Inliners International Forums General Discussion Drive Train 4 Leaf Springs on Race Car

Hello:

Are there people out there that would have any ideas on spring setups for an Early Stock race car, or where I could possibly find any information? We run on a 1/4 asphalt track. Car weights 2200 lbs., and we turn a 250 at 6,000. I am familar with the Steve Smith books, but don't think they address any front leaf spring setups. In otherwords, coils are not an option by rules.
Thanks for any help.

It would help to know what the chassis front suspension set up is like. Does the car have parallel front leafs like the older Chevys or does it have a transverse leaf like the early Fords used? either way the right side will need to be stiffer than the left side by about 50 to 100% depending on the track bank. With a parallel leaf set up this is fairly easy. You just add or remove leafs to get the spring rate or handling feel you need. On a Ford buggy spring front end it gets a bit more involved. One of the most successful transverse front set ups was called the Flemke Front End named after Eddie Flemke, a modified pilot from Connecticut. What he did was basically cut the single spring in half so each side could be different. Each side also had a jacking bolt for adjusting wedge and ride height.
This set up also involved a special front chassis pad be made up that had 2 center bolts and 2 more U bolts to locate and hold each side of the spring. Radius rods also needed reworking to keep the axle from wobbling on the now cut in half spring. To get an idea what this looks like check out some of the ads in street rod magazines.
There is an independent nostalgia front end being offered that uses this type of spring set up but the beam axle is also in 2 pieces, the Flemke front end used the axle in one piece.

As far as actual spring rates go you can't use the formula for rating coils. Leaf rates change as the spring deflects and is also effected by the amount of travel the free end shackle allows. Toss in a jacking bolt somewhere on the moveable part of the spring and things change again as you have actually shortened the spring.
Tapered leafs and mono leafs further add to the mystery.


good luck with the project,
Mike

Mike: Thank you very much for the reply. I didn't want to get too "wordy" in that first post. Like mentioned, the track is 1/4 asphalt, with 10 degree banks. The springs are parallel. We have AFCO sliding adjusters on the car, but are not running any "drag" links, or anything like that. We have thought about these things, but we're worried about the binding between the springs and additional items like a panhard bar etc.It is a 32 sedan on a Toyota frame w/ the parallel springs front and back. 55% left and 54% rear on weights. Pinion at 5 degrees. That's about all I can think of right now. Sure appreciate the help.

You're welcome. I hope it at least gave you something to consider. I mentioned the shackles and not sliders because I didn't know how deeply involved you were. Sliders are the way to go. The easiest way I ever figured out how to allow for a proper length slider slot was to measure an unmounted spring from eye to eye with the tape snug to the arch of the spring. Lets say its 44 inches. Then measure from eye to eye in a tight straight line. Lets say its 40 inches. 4 inches is the maximum the spring will extend if and when it flattens straight out so to prevent binding in the slider the slot needs to be 4 inches long.
AFCO and others usually have enough travel but it doesn't hurt to check.

If you end up placing a jacking bolt in direct contact on a spring your rates will change. A jacking bolt set up on the slider won't have any effect on the springs rate and is usually easier to deal with when sorting out your chassis handling. Even with parallel front leafs the axle can move side to side under cornering stress so a panhard bar of some sort will be helpful.

The only other thing that is a pain is setting up for different caster angles left and right. With a beam axle this involves 2 separate bends, or getting one side correct with a caster shim and then bending the other side alone.

10 degree bank isn't a lot. I might go about 50% stiffer on the right to start with and if the car is loose and doesn't seem to respond to the usual adjustments then I'd keep stiffening the right front until it tightened up. Just as examples: 600lb LF and 900lb RF, or 800lb LF and 1200lb RF. (RF is 1/2 again more than the LF.)

Mike

CIRCLE FAN --contact INLINER JIM MOORE ( FLA ) -- mooreofour@aol.com -- He has TONS of vintage oval experience ( and runs a 250 )-- DON

Don: Thanks much, will do. We ran a IMCA car a couple of years ago, I have a little knowledge on coilovers, but nothing on this kind of a set up. Also went thru three motors last season trying to bore them at 4 inches. Just couldn't keep the cylinder walls in them at just over 12:1. Was on this site a month or so ago as "Wantabefast", but misplaced my password and could not get any responce to fix it, so just re-registered. Thanks again for the info. Tom