Q. In 1988, Chevy trucks went (as I understand) from a "mild" steel frame to a low-alloy high-strength steel. The downside is welding on the frame was discouraged. No more weld-on hitches. If a change in wheelbase was required on one of these later frames, is there an acceptable welding procedure that would work? The obvious things would be to use low hydrogen rods, pre-heat, post-heat, and the like. The other two practical options I can think of would be:
• Cut the frame to butt it together, and use a formed channel that fits inside the frame; bolt it together with Grade 8 bolts and proper torque specs.
• Use a pre-'88 frame and simply cut and weld it; then weld reinforcements inside the frame channel.
Please comment on the feasibility of these procedures, or possibly offer another suggestion.
Mt. Sterling, Kentucky
Via the Internet
A. The reason welding is not recommended on high-strength steel frames is because the frames are heat treated. When the frame is heated (by welding, or pre- or post-heating for a weld) the heat treatment is lost, and you'll have a weak spot in the frame.
I can't recommend any solution that relies on bolting sections together-it's just not a good way to join frame members that are subject to repeated, heavy bending and twisting loads.
I'd say that using a pre-'88 frame is probably your best option!