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.