Plastic Grille Repair

During the late Sixties, most domestic car manufacturers started using ABS plastic for many body parts. There were several reasons for this, the most blatant of which was cost. Why are you not surprised? Reducing vehicle weight was the second major reason, and plastic seemed the logical way to do it.


One area they addressed is the front grille. It would be damaged in an accident whether it was metal or plastic, so why not damage cheaper-to-replace plastic? However, as the plastic ages, it becomes progressively more brittle from UV rays, ozone and temperature changes. After 30-plus years, this 1969 GM plastic grille was showing its age, full of cracks and discoloring. For the dedicated restorer, fixing an original part is an important part of the process, so we'll give you a couple of hints on how to accomplish this task. The investment is small and the rewards large.

Damage
After removing your grille and any metal trim, carefully inspect the piece for broken contact points, stress cracks or dings from rocks and the like. This grille had been seriously damaged from above, either by something falling on it or someone leaning heavily on the top edge. After a thorough inspection, we determined that automotive body filler should be used to patch some of the cracks and a bonding agent used to glue the badly broken areas back together. Since some of the mounting tabs have literally been broken off, we will have to do some fabrication to fix the damage.

Grinding
We used a grinding tool to enlarge the cracks and broken areas in order for the body filler to get a better bite on the surface. A larger and deeper contact area than the small original cracks will provide a better adhesion base for the repair. The material will flow into the grooves we created and flow completely between each piece. Once the material has hardened, any overlap or runs can be sanded from the surface. Use caution with the grinder as you can cause more damage than you're trying to fix with a quick slip. Simply take your time and tread lightly.

Cement
We followed the mixing instructions and applied the pasty body filler to the smaller cracks. You can control the speed that the filler sets up with the amount of hardener you use. The bonding agent has more of a liquid consistency, so we used it to fill and glue the big cracks. If you have trouble keeping the sections under repair together, try using tape to hold the parts until the adhesive dries. We allowed all the materials to cure overnight. A mounting point at the rear was broken off completely, so we used a combination of materials to glue it back in position. It isn't pretty, but it is holding and invisible.