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THE ROCK GODS
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Seem like up til 6-7 years ago, radius arms, like that on old broncos were a good upgrade for alot of wheelers, now that everyone has the ability to do 3 and 4 links, radius arm suspension sucks now? It use to be an upgrade from leaves for many jeep owners, it was strong, flexed great, the price was right and easy to fabricate.

Want Advice on my Plans

I am building a CJ5 on 35s with about 100"WB, on a very tight budget, and have been considering using radius arms for the rear suspension, panhard bar and TJ coils. I would just keep the springs, but i need to move the axle way back to fit the TH 400 tranny (long SOB), so leaves wont work.

If it was ten years ago, this would be a trick setup, Now its lame? I understand why 3-4 links are better, but by the time you get it done with DOM, heims, inserts, etc. its very pricey, I dont have that budget for this project.

Here is what I want to do for the rear suspension, I am going to use the exsisting leaf spring mounts on the frame, instead of the leaf springs bolting in that space I will make 2 arms out of 2 1/2 in box. the arm will have a 3/4" heim on the end that bolts to the exsisting front leaf spring bracket, the other end of the arm will go back to the leaf spring bed and attach to the spring bed with U bolts, just like the leafs did. I will also run a panhard, so basically a fixed two link with a panhard. The arms will be about 40"

When i first started going to CAL ROCKS,(several years ago) there was a lot of vehicles with this swingarm type suspension, that just u-bolted 2 1/2"box to leaf beds and extended the arms to the framerails or triangulated them to the center cross member and just used one big heim....


All you trust funders that just tell me to go with a 3/4 link, thats not the advice i can afford, Im going to do this setup, just want advice to make it the best I can with my financial constraints of available funding. (my new mission statement)


Shawn
 

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Keep leaf springs in the rear if you're worried about money. It's not like they don't work.
 

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maybe its cause its 5:30 am but I have absolutely no clue what the hell you are trying to say.

Edit: nevermind I figured it out.

You would need some way to allow the arm to twist. SunRay engineering has some twisties that would work for that. They use a XJ bushing on the end so it will not transmit vibration like a heim, and they last longer too.
 

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You need bushes on the axle end, radius arms have a lot of twist when the axle is flexing.

Radius arms on the rear are a bad idea, too much antisquat when climbing.

Instead, why not build a 3-link with a-frame for the rear. Install 2 trailing arms where you would have put the radius arms, and make an a-frame above the axle. You probably still won't have ideal arm lengths but it will be better than radius arms.
 

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Radius arms are a decent setup, thats why a lot of people have them, but when you start putting $$ into a rig, you can see Radius arms have lot of limits on them, I don't miss my radius arm one bit, linked is way better.
 

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I have rear radius arms that are extended about 12" with 1" heims on them in the rear of my Bronco and I absofrigginlutely hate them. They work good for the few hours they are straight before I go wheeling with them then they hang on every rock I hit and get bent all to shit and have to make new ones every few months. I say either save up for links or get creative with leaf springs.
 

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Radius arms aren't meant for rear suspensions, and not just because they aren't meant for that much load, but because the whole geometry aspect totally sucks.
 

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Just run a 1 link like Terry Howe and all the comp guys from CS used to. Bolt it up like leaf springs. Build the whole deal for 100 bones..



true oldschool that works w/ no breakage.
 

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run it through that one guy's link calculator. Just pretend that the upper and lower links mount to the frame at the same point. Chances are, 40" will be too short, to get under 100% antisquat. Get a bunch of XJ lower control arm bushings from the junkyard. If both radius arms are firmly mounted to the axle, there will be absolutely no flex, unless the radius arm bends. If one wheel is higher than the other, the radius arms will be at different angles. The way you described it, you would have a sway bar with the axle housing acting as the torsion spring. Axle housings aren't very spring like.

the right way to do a radius arm system:
Make a simple control arm with a rubber joint at the axle end. Run that link from the frame to a mount on the axle tube. Make a short (12" to 24") link to go between a mount on the top of the first link and a mount about 6" or so above the lower axle mount, with rubber joints at both ends. The rubber allows the links to be at different angles to the axle. The more rubber, the more flex. There are plenty of aftermarket long arm kits for TJs with the fronts set up this way. Take a look at those.
 

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I forgot a pretty good altenative. One radius arm, and one regular link.

Make a regular link, with a joint at either end. put this from the frame to the axle tube. Make another link that is shaped like a Y or y. Put it to an upper and lower mount on the other side of the axle. The minimum motion of the joints to the axle where the radius arm connects needs to swing left to right, because of the panhard rod's arc. Minimum, the joint on the regular link needs to move up and down, and left and right. both joints on the frame need to move up and down, left and right, and twist radially.
 
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