A common issue for any owner of mid-90s and newer cars is dealing with broken interior plastic. No car is more fraught with busted plastic than the 4th generation GM F-body, which is the 1993 to 2002 Chevrolet Camaro and Pontiac Firebird. Due to the poor design of the factory door panel, there is considerable stress in the upper rear section of the door panel. Within 20,000 miles, just about every Camaro and Firebird owner experiences this problem. Since GM stopped producing this panel several years ago, finding a replacement is not easy, so a door panel repair is in order.
Finding The Right Door Panel Repair Technique
There are many tales of how to repair the panels floating around, some work, some don’t. The problem with these repairs is that they do not address the real problem, which is the need to flex. Even a little flex will help alleviate the stress that causes the panel to crack. Most repairs are done using fiberglass resin and cloth, which does not flex well at all. Eventually, it just breaks off. To solve this problem, we had to find a different solution.
The OEMs have been using structural body adhesives for some time now, even the 2000 Pontiac Trans Am we are working on uses this to secure the doors to the body. This special adhesive is designed to bond to just about anything- metal, wood, fiberglass, plastic, it does it all. Once cured, the adhesive is very strong yet is has a slight yield, it will give just enough to relieve the pressure while holding fast to the plastic. The one problem with it is the method of delivery.
Structural body adhesive must be mixed in a certain ratio, which requires an expensive mixing gun that utilizes metering tubes and mixing tubes. This is great for using the adhesive in large amounts, but all we need is a small batch. We discovered the same type of product in an easy-mix package from Bondo. It has most of what you need for the basic repair. We also needed some CA glue (Cyanoacrylate, or super glue), some sand paper, light body filler, and texture paint.
Preparing The Door Panel
As with any repair like this, the surface must clean and well prepped. We cleaned the panel and then sanded it with some 80-grit sandpaper on both sides to give the epoxy some grip.
If you want the repair to last, you have to stop the crack. This is done by drilling the ends of the crack with a small drill bit. A crack will continue to tear the plastic unless you remove the stress point, drilling does just that.
We also sanded the inside edges of the crack, adding a bevel. This provides more surface area for the epoxy to hold.
Starting The Door Panel Repair
The epoxy is mixed up in a 1:1 ratio, and then lightly applied to the panel.
There must be a backing for the repair as well; simply spreading the adhesive across the break won’t last unless there is solid structure underneath. This can be steel, plastic or wire mesh. We used a small piece of wire mesh. The front side of the panel was treated with some more epoxy, just a little.
Once cured, the refinishing was completed. We lightly sanded the outer surface with 200-grit sandpaper, and then used some 3M glazing filler to smooth out the repair. You don’t want big scratches on the outside, those are hard to cover. Once the filler was cured, we finish sanded it with 200 grit, then 320 grit. The glaze sands very easily and works really well for this type of work.
Painting The Door Panel Repair
Now that the repair is done, we have to paint it. This is tricky and you may want to practice on some scrap cardboard or metal. We used two types of paint – a bumper trim paint for texture and then a color match paint for the color. This car has a black interior, so it is easy. We laid down five coats of bumper trim paint, holding the can about 12-16 inches from the panel (this is important for the texture), and then dusted it with the black interior paint until the sheen matched. Each coat takes 10 minutes or so to dry, you want to check the sheen after each coat. You can even go back and forth with the two products, provided the colors match.
We spent several hours repairing one door panel on the Trans Am. The finished product looked so much better than the original finish, we will likely be refinishing the entire interior. We drove the car around for several months before writing this story to gauge the longevity. With previous repairs, the cracks showed back up within a few weeks, but after several months, this repair has shown no signs of returning.
Check out all the paint & body products available on NAPA Online or trust one of our 16,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on door panel repair with Bondo, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Source: NAPA Know How