Weight Transfer and Suspensions

I have seen the CalTracs work with stock springs and the so-called SS springs. They are a step up from the old slapper bars. That lowly pinion snubber has been one of the most efficient traction devices ever put on a car. They absolutely were used on the factory S/S cars WITH the SS springs! When I was with Ronnie Sox, he wouldn't race without one in that '68 Barracuda. You know that bad boy was a stick! The way Ronnie liked the rear was with those big ol' higher arched SS springs and an adjustable snubber set 1-inch away from the reinforced floor pan with him sitting in the car. He would heat the tires and give it a dry hop test by revving to around 5,000 rpm and giving the clutch a quick "snatch". From that little thing he knew the car was going to do its job. The snubber is very old technology but still worthy of respect. I used it on my Hemi Roadrunner 4-speed and Jake King engine. It works on a principle of physics: for every action there is a reaction, equal and opposite. When shock force is applied, the pinion tries to climb the ring gear but it is trapped in the housing and can't so the whole housing tries to twist nose upward. The snubber is mounted on that nose and when it contacts the floor pan spot, it pushes up. Whatever force prevails pushing the body up applies an equal pressure forcing the rearend and tires onto the pavement. This improves traction. The SS springs have a special leaf bias as well as more arch and they can ride like a buck board! The front half of the spring has more and stiffer spring leaves. They are very firm and do not wrap up and cause wheel hop. The front half of the spring then works similar to a ladder bar. As the pinion tries to rotate up, it is restrained by the spring, forcing the spring to lift the back of the car at the point of the front perch. Again, for every pound of force used to lift, an equal pound is reversly applied to the tires. For this reason, a lot of racers found the pinion snubber unnecessary and didn't use them. I saw a lot of guys put them back on when they went to tires like 14 x 32s!
You can get some advantage by making the front spring hanger adjustable and keep shims on hand to correct the pinion angle. A proper rear geometry will push as closely to the car's "instant center" as possible. You can draw an imaginary line from the tire contact point through the front spring eye and beyond to see just where it is pushing. Positioning the front spring eye lower moves the push on the instant center farther forward. All of this stuff is affordable and doable for most people racing leaf spring cars. Take a look at Poison Dart's pictures. That is a high dollar, high tech and well set up car! We should all have one of those!
It is important to know the center of gravity of your race car. The lateral CG is usually a line going down the side of the car from the ground to the cam centerline. The vertical CG can be found with scales or you could use my crude but effective method: Use a floor jack on each side and move them until you find the "teeter-totter" balance. You can mark it on the door with a piece of tape. Now you know the "magic" push spot. I'll explain the mechanical advantage of this and then I'll shut up: Pretend your car is a refrigerator and you stand it up on the back bumper. You want to push it back to the wall so where do you push it? Push below the CG and your feet will slip and the "frige" doesnt move. Push towards the top and leverage force diminishes. But push anywhere near that center of gravity and the "frige" is easily moved; force accomplishes work. Now put the car back down on all four paws...the principle is the same.
Ladder bars can really work but the ultimate is the four link. I have seen a lot of racers use both with absolutely no idea of how to set them and why.
Pat