I replaced the 1000 cc gasoline engine of my suzuki sierra truck with 1800 cc toyota 1c diesel engine. As the weight was increased by about 90 Kg.,I had to put one additional helper leaf in the front suspension for that. But this made me faced with the problem of suspension going stiffer which makes the truck's body to crack when road is not good. Now I want some solution to this problem. One alternative which comes to my mind is to change the length of helper leaf or to replace the leaf spring suspension system with coil spring type suspension or a combination of them.