Thanks Kevin, I've worked with 4140 in our fabrication/machine shop many times, unfortunately in this case we don’t know whether the bars are 4140 or not. At one time many moons ago we did make torsion bars for midget racecars. We used 4140 for the torsion arms but the torsion bars were 5160 and we would turn the center section to different diameters to give a different spring rate. The subject of heat treat is a rather involved one and heat treat of alloys is best left to a qualified heat treat facility.
There is a good chance that the springs for your truck are 5160 or a similar alloy. But to get back to the stabilizer bars, they would almost have to be made from a high silicon spring steel like 5160 to allow each side of the suspension to work independently, the purpose of the bar is not to lock the two sides rigidly together but to tie them together within a limited range of independent movement. After thinking about this for a while, I don’t think that 4140 would be the best choice. It is a chromium, molybdenum, manganese low alloy steel and is noted for toughness, good tensional strength and good fatigue strength, which means that it is not really a very good spring. I’m afraid that a 4140 bar would give you a pretty rough ride over an uneven road.
Well I’ve bout beat this one to death and I think my mind is about made up, I’m goona go with one of the CPP anti-sway bar kits rather than try to modify one. They are reasonably priced and fit the original holes without having to drill new holes or modify the original parts in any way.
Denny Graham
