Two questions.

1) Do I need to shim up the bumper to mate with the Flexglass bumper? The car is a 75 and I took out all the bumper shims to align the new bumper cover. I know that tail lights will be attached to the bumper cover and not the bumper anymore.

2) Is normal polyester based body filler a good element to fill all the areas where the new bumper doesn’t quite line up? I can see I will need to build some areas as much as an 1/8” to get the lines to match.

 

I shimmed the aluminum reinforcement to meet the cover. You should be able to bolt the bumper back to the reinforcement at the tail light area. If not, DO NOT FORCE IT!

I used short strand fiberglass filler (Marglas) to fill the cover then finished it with glaze coat. When doint this, put a layer of 2" masking tape on the body side. This will keep the fille from sticking when you build up the cover and make it much easier to clean up.

You can use body filler if you would like. Just make sure you rough up the surface before applying it.

Good Luck!

 

First, loosen and adjust the aluminum reinforcement so that the new bumper fits the body lines and does not touch the reinforcement (don't tighten the reinforcement until the project is done). You may need to remove the horizontal rubber strip for a better fit. Due to variances in fiberglass molds and the thickness difference, the new bumper may not fit over the tail light brackets and they may need modification or relocation on the reinforcement. These are an important mounting point for the new bumper and must be utilized to properly strengthen the rear end and take stress off the quarter panels and deck. Your tail lights will mount as they did with the old bumper (you'll probably need to cut all of the holes). The new bumper should fit flush with the body (without stressing it)before you drill the mounting holes or add filler. Rear bumpers generally fit very well after a little sanding and patience, don't resort to filler until you have your best fit. You can sand through the gel coat if necessary in specific areas to improve the fit. You must remove the gel coat before adding any fillers. Use Evercoat "Vette Fill" for adding material to the bumper, you should not need any filler on the body. By the way, now is a good time to check and replace the rubber fuel lines from the sender to the frame while they are easy to get to.

 

Unfortunately the bumper cover doesn’t fit exactly to the body. It is just slightly shorter in width then the body. I have made a best fit, but it will need some filler.

Thank you for the info.