Front springs....

[340D]

I have a 1980 Dodge D50 that I drag race. I would like to lower the front of the truck about 1 inch. I was told if I cut a little off the coil spring to lower it , it would make the spring a little bit stiffer Is that correct?

[Merrill]

Cut half a coil off for about 1 inch. The spring rate will not change. It's still the same spring, just shorter.

[pennyman1]

For hAlf a coil cut, the spring won't get stiffer. Cut off more and its a different story

[Merrill]

The spring rate doesn't change no matter how much you cut off. It just gets shorter and the shock compresses making a stiffer ride.

[pennyman1]

Only if the coil spring is made to be cut - a regular spring gets stiffer as it gets shorter do to less material to support the load. It took a long time for me to understand it, but it is true. Its a material science thing.

[Merrill]

Spring rate is determined by the material, thickness of the winding, heat treatment, process, and a dozen other factors. By cutting it, you are only making it shorter. The spring rate does not change by it being shorter. The amount it compresses does not change by it being shorter. The structure does not change by it being shorter. The material does not change by it being shorter.... the list goes on. All you did was make it shorter. Changing geometry of your suspension, and compressing a shock further, will stiffen the ride. The material that determines the spring rate will not change just because you made it shorter by cutting off a turn or two.

A perfect experiment would be taking a spring, cutting it, installing it, and taking a drive. It would feel stiffer because the shock is compressed further limiting it's travel and valving ability. If you space the shock out for longer travel, but kept the cut spring in there, the ride would improve. The spring rate didn't change, but you gained a softer ride.

Same rules apply to suspension geometry. If your suspension hits it's binding point at X degrees, and the shorter spring made the suspension sit right at that point, or very close, you will get a stiffer ride as well.

Point is, you can't change the rate of a spring by making it shorter. A progressive spring may change by removing portions, but not a regular spring and none of these trucks came with progressive rate coil springs.