I have a car with ABS plastic door panels. These door panels are prone to crack at the trim where the panel meets the window. It seems that stress is applied to areas of the door panel and it causes the cracking. I’ve replaced one door panel and it was very expensive and now the passenger side has started to crack. I caught before it got very big but now I’m working on ideas on how to prevent it from getting bigger or even happening to the new door panel. I have the old panel to do some practice work on so I’m open to suggestions. I was thinking of using a composite to reinforce the back but I don’t have a clue what to use or if it would even work. To repair the small crack I have I will probably buy a plastic welder and fix the crack then I would like to reinforce it. Any suggestions and ideas would be appreciated.
A pu adhesive intended for repair of ABS car bumpers would probably work fine. Bond some sheet aluminuim over the areas subject to cracking might do the job.
As with most auto repairs, I think you can just hit up an auto-parts or hardware store, and find fiberglass repair kits. As for the resin melting the ABS, I can’t say. But any sort of good epoxy coating fiberglass on the plastic, will take away the stresses at the crack zone.
You can always use a plastic welder first if you want. Then renforce the back with fiberglass. I’m sure 2 layers would work well.
Polyester resin doesnt stick to ABS very well, so while it is certainly possible to reinforce ABS with GRP, you may have to contend with poor bond between the 2 materials.
Buick and Chevrolet used aluminum sheet to stiffen their interior door panels. Sounds like a great idea to me.
Uhhemm, pardon the Tony Stewart in me, but Home Depot sells aluminum flashing in rolls in the roofing department. lol Werksberg is laughing his butt off right about now 
I have read (but can’t find reference) that you can heat treat PVC to get a resin, PE or epoxy to bond better. I’ll post when I find it. There’s also these guys…
http://www.neopoxy.us/adhesives.html
Who claim they get full bonding to PVC’s with their epoxy adhesives. I’ve used Interlux 2 part epoxy putty to fix plastic parts with good results. I believe it’s stuck well but not truly bonded.
Wouldnt it be a whole lot easier just to get some PU adhesive, designed for repairing ABS car bumpers?
Yeah probably CB! lol I used what I had as I just got done fixin’ a few small gouges in the bottom of my boat. It ain’t pretty but it worked.
I’ve been using this two part glue for repairing ABS cracks… it sucks. It doesn’t actually bond to the ABS and in about 5months of being on my motorcycle the crack has reared it’s ugly head once more. I was disapointed because i spent so much time and $ repainting all the abs panels on the bike.
I guess that is a bit off topic though.
The ABS bumper repair products generally work very well indeed, and here in the UK are easily available, and should be fine on most plastic fairings.
ABS is a modified PolyStyrene and PER will melt it.
Another way is to stop the crack by drilling a little stop hole well at the end of each crack.
Go to a plastics warehouse and they sell solvents (not a glue but a solvent to melt the pieces back together) like Weldon for any plastics.
Tape the outside to prevent runs or leaks to the outer finish side.
Clean with rubbing alcohol (acetone may melt it or worse…)
Use a needle applicator to run the solvent into the crack and let it sit for a day or two as strength increases with time drying.
But the sounds of it, the whole ABS panels are degrading (non made in the USA ABS?) from no UV protection…
Poor design is really the cause. The car isn’t that old and the door panel is even less old. The panel is only a couple of years old. There are 3 notches in the door panel along the top where the rubber trim that meets the window is stapled to the plastic. It’s at one corner of each notch where the cracks seem to form. From what I’ve read a lot of people blame the rubber trim being stapled to the panel but I really think it has more to do with the notches.
Right now the plan is to plastic weld the crack and then try to reinforce the area. Seeing as the crack is very small I would like to keep from making the panel look too bad. I caught the crack before it got too big and you can only see it when you are very close to the panel (within a few inches). I thought about drilling a hole to stop the crack from spreading but that will make the area more noticeable.
That doesn’t sound like a bad idea. Do you have a link to give me an idea for the adhesive?
Any good car body repair supply place will stock pro quality PU adhesive kits intended for bumper repairs.
However these are generally quite costly, so have a look in car parts place, which should have smaller kits for home users.
Tech details of these products can be found by having a looking on the Wurth site, and using the search option.
Thanks for the help. When I posted I was thinking of a way to use carbon fiber or fiber glass to reinfoce the panel but with your suggestions I’ve started thinking of other things I could do. Since I’ll be plastic welding the crack I’m toying with the idea of plastic welding another piece of plastic to give the area more support too.
Quick question does the PU adhesive cause a smell after it’s cured? Since this is for inside the car and seeing some serious heat being in Texas I thought I should ask.
If you have proper plastic welding gear, and the right filler materials, it would be easy to give the repair some extra strength, by adding some thickness to the plastic where it tends to break. However if plastic is becoming brittle through UV exposure, repair is going to be difficult no matter what method is used.