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Old 07-08-2004, 03:52 AM   #1
SquattyD
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Extended and Boxed Radius Arm Build

One of many ways to extend and reinforce your radius arms for more flex.

Ok here we go. Youre going to need some parts, some tools, some metal, some skill, and some free time. All images are thumbnails, click on them for medium sized pictures, and then on 'full-size image' if you're over 65 and still can't see shit.



These are most of the tools I used. (Top to Bottom) Straightedge, 2" x 3" x 3/16" Angle Iron (2 35" sections for each arm), a stock Ford radius arm (any 4wd 60's or 70's truck would have em, most use 78-79 Bronco arms), a Radius Arm Extension (I bought mine from Stonecrusher ), 3/16" plate steel, foam board template, assorted clamps, 4.5" angle grinder with flap and cutting wheels, a tape measure, a contour gauge (not really needed, helps, got mine at Lowe's) a Sharpie marker, and an Xacto Knife. You will also need a welder. I use a Millermatic 175 Mig welder. Safety equipment is also nice, gloves, safety glasses and face shield is good to have.

First lets fit the extension onto the arm. Using the grinder with a flap wheel, I bevel the end of the arm so that more surface area will be exposed when welding.

See? Makes a V shape.

Alright, you can weld it now, but I just leave it alone and do all my welding at the end. So lets do that. Next we will cut the angle iron to fit the arm better. Lay the arm onto a section of angle iron.

There are 2 holes in the radius arm near the head where a shock mount previously was. I found the angle iron laid nicely onto the arm if the end of it was aligned with the middle of the first hole. The arm is 3" wide at this point, and guess what, so is your angle iron. Go down to the other end of the arm, and mark the angle iron where the extended arm ends, and its width at that point. Now remove the arm, and using your straight edge, draw a line from one end of the arm down to your mark. Your outline should be in the shape of a big triangle, with one end being 3" wide, and the other about 1.75" (okay, not a real triangle, but whatever its called. Geometery was a long time ago). You dont want to follow the contour of the arm, because wont be able to curve the other piece of angle iron to match it. If you used 4 pieces of flat stock instead, this would work. But that means twice as much welding. Okay enough talking, lets start cutting.

Clamp the angle iron down to a table and get out your angle grinder and a cutting wheel. If you have a torch or a plasma cutter, go screw yourself. You could also use a circular saw with an abrasive blade, or a mill, horizontal bandsaw, whatever. Just get it done already. Geez.


Now start cutting. Then when youre all done with that...do it again on another piece of angle iron. Clamp the one you just did in place on the arm, so when you measure the second one, you don't do it the opposite way, cause then they wont fit together. The two pieces should look identical when laid side by side. Check it.

Not a very good picture, but you should get the idea. Okay next.

You have to grind the radius arm some so that angle iron lies nice and flat on it. That ridge that runs along the top and the bottom, hit that with the flap disk . You dont have to do the whole thing, just like 6" near the head of the arm.

Also grind on the extension some, again so the angle iron lies nice and flat. That ridge at the end of the stock will need to come down some too.


Couple more cuts then we start welding. Cut down the angle iron so that it ends about 1/2" BEFORE the extension does. You will need room to weld the box to the arm. Then you can grind it and make the cool tapered-from-square-to-circle-shape. You will also have to trim the 2" side of the angle iron down to around 1.75"

Okay boys and boys, break out that welder. And a torch too if you like. Doesnt have to be an oxy/ac setup, just a Bernzomatic will do. I pre-heated the arm and the extension a little for extra good penetration. You know the kind, the kind that makes the ladies go "Ooooo!". Since the arm is cast steel it should really help. Plus you get to play with the torch. Which is always a bonus.


Take one piece of angle iron and clamp it to the arm so that the skinny part of the angle iron is on the BOTTOM of the radius arm. This will be the side that gets dragged across the rocks, so we are going to weld it on the INSIDE, and then weld the top piece to it and to the arms on the end. Get it? No! Well then tough shit..your prob from Arkansas.

You dont have to weld the whole thing. Just wherever the hell you feel like. Next, throw that second piece on top. Line it up and then clamp that bitch down.

This picture is actually of me tring to close the gap between the 2 pieces. When I first clamp them, I use 2 clamps at each end, one on each side of the arm, and then tack weld it. Then I move the clamps in as shown, and try to close up any small gaps I may have. Okay, enough tack welds. Lay some beads you lazy pos.

Glob em on, you'll grind em down later anyway.

Now for the end, just weld around and around, building up a "ramp" of weld from the box to the end of the extension. It is best to weld with the arm horizontal, because I find that if you weld with it vertical, alot of slag gets into the extension and messes up the threads for the heim joint. So do as I say.



Ta-da! It's kinda done. At least most of the welding is done. Tomorrow kiddies, we will cut out a template for the 2 pieces of metal near the head of the arm, weld that in place, and then spend about 2 hours with the grinder and a flap wheel makin it all look purty. After that, paint and install. God I'm so cool. Stay tuned.
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Old 07-08-2004, 04:30 AM   #2
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Sweet writeup!!
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Old 07-08-2004, 07:29 AM   #3
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What a great write-up! Informative, detailed, and humorous! I give it two thumbs up! This is exactly what I intend to do, and will definately be following this write up!

Way to go!
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Old 07-08-2004, 08:07 AM   #4
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Talk about beefy.. Great write up Squatty.
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Old 07-08-2004, 05:29 PM   #5
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**Part Two**

Y'all ready? Okay lets go. Now you get to be an "artist". Get your foam board, tape measure, Xacto knife and Sharpie marker. I also use a contour gauge, but its not neccesary. Ok trace out a pattern on the foam board of a piece that will fit the low spot in the arm at the head.

Test fit your template, and when you are happy with it, hug yourself and then trace it out on the plate steel. It doesnt have to be perfect, you are going to be welding and grinding it anyway.

Now cutting this can be kind of tricky, unless you have a torch or plasma. Just do your best, cut the straight lines with the grinder and I cut the curves with a saber saw. the regular Skil blades work well, their Ugly blades, which are awesome on a sawzall, dont do that well in the saber.

Now look what you've done. You have made quite a mess havent you. Metal dust everywhere. You dont want your mom yelling at you for messing up her garage. Get out the dustpan and do a little clean up. Maybe have a sodey-pop for refreshment at the same time. Dont worry I'll wait.

Okay, back to work. Throw your pieces onto the arm, see how they fit. Not too bad. Take your marker and color in the areas you need to grind a bit to make it fit better. Leave a gap between the box and the C shaped metal you just cut. Not much, about as thick as a cutting wheel or so. Also, bevel the wide flat edge like we did on the extension. You will be butt-welding the box to the C shaped piece, and the gap and the bevel will make welding it easier and get better penetration (giggle, giggle).

Bling! Note the gap.

Okay, secure the piece to the arm. I like to use a magnet so that the box and the C are level, and a clamp to hold it. The bolt is a good spot for your ground.

Tack tack tack.

Avoid tacking around the C. This is the only weld you cant smooth out nicely, so lay you best lookin beads here. With no tacks, they should come out nicer. Repeat the tacking process on the other side, and then fully weld each piece. Here is a shot of the butt-weld.

Another shot of the fully welded C.


Next you are going to have to fill in the valley created by the new metal. See it here.

I use my .030 wire for this, cause I really dont like using it for anything else.


After you are all done welding, you can start grinding....for awhile.

Weee...that part is done...takes less time on the web.

Make sure you do the end by the heim joint too. Remember that ramp of weld we built up? Well, start smoothin.

Two shots cause neither is very good.

Grind the welds that run the length of the arm too if you like.

Now you can paint it or just leave it out in the rain to rust away. Your choice.


Alright the fun and games is over. Here are a few things you should avoid.
  • Don't catch your shirt on fire.

It pretty much ruins the shirt. Got a new shop towel tho. Welder or grinder with do this, I did it with the grinder, twice in fact, same spot. Now I dont have to lift my shirt when I go to the bathroom (there is a large burn hole in the groin area for those that didnt get it).
  • Don't buy cheap welding gloves.

These are my 8 dollar gloves from Cyberweld. Worked well for about a month, but then if i got too close, the leather would shrink and turn crispy. Mmmm...fried burgers.
  • Don't weld while wearing shorts.

Especially when your chair and the bench you are welding on are the same height, resulting in a nasty sunburn on your inner knee. Which hurts everytime you bend it. Which really sucks cause you have to do alot of that when walking, or sitting, or sleeping.

Ok then, now you know all of my secrets. I can't make any money off of you shlubs by sellin em to you, cause now you can do it yourself. Well, except for you losers with no tools....nah I'm just kidding. You're all losers.

Now go take a shower for god's sake. You're filthy. And those clothes better go right into the hamper, dont leave them on the ground...geez. Slobs.

**Final Statistics**
  • Extended 10.5"
  • Total Length: 44.5"
  • Total Weight: 33lbs
  • Damn Sexy

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Old 07-08-2004, 07:05 PM   #6
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nice work shlub
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Old 07-08-2004, 07:27 PM   #7
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very nice write up and work
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Old 07-08-2004, 10:05 PM   #8
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nice arms...how do they ride and will you produce any?
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Old 07-09-2004, 01:02 AM   #9
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Dont know how they ride yet...I am building a frame from the ground up and they will be going on that...so that has to be finished first.

I may be persuaded to produce em, it's alot of work. But not right now, I have to finish my own truck.
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Old 07-19-2004, 12:31 AM   #10
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Make sure you show us your secrets to building the radius arm brackets to work with them..You know some of us cant do anything on our own.
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Old 07-19-2004, 02:27 AM   #11
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I need to do some of these for the 79 im putting together
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Old 07-19-2004, 03:02 AM   #12
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Quote:
Originally Posted by Snopro
Make sure you show us your secrets to building the radius arm brackets to work with them..You know some of us cant do anything on our own.
oh i built those weeks ago. dont have many in progress pics but they are pretty simple. ill post some pics later.
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Old 07-19-2004, 11:09 AM   #13
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wowzers those kick ass , I wish I had the stuff to fab metal
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Old 07-19-2004, 02:24 PM   #14
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My printer hates you. I have been looking at my angle iron for 3 weeks NOT wanting to tackle this.

Thanks a TON
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Old 08-08-2004, 03:28 AM   #15
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what was your diameter of your DOM if I might ask?

Im going to be doing something similar to this but running a RE flex joint instead of a heilm
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Old 08-08-2004, 03:45 AM   #16
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Quote:
Originally Posted by SquattyD
Dont know how they ride yet...I am building a frame from the ground up and they will be going on that...so that has to be finished first.

I may be persuaded to produce em, it's alot of work. But not right now, I have to finish my own truck.

i tihnk you should you could make real nice money i bet. if you could sell them like 3rdy party to skyjacker some place..
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Old 08-08-2004, 05:20 PM   #17
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the hard part is getting cores, the extra radius arms to build these. i had alot of people ask me about wristing arms for them but not too many could get the arms to send me or wanted their rigs unuseable while they sent me theirs.
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Old 08-08-2004, 08:08 PM   #18
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the hard part is getting cores, the extra radius arms to build these. i had alot of people ask me about wristing arms for them but not too many could get the arms to send me or wanted their rigs unuseable while they sent me theirs.
yeah and even when you do find them in a yard there is a good chance they are bent.
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Old 08-09-2004, 01:06 AM   #19
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hey SquattyD any progress on the install of the rear arms?
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Old 08-09-2004, 10:35 PM   #20
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yeah i started bolting everything to the frame today. hopefully a rolling chassis soon. the DOM is 1.5", 1/2" wall. plus then the 3/16" angle iron around it. i need either a bigger heim or re flex joint. they 3/4's are too dinky.

i couldnt sell them to skyjacker or anything, becuase they could do something in house for way cheaper if they wanted to. and something way better im sure. i just wanted longer arms, and i didnt have the money for another set of duff's. each one takes me almost a day to build, and like they said, cores are hard to find. if i had a plasma things would go faster, but i dont, but someday.
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