.
1" -14 Grade B7 (whatever B7 means) threaded rod welded to the Flex joints.
1" -14, 3/8" nuts for jam nuts.
1" -14 couplings for my threaded inserts.
3"x3", 3/16" thick tubing for the frame end mounts.

How does this sound so far?

I wasn't able to find much on what to use for the juncture where the upper arm meets the lower arm. I did find one post where Crash mentioned that he was eating up rubber bushings on the axle due to using rod ends at the LCA/UCA juncture, but I thought pretty much all the flex was going to be done through the RE joints at the frame end. Any suggestions?

 

[CRASH]

I've spent the past few days searching up information on building a set of radius arms for the Jeep and would like a critique of my plans before I go and buy materials.

I want to use 2", 1/4" thick DOM for the lowers.
1.5", 1/4" thick DOM for the uppers.
Stock style rubber bushings for the axle ends of the upper and lower arms.
Big RE Flex joints for the FRAME END of the lowers.
1" -14 Grade B7 (whatever B7 means) threaded rod welded into a 1.5" x .120 sleeve in the lower arms.
1" -14, 3/8" nuts for jam nuts.
1" -14 couplings for my threaded inserts, welded to the large RE joints.
3"x3", 3/16" thick tubing for the frame mounts.

How does this sound so far?

I wasn't able to find much on what to use for the juncture where the upper arm meets the lower arm. I did find one post where Crash mentioned that he was eating up rubber bushings on the axle due to using rod ends at the LCA/UCA juncture (I don't know where you saw that, I've never used a hard joint there, except on Phils rig, and that is a special case.), but I thought pretty much all the flex was going to be done through the RE joints at the frame end. Any suggestions?

Corrections in red

In a typical radius arm setup, the axle tries to twist as it articulates. So you need three bushings at the axle. In Phil's case, the radius arms are so long, and so triangulated that the twisting is minimized, and we used a small RE joint at the juncture of the upper and lower. This leads to more control and less slopppiness under braking, which can be a problem when you have 3 joints a'-floppin'.

 

[Israel]

Corrections in red

In a typical radius arm setup, the axle tries to twist as it articulates. So you need three bushings at the axle. In Phil's case, the radius arms are so long, and so triangulated that the twisting is minimized, and we used a small RE joint at the juncture of the upper and lower. This leads to more control and less slopppiness under braking, which can be a problem when you have 3 joints a'-floppin'.

Thank you for the corrections! I actually meant to say that the RE joint was going at the frame end. So you suggest welding the coupling to the RE joint instead of in the tube? Is that for more weld area on the joint? I hadn't thought of that, but it sounds like a great idea.

So I should plan on one upper link instead of two, right?

Here is the thread I was referencing, post #9. I probably read it wrong.
http://www.naxja.org/forum/showthread.php?t=24690&highlight=radius+arm+heim

 

[Israel]

Also, what do you suggest for the juncture between the upper arm and the middle of the lower arm? Would a heim be OK if I go with one upper arm?

 

[CRASH]

Thank you for the corrections! I actually meant to say that the RE joint was going at the frame end. So you suggest welding the coupling to the RE joint instead of in the tube? Is that for more weld area on the joint? I hadn't thought of that, but it sounds like a great idea.

So I should plan on one upper link instead of two, right?

Here is the thread I was referencing, post #9. I probably read it wrong.
http://www.naxja.org/forum/showthread.php?t=24690&highlight=radius+arm+heim

If you are going with a single upper, I would use RE joints or heims everywhere.

If you are doing two uppers, I would use all rubber at the axle end. Yes, it uses some bushings, and it feels a little soft under braking, but you can only get away with less bushings if your suspension has a lot of triangulation, such that it doesn't impart very much twist on the axle tube. Does that make sense?

 

[Israel]

If you are going with a single upper, I would use RE joints or heims everywhere.

If you are doing two uppers, I would use all rubber at the axle end. Yes, it uses some bushings, and it feels a little soft under braking, but you can only get away with less bushings if your suspension has a lot of triangulation, such that it doesn't impart very much twist on the axle tube. Does that make sense?

It makes perfect sense, actually, thank you!

This is for my Dana 30 and will use the stock axle bracketry with the pass. side upper mount reinforced a bit. When I get the Dana 44 in there, I was hoping to convert a lot of this to a URF 3 link with the two lowers and a single upper "torque arm", so I was planning on making a crossmember for the lowers similar to what you and Jes have done and just leave the upper mount out until later on.

Would the use of a crossmember triangulate the lowers enough that I would have to use solid joints on the axle instead of the rubber bushings as I was planning?

 

[CRASH]

The more triangulation you have of the lowers, and the longer they are, the less rubber you need. On Phil's the lowers are a bit over 40" and they are about 10 inches apart at the member (IIRC). Now, remember, the more you triangulate the lowers, the more interference you get with that short upper and the pinion yoke. Phil's is very close and needed a bend to clear. Move teh attachment point of the upper and lower back farther than the typical RE setup, and you'll be fine.

I think I would still use the the OEM bushing in the axle UCA mount and the LCA mount at the axle. Leaving only the OEM UCA bushing would not allow enough deflection, and they are a PITA to change.

 

[XJ_ranger]

Now, remember, the more you triangulate the lowers, the more interference you get with that short upper and the pinion yoke. Phil's is very close and needed a bend to clear.

and still needs more bend to efficitvely clear -

 

[CRASH]

and still needs more bend to efficitvely clear -

Get to it!

 

[ZJ_95]

damn, speakin of trail poperutsy, hey they even catched frankinswash in the background

 

[stupidfast]

how triangulated can you acctualy go with 2 lowers and a single upper on the diff side? i can understand how it would cause less binding. you cant make any significant mounting point changes on the axle so it would have to be on the frame side right? i never thought about triangulating a long arm system. just how much better is it than having the arms perpendicular to the axle more like stock?

 

[CRASH]

how triangulated can you acctualy go with 2 lowers and a single upper on the diff side? i can understand how it would cause less binding. you cant make any significant mounting point changes on the axle so it would have to be on the frame side right? i never thought about triangulating a long arm system. just how much better is it than having the arms perpendicular to the axle more like stock?

The more triangulated, the less bind under articulation. The limiting factor, as you point out, is interference with the diff, yoke and driveline.

No need to triangulate when running a single upper, as there is no bind.

Think of the One-link principle, the more triangulation on your radius arms, the closer you get to the One-link.

 

[rokspydr]

I used 1 1/4" aurora's on the lowers and 3/4" on top. I am still on the origional ones 4 years later and no bind. I am not sold on the idea of threaded rod.

 

[MontanaXJ]

1" -14 Grade B7 (whatever B7 means) threaded rod welded to the Flex joints.
1" -14 couplings for my threaded inserts.

Instead of welding in threaded rod and welding up a coupler to an RE joint, have you considered getting the large Welded SuperFlex Assembly (PN# RE3767) and the weld in spud (PN# RM12060).

I have been thinking of going 3 link this winter, and since I already have RE adjustable short arms, I will already have most of my link ends. I will have to get get 2 more large SF joints and 2 weld in spuds for my lowers. I already have 3 feet of 1" 14 all thread for making a track bar so that can be used with my 2 small SF joints for my upper. I might use a large Heim at frame end of upper for space.

Greg

 

[Israel]

Instead of welding in threaded rod and welding up a coupler to an RE joint, have you considered getting the large Welded SuperFlex Assembly (PN# RE3767) and the weld in spud (PN# RM12060).

I have been thinking of going 3 link this winter, and since I already have RE adjustable short arms, I will already have most of my link ends. I will have to get get 2 more large SF joints and 2 weld in spuds for my lowers. I already have 3 feet of 1" 14 all thread for making a track bar so that can be used with my 2 small SF joints for my upper. I might use a large Heim at frame end of upper for space.

Greg

I hadn't seen the welded assemblies yet. I've ordered all my materials, but the tubing so I guess I'll be sticking with Crash's revision of plan A. I have to ask, 'though, how do you expect me to weld to a potato?

...and the weld in spud (PN# RM12060). ...two weld in spuds for my lowers.

Sorry, I couldn't resist!