I built these new radius arms for my Bronco Buggy project. They are 1 3/4" .250 wall DOM. Do you guys think they will be strong enough under a 3,000-3,500 pound rig? I'm thinking I might want to add a brace down the top and bottom:confused:

I could see them turning pretzel with a nice hard hit.

depends on how hard you are on shit.

I haven't bent my 2" .25" dom arms, but I know of several people who have. I figure it's just a matter of time for me. I'll reinforce the next set I build.

mine were 2" 1/4 wall and i smashed them on all kinds of rocks. I would probably add a tube on top with some bracing or sleeve them

I think your Radius arm to Tube part looks secure.
But yes 1 3/4 1/4 wall tube can bend. Sleveing it now with with some 2 " .12o would be nice. But if you never bent a stock radius arm, you won't bend these.

There is also the option of welding a piece of angle iron on the top and bottom, but I like the idea of sleeving them.

theres only one way to find out if there strong enough. but i would sleeve them just to make sure.

Thanks for the replies, I'll post up some pictures after I brace them up:D

Mine are built the same way with 2" .250 wall dom and are on a 78 bronco with a big block and d60s with 38s. I just cracked them at the joint of the old radius arms and new tube. Welded them back up am going to sleeve them. Also im sure my rig is at least 6000 lbs.

IMO vehicle weight will have very little to do with it. That tubing size and wall thickness will take rock hits just fine... but that is not what you need to worry about. That one arm must control the wrap of the entire axle... Tire size is probably the biggest contributing factor to that arm failing. So what tire size are you running?

I will offer up my personal experience with a radius arm setup with big tires.

I started out with the first arm pictured. I actually made a few repairs to it, but you can see it's bent. That was 1.5"x0.25" dom with 1.5x1.5" angle. There was 6" of vertical seperation at the axle which is basically what a stock ford radius arm has. It's just in a horizontal plane vs a vertical plane.

So I built the second arm pictured from scratch. That one is 1.75"x0.375" dom with a piece of 2"x6"x0.188" hacked on to it... Added another 3" of vertical seperation at the axle for a total of 9" and bent that arm pretty quick.

I run 42's, ford 4.0 v6, 5spd, dual cases, 5.13's with a 120:1 crawl ratio. I've been known to wheel over some curbs at the mall a time or too... so I play hard. Honestly I'm done with the damn radius arm shit and would really like to toss the entire setup.

My honest opinion, if you run a large sized tire and have some low gears... you will bend that arm. But what do I know? :flipoff2:

I wouldn't say vehicle weight has little to do with it bending. If a 2500 pound rig slams into a 1 foot tall ledge, there is alot less momentum to be absorbed by the radius arm as opposed to my 5000 pound pig. And for the bending from torque: a heavier rig takes alot more to get it moving, so more force is applied to the arm(s).
And on your arms: How well does it flex? I wouldn't think that it would be all that great with the lack of a bushing on the axle end. I'm sure you know, but as it articulates, the radius arm needs a small amount of movement on the axle end also for twisting. Hence the C bushings on the stock setup.

And hell, while you're making something like this, why not wrist one side for even better flex?

I wouldn't say vehicle weight has little to do with it bending. If a 2500 pound rig slams into a 1 foot tall ledge, there is alot less momentum to be absorbed by the radius arm as opposed to my 5000 pound pig. And for the bending from torque: a heavier rig takes alot more to get it moving, so more force is applied to the arm(s).
And on your arms: How well does it flex? I wouldn't think that it would be all that great with the lack of a bushing on the axle end. I'm sure you know, but as it articulates, the radius arm needs a small amount of movement on the axle end also for twisting. Hence the C bushings on the stock setup.

And hell, while you're making something like this, why not wrist one side for even better flex?

You need some more wheeling time in at the mall :flipoff2:

Watch this video (http://www.youtube.com/watch?v=P6qNmdHh8Zk) My radius arm is no more bent than it was before that.... how's that for hitting a wall with a 5,000lb rig? :flipoff2:

I have plenty of flex. However flex is over-rated... learn how to drive like an asshole and you don't need flex :flipoff2:

Look closer, there are bushings at the axle :flipoff2:

the passenger side is technically "wristed" with a single bushing at the axle :flipoff2:

You, like I did... under-estimate the amount of force required to control big tires. I think I've pretty much taken *radius arms* to the extreme... it works ok. But it ain't that great either when you consider the weird handling characteristics and mediocre suspension geometry.

You need some more wheeling time in at the mall :flipoff2:

Watch this video (http://www.youtube.com/watch?v=P6qNmdHh8Zk) My radius arm is no more bent than it was before that.... how's that for hitting a wall with a 5,000lb rig? :flipoff2:
Never said it would bend the first time, or ever, I was just posing a situation.
I have plenty of flex. However flex is over-rated... learn how to drive like an asshole and you don't need flex :flipoff2:

Look closer, there are bushings at the axle I stand corrected, thanks for clearing that up. :flipoff2:

the passenger side is technically "wristed" with a single bushing at the axle :flipoff2:And sorry, the wristed comment wasn't directed towards you, but OP

You, like I did... under-estimate the amount of force required to control big tires. I think I've pretty much taken *radius arms* to the extreme... it works ok. But it ain't that great either when you consider the weird handling characteristics and mediocre suspension geometry.
I'm not trying to undermine your trial and error, just asking some questions and posing some situations.
:smokin: