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UCA axle end bushing options?

maxbraketorque

NAXJA Forum User
Location
PDX
After doing a bunch of reading, it seems like the options are using a factory style rubber bushing, standard polyurethane, RE Superflex, or IRO Johnny joint style. I'm hoping to stick with a bushing that minimizes NVH. A few questions:

- Any recommendations on a ​good quality factory style rubber bushing?
- Does anyone know of a dual durometer bushing in factory bushing dimensions or something similar?
 
I put in Moog factory style/OE Clevite a couple years ago and it has been fine.

That said, someone else on here has been having issues with the same thing, more recently purchased and installed.

The current supply chain does not instill confidence in anyone's parts.

I would give serious consideration to the Johnny Joint option, mostly on account of the hope that those parts are going to be honest examples of what they are represented to be, rather than a last resort to fill a box.
 
I haven’t tried it yet, but I was advised in a previous thread here that JK axle end UCA bushings fit the XJ brackets and upper control arms and will let you run 1/2” bolts (requires drilling the UCA out of course). That’s my plan if I need to do UCA bushings in the future.

I would NOT do Johnny Joints in a parallel four link due to binding. Especially if you already have hard joints on the other end of the uppers.
 
I haven’t tried it yet, but I was advised in a previous thread here that JK axle end UCA bushings fit the XJ brackets and upper control arms and will let you run 1/2” bolts (requires drilling the UCA out of course). That’s my plan if I need to do UCA bushings in the future.

I would NOT do Johnny Joints in a parallel four link due to binding. Especially if you already have hard joints on the other end of the uppers.
I thought JK have a larger OD bushing. Apparently not? I've got a radius arm setup.

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I would NOT do Johnny Joints in a parallel four link due to binding. Especially if you already have hard joints on the other end of the uppers.

Does anyone have actual evidence of this causing issues on minor lifted/flexy jeeps? I understand the bind during flex of a 4 link very well, yes... it exists.

There are likely thousands of Jeeps with Currie kits with JJs on all ends. I feel we would be hearing of consistent issues ripping off brackets, but that appears to be just as common without them as with them.
 
Not sure if gearwhine means

Johnny joints are good all the way around.

Because im cheap in run poly on the axle end and heims on the frame side. No binding.
Has to be a flex joint at the frame side or the material will tear apart or super soft rubber.

Reminds me SFR has soft poly joints

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Does anyone have actual evidence of this causing issues on minor lifted/flexy jeeps? I understand the bind during flex of a 4 link very well, yes... it exists.

There are likely thousands of Jeeps with Currie kits with JJs on all ends. I feel we would be hearing of consistent issues ripping off brackets, but that appears to be just as common without them as with them.

Nothing statistical or calculated, just anecdotal evidence that when you put in too many hard joints, you kill the bushings faster. https://www.naxja.org/forum/showthread.php?t=1163828
 
ive seen a couple trusses cracked and UCA mounts tearing from poor joint selection on a parallel 4 link and radius arm setup. poly/rubber at one end of each control arm is a must.

take your hands and make a peace sign. now point those peace signs away from you, parallel to each other. these are your 4 control arms. twist one wrist up, and one wrist down. notice that the peace signs are twisting in opposing directions. this is the inherent bind associate with a parallel 4 link and radius arm setup. if everything was rigid, your axle would not be able to articulate. improper joint selection will absolutely destroy something.
 
It should be noted that a Johnny Joint has a bushing inside. A heim joint (rod end) does not.
 
I think of you are running a radius setup all 4 axle bushings should be rubber. I have personally seen a grade 8 bolt break from the stress of Johnny joints at the axle end. (It was an upper driver side) flex joints such as Johnny joints have very little deflection, and you need a decent amount in a non wristed radius arm setup.

For a 4 link it depends on the design... if your setup has quite a bit of caster change when drooped out you need rubber at the axle to account for the twisting forces the axle sees when one side is at full bump and the other is at full droop ..

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I think of you are running a radius setup all 4 axle bushings should be rubber. I have personally seen a grade 8 bolt break from the stress of Johnny joints at the axle end. (It was an upper driver side) flex joints such as Johnny joints have very little deflection, and you need a decent amount in a non wristed radius arm setup.

For a 4 link it depends on the design... if your setup has quite a bit of caster change when drooped out you need rubber at the axle to account for the twisting forces the axle sees when one side is at full bump and the other is at full droop ..

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i agree. the PTFE/teflon/delrin/what ever it is... ring in a johny joint does not allow for the same deflection that a true bushing does. barnes also offers threaded bushing link ends.
 
Metalcloak Duroflex looks impressive. I may have to go with that.

Just to be clear, I have not used them. I want to. My Builds are changing by the minute. All of you are having a Baaad influence on me. Mainly, going with Ironman Long Arm setup front and rear.
 
Both the radius (long) arm and the triangulating arm have Johnny-type joints at the back end. Rubber bushings are currently used at the connection to the axle. I'm somewhat puzzled as to how much radial flex and off-axis bending flex is needed with a radius arm setup. My thought is that less off-axis bending flex is needed compared to a dual-control arm setup, but perhaps more radial flex is needed. I need to find some time to remove the springs and shocks, and then manually flex the suspension.
 
Your movement/flex descriptions are a little vague but on my radius arms I run super-flex joints at the crossmember and standard rubber joints at axle and the upper arm tie-ins. I have almost no bind because my arms are located further inboard than most of the manufactured set-ups. There would be absolutely no bind if you could make them meet at the same point on the crossmember.
 
The RC long arm mounting point on the unibody rail is about 1/2 - 3/4" further inboard than the stock lower control arm mounting point. Now that you mention this, I suppose that moving the mount point further inboard produces some triangulation, but its not obvious to me how that affects flex requirements. I really need to manually flex the suspension or simulate it.
 
The RC long arm mounting point on the unibody rail is about 1/2 - 3/4" further inboard than the stock lower control arm mounting point. Now that you mention this, I suppose that moving the mount point further inboard produces some triangulation, but its not obvious to me how that affects flex requirements. I really need to manually flex the suspension or simulate it.

Stick both of your arms straight out with your top fingers in a "v" and move one up and arm down and you will see the torsional problem.
 
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