Thread: How to build an early hotrod frame

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There is one other variation of the "suicide" style front end, that I am going to touch on this morning, because over the last year this seems to be goining a lot of popularity. In this style, the front suicide mount is the same as in the post shown previously. The big difference is that instead of the spring setting above the axle, it sets behind the axle and the spring perches are bolted into sockets that are either welded into the wishbones, or sometimes into the radius rods themselves . This is quite an acceptable front end treatment, and it looks very good on some of the more radical fenderless rods. the big thing to watch out for here is that you keep the spring as close to the side of the axle as possible without interferance, and make absolutely certain that the spring perches pass thru a sleeve which is securely welded into the batwings or radius rods. Failure of a butt weld in a situation like this can kill you very quickly. Another good point to remember is that the farther it is from the center of the spring to the center of the axle, the greater will be the effect on the spring rate. AND---when you are planning your frame layout, you now have to take into consideration that their is an offset between the center of the spring and that of the axle, so the center of the suicide perch plate will not be on the center of the axle.
With suicide perches, as well as with conventional spring over axle crossmembers, the actual surface that the underside of the leaf spring bolts against should be tipped down at an angle of 6 degrees at the rear side, to give the axle kingpins the proper caster angle. For all beam type and tubular axles, the kingpins should lean towards the back of the car, at the top of the kingpin by an angle of 6 degrees.This is best accomplishe by welding the crossmember or suicide plate in at an angle of 6 degrees relative to the top surface of the framerail. You do not have to take into acount the angle which your car will be setting at because of "rubber rake" caused by running large tires on the rear and small tires on the front.