Collision Repair Fundamentals
Disassembly and Reassembly
Plastic Repair
Aluminum and Steel Small Dent Removal
Preparation for Refinish
100

What is the primary purpose of a vehicle’s frame or unibody structure?

The frame or unibody structure provides the vehicle’s main support. It maintains the shape of the vehicle, supports all components (engine, suspension, body panels), and helps absorb and distribute crash energy to protect occupants.

100

Why is it important to label and organize fasteners and parts during vehicle disassembly?

Labeling and organizing parts prevents loss or confusion during reassembly, saves time, and ensures components are reinstalled in their correct locations.

100

What are the four common plastic repair methods used in collision repair, and when would you typically choose each one?

  • Plastic Welding – Used on thermoplastics to fuse material together (good for cracks and splits).
  • Plastic Adhesive Repair – Uses chemical bonding agents (good for SMC, composites, or when welding isn’t ideal).
  • Plastic Stapling – Uses heated metal staples to reinforce cracks from the backside (adds strength).
  • Plastic Reshaping – Uses heat to return plastic to its original shape (used for warping or distortion).
100

What are the main differences between steel and aluminum panels in collision repair, and why must technicians treat them differently?

  • Steel: Stronger, heavier, has “memory” (returns toward original shape), can be heated for shrinking.
  • Aluminum: Lighter, softer, no memory (stays where moved), work-hardens quickly, sensitive to heat.

Why different treatment:

  • Aluminum is more easily damaged during repair and requires controlled techniques.
  • Steel can handle more aggressive straightening and heat shrinking.
100

What are the main layers of an automotive refinish system, and what is the purpose of each?

  • Substrate (metal/plastic): The surface being repaired
  • Primer (etching or surfacer): Promotes adhesion and fills minor imperfections
  • Sealer: Creates a uniform surface and improves topcoat adhesion
  • Basecoat (color): Provides the vehicle’s color
  • Clearcoat: Adds gloss, protection, and durability (UV and chemical resistance)
200

What is the difference between structural damage and cosmetic damage in a collision repair context?

Structural damage affects the integrity of the vehicle’s frame or unibody (e.g., bent rails, misalignment), which can impact safety and drivability. Cosmetic damage only affects appearance (e.g., dents, scratches, paint damage) and does not compromise structural strength. 

200

What safety precautions should be taken before beginning vehicle disassembly?

Disconnect the battery, wear proper PPE (gloves, eye protection), secure the vehicle, and be aware of hazards like airbags, sharp edges, and fluids.

200

Explain the basic steps involved in plastic welding. Why is it important to identify the type of plastic before starting the repair?

Basic steps for plastic welding:

  1. Identify the plastic type (PP, TPO, ABS, etc.)
  2. Clean the repair area thoroughly
  3. V-groove the crack to allow filler material penetration
  4. Preheat the plastic
  5. Use a plastic welder to melt and fuse the base material and filler rod
  6. Allow to cool properly
  7. Sand and finish

Why identification matters:
Different plastics melt at different temperatures and require matching filler material. Incorrect identification can lead to weak repairs or failure.

200

What specialized tools and equipment are required when repairing aluminum panels, and why can’t you use the same tools used for steel repair?

Required tools/equipment:

  • Dedicated aluminum work area
  • Aluminum-specific hammers and dollies
  • Non-ferrous sanding/grinding tools
  • Aluminum dent repair systems (glue pull systems, special studs)
  • Clean air and dust extraction systems

Why not use steel tools:

  • Steel particles can embed into aluminum and cause galvanic corrosion
  • Aluminum requires softer, more precise tools to avoid stretching or tearing
  • Cleanliness is critical to maintain repair integrity
200

Why is it important to follow proper mixing ratios when preparing automotive paint, and what can happen if they are incorrect?

  • Proper ratios ensure correct chemical reaction, curing, and performance
  • Ratios involve paint, reducer, and hardener (depending on system)

If incorrect:

  • Too much hardener → paint can become brittle or dry too fast
  • Too little hardener → improper curing, soft finish
  • Incorrect reducer → poor flow, runs, or orange peel
  • Overall result: poor adhesion, finish defects, and possible failure
300

Why is it important to follow manufacturer repair procedures when fixing modern vehicles?

Following manufacturer repair procedures ensures the vehicle is restored to its original safety standards. Modern vehicles use specific materials (like high-strength steel or aluminum) and designs that require precise repair methods. Ignoring these procedures can weaken the structure or cause safety systems to fail.

300

Why is it necessary to document the disassembly process (photos, notes, etc.)?

Documentation helps ensure accurate reassembly, provides a reference for part placement and condition, and supports insurance or repair records.

300

Compare plastic adhesive repair and plastic stapling. What are the advantages and limitations of each method, and in what situations would one be preferred over the other?

Plastic Adhesive Repair:

  • Advantages:
    • Works on more material types (including thermosets)
    • No heat distortion risk
    • Easier for cosmetic repairs
  • Limitations:
    • Can be expensive
    • Requires proper surface prep
    • May not be as strong structurally as welding in some cases

Plastic Stapling:

  • Advantages:
    • Adds strong reinforcement to cracks
    • Quick and effective for backside repairs
  • Limitations:
    • Requires additional finishing on front side
    • Not a standalone repair (usually combined with welding or adhesive)

When to choose:

  • Use adhesive when working with non-weldable plastics or when heat could cause damage
  • Use stapling when reinforcement is needed, especially for stress cracks or high-load areas
300

Describe the proper repair process for a minor dent in a steel panel versus a minor dent in an aluminum pane

Steel Repair Process:

  1. Clean the damaged area
  2. Access backside if possible
  3. Use hammer and dolly to reshape
  4. Apply controlled heat if shrinking is needed
  5. Grind/sand smooth
  6. Apply filler and refinish

Aluminum Repair Process:

  1. Clean and isolate work area (avoid contamination)
  2. Use light, precise hammer and dolly work or glue pull system
  3. Avoid excessive heat (can weaken metal)
  4. Work slowly to prevent stretching
  5. Sand and apply appropriate filler
  6. Refinish

Key Differences:

  • Steel allows heat shrinking; aluminum does not (or very limited)
  • Aluminum requires more finesse and patience
  • Aluminum work-hardens, so overworking can cause cracking 
300

Describe the proper steps for preparing a panel for refinishing before applying paint.

 

  1. Clean surface (remove wax, grease, contaminants)
  2. Sand the area to remove old finish or create mechanical adhesion
  3. Repair imperfections (body filler if needed)
  4. Apply primer and allow to cure
  5. Block sand primer smooth
  6. Clean again to remove dust and contaminants
  7. Mask surrounding areas
  8. Apply sealer if required 
400

What role do measuring systems (such as computerized frame measuring) play in collision repair?

Measuring systems, especially computerized ones, are used to check the vehicle’s dimensions against factory specifications. They help technicians identify hidden structural damage, ensure proper alignment, and verify that the frame or unibody is restored accurately after repairs.

400

What is the correct procedure for removing and reinstalling bolt-on body panels to maintain proper alignment?

Mark original positions, loosen fasteners carefully, support the panel during removal, and during reassembly align panels using reference marks, adjust gaps evenly, and torque fasteners to manufacturer specifications. 

Rear to front.

400

A technician is repairing a cracked plastic bumper cover with missing material and distortion.

  • Which repair methods would you use (plastic reshaping, welding, adhesive, staples)?
  • In what order should they be performed, and why?

Recommended methods & order:

  1. Plastic Reshaping – Heat and return bumper to original shape first
  2. Plastic Stapling – Reinforce cracks from the backside
  3. Plastic Welding or Adhesive Repair – Fill cracks and rebuild missing material
  4. Finish Work – Sand, apply filler if needed, and refinish

Why this order:

  • You must restore the shape before locking anything in place
  • Reinforcement ensures durability
  • Filling/repairing after reinforcement ensures a strong bond
  • Finishing is always last for appearance
400
  • How would your repair approach differ for each panel?
  • What safety precautions and contamination concerns must you consider?
  • Aluminum Fender:
    • Use dedicated aluminum tools
    • Prefer glue pulling or light tapping techniques
    • Avoid excessive force and heat

Safety & Contamination Concerns:

  • Separate tools and workspaces for aluminum and steel
  • Prevent steel dust from contacting aluminum (corrosion risk)
  • Use proper PPE (eye protection, gloves, respirator)
  • Maintain clean work environment for aluminum repairs
400

After painting a panel, you notice defects such as orange peel and runs in the clearcoat.

  • What caused these issues?
  • How would you correct them?

Causes:

  • Orange peel: Improper gun setup, incorrect viscosity, spraying too dry, or poor technique
  • Runs/sags: Too much material applied, spraying too close, or moving too slowly

Corrections:

  1. Allow clearcoat to fully cure
  2. Wet sand the affected area (e.g., 1500–3000 grit)
  3. Buff and polish to restore gloss
  4. If severe, sand and reapply clearcoat
500

Explain the order of jumping a vehicle from another donor vehicle.

  • Red clamp to dead battery (+ terminal)
    Attach the positive (red) clamp to the positive terminal on the dead battery.
  • Red clamp to donor battery (+ terminal)
    Attach the other red clamp to the positive terminal on the donor vehicle’s battery.
  • Black clamp to donor battery (– terminal)
    Attach the negative (black) clamp to the negative terminal on the donor battery.
  • Black clamp to ground on dead vehicle
    Attach the final black clamp to an unpainted metal surface (engine block or frame) on the dead vehicle—NOT directly to the battery negative terminal. This reduces the risk of sparks near the battery.
500

How can improper disassembly or reassembly affect vehicle safety systems and overall repair quality?

4 different things 

Incorrect procedures can damage wiring, sensors, or mounting points, leading to malfunctioning safety systems (like airbags or ADAS), poor panel alignment, noise issues, reduced structural integrity, and compromised crash performance.

500

You are given a thermoplastic bumper with multiple types of damage: cracks, torn mounting tabs, and warping. Develop a complete repair plan that includes:

  • Identification of the plastic
  • Selection of repair methods (welding, adhesive, stapling, reshaping)
  • Surface preparation steps
  • Structural reinforcement
  • Finishing procedures

Justify each decision based on durability, cost, and OEM repair standards.

Complete Repair Plan:

  • Plastic Identification:
    • Locate ISO symbol or use a burn/test kit to identify material (e.g., PP, TPO)
  • Repair Method Selection:
    • Reshaping for warped areas
    • Stapling for crack reinforcement and tabs
    • Plastic Welding for thermoplastics (preferred for strength)
    • Adhesive Repair if material is non-weldable or for tab rebuilding
  • Surface Preparation:
    • Clean with plastic cleaner
    • Remove contaminants (wax, grease, paint)
    • Sand and V-groove cracks
  • Structural Reinforcement:
    • Install staples on backside of cracks
    • Use mesh or backing material if needed
    • Apply welding rod or adhesive to rebuild structure
  • Finishing Procedures:
    • Grind/sand repair smooth
    • Apply flexible filler if needed
    • Prime with adhesion promoter
    • Paint and refinish

Justification:

  • Durability: Welding + reinforcement provides strongest repair
  • Cost: Combining methods avoids full replacement
  • OEM Standards: Following proper identification and approved repair methods ensures safe, long-lasting repairs
500

You are evaluating damage on a modern vehicle with both high-strength steel (HSS) and aluminum body panels. Develop a complete repair plan.

Damage Analysis & Repair vs Replace:

  • Follow OEM guidelines
  • Replace HSS components if damage exceeds repair limits (cannot safely reshape)
  • Repair aluminum only if within allowable deformation limits

Tool & Workspace Setup:

  • Separate aluminum repair area
  • Dedicated aluminum tools and dust extraction
  • Proper welding and repair equipment for HSS

Repair Techniques:

  • HSS:
    • Limited or no heat (can weaken structure)
    • Use approved pulling methods
    • Sectioning or replacement often required
  • Aluminum:
    • Controlled reshaping with minimal force
    • Glue pull or specialized dent repair
    • Avoid overworking to prevent cracking

Heat Limitations & Structural Considerations:

  • HSS loses strength when overheated
  • Aluminum weakens and distorts easily with heat
  • Always follow OEM temperature limits

Corrosion Protection & Finishing:

  • Apply anti-corrosion coatings
  • Use proper primers and sealers
  • Ensure isolation between dissimilar metals
  • Refinish using manufacturer-approved processes

Justification:

  • OEM Procedures: Ensure safety and proper structural integrity
  • Safety: Prevent weakening of advanced materials
  • Repair Quality: Proper techniques ensure durability and appearance
500

You are refinishing a repaired panel on a late-model vehicle and must blend the new paint into the existing finish. Develop a complete refinishing plan that includes:

  • Surface preparation
  • Color matching and blending techniques
  • Spray application steps
  • Environmental considerations
  • Final finishing and quality control

Surface Preparation:

  • Clean and sand adjacent panels for blending
  • Apply primer, block sand, and seal as needed

Color Matching & Blending:

  • Use paint code and spray-out card to verify match
  • Adjust color if necessary (tinting)
  • Blend basecoat gradually into adjacent panel

Spray Application:

  • Apply basecoat in light, even coats
  • Extend each coat slightly further for blending
  • Apply clearcoat over entire panel or blend area

Environmental Considerations:

  • Maintain proper booth temperature and airflow
  • Control humidity and dust contamination
  • Use proper PPE (respirator, suit, gloves)

Final Finishing & Quality Control:

  • Inspect for color match, gloss, and defects
  • Wet sand and buff if needed
  • Ensure smooth transition between old and new paint
  • Follow OEM and shop quality standards

Justification:

  • Proper blending ensures an invisible repair
  • Environmental control prevents defects
  • Following procedures ensures durability and professional results
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