Radius arm joints

sean883 · Mar 14, 2010

I'm getting ready to build a set of radius arms for my XJ. My original plan was Ballistic joints on both sides of upper and frame side of lower, axle side lower would get a rubber bushing.

I was told by a reputable longarm producing company that i was good to go with joints on both side of the upper. But everything else i read says i need rubber bushings at all axle side mounts. So what should i use?

old_man · Mar 14, 2010

I have run RE Super joints for several years and like them. You have to keep them tight, but that is just normal maintenance and is easier than replacing worn joints.

ktm racer 419 · Mar 15, 2010

with radius arms you need a source of deflection.

achieved by rubber bushings.

the rubber bushings are also needed to keep the long arm from flopping around.

i reccomend having them at the lca mounts on the axle and in the stock upper control arm mounts. flax joints are good where the upper meets the lower and at the body side of the lowers

sean883 · Mar 15, 2010

ktm, i believe you ran a radius setup with only one upper, would you suggest that over both uppers? I have aftermarket mounts so i'm not worried about the strength with only one upper.

ktm racer 419 · Mar 15, 2010

sean883 said:
ktm, i believe you ran a radius setup with only one upper, would you suggest that over both uppers? I have aftermarket mounts so i'm not worried about the strength with only one upper.

true.

its essentially a wristed radius arm.

if you do this, run all hard joints. = less axle wrap. and more than a 10 mm bolt for the upper.

Goatman · Mar 16, 2010

If you're going to run rubber on one end of a lower arm, I think it's best to have the rubber at the frame end. The axle end takes more deflection than the frame end, so rubber will last longer at the frame, and rubber isolates better so you theoretically would have less vibration and harshness if the rubber was at the frame side. It doesn't matter that much, but I see an argument to put the rubber at the frame and I see no argument to put the rubber at the axle.....on the lowers.

FLEX--J · Mar 16, 2010

sorry i hate to jump in on this discussion but i just bought a new jeep with serious flex in the front framehorns when you steer. i really need some help

sean883 · Mar 16, 2010

Goatman said:
If you're going to run rubber on one end of a lower arm, I think it's best to have the rubber at the frame end. The axle end takes more deflection than the frame end, so rubber will last longer at the frame, and rubber isolates better so you theoretically would have less vibration and harshness if the rubber was at the frame side. It doesn't matter that much, but I see an argument to put the rubber at the frame and I see no argument to put the rubber at the axle.....on the lowers.

That makes sense to me as thats how i ran my RE SF lowers, joint at axle and rubber at frame.

FLEX--J said:
sorry i hate to jump in on this discussion but i just bought a new jeep with serious flex in the front framehorns when you steer. i really need some help

Maybe your frame is cracked around the steering box? If you start a thread of your own with a title pertaining to your issue you will probably get more help.

ktm racer 419 · Mar 16, 2010

Goatman said:
If you're going to run rubber on one end of a lower arm, I think it's best to have the rubber at the frame end. The axle end takes more deflection than the frame end, so rubber will last longer at the frame, and rubber isolates better so you theoretically would have less vibration and harshness if the rubber was at the frame side. It doesn't matter that much, but I see an argument to put the rubber at the frame and I see no argument to put the rubber at the axle.....on the lowers.

i value your technical insight every time i read it...

but on a radius arm setup in question, are you implying that the stock upper rubber bushings are more than enough to compensate for the inherint binding?

on a "wristed" setup i would agree however that rubber on the body side is more ideal

Radius arm joints

sean883

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old_man

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ktm racer 419

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sean883

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ktm racer 419

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Goatman

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FLEX--J

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sean883

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ktm racer 419

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