Dont do it. Very dangerous. Springs are progressively wound (ie compress differnet amounts depending on weight). Keeping it simple imagine that half the spring compresses under half a ton and the other half compressess under a ton. If you cut it in half you are loosing the first amount of compression, so with between half a ton and a ton of weight on it, the spring will do fu*k all.
If ive got that completley wrong someone feel free to correct it.