540 vette

I molded in the front and rear bumpers on my 80. I used the flex fit bumpers. The reason I used them was that I had no intention of molding in the bumper but the flex fit bumper fit like garbage and by the time I cut them to fit, molding was the only option. Now I have molded in bumpers before with no issues. I have done them on a 77 I had and used standard resin and mat and had no shrinking or cracking issues.

Well I molded in the bumpers on my 80 using standard resin and matte everything was painted and went fine until the bumper heated up and only one small section of the d/s front bumper and rear bumper would show some shrinkage. Ground it down and used the proper SMC resin, I only did the areas that were affected. Painted the car and sure enough the same spots showed shrinkage when they heated up. Next up was the West system. Same thing after painting, area heated up and showed the same lines. This time I ground the areas a little and just used plastic and repainted and got the same results.

Well I have tried everything that is available and I am not painting the car again. I honestly think the problem is caused by the flex bumpers. They are made of thinner fiberglass than normal glass bumpers. Maybe that is causing it to shrink in those spots. It really weird because the only affected spots are about 6 inches on the d/s front bumper and about 4 inches on the side of the d/s rear bumper.

DUB

YES...you will not get this to go away.

QUESTION 1: What filler ...if any did you use OVER your laminated areas????

QUESTION 2: Did you apply heat with an infrared heater on all laminated areas????

QUESTION 3: What material did you use to attach the bumper to the body????

I agree..I will NOT install flex glass bumpers on a Corvette for any cost. And...if you put rigid fiberglass bumpers on your car and plan on molding them in...which I do not do any longer either....You need to laminate more fiberglass and resin in this type of bumper also to give it more strength.

For any person reading this wanting to mold in their bumpers...just consider this. A person can not expect the bumper to be perfect when its thickness and rigidity is no where near to the body panels that it is being boned to. And with a few service operations that require the bumper removed...just be prepared when time and costs can exponentially increase due to a panel can not be removed to do a repair.

DUB

540 vette

I used Rage Gold for any filling. No heat. Bolted everything together, just like the last car I molded the bumper on and it lasted for years. I honestly think it was the flex bumpers.

The thing that is odd is that it only happened to the drivers side and in a small area.

DUB

You must have the touch. I have a process that is quite different.

DUB