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Page 20
3LINK SETUP

NEW

I first became aware of the 3link rear suspension possibilities back in the fifties. I read of the success of the C-Type Jaguar at Le Mans and how a 3link suspension had helped it to accelerate out of the corners. As far as the dragracer is concerned, it would have been helpful if Jaguar had applied the 3link's success to the production cars, but, unfortunately for the dragracer, this was the time when many manufacturers...Jaguar included...were switching to IRS.

In the fifties, I was given the opportunity, as one of the original Ramchargers, to apply the 3link to the C/A club car. A series of unfortunate events resulted in the use of what amounted to a 4link on the club car, but I continued...through the years...to occasionally attempt to simplify my calculations. And, they certainly did become simpler. The original equation set had so many unknowns that...well, it was ridiculous! I had pages and pages of derivation. And, remember, this was in the days of the slide rule.

This, as you see, is very simple. Even the weight of the car falls out! And, with increased simplicity comes increased accuracy and reliability. The source code is available, so, for instance, if you're handy with HTML and Javascript, you can play all kinds of games. Since I merely modified an old program, the HTML here is quite crude. (I'm self taught and I'm still learning.) With this setup, the tire loading will be equal...right to left...all the way down the strip and the car will neither squat nor rise. And, you can throw away your ARB.

I'm assuming you know enough to point the links, all three, at the instant center in the side view. Their actual length is not critical, so long as their angles do not change drastically during launch. The launch area is not as smooth and flat as a billiard table. Don't even think about using the lower links to locate the axle from side-to-side. Use a Panhard rod. Those links are carrying enough load as it is. And, with regard to the links, use "beefy" links, not any of that "spaghetti" tubing I've seen in some commercially available 4links. In the top view, the links should be parallel. Just use a little common sense. Take a tip from some of the production suspension pieces and go on the safe side. The extra weight doesn't mean that much. If you're concerned, reduce driver weight. I've seen a few "string beans" at the strip, but they seem to be in the minority.

wheelbase =

axle ratio =

effective tire radius =

CG height =

instant center "up" =

vertical to upper rear =

horizontal to upper rear =

vertical to lower rear =

horizontal to lower rear =

ANSWER:

upper link offset (inches)

instant center "out" (inches)

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