What are the main differences between stock and hotchkis coil springs?

[Nicks67GTO]

The title says it all. Is it material used? Is there a distinct performance advantage when paired with good bilstien shocks? Whats the difference?

[ccmc]

stiffer coils, usually that means thicker steel, and for mine (1969 Camaro) I ordered the shorter drop springs. Stock coils are usually around 250 lbs and I think I read that hotchkis springs are around 650 or 550 lbs.

[Twentyover]

Usually the major differences are geometry- in this case free length and rate. Rate is mostly a function of different wire diameter, #active coils. To a lesser extent ID and OD of the spring.

Most springs are made of basically the same material- and the shear modulus of steel, which is a property determining rate, is pretty much the same for all steels.

Shocks should match dampening with spring rate- a higher spring rate requires stiffer dampening than than a softer rate. Any shock manufacturer can provide greater or lesser dampening.

Not sure exactly what your trying to find out.

[SLO_Z28]

Hotchkis springs will have a higher rate than the stock springs, and a lower installed height. This will lower the car, and that has a few handling advantages. The stock springs are in the 275# range, so that means if your car goes to turn and you get 1200lbs of weight transfer to that corner, that a stock spring will travel 4.36 inches, but a 625# springs (in the neighborhood of hotchkis stuff) will travel 1.92 inches. The car will stay flatter in turns, and as a result be much easier to drive and handle better. Shocks are a timing device, they time the spring oscillations, and there are a lot of variables in how to properly time the spring as long as you know in general the specs of the car you can get really close, Hotchkis spends some time engineering the shocks with Bilstein so you're not getting an off the shelf unit, you're getting one made for your specific application.

The best part about the hotchkis stuff is that with all these gains, you don't really have any compromises, you still have a compliant ride that is completely fine for daily driving that give the driver a confident feel and capable feel. They really do spend some time engineering these kits, and the matched sway bar, spring, and shock kits take all of the guess work out of it, and are as capable as some of the fastest PT cars but not harsh to the point of being prohibitive to drive, its still fun to jump in a hotchkis car and go for a cruise or spirited drive.

[Henesian]

You need the Herb Adams Coil Spring Rate formula to understand it fully. It all depends on the thickness of the wire in the spring, the height, and the number of coils. The stock ones are soft, because they're too tall, have too many coils, and too thin of a wire. The Hotchkis springs are about 14-15" tall and have a thicker wire, so it means less coils and a stiffer spring, and they lower the car. HOWEVER!!!! two springs can be the same spring rate, but act completely different. I have 13.25" tall springs from an 80s Chevy diesel S10, and they're 700 lbs/in, but lower the car around 3". The Pro-Touring F-Body GT springs lower the car MORE, and have the SAME free height as the S10 springs, because they have thinner wire, so they're only 600 lbs/in. I know this is true, because the guy I know who has them has a .75" tall coil spring spacer, when I have a .5" coil spring spacer, and the cars are the same height. Compared to the Hotchkis springs, they lower the car alot more because the wire is too thin for that free height. The Hotchkis springs have the same wire as my S10 springs, but around an inch more of free height, so they don't lower the car as much and aren't as stiff.

A 600 lb spring will always lower the car when compared to a stock spring. A lowering spring will always be alot stiffer than a stock spring or else you'd bottom out on like every bump and the suspension geometry would be totally off, and that's just physics lol. The Hotchkis springs are a good compromise between Full Race and Stock in our cars.