Why aftermarket radius arms?

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I get that with larger lift kits, that you need to correct for caster. What I don’t quite understand is how a radius arm, that is the same length, & same bushing material allows for more flex? In my case I’m running a 35” tire with 2” of lift. Flex is pitiful, a little better without the sway bar. But I’m not going to spend radius arm money without understanding how they benefit flex. Thanks!

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Zjohnsonua

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Given the same bushings, articulation is closely the same between varying designs, as bushing bind is the limiting factor in radius arm designs. There is only so much deflection allowed as the articulation cycles and tries to twist the axle housing. Never understood the front sway bar on radius arm designs as the design effectively makes the axle itself a very stiff bar.

Some arms also provide for a corrected axle position which allows for full articulation without putting tires into sheetmetal.

The only radius arm designs I've seen that truly improve articulation have a mechanism to de-couple one of the arm bushings from each arm, like this:

 
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If
I get that with larger lift kits, that you need to correct for caster. What I don’t quite understand is how a radius arm, that is the same length, & same bushing material allows for more flex? In my case I’m running a 35” tire with 2” of lift. Flex is pitiful, a little better without the sway bar. But I’m not going to spend radius arm money without understanding how they benefit flex. Thanks!

View attachment 3164277
If your 80 doesn’t flex well, your shocks are too short. You’ll mutilate your axle side bushing bushing in the process but you can totally get your front end to flex

A03ACA75-09E7-422B-A943-1CB006114FDB.jpeg
 
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But I’m not going to spend radius arm money without understanding how they benefit flex

From Delta's site:

Our arms are considerably narrower than stock arms and allow for significantly more flex without interfering with the axle mounts. That’s what lifts are for, right? FLEX

AFAIK, the biggest gain is from not having to run caster correcting bushings, particularly urethane ones.
 

Zjohnsonua

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Delta makes good products which solve several problems. If you want buggy-like flex, investigate a 3 link. All depends on what your goals are - these remain to be stated.
 

mudgudgeon

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The number 1 reason for aftermarket arms is caster correction.

There's products like Superior Engineering Superflex arms that alter the bushing layout for more flex.

I agree with the comment above about shocks limiting flex. There's things that can be done to get stock radius arms to flex a lot more than they typically do
 

Somebodyelse5

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@landtank and @eimkeith both make great caster correction solutions and are considerably cheaper than going with new radius arms. They are also kind enough to list the caster correction you should expect when installing their products, which is cool.

New radius arms are an expensive solution to a simple problem, and are only marginally better than the plate or bracket solutions. if you are really after flex don't mess around... 3 link it.
 

QuackAxel

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Just burned my eimkeith brackets on last weekend. You don't have to sacrifice the stock holes , incase you want to go back one day? Also you can see they move the axel forward 25mm, which helps with large tire clearance. Main benefit is they move the radius arm down,( not sure on that distance) which corrects the castor.

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CalnSam

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those weld on drop brackets look sweet... is there any concern about the panhard bushings wearing prematurely after? it would seem like 25mm forward would put the panhard out of parallel with the axle.
 
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I get that with larger lift kits, that you need to correct for caster. What I don’t quite understand is how a radius arm, that is the same length, & same bushing material allows for more flex? In my case I’m running a 35” tire with 2” of lift. Flex is pitiful, a little better without the sway bar. But I’m not going to spend radius arm money without understanding how they benefit flex. Thanks!

View attachment 3164277

Short answer, radius arms primary function is to correct caster and (sometimes) driveline angle. But they can also provide a little additional flex in one of the following two ways:

1) Delta arms have a narrower profile at the axle side, which allows more articulation. With the stock arms, there is some articulation available by squishing the bushings, but at a certain point, the arm itself binds against the brackets on the axle. The Delta arms are a little narrower than stock to reduce this binding effect. It is also possible to grind down your stock arms at the axle end to narrow the bushing mount area to achieve the same thing.

2) Superflex arms relocate the mounting points on the axle side to allow for more flex without binding.

You can also get a ton of flex hillbilly style with the hitch pin mod.

Aftermarket arms have other benefits, like pushing the axle forward (if desired), and correcting caster without drilling any holes in your axle mount brackets, or welding anything onto the underside of the truck.


Whether any of these solutions are worth your money is totally up to you. If your only goal is more articulation, you might have better luck with a spring with longer free length and longer shocks.
 
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those weld on drop brackets look sweet... is there any concern about the panhard bushings wearing prematurely after? it would seem like 25mm forward would put the panhard out of parallel with the axle.
Its a no go for me with those or anyone seriously into rock crawling as the factory bracket at the chassis is already dragging on rocks and taken a beating....if you want to relocate the axle forward, get longer arms like the delta.
 

QuackAxel

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I have read multiplie threads testing the eimkeith brackets and everyone says they slide over everything. I havent tested uet my self. As soon as I can afford the delta arms I'm going to get some. They are narrower , which helps with flex as well.
 
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I have read multiplie threads testing the eimkeith brackets and everyone says they slide over everything. I havent tested uet my self. As soon as I can afford the delta arms I'm going to get some. They are narrower , which helps with flex as well.
I am no engineer for the brackets, but just by looking at them, you already lost more than 2 inches of ground clearance with them. Imagine went from 35" to 33" tires....
 
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Its a no go for me with those or anyone seriously into rock crawling as the factory bracket at the chassis is already dragging on rocks and taken a beating....if you want to relocate the axle forward, get longer arms like the delta.
I think it depends on where you wheel. It seems fine in Utah. I did cliffhanger and tried Pritchett. You definitely hit the brackets a lot but I never really got hung up on them.
 

Somebodyelse5

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I am no engineer for the brackets, but just by looking at them, you already lost more than 2 inches of ground clearance with them. Imagine went from 35" to 33" tires....
Its a no go for me with those or anyone seriously into rock crawling as the factory bracket at the chassis is already dragging on rocks and taken a beating....if you want to relocate the axle forward, get longer arms like the delta.
Anyone who seriously rock crawls should be doing a 3 link.... otherwise, we are all just man bun overlanders.
 
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Short answer, radius arms primary function is to correct caster and (sometimes) driveline angle. But they can also provide a little additional flex in one of the following two ways:

1) Delta arms have a narrower profile at the axle side, which allows more articulation. With the stock arms, there is some articulation available by squishing the bushings, but at a certain point, the arm itself binds against the brackets on the axle. The Delta arms are a little narrower than stock to reduce this binding effect. It is also possible to grind down your stock arms at the axle end to narrow the bushing mount area to achieve the same thing.

2) Superflex arms relocate the mounting points on the axle side to allow for more flex without binding.

You can also get a ton of flex hillbilly style with the hitch pin mod.

Aftermarket arms have other benefits, like pushing the axle forward (if desired), and correcting caster without drilling any holes in your axle mount brackets, or welding anything onto the underside of the truck.


Whether any of these solutions are worth your money is totally up to you. If your only goal is more articulation, you might have better luck with a spring with longer free length and longer shocks.
Word, thank you. That makes sense.
 
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I think all this considered. I’ll replace the caster correction bushings with stock bushings & put a pair of “rock hooks” on. (Radius arm drop brackets). I can add a welded “slider” to the back side of the radius arm drop brackets to minimize the “hook” effect.
 

Broski

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Anyone who seriously rock crawls should be doing a 3 link.... otherwise, we are all just man bun overlanders.
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If you think your to the point with your 80 that it needs a three link then it's time to move up to a buggy. Man bun or not :doh:

Stock arms 2.5" lift 10.5" travel shocks on 39s
 

QuackAxel

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Its a no go for me with those or anyone seriously into rock crawling as the factory bracket at the chassis is already dragging on rocks and taken a beating....if you want to relocate the axle forward, get longer arms like the delta.

I think anyone "serious" about rock crawling is not driving an 80. Just my opinion, you can attempt to make it into a rock crawler, but at that point you don't end up with much "80" left.

I think what's great about our trucks is how versatile they are with very little input. Tires, small lift (with proper adjustments), some protection and your good to go on 90% of the trails. Plus you can hit those trails and then hop back on the hwy and go 75 home. No trailer needed.
 

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