Plastic Structure Repair

Before proceeding, refer to General Plastic Repair Instructions  and Plastic Repair Precautions .

Fig 1: Identifying Damaged Area
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1. Clean and inspect the damaged area. Refer to General Plastic Repair Instructions .
Fig 2: Clamping Damaged Area
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2. Clamp or tape the damaged area in order to maintain alignment.
3. Prepare the damaged area for the installation of a backing patch.
   • If the rear of the damage is accessible, proceed with steps 4 through 6.
   • If the rear of the damage is not accessible, proceed to step 7.
Fig 3: Preparing Damaged Area
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4. Scuff the inner surface with a #80 grit disc on a D A sander or by hand if the access is limited.
Fig 4: View Of Repair Material On Inner Surface
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5. Determine the proper repair material. Refer to Repair Materials - Flexible Plastic Part  orRepair Materials - Rigid Plastic Part .
6. Mix the repair material following the manufacturer's instructions.
7. Apply, follow the manufacturer's instructions, the repair material to the inner surface.
Fig 5: View Of Applied Backing Patch
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8. Apply a backing patch and proceed to step 21. Refer to Backing Patch Fabrication .
Fig 6: Sanding Underside Of Repair Area
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9. If the rear of the damaged area is not accessible remove some of the damaged material in order to form an access hole through which you can slip a backing patch.
10. Cut a backing patch from a scrap piece of panel. Refer to Backing Patch Fabrication .
11. Sand the mating surface of the patch.
12. Reach through the access hole and sand the underside of the repair area.
Fig 7: Threading Waxed Wire Through Holes
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13. Drill 2 holes in the backing patch.
14. Thread a piece of waxed wire through the holes in order to assist in holding the patch in place after installation.
15. Determine the proper repair material. Refer to Repair Materials - Flexible Plastic Part  orRepair Materials - Rigid Plastic Part .
16. Mix, follow the manufacturer's recommendations, the correct repair material.
17. Apply, follow the manufacturer's recommendation, the correct repair material to the mating surface of the patch.
Fig 8: Pulling Up On Waxed Wire
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18. Slip the patch through the access hole.
19. Pull up hard on the waxed wire until the repair material squeezes out on all sides.
Fig 9: Holding Patch In Position
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20. Twist the wire around a piece of wood in order to hold the patch in position until the repair material cures.
Fig 10: Curing Material Using Heat Gun
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21. Cure the repair material according to the manufacturer's instructions.
Fig 11: Clamping Damaged Area
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22. Remove any tape, clamps, or waxed wire used to maintain alignment.
Fig 12: Removing Damaged Edges
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23. On the outer surface of the panel, bevel the damaged area with a #50 grit Roloc disc in order to extend the contact between the repair material and the substrate.
Fig 13: Preparing Damaged Area Using Sander
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24. Using a D A sander, feather out several inches beyond the damaged area in order to remove any paint or primer from the substrate, and provide a proper adhesion surface.
    • Use a #80 grit disc on rigid panels.
    • Use a #180 grit disc on flexible panels.
Fig 14: Applying Repair Material
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25. Carefully and smoothly apply a light coat of repair material to the damaged area.
Fig 15: Identifying Repair Patch
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26. Add mat material as needed to strengthen.
27. Apply a final layer of repair material (1) at a slightly higher level than the surrounding area.
Fig 16: Curing Material Using Heat Gun
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28. Cure the repair material according to the manufacturer's instructions.
Fig 17: Preparing Repaired Area (Rough Sanding)
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29. Rough out the surface using a #80 grit disc on a D A sander or a curved-tooth body file.
Fig 18: Sanding Repaired Area
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30. Finish sanding using a #220-320 grit wet or dry sandpaper on a sanding block.
31. Prime and refinish as necessary. Refer to GM 4901 M-D for a listing of approved materials. Follow the procedures recommended by the material manufacturer.