Vehicles have had some sort of plastic trim since the 1930s when the OEMs made knobs, handles, and other interior bits out of Bakelite. All plastics, even today’s formulations, will eventually fade, chip, crack, and just outright break. While you might just toss a broken piece of plastic trim or just learn to live with it, many pieces can be repaired to live again.
There are all kinds of products out there for plastic repair, but most plastics can easily be repaired with good old JB Weld or cyanoacrylate (CA), otherwise known as super glue. The really oily types of super glue don’t stick very well, but JB Weld works on dang near anything.
Repairing a broken tab is relatively simple, but what about more complex problems such as a missing piece? We are going to show you how to fix your broken plastic trim with some surprisingly simple tricks. Our example is a seat trim cover for a 1974 VW Beetle. When we recently installed new seat covers, and when we removed one of the covers the main side screw boss fell apart. It also has a few cracks that need to be repaired.
Cleanliness is the key to plastic repair. Plastic tends to be a little oily, so you need to scrub it with a good all-purpose cleaner. We also scrub the repair areas front and back with a Scotch-Brite pad to give the glue some mechanical bond. We drilled each end of the cracks with a 1/8 inch bit to stop them from spreading and to relieve the stress in the plastic. Just like a metal weld, the edges are leveled with sandpaper.
We are using two different materials to fix our panel—JB Weld KwikWeld Epoxy for recreating the screw boss area, and cyanoacrylate glue with a quick-cure accelerator to fill the cracks and blending the repairs.
The trick to using CA glue is getting the right thickness for the job. For our project, we used medium-thick glue, which flows like slightly warm syrup and is good for filling small gaps. Thicker glue flows more like cold syrup and is good for filling large gaps. Thin glue flows like water and is good for bonding parts.
Other items we used to complete the repairs is small bit of modeling clay to recreate the missing piece of the screw boss; masking tape; 80, 150, 220, and 320 grit sandpaper; Rust-Oleum Truck Bed Coating to replicate the grain pattern; and Rustoleum Painters Touch semi-gloss black paint to finish the job.
The entire process took us about two hours to complete. Preparation is the key to success, and remember to use only as much glue as you need; adding more will not fix the problem. Now go out and fix those broken plastic bits!