I-CAR Structural common mistakes
I-CAR Structural · Understand the traps and how to avoid them.
Judging repairability from a visual walk-around and writing an estimate before locating and identifying the vehicle's ultra-high-strength steel (UHSS) and press-hardened components in the OEM repair information.
Candidates carry over habits from mild-steel era vehicles where damage visibility tracked with damage severity; modern structures can have hidden deformation in high-strength grades that must not be straightened, and the repair procedure is defined by material and heat-treatment, not by what is visible.
What to do instead
Establish a fixed sequence for every job: identify the vehicle and body style, pull the OEM body repair manual and the specific sectioning/straightening statements, locate material callouts on the structural components, then assess damage. Ask 'what grade is this part and does the OEM permit repair?' before estimating any operation.
Treating 'high-strength steel,' 'advanced high-strength steel,' and 'ultra-high-strength steel' as interchangeable labels, and applying the same straightening, sectioning, and welding rules to all of them.
The terms are used loosely in training material and in the shop, and candidates memorize the acronyms without anchoring them to a tensile-strength range and the repair consequences that follow from that range.
What to do instead
Build a mental ladder by tensile strength (mild/low-strength, high-strength, advanced high-strength including dual-phase and TRIP grades, and ultra-high-strength/press-hardened boron grades), and attach the consequence to each rung: which may be straightened, which must be replaced, which require specialized welding or rivet bonding, and which OEMs prohibit heating.
Taking a single dimensional measurement, or measuring only the damaged side, and declaring the structure within tolerance.
Candidates treat measuring as a pass/fail check on the visibly damaged area, forgetting that a collision produces a load path and that the opposite rail, apron, or strut tower is often the reference that reveals sway or mash.
What to do instead
Measure the full control set the OEM or measuring system specifies, compare to the published datum dimensions, and compare side to side. Record before-and-after readings and use the readings to drive the pull rather than confirming a decision already made.
Continuing a pull after the target dimension is reached, or pulling in a single direction and relying on brute force to bring a rail or apron back into position.
Candidates equate 'more pull' with 'more correction' and do not account for springback, memory, and the risk of stretching metal or tearing welds and adhesives elsewhere in the structure when the load is applied along the wrong axis.
What to do instead
Plan the pull before anchoring: identify the direction of the original impact, use multiple pulls and opposing or complementary anchors, pull to slightly past the target to allow for springback, and re-measure between pulls. Stop and re-evaluate if the structure stops responding rather than increasing force.
Assuming any squeeze-type resistance spot welder in the shop is approved for the steel being joined, and welding UHSS or boron steel with a setup intended for mild steel.
The welder looks the same regardless of the material, and candidates focus on the equipment rather than on the OEM weld schedule, tip configuration, and current/time settings that the specific steel grade requires.
What to do instead
Before welding, confirm the OEM permits squeeze-type resistance spot welding at that location, match the welder and tips to the material and stack-up, and verify settings against the OEM weld schedule. Perform a test weld on representative material and check nugget size and failure mode (weld should pull a nugget, not peel cleanly).
Making a sectioning joint wherever it is convenient on the replacement part, rather than at the OEM-specified location, and using a butt joint where an offset or backing joint is required.
Candidates optimize for fit-up and access, and treat sectioning as a fabrication problem rather than a structural one; the OEM specifies joint location and type to keep the weld out of high-stress zones and to preserve crush behavior.
What to do instead
Locate the OEM sectioning procedure for that exact part and follow the specified cut location, joint type, and weld or rivet pattern. If no procedure exists for that part, do not improvise a structural joint; replace the assembly or consult the OEM position.
Replacing a panel and skipping or shortening the corrosion protection steps, such as omitting cavity wax in closed sections or coating only the visible exterior seam.
Candidates finish when the panel looks right and the gaps are even; hidden cavities and hem flanges are invisible after assembly, so the omission does not show up until years later as perforation.
What to do instead
Treat coatings as a required operation with its own checklist: clean and prepare bare metal, apply the specified primer and seam sealer, apply cavity wax or inner-panel protection through the designated access points, and restore any anti-chip or sound-deadening material. Verify access points before the panel is closed up.
Using a rivet bonding or adhesive bonding procedure with general-purpose adhesive or generic rivets, and skipping the surface preparation and cure-time discipline the joint depends on.
Candidates see adhesive and rivets as fasteners rather than as an engineered joint system, and shortcut the abrasion, cleaning, and clamping steps because the bond 'looks fine' immediately.
What to do instead
Use only the OEM-approved adhesive and rivet part numbers for that joint, follow the specified surface preparation and primer, respect open and closed assembly time, clamp or fixture per procedure, and do not disturb the joint until the specified cure is reached. Confirm the OEM permits adhesive bonding at that location at all.
Planning a repair on a mixed-material vehicle (aluminum structure with steel attachments, or steel with aluminum closures) without isolating the dissimilar metals and adjusting fasteners, welding, and tools for each material.
Candidates apply an all-steel mental model, and the visible surface often looks similar; the galvanic couple, different thermal expansion, and material-specific fasteners only matter if you consciously identify each material first.
What to do instead
Map the materials on the specific vehicle before planning: identify aluminum, steel, and composite components, then apply isolation (coating, barrier tape, isolating washers), material-specific fasteners, and dedicated tools. Never allow steel and aluminum to make direct contact, and keep aluminum and steel work areas and abrasives separate to avoid cross-contamination.
Treating the pre-repair inspection as a formality and not documenting the inspection findings, measurements, and material identification before work begins.
Candidates are focused on the repair and see documentation as paperwork; but undiscovered prior damage, hidden structural deformation, or an unrepairable material is exactly what the inspection is meant to catch, and without a record there is no basis for a supplement or a repair-versus-replace decision.
What to do instead
Use a written inspection sequence and record it: VIN and vehicle identification, OEM procedure references, material callouts, measurement readings with datum values, and photographs of hidden damage. Use those records to justify the repair plan and any supplement before cutting or pulling.