http://www.buggymasters.com/forum/sh...?t=2243&page=7
post 605.
masteryota is correct in saying that you will change the coil's spring temper by welding/heating. trying to control this aspect is a bit of a crapshoot. I did it by using more of the soft spring than i needed, giving it a very shallow cut with the angle grinder, clamping it closed then welding it on a low temp setting,
fur purpose of discussion/ "historical context" LOL ... former GM engineer Herb Adams, aka "father of the Trans Am" and founder of VSE taught me that when cutting coils for cars with spring pockets/stops in the lower arm, ALWAYS heat and quickly flatten the last 1/2 coil so it sits the pocket correctly. More often than not, this step is not done and the coil doesn't really sit correctly and the spring base doesn't spread it's load evenly. it's not visible/measurable when it's installed so a lot of shops/homebuilders just make the cut and slap them in ---see that happen on "reality" tv quite often. heat then crush was/is also used to change spring height in lieu of cutting, though cutting is a more accurate method of getting the desired result.
If i had oxygen in my tank when i did mine, i would have heated and bent the shallow cut final coil of the soft spring to sit flat rather than welded it.
if you have some old atv springs lying about, with playing with/modding those might be worth your time as rates that work for the fronts or rears are difficult to find. end result of my experiment worked otu really well, though i have decided that fox flats will hopefully be on all 4 corners before the next race in the spring. (weight savings, cut shock fade--a problem i have up front, increase in wheel travel)