Thread: How to build an early hotrod frame

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This is a car I am designing for a gentleman in North Carolina. It is a model A sedan, chopped 4". He has purchased a Speedway Motors complete front end with 6" dropped axle, a set of Carerra coil over shocks, which end up 11 1/8" center to center of eyes when compressed under a weight of 500 pounds each (he built the jig shown earlier in this thread to determine that dimension). The wheels are 15", diameter and the outside diameters shown are measured from my own roadster pickup. He plans on channeling the body 4" over the frame, and I have advised him to extend the wheelbase as shown, in order to allow fitting a small block chev engine with HEI distributor into place, with a 4" recess in the firewall. The drawing is "to scale" and I hav a few comments to make, based on what I am seeing. #1---I don't really like a 6" dropped front axle---why---well, the batwing welded to the axle (which the hairpin radius rods attach to) hangs down about 3 1/4" below the axle centerline. If you use a tire of the diameter I am showing, then the underside of that batwing is only about 2 3/8" off the ground.---This is not a problem when going over speed-bumps, as the tire will lift the axle up when you drive over one. The big danger is that if you blow a front tire and it comes off the rim, you will lose all steering and control, and go sliding down the road on the underside of the batwing.
#2---The design, as I have it, allows about 4 3/4" clearance between the top of the rear axle housing and the underside of the framerails. You need this much to avoid "bottoming out" when you hit a bump.---BUT---you can see what is happening with the kickup, when its that large. There is no way to run a back seat in that sedan. Now to a lot of folks, that don't matter---I just wanted to point out what you give up to have a channeled and low model A hotrod. #3---look where the pinion centerline ends up, on the rearend---yes, it is above the framerail and above the "floor" of the car. This means that the fellow is going to have to run a driveshaft tunnel full length of the passenger compartment, in a car which is pretty damn narrow to start with!!! #4---The motor is going to have to set up high in the frame, in order to keep the transmission output shaft from being way lower than the pinion centerline---this will mean that a huge transmission tunnel will also encroach on the pasenger compartment. #5---This car will look absolutely killer. It will get a lot of attention wherever it goes, and is the absolute epitome of what hotrods are supposed to look like. It will be uncomfortable as Hell for long distance driving, because you will end up with very little seat cushion, so will be driving around with your legs pretty well straight out but man, will you ever look cool while doing it. ---Brian