Preparing for door panel repair

I've been doing the research and will be getting ready to repair my cracked driver's door panel when the weather breaks and becomes more spring like.

I was curious what kind of plastic people are using to reinforce the back side of the panel. Can I get some some sort of flat stock somewhere or do I have to use the plastic from an actual door panel?

Try the archives... https://gmlongroof.4umer.com/t12146-door-panel-dilemma

Lots of great stuff in there...

You can get styrene flat stock from hobby stores. The brand name is Evergreen Plastics. If you do not have hobby stores near you, you may be able to get it on line. The have different thicknesses up to, I believe, 1/8 inch. The 1/8 inch is sufficient to reinforce the door panels. You can also use pieces of other door panels. Sometimes the shapes of the door panel pieces lend themselves to the shape of the door where you are repairing it. You can also add some fiberglass window screen to the panel joint and use the solvent to allow you press it into the plastic like you would use resin when making a fiberglass reinforced part (do this after the initial MEK gluing of the panel dries). After adding the fiberglass screen, put the reinforcement over it for even more strength in the already stressed area.

Always work from the back side of the panel.

Thanks for the replies. I've read the post that Andebe referenced numerous times and it is an excellent guide for doing the repair. I like the idea of using the flat stock the best as it seems very easy to store. I have very limited space.

I just did a web search on working with styrene (HIPS) and am amazed at how much info there is. I have not taken the door panel off yet so I'm not familiar with the shape of the back side where the crack is but I'm hoping to be able to shape the styrene if there is any contour to the back side of the panel. I should be able to apply heat with a heat gun while the sheet is resting on top of a form. I guess the trick will be getting the form just right and applying even, gentle heat. Maybe I won't have to shape it, we'll see.

I see HIPS is available in quite an array of thickness while 1/4" seems to be the thickest. It seems to me that 1/4" may be overkill and may be harder to mold. I saw in the referenced post that Fred recommended to double up the 1/16" sheet. Does that mean 1/8" is ideal or just recommended based on the materials on hand? Would 1/4" be better? When I look at my ruler 1/4" seems really thick. Is there any chance that thicker material could cause clearance issues when fitting the panel back on? Once this stuff is applied there is no chance of getting it off easily.

I would suggest the 1/16 or 1/8 inch. The 1/4 inch is overkill, and depending on where the repair is, it could cause interference. It is also difficult to cut, and mold. You can probably heat form the plastic, but you need a pusher to force it into the contour of your mold. It is easy to overheat the plastic, so be careful. Make sure the surface you are gluing is smooth. You can make the joint stronger with the fiberglass screen technique. I have used it at the bottom of the courtesy light opening, and it makes it a lot stronger. You can even put the screen between layers if you are doubling up the 1/16 inch styrene making it even stronger.

The back is basically the same contour as the front, given the thickness of the plastic. The only area that is difficult to work with is at the bottom of the courtesy light opening. There is very little plastic to attach to.

When doing the initial gluing of the part, you can use weights, tape, and clamps to hold the panel in position while the glue dries. Just do not use them on the visible side directly on top of the glue joint, or it will mar your finish. Stay about an inch away from the glue joint.

I have checked on the MEK substitute, and I would NOT recommend it. It does not do nearly a good of a job as the real MEK.

Thanks Fred for the additional tips. It will help tremendously to know what to expect before getting into the repair. Good thing I was able to get the real MEK.

Would there be any advantage to melting some of the styrene in the MEK to make it thicker? Or is it not really that big of a deal to work with the watery MEK? I have a glass dropper I can use to apply the MEK. It seems like that may be easier than brushing it on. I'm planning on playing with some of the styrene and MEK before attempting to touch the door panel so I may just try different things and see what feels better for me.

I melt some plastic in MEK for areas I can not get strips of plastic into. I make a paste, and apply it over the fiberglass screen that I have embedded in the back of the panel over the repair. It adds some strength.