radius arm questions

Cashion731

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Mar 13, 2018
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Wilson
I have a 79 f150 that I recently bought. I am new to 4x4 offroading but I am mechanically inclined and a welder by trade. My concern is I'm not getting as much flex out the front as I should be. 6" superflex coils. Not sure what RA I have but it's tubular and heim end. My caster angle is way off. Springs look like they about to pop out of lower spring buckets. My question is can I bend my tubular RA to correct caster angle and not effect flex in a negative way?
 

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You can get shims from Broncos grave yard to correct the issue. Probably a free other places too.
 
I believe mine already has 7° bushings but not sure how to tell. They are obviously new bushings I would assume the dude who built the truck put degreed bushings in considering how well the rear 4 link was done
 
Radius arms inherently bind during flex because they are fighting each other torsionally. Currie or someone came up with a wristed radius arm setup that allowed the passenger side arm to rotate freely around the tube and still control axial movement. Worn out rubber bushings will flex best. Heims are probably THE worst thing for flex (and the forces will wear out the heim/rod end quickly). If they are replaceable joints, you could find some that have rubber bushings with the same thread and bolt diameter, and swap them in. I'd replace the lower 2 if you have that option, since bushings are better at handling mud and road grime.
 
Thanks. Most research I did said the same thing. To ditch the RA and go 3 link. I may go that route eventually but will wait and do a D60 swap at the same time. Flex ain't the main issue. Main issue is caster angle. JBG said with the 6 inch lift coils it needs 7 degree c bushings and 4 inch drop brackets. My main question is why can't I bend the RA to correct caster instead of drop brackets and loosing ground clearence
 
jeepinmatt said:
Radius arms inherently bind during flex because they are fighting each other torsionally. Currie or someone came up with a wristed radius arm setup that allowed the passenger side arm to rotate freely around the tube and still control axial movement. Worn out rubber bushings will flex best. Heims are probably THE worst thing for flex (and the forces will wear out the heim/rod end quickly). If they are replaceable joints, you could find some that have rubber bushings with the same thread and bolt diameter, and swap them in. I'd replace the lower 2 if you have that option, since bushings are better at handling mud and road grime.
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He talking bout Ford radius arms big dog--though you are correct rubber c-bushings flex better and bc broncos did sell a "wristed' housing.
You can wrist one arm to help but the stiff ass superflex springs are what's hurting, especially if the arms have already been extended. Your options with a cast wedge 44 are bend the arms a little, find the correct castered c bushings, radius arm drop brackets, or cut and turn the knuckles. Or lower the truck some.
 
Thank you. I was pretty sure they were my options. Considering the front is no where near tucking I will lower the truck a couple of inches and bend radius arm. Can I cut the coils or should I buy new 4 inch coils? Also have a set of early bronco coils 200 spring rate if u think that is better than the 300 spring that's in it now?
 
Cashion731 said:
Thank you. I was pretty sure they were my options. Considering the front is no where near tucking I will lower the truck a couple of inches and bend radius arm. Can I cut the coils or should I buy new 4 inch coils? Also have a set of early bronco coils 200 spring rate if u think that is better than the 300 spring that's in it now?
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That would be worth a try as long as they are tall enough, they will ride a lot better. All the major lift manufacturer's springs for those generation broncos and trucks were way too stiff, even worse you have a rear suspension that moves well so the front doesn't do anything.
 
coils.jpg

these or James Duff stuff are good.
4insprflxcoils.jpg

Deavers from Bronco Grave Yard also very good.

You can heat and bend the arms. They are cast steel. Try to make a longer radius over kinking them and weld in some side gussets. This is going to make the rear bushing bind some. I prefer a small drop, 7 degree bushing, smaller lift, lengthened and different ends welded on the arm. I did all this and was fairly happy a while. Now I'm ready for a 4 link. With welded wedges I'd mod the old arms and lengthen, or fabricate lengthened arm with all of what I wanted. Fabricated lengthened arms will get you by with less drop bracket as well.
 
WARRIORWELDING said:
coils.jpg

these or James Duff stuff are good.
4insprflxcoils.jpg

Deavers from Bronco Grave Yard also very good.

You can heat and bend the arms. They are cast steel. Try to make a longer radius over kinking them and weld in some side gussets. This is going to make the rear bushing bind some. I prefer a small drop, 7 degree bushing, smaller lift, lengthened and different ends welded on the arm. I did all this and was fairly happy a while. Now I'm ready for a 4 link. With welded wedges I'd mod the old arms and lengthen, or fabricate lengthened arm with all of what I wanted. Fabricated lengthened arms will get you by with less drop bracket as well.
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I have deaver springs front and rear now. The RA are DOM tubular with heim ends. Not sure what length they are?
 
I would not bend the radius arms. You can fab some new brackets and drop the heim ends down more but that won't net much caster.

My vote is for a lower ride height and check the c-bushings. They will say what degree they are. You just need to remove one of the end caps off a radius arm.

If caster is no good even with 7 degree bushings, the best way to cure that is to cut and turn the inner C's on the axle housing, which isn't an easy job.

A combination of a softer spring and less ride height should be good enough. If you have deavers, you can cut them and see what they do. If they are not a progressive spring like posted above, throw them away and buy some new ones. WH would be a great option.

We can get some impressive flex with extended radius arms in our early Broncos. A 3 link isn't necessary. Drivability will always feel a bit vague. Don't expect it to drive like a modern vehicle. Check your track bar bushings often and minimize the slop in the steering. Use a good steering stabilizer. All these help a great deal. There is way more to it than just caster.
 
broncosbybart said:
I would not bend the radius arms. You can fab some new brackets and drop the heim ends down more but that won't net much caster.

My vote is for a lower ride height and check the c-bushings. They will say what degree they are. You just need to remove one of the end caps off a radius arm.

If caster is no good even with 7 degree bushings, the best way to cure that is to cut and turn the inner C's on the axle housing, which isn't an easy job.

A combination of a softer spring and less ride height should be good enough. If you have deavers, you can cut them and see what they do. If they are not a progressive spring like posted above, throw them away and buy some new ones. WH would be a great option.

We can get some impressive flex with extended radius arms in our early Broncos. A 3 link isn't necessary. Drivability will always feel a bit vague. Don't expect it to drive like a modern vehicle. Check your track bar bushings often and minimize the slop in the steering. Use a good steering stabilizer. All these help a great deal. There is way more to it than just caster.
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Thanks. I will pop off cap today and check c bushing. I also will cut 2 coils off the deaver superflex spring which should lower roughly 2 inches? Not sure of all the steering component names but I think it has crossover steering? I will post pictures tonight
 
braxton357 said:
He talking bout Ford radius arms big dog
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Excellent point. I just saw tubular & heim joints and assumed the heims were at the axle end also.
 
Cashion731 said:
Thanks. I will pop off cap today and check c bushing. I also will cut 2 coils off the deaver superflex spring which should lower roughly 2 inches? Not sure of all the steering component names but I think it has crossover steering? I will post pictures tonight
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Cutting 2" worth of spring doesnt mean that it will drop 2". Just depends on the spring rate and the weight on them.

Also, dont plan to air down those tires unless you get different wheels. 16.5s have no safety bead, so they will come loose quickly if you air down.
 
1st check to see if the degree bushing are in fact what they are supposed to be.
2nd while checking maker sure they got installed correctly.
3rd i would put those RAs in a tube bender and gain some rotation.

I am very curious how the C bushing area was accomplished on the axle end. Was it a modified stock piece or fabricated entire section? The pic of the rubber bushing may be perspective but it doesn't look seated or happy about its position.

Another thing to look for is the drive shaft slip. Is it bottomed out?
Shocks need a looking over as well. Are they limiting you up or down?

If you lower it expect to rework some steering lengths.
I'd also want to correct some of the steering angle and shoot for a flatter profile on the track bar and drag link. Keep each in the same plane and relatively the same length. High steer would go along way toward correcting both. But then again I remember this being a band aid from previous post for a Dana 60 install.
 
I will get better pictures tonight. Also what length would a stock RA be? And what exactly is a extended arm? Is it just a lengthened RA or is it a lengthened arm with the frame mounts moved rearward?
 
If I'm going to spend the time and money to do a 3 link then yes I would wait and do it to a D60. But for now I'm trying to get it to drive better for sure and hoping for better flex. Anything over 35 is sketchy!!!! It wanders so bad. My guess was caster bc the pinion is at a great upward angle and the lower spring buckets are leaning way forward. Thats why I was considering bending the arm to gain caster and fix spring buckets.
 
Cashion731 said:
If I'm going to spend the time and money to do a 3 link then yes I would wait and do it to a D60. But for now I'm trying to get it to drive better for sure and hoping for better flex. Anything over 35 is sketchy!!!! It wanders so bad. My guess was caster bc the pinion is at a great upward angle and the lower spring buckets are leaning way forward. Thats why I was considering bending the arm to gain caster and fix spring buckets.
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The pinion angle and amount of lift is most likely why the builder left this steering angle in less than perfect condition. If you don't change the RA mounts by pushing them rearward the axle gets pushed forward. By the pic I am guessing those are not terribly longer than stock.

1112-4wd-03%2B1972-ford-bronco-early-redux-part-1%2Bradius-arm-bushings

here is a good pic of a factory arm location. How is it related to yours compared to the body mount? Original Fords were actually quite long. I almost wander if the C portion was rotated some in fabrication compounding the problem you are facing.
 
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