How to Tune Spring Rate and Ride Height with Stock Springs

Back in '92, Terence and I had been thinking for months about the best way to lower our '80 civic. Cutting the springs would increase the spring rate by the same percentage the springs being shortened. However, the actual spring rate of a suspension is REDUCED since a suspension can never use up the entire travel of a spring due to:

• springs are always compressed a bit when the car is at rest,
• when suspension bottom-up, spring is never fully-compressed or otherwise suspension arm will break due to infinity spring rate.

So instead of cuttings springs, we welded straps to hold windings of the springs together for the '80 civic. The difference was to have the otherwise-cut portions of the springs to act as spacers for the springs themselves. The result was amazing since the "spacer-effect" had another side-effect. If say 2 windings are needed to be cut in order to get a certain ride height, more than 2 windings are actually needed to be strapped together to get the same ride height since the "spacer-effect" makes the ride height taller. The resulting spring rate was much stiffer than aftermarket springs. Another advantage of strapping the springs is that either ends of the springs are still factory-cut/bent. That means the springs can still fit in the spring seats nicely as before.

I did the same techniques to my '85 Corolla GTS, although I didn't lower it as much as the civic. Spring rates were just a bit stiffer than aftermarket springs. The ride quality degradation by the springs were even less noticeable than putting in new shocks. However, I found the car still understeered quite a lot in my first autocross race and I decided to cut a bit of the front springs and strap a bit more windings for the rear. Since then, the car handled excellent in autocross racing but the oversteering setting makes the car performed a bit worse on the streets. I found the rear inside tires too easy to spin when full-throttle exiting right corners at intersections. Before the modification, the car had achieved more than "1G" w/ mild oversteer in a 270-degree highway on-ramp. But after the modification, it started to oversteer significantly well before approaching 1G.

Generally speaking, strap your stock springs to lower your car to get stiffer spring rate and cut your stock springs to get softer spring rate. By carefully mixing the two methods, a wide variety of custom spring rates can be achieved for any reasonable ride height. Since cutting a spring cannot be reversed, start with strapping and later susbtitute part of the strapping with cutting.

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