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I have given up on buying a used fiberglass front bumper. SO REPLACING THE BUMPER IS NOT THE POINT OF THIS POST. This is about repair...
So I am going to repair the original urethane one.
Decades ago I drifted in the snow, and tapped a divider with the front bumper.
The urethane is not cut, not split, but there is a low spot that needs to be filled.
What material can I use to fill this low spot. I saw on youtube that someone used epoxy on top of urethane.
That did not seem right, but I don't know.
So my question is... what type of products are out there that can be applied (similar to bondo) and sanded to fill the low spots in my original 84-90 urethane front bumper.
Thank you very much... and remember... I know I can buy a new one... this is about repair!!!
Last edited by lawcorvette; Oct 6, 2025 at 05:35 PM.
You have made it clear you don’t want to hear about replacement. However, this bumper isn’t like old ones on things like the 69 GTO where they’re difficult to repair but can be. This bumper is plastic. Thin plastic. Any type of filler will not last and that’s why so many of these bumpers have spider cracks under fresh paint jobs. Here’s a picture of a 92 bumper I’m replacing. It’s about 1/8” thick plastic.
Here’s also a pic of a 69 GTO Endura bumper I’ve just restored and used SEM epoxy and special bumper filler followed by Transtar 1201 flexible primer. None of these products would work on the thin plastic of these corvettes. If you have to repair it you would need to use heat and try to get the plastic to reform flat. There are plastic bumper repair kits that are similar to fiberglass repair where you use material, but that is for repairing cracks.
What method you use will depend on deep the depression is. When I did mine I wasn't filling in a very deep area, just leveling out a few scratches and a high/low area. I used Colad UV putty, which worked well (so far no issues). If it is a deeper area then you will want to use a product made for it, 3M has a product that works well. I did not need to use it, but you may.
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Originally Posted by RWDsmoke
I leveled a dent in my bumper by clamping an aluminum plate on each side with c clamps and heating with a heat gun to about 250 degrees.
^^^====Try this first as it's likely what a bumper repair shop would do first. Minimize any filler needed to level a spot by "bending" the bumper back straight!!1
I have given up on buying a used fiberglass front bumper. SO REPLACING THE BUMPER IS NOT THE POINT OF THIS POST. This is about repair...
So I am going to repair the original urethane one.
Decades ago I drifted in the snow, and tapped a divider with the front bumper.
The urethane is not cut, not split, but there is a low spot that needs to be filled.
What material can I use to fill this low spot. I saw on youtube that someone used epoxy on top of urethane.
That did not seem right, but I don't know.
So my question is... what type of products are out there that can be applied (similar to bondo) and sanded to fill the low spots in my original 84-90 urethane front bumper.
Thank you very much... and remember... I know I can buy a new one... this is about repair!!!
I'd defer to the guy above that has two Pontiacs in the background (GTO and what looks like a 74 Super Duty). But my daughter just repaired an SMC trunklid for her car. That's not the point of this though, we inadvertently used the incorrect stuff the first time, which I THINK is the right stuff for the bumper (you'll see that in the video). If I'm not mistaken, the bumpers are Reaction Injected Molded urethane compounds (RIM). For that, there's the 3M SMC repair. It's not really SMC, don't even know why it's in there, but it's really good stuff. It remains flexible after the repair. But preparation (sanding to make sure it looks flat) is important.
Like her car, our C4s are made up of SMC, RRIM, RIM, and TPO for all the different parts.
Another option though... have you thought about getting a used bumper? Corvette Generations here in Central Florida has a junkyard of about ~50 C4s. Might be worth checking out.
Urethane bumper repair
