Mastering Plastic Repair

October 14, 2018 | By | Reply More

Plastic reconstruction is simple. We offer tips on deciding between reshaping, adhesive bonding or plastic welding for your repair.

Body panels from a 1990 BMW Z1.

BMW has extensive experience with plastic body panels. Shown here in red are all of the plastic body panels from a 1990 BMW Z1.

Use of plastic in vehicle manufacturing helps improve fuel economy, reduce emissions, design safer structures and create unique body shapes and aerodynamics. With every ten percent reduction in vehicle weight, engineers can extract a corresponding six-to-eight percent increase in fuel economy. By 2020 the amount of plastic used in the average car will reach almost 800 pounds, double the 2014 amount of approximately 400 pounds, according to the report “Weight Reduction in Automotive Design & Manufacture” by industry forecaster IHS Chemical. If you haven’t already, you should be developing plastic repair skills. The good news is, it’s easy.

Safety Caution

The adhesives used in plastics repair can cause eye, skin and lung irritation. Avoid eye and skin contact. People who are allergic to isocyanate should avoid handling polyurethane and plastic adhesives. Both contain isocyanates.

New Plastic Parts


Mask off areas that contain raw plastic substrates that are not to be painted.

If installing new OEM primed plastic parts, start by inspecting the component for any damage. If you find only minor imperfections, such as fine scratches that do not penetrate through the as-shipped e-coat or primer, you can sand out the blemish using a fine grit paper such as P600 or P800. Then rub down the entire part with a ColorSystem Soft Pad Gray.

If the panel or bumper contains raw plastic substrates, check your repair information to see if you should not paint any portion of the component. If so, mask or tape off that area of the part.

Three Plastic Repairs: Reshape, Bond or Weld

Reshaping, plastic bonding and plastic welding are three different methods available for repair of exterior body and other plastic panels. Each has features that make it advantageous for some applications but perhaps less so for others. Selection of the appropriate repair method is dependent upon the type and extent of the damage. You can find guidelines for which damage conditions suggest which repair method by searching in the BMW workshop information system ISTA.

Repairable plastic components include bumpers (excluding the 2000-2003 Z8 Roadster), side sill trim, door outer skin, roof, decklid, soft top (convertible) compartment lids, and other parts made of composite materials. You cannot repair tanks that contain fluids, including fuel, coolant, brake fluid, windshield washer fluid, and other liquids. If cracked or damaged in a manner that results in the potential to leak, you must replace them.

Different plastic types require different repair procedures. However, if you are using adhesive for plastic bonding, or reshaping minor dents using mild heat, you don’t need to worry about the material type. Your BMW repair information will specify which repair procedure is best for a given plastic component. You only need to identify the material type if you are using the


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Category: Structural

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