Structural Repair and Straightening Procedures
Plan before you pull
A straightening plan names the anchor points, pull direction and height, number of pulls, and the measurements checked between pulls. Pull opposite the impact direction, along the line the force traveled, and use multi-point or simultaneous pulls on severely damaged units so load spreads through the structure.
Heat rules
Mild steel and conventional frame steel can be straightened cold; heat is a last resort and only with OEM approval. HSS work-hardens and loses strength when heated above roughly 650 °C (1200 °F). Boron/UHSS must not be heated at all - no torch straightening, no heat to relieve stress. Controlled cold pulls are the default on modern structures.
Doing the pull
Anchor at OEM tie-down points, never through suspension holes. Pull slowly and watch the gauge and tape; stop and measure often. Pull slightly past target (overpull) and release to allow springback, but never so far that you create new damage. Watch for secondary damage at clamps - a poorly placed clamp tears a hole that becomes a new repair. Remove glass, interior, and fuel-system risk items first.
Repair or replace
Replace rather than straighten when a rail is kinked, torn, cracked, heavily corroded, or damaged inside a crush zone. Straighten when damage is a smooth bend outside the crush zone and dimensions can be restored.
Rule of thumb: if a controlled pull cannot bring a control point within ±3 mm, stop pulling and change the plan - more force is not the answer. Traps: heating UHSS, pulling from a single point on a unitized body, and skipping the post-pull measurement.