ASE B3 Non-Structural Analysis & Damage Repair cheat sheet

Measure body dimensions against the OEM control-point chart; tolerance is typically ±3 mm, and any reading outside that band indicates structural movement.

Classify damage by zone: direct (impact area), induced (adjacent buckles), and inertia (remote transfer through the structure).

Use a tram gauge or a dedicated measuring system to compare diagonal cross-measurements; unequal diagonals on a symmetric opening indicate sway.

Gauge a panel's coating thickness before sanding; factory e-coat plus primer is typically 0.1–0.2 mm, so readings well above that signal prior refinish or filler.

Magnetic thickness gauges do not read accurately on aluminum, plastic, or composite panels; use an eddy-current or ultrasonic gauge instead.

A kinked or crushed rail, apron, or hinge pillar is a replace-not-repair decision because the section has lost its designed crush geometry.

Scan for diagnostic trouble codes and check for undeployed airbag modules before disassembly; damage analysis includes restraint and electrical status.

Document pre-existing damage, aftermarket parts, and prior repairs with photographs before any teardown begins.

Set the gap and flush before tightening fasteners fully; snug bolts, align the panel by hand, then torque to specification.

Hinge adjustment sequence: loosen the body-side hinge bolts to set the panel fore/aft and up/down, then the door-side bolts to set the panel's angle and flush.

Gap tolerance on most late-model vehicles is roughly 4–6 mm with flush variation held to about ±1 mm; consult the OEM body repair manual for exact values.

Adjust the striker last; a misadjusted striker can mask a correct hinge alignment and cause a latch to bind or rattle.

Use a panel gap gauge or plastic shims to hold an even gap while fasteners are torqued; do not pry on painted edges.

A door that drops when opened usually indicates worn hinge pins or bushings, not an adjustment error.

Check that the latch engages the striker centered and that the door closes with a firm, even effort before final torque.

Hood and decklid alignment is set at the hinges first, then the latch/striker, then the bumper or corner stops.

Steel with a yield strength above roughly 550 MPa (high-strength and ultra-high-strength) generally must not be heated for straightening; heat destroys the temper.

Boron and martensitic steels are replace-only at many OEMs; never section or heat these grades unless the OEM procedure explicitly permits it.

Panel bonding adhesive requires a clean, abraded, correctly primed surface and a specified clamp or cure time; adhesive does not replace welds at structural joints.

Squeeze-type resistance spot welding (STRSW) is the preferred replacement method for factory spot welds; match the OEM weld count and spacing.

MIG plug or stitch welds are used where STRSW is inaccessible; continuous seam welds are reserved for locations the OEM specifies.

Apply weld-through primer or cavity wax to interior surfaces of replaced panels to restore corrosion protection; never leave bare metal inside a closed section.

Use a hammer and dolly for stretching and a slapping file or pick hammer for shrinking; over-shrinking causes oil-canning.

Galvanized and aluminum panels require dedicated tooling and filler systems; cross-contamination with steel tooling causes corrosion and poor adhesion.

Identify the plastic by its ISO code molded on the back of the part; repair only thermoplastics with a compatible adhesive or welding rod.

Thermoplastic bumpers are repaired by hot-air or airless plastic welding using a rod of the same base material, or by two-part plastic adhesive.

Thermoset composites (SMC, fiberglass) are repaired with resin and reinforcement, not plastic welding; the resin cures by chemical reaction, not melting.

A flexibility additive is added to refinish materials on flexible bumpers so the paint film flexes with the substrate and does not crack.

Adhesion promoter is required on most polyolefin plastics (PP, TPO) because their low surface energy prevents paint bonding.

A tear that reaches a mounting point, or damage through a reinforcement rib, is a replace-not-repair decision.

Reinforce a repaired crack from the backside with a patch or mesh; a front-only repair will telegraph and fail under flex.

Use a plastic repair adhesive's stated open and cure times; forcing cure with heat can trap solvent and cause later blistering.

A door glass regulator's position must be set with the glass in the full-up position before the motor is attached; otherwise the travel limits are lost.

Normalize (re-initialize) power window motors after battery disconnect or regulator replacement by cycling the glass fully up and holding the switch.

Check the window run channel and weatherstrip for pinching before condemning a regulator; a slow window is often a friction, not a motor, fault.

Windshield urethane must be a high-modulus, OEM-specified adhesive; safe drive-away time is set by the adhesive manufacturer and is typically 1 hour minimum.

Urethane bond requires a primed frit and a clean, dry pinchweld; the bead must be continuous with the specified width and height.

Glass bonded to a vehicle with a passenger-side airbag requires the OEM-specified urethane and a full-cure or safe-drive-away procedure.

Track and roller wear shows as a glass that tilts or rattles in the run channel; replace the regulator assembly if the track is worn.

Check door glass for correct fore/aft and in/out position against the roof rail and belt molding before tightening the regulator fasteners.

Retaining clips are single-use on most late-model trim; a reused clip loses tension and causes rattles or detachment.

Adhesive-backed trim requires a clean surface wiped with the manufacturer's recommended cleaner and a specified adhesion promoter.

Double-sided trim tape needs pressure, typically 15–20 psi rolled over the full length, and a minimum dwell time before exposure to water.

Two-sided tape thickness and hardness are specified by the OEM; substituting a thicker tape changes the flush of the trim to the body.

Emblems and badges are located by pilot holes or a template; measure and mark the position before removal to restore original placement.

Roof rails, spoilers, and luggage racks attach to reinforced body points; never drill new holes in an unreinforced panel.

Check that trim does not interfere with door swing, glass travel, or sensor fields (parking, blind spot) before final installation.

Fasteners into plastic retainers should be torqued to specification; over-torque strips the retainer and creates a future rattle.

Disconnect the battery and wait the OEM-specified time (commonly 1–3 minutes) before working on or near airbag modules.

Never probe an airbag squib or connector with a test light or ohmmeter unless the OEM procedure specifies it; the current can deploy the module.

Store an undeployed airbag module face-up with the trim cover away from you; never point the deployment side at a person.

A deployed or replaced airbag module, pretensioner, and the control module usually must be replaced together per OEM procedure.

After any restraint deployment, inspect and replace the clock spring, seat belt pretensioners, and any damaged sensors per the OEM.

Use a scan tool to read and clear restraint codes; a hard code that returns indicates a circuit or component fault that must be diagnosed.

Seat belt webbing that is cut, frayed, or stretched at the buckle stalk is replaced as an assembly, not repaired.

Do not disable or defeat the occupant classification sensor or seat weight sensor; doing so disables the passenger airbag.