can someone tell me if some of the fe dragster builders went to a single radius rod on each side instead of a hairpin or a 4 bar? what i am asking basically if you could use the torsion bar arms as the lower links? i know some of the woody gilmore cars used a wishbone setup in the center underneath the torsion tube.also anybody have any pictures of those 1968 era sbc junior fuel cars the ones that weighed in at 800 or so lbs. thanks mike
Sure. Just make sure the ends of the torsion tube are supported. The bar arms have to be linked directly to the axle. Give some thought to how the caster will change as the chassis moves up and down.
Woody, SPE and RCS all had center links one time over another to help support the torsion bar arms for centering. Two single radius rods were to control caster angle. 4 and 3 pivot point and hair pin radius rods set up seem to bind up and bow the radius rods during travel if you didn't have them correctly set since the pivot points were different with the torsion bar arms and radius rods. Go to cacklefest.com and look at the thread on Pat Foster's last Fueler, RCS chassis with parallel short arms with the torsion bar arms.
Four bar and hairpin radious rods must have the torsion arms sloted where they attach to the front axle as the pivot points travel at different arcs.
SPE. Ours I moved the radius rod mount from the top of the frame rail to the center between because of the body. It also has the little link from the axle to the torsion bar. Lippy
My altered (a Ken Cox chassis) has the torsion bar in front of the axle, and uses the arms for the lower links.
If you use hairpins or 4 bar you'll need to slot your torsion bar arms because you will have two conflicting arcs and the torsion bar will bind and no longer provide a springing action. I like to use an upper bar about 32" long with the torsion arm being the lower link. Sure there will be a little caster change thru suspension travel but not enough to make a difference. Plus I think it looks right on those style of cars. Alot of experimenting went into those cars in the day. But I think most of it was just for product identity. So when people went thru the pit they could say that's a RCE car or SPE car etc.
Heres' how ii do it, torsion arms low, radius rods high and leaves room for steering travel (it'll change height a couple inches depending on castor)
The torsion bar I was taught to build consisted of a piece of 1/2 4140 bar stock. We turned 3/8 N.F. threads on each end. Then we took a peice of 1 3/8 1020 cold roll round solid and broached it with a 1/2 broach in the press. this piece was centered in a peice of 1 1/2 x .058 4130 tubing and welded in place using rosette welds. We then took some white Delrin material and made bushings for the ends of the 1 1/2 tubing. Don't forget to weld rings on the ends of the tubing so the thrust surface of the bushing has something to push against. The torsion arms were made out of 1/4 4130 condition N plate. We broached those peices stacked and tacked together. It's very important that they are sinc together. The torsion bar was sent out and heat treated. The way the torsion bar works is it is anchored in the middle with the two end left to rotate in the Delrin bushings. That's your torsional effect. Dampening is through pre-load on the mounting nuts for the torsion bar arms. That is why you need a good thrust surface for the bushing. This setup held up a small block Chevy to a blown Hemi. These are the torsion bars we Used on Tim Conder's cars. I hope that helps explain it to you VoodoKustoms. Also there only about 18" long overall, very compact.
Choke, when you say "Heat Treated" , how hard was the bar ? Rockwell C scale 39-40 after heat treating ?
Choke, can you explain how or what you did to the torsion bar to anchor it? I saw the part about broaching the 1/2" (square?) - so I am thinking your torsion bar was then also square? Or did you use round and do something else to get the square in the middle. Thanks
A lot of the old cars used 3/4 inch wide leaves stacked to make a 3/4 square. My Fuller car was this way. The stack of leaves were in the torsion tube and a bolt was threaded in the middle of the tube contacting the center of the leaves for pre-load. I have seen 3/4 socket pieces used to mount the arms with a plate on the end of the tube and a plate with three holes and thru bolts to keep the arms on. Hard to explain. I think Don Ross's are that way, I mean the caps on the ends of the torsion bars. Lippy
VW's used stacked leaves in this manner- I suspect this is where the original stuff came from. VW leaves, sockets, man those guys were creative back then!!!
I got some VW stacked leaves and had planned on using them and doing the socket thing till King Chassis came up with the Dragmaster torsion bars. It would have had it looking a lot more like Bobby Vodnicks car in 1963.
I finally am. Last night I put the powder coated headers on and this weekend I'm finally going to get the gear drive for the cam installed. My mom in lay passed away about a month ago from cancer. For several months before that I was keeping the house going and doing the single parent thing while my dear wife spent time with her mom. We're christians and so was she so it's all good, we'll see her again. Oh, wait a minute.... I am at work and lunch is over. I really better get back to work!