How to repair a broken headlight tab or bumper mount

A headlight and a bumper hang on a few plastic tabs. In a light knock, those are what break: the part is intact but sits loose, rattles and hums over bumps. A new headlight housing is expensive, while a tab can be restored in an evening — if you give it both a metal frame and solid plastic around it.

What a headlight is made of and what must not be heated

The headlight housing is usually polypropylene (>PP<, sometimes filled — >PP-GF< or >PP-T20<), and the clear lens is polycarbonate (>PC<). Don’t heat the lens: polycarbonate clouds, yellows and cracks. Work on the housing only, cover the lens with a wet cloth or foil and move connectors and wires aside. Always take the headlight off the car.

If the tab broke off in one piece

1. Clean both halves of dirt and paint and degrease them. Fit them together without a step and hold them with a clamp or masking tape on the front.
2. Staple across the break. Flat staples on a flat tab, 90° corner staples on a tab at an angle to the housing, inside-corner staples in an inner corner. Two or three staples on each side, each going in to about half the thickness.
3. Wrap it in mesh. Cut a strip of reinforcing mesh extending about 2 cm past the break on each side and melt it in with a smoothing tip. Stainless mesh stays stiff when heated and doesn’t rust inside.
4. Cover it with rod. Rod of the same plastic as the housing goes over the mesh so no metal shows.
5. Restore the hole with a drill once fully cool, rather than piercing it hot.

If the piece is lost

You can grow the tab back. Mesh becomes the frame and rod the body.

1. Shape the frame. Cut mesh with a margin, fold it in two and bend it to the shape of the lost tab. Stainless mesh is stiff and holds its shape.
2. Weld the frame to the housing with corner or flat staples and melt the mesh edge into the base.
3. Build up the plastic. The mini extruder feeds rod straight onto the mesh and smooths it — in layers, letting each one set a little.
4. Shape it with the triangle tip, sand once cool and drill the hole.

A bumper mount is the same, just bigger

Bumper tabs near the wings and headlights are repaired the same way: staples across the break, mesh on the back, rod on top. Bumpers are mostly PP or TPO — pick the rod by the marking on the inside. For long cracks next to a mount, S-shaped staples reinforce the seam along its whole length.

How long it takes

A tab that broke off whole takes 20–30 minutes including prep. A new tab built on mesh takes about an hour: most of the time goes into building the plastic up in layers and letting each cool.