HELP....Seat/Tail Light Cowl Repair Tips

I'd like to get some advice on how to stop the crack filler on the outer side from cracking on this repair. I started out with some small cracks in the usual spots. I reinforced the back with fiberglass. Now I'm trying to fix the outer side. I tried a bondo type crack filler at first but that was not flexible enough. I went to the local paint store and was told to try this SEM bumper repair bonding agent. But as of so far it cracked out on me again. Maybe I didn't prep it good enough to bond right ( I used a ball dremel to cut a small V shape ) or maybe I still need to work it a bit more. It is getting a bit late tonight so I gave in. Can some of you give me some advice?
THANKS

 

that stuff is crap... you need to stop the crack... I would drill a small hole at the end of the crack cut a trough in the crack weld with plastic... sand prep prime and paint
the tail section on the gen 2 by npow are all brittle and will keep cracking.. your best bet would be to get some racing plastics and retro your lights into them....

 

Crusty is spot on. That crack is going to continue unless you stop it. And the very small hole at the end of the crack is the answer. But makes sure you have the end of the crack.

Many people here have had a lot of luck with this product. It didn't work for me but many here who seem to know a lot more than me seem to have had success:

PLASTEX PLASTIC REPAIR KITS

When it dried, it dried quite hard and sands well. I was trying to "weld" two pieces together and maybe I was expecting too much of it. But to fill in a crack and med your type of repair, I would think it would perform great

 

Thanks Guru...Thanks Crazy!!!
All I can say is....Duaaa to the drilling the crack. Don't know why I didn't think of that since I used to do it in the avaition field when I was like 16. We won't say how many moons ago
I tried the local shops for the Plastex but no go.
Will try to order on-line with the handy link Crazy sent.