Hello everyone, It has been a while since I have posted anything so I figured I would just toss out my issue and see if anyone has some suggestions for me or can point me in the right direction.

Upon sanding down my new rear bumper and prepping for primer blocking and paint. I would be lying if I said I was surprised to find that the bumper has some low spots, one in particular is a low spot that is about 4 inches wid and 3 inches tall of a low spot that is approximately 1/8" deep or so. Its to a point that I am a little concerned about putting body filler on it or even the fiberglass filler. I was thinking I should probably just rough up the low spot and put actual fiberglass and resin in the low spot to bring up the low spot. The bumper only has the gel coating on it so it does not have any paint on it. My main question is how much should I get into the fiberglass to ensure I get a good adhesion. should I just rough it up with some 40-80 grit or should I get into the fiberglass some and dish out the low spot some and then build it back up. Any help or guidance on where to look would be great. I've done some searching and research on fiberglass repair but haven't seen this particular senario that I can remember. Thanks in advance everyone.

 

J, is this for your '74 Corvette?

It would probably be helpful if you posted a couple of pictures of what you are describing. Is it an original urethane bumper cover or one made of a different material.

Also, if it is the original bumper or even one more than about 10 years old, it might be prudent to start with a new one. As urethane bumpers age they become more brittle and rigid. How rapidly they age varies with the environment they are in and also how many time they have been painted previously. A little more information about the bumper you're working with will get you some more meaningful responses.

Good luck... GUSTO

 

I appreciate the reply. I was pretty vague in hindsight. Yes this is for my 1974 Corvette

I will post some pictures of what I have but in the mean time the bumper is a new unpainted fiberglass replacement bumper, 1 solid piece with the mock 2 piece look. I don't know much more about it since the previous owner had purchased it but never prepped it or put it on the car. I've test fitted it a couple of times and have started scuffing the gel coat to get ready for primer when I noticed the wave/low area. I was using a wide (12"ish) block to keep the bumper straight on the flat areas. I will try to get pictures posted within the next couple of days.

 

They do sell a flexible filler to repair bumper fillers. Check your local auto body supply shop. I've used it several times on bumper covers with no issues.
The headache is trying to block it flat when everything around it is flexing. But it can be done.

John

 

J, here are a few links to some good tips on fiberglass bumper installation. The 1st one was posted by Forum member DUB who runs a Corvette Shop in Charlotte, NC. He's posted lots of responses and helpful tips here on the Forum and is always willing to answer questions when folks run into a problem. He doesn't post as much lately, but if you need his assistance you can click on his name ans send him an email as well. I would definitely read through that post first.

Good luck... GUSTO

Installing a RIGID fiberglass front bumper cover for a 1975 Corvette

https://www.corvetteforum.com/forums...b-bumpers.html


https://www.facebook.com/DynamicCorvettes/videos/c3-fiberglass-bumper-installation/409026083329323/