Since this is a traditional site, go to the junk yard and find a good used set. Less work, parts are available and junk yards are fun.
U-bolts, mono-ball housing, truck arm saddle, rubber bushing bushing and housing mono ball and housing completed arms Pm me if you have any questions
House of Fab...really nice and your pics make it easy for anyone to fabricate a quality set on their own. I see some stuff I would have done a little differently on Andys arms if I had seen those pictures prior. Just would have made the whole process a little easier... Very cool post. Thanks!!!
Not truck arms per say...but I thought these were interesting. http://www.speedwaymotors.com/Old-School-38-Ladder-Bars,41984.html
Mr.Gasket makes perches, cheap I usually get Ubolts from a local leaf spring shop (writeway spring-in Tacoma)
Even square or round tubing will twist SOME over a long length. Truck arms are usually about 5' long, unless on a short rod. If they are really stiff they will act just like ladder bars, except they will work a little better due to the inward angle. The very stiff truck arm bars are really made more for drag racing. They will handle a lot more acceleration power, and don't need to flex. Even ladder bars will flex some when one wheel is jacked up, just not very much and it takes a lot of weight difference (like jacking up one side of the car). Light (1/8" or less) steel rectangular tubing will flex enough. The general idea is to keep the rear axle flat (parallel to the road) with enough flex to handle variations in road surface. Even stiff truck arms/ladder bars will ride good on a smooth road. Get on a bumpy road and the rear axle will bounce around a lot, as one wheel receives the same motion/jar as the other. The longer the ladder bar the smoother the ride -- same applies to truck arms -- because long ones will flex some. For handling and acceleration stiffer is actually better to a degree, but for ride quality the more they flex the better. Long rectangular or square tubing arms should be a good compromise between ride and handling. They won't flex as much as stock or I beam arms but should flex enough. I bet you can jack one side of the vehicle up at least 4" before the other wheel starts to lift. I had 34" ladder bars under my car at one time and could jack one side up about 3" before the other started to lift. With 60+" truck arms angled in it should have at least twice as much movement. 6" is more than enough for the vast majority of paved roads.
Don, You are absolutely correct abut the twist and that is where a lot of rodders miss it whtn using tubular arms. What we do here is pretty much how they used to do it in NASCAR, we take two pieces of 1x3 or 1x4 tubing and skip weld them together, then bend the crooked end in a press ( or have them bent if we don't have access press to use). Then we cut the outer flange off the tubing leaving it as an I beam. There is a that we make our own, length is important, and no two cars are the same, you want toe front pivot point to be even with the front U joint when the car is at rest. We also triangulate them the front pivot point landing just on either side of the U joint. I have tried several different approaches to the front pivot point and found that the front bushing from a Chevy truck actually works the best. I have also tried several spring setups and like the Daytona style mount best (behind the axle).
I would think that ladder bars or truck arms used in conjunction with a parallel leaf spring setup would need cage type mounts on the axle to allow the axle housing to rotate with the ladder bars controlling housing rotation. Seems to me that if you had both the ladder bars or truck arms and leaf spring perches controlling rotation you would have a strong potential for binding.
Ladder bars with leaf springs need something to let the spring move under the axle. Otherwise it would bind. Chevy used leaf springs with a torque tube. There was a pivot under the axle (between axle and spring). You'd need something like that.
The 40 Ford I have has a set of original Chevy truck arms and an Olds rear. Tubular shocks and an original spring, no reversed eyes. It rides decent and there is no wheel hop or any other traction issues. The only issue is little room for exhaust. The triangulation is similar to the original Ford design. I have abused it some , well more than a little and it will plant the tires when the clutch is vigorously applied! I have seen several short track oval racers with these arms applied, including a Chevelle Bobby Allison built in his Hueytown shop.
How about using square tubing but with the flex built into the front rubber bushings? Ford had the same type design on their twin I beam front end and they used a double doughnut type rubber mount. You could weld a big bolt on the front of your arms and use the Ford rubbers.
There was a big thread like this about a week ago, I will use the box tube split and flipped into a I beam shape. I believe that the arms have to twist to provide any kind of decent ride and still locate the rear.I will mount mine on the leaf spring mount pads on the rear end housing as I will be using coil-over shocks for suspension.May even be able to use the stock U-bolts.
The only reason truck arms were designed to flex is the front bushing. Now that uniballs of the required strength are readily available any tubing is doable. This is what I did. The arms are composite and weigh only 12.5Lbs. each. The ride is really nice and the handling is surprising. I aquired the arms from a leaf spring manufacturer. They were made for a 3/4 ton truck so I feel good about them holding up.
Every drag racing parts manufacturer offers housing floaters to use with leaf springs and ladder bars/4 link. If they weren't needed, they probably wouldn't make them.
That's called a floater, some use a caged floater and others just build ears on the rear. That said there is a world of difference between a truck arms and ladder bars. Truck arms are like a swing arm on a motorcycle and are actually a more forgiving suspension for something that needs to go around corners and over bumps. There is actually another use for that style of suspension that none of us ever thing about, if you want to go mid engine and don't want to mess with a 180 degree V drive and a big offset on your rear end you can actually make them beefy enough to mount your engine to the arms and let it float with the rear end. Something for you guys with the econoline pickups to think about.
I used a pair of used NASCAR arms. To make ladder bars for my car. Got them at a place called Second Chance Race Parts in Mooresville NC. Was down there visiting when I found out about the place and stopped in. I remember them being kind of cheap to buy. But I don't know how much they would be to ship. Or even if the place would. Made brackets by tack welding two pieces of 2x3 box tubing together side-by-side and running a 3" hole saw down between them. Cut the welds off and had two brackets the same. Got the U-bolts from a local spring shop. And made some brackets for the front. If I was going to make some from scratch, I would make them a bit longer. They do look a little short on the car.
years ago when i set up my 51 chevy's rear, i used 1 1/2 x 3 3/16 tube, poly bushings up front, close together. at the axle, i fabbed a integral lowering block to the tubing arms which happens to increase the leverage of the axle working against the arms. in testing without shocks installed, my recollection is that i was getting ~18" of articulation from side to side. plenty, i think, considering i never pose my junk at goofy angles, nor do i rock crawl with it. the reality is: tube arms can flex just fine. don't build them out of 3/8 tube. don't run them parallel like a 2-link, keep the leading end close together. forget what nascar does, they put damn restrictor plates on their intakes fercryinoutloud. if nascar were to use the best rear suspension, they'd have IRS! the truck arm setup for the street is a very simple design to execute that is hard to mess up. no need to overcomplicate it or add unnecessary hours of fab time for rookies by splitting tubing to make an I-beam because it's what nascar does. as far as ride, there are many other factors that will play a much greater role in ride quality than the cross section of your arms. just the opinion of a guy who has truck arm setups done both the "right" and "wrong" way.
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