I See Cracks
Thread Starter
Instructor
Joined: Jun 2008
Posts: 149
Likes: 0
I See Cracks
My urethane bumper was so called primed and ready to paint when I bought my vet (along with the rest of the car) however, I see tiny craks in primer on the bumper.
Whats up with that and how do I fix it.
How would I know if my bumper needs to be replaced or not, it seems very flexible but it looks sound.
Whats up with that and how do I fix it.
How would I know if my bumper needs to be replaced or not, it seems very flexible but it looks sound.
Burning Brakes
Joined: Jan 2006
Posts: 1,223
Likes: 174
From: Fort Wayne IN
You will have to grind down the cracks and see how deep they are. If they are in the topcoat/paint/sealant/primer that can be fixed easly. If they are in the bumper and there are only a few of them, you might be able to fill them with resin, but if there are a lot, you will need to replace the bumper or they will keep showing through.
Pro
Joined: Dec 2002
Posts: 560
Likes: 1
From: Mooresville NC
Since urethane flexes, it doesn't appear that a flexing agent was added to your primer or if it was it's not adhering correctly. It's been a long time since I last painted a car, I don't know if they changed the name of that product (flexing agent). If you are going to paint the bumper yourself, I would start researching out a couple of paint books. Rattle can painting won't work unless it specifically states it can be used on flexible bumpers. Fiberglass bumpers won't have this problem. The previous owner of mine obviously didn't do this because it's a PIA to paint the car, then mix new paint for the bumpers. I now have spider cracks in the front. The back looks like it was painted off the car, so that looks great.
Good luck.
Good luck.
Racer
Joined: Aug 2006
Posts: 493
Likes: 1
From: yarmouth ma
do not grind anything! sand down that bumper with 220 wet sand paper, get all that garbage primer off there. buy some spi epoxy. (look on forum for number) spray epoxy over bumper (sand 400 grit after 220 before epoxy) you will not need a flex additive. then paint with urethane paint and clear, then you will be done.
Thread Starter
Instructor
Joined: Jun 2008
Posts: 149
Likes: 0
ok do I use water with the 2220 wet sand paper....I know that sounds stupid but I just want to do it correctly.
Also, does the urethane paint come in many colors that will match the paint for the rest of the car?
Thanks, K
Also, does the urethane paint come in many colors that will match the paint for the rest of the car?
Thanks, K
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Drifting
Joined: Jan 2004
Posts: 1,991
Likes: 3
From: Piscataway NJ
I had this problem on my 77 they were hair line cracks.And it was in the paint not the urethane bumper. I used 220 dry by hand then 320 wet. Just keep a good eye on the cracks as they dissapear. Like the previous post do not grind anything. I am old school I used lacquer with the flex additive. The bumpers and the body always were a shade off.
Drifting
Joined: Oct 2004
Posts: 1,259
Likes: 7
From: Ontario
ok, do yourself a favor and replace those old urethane bumpers before you paint the car. Don't **** around with them, you are waisting money and your sweat. They degrade over time. Get either new ones or the flexible fiberglass ones. My preference is fiberglass. You will be sorry down the road trying to save them...even if your current problem is only with the primer replace them. You do not want to put a new paint job over 25+ old urethane. They go wavy and crack, orginal C3 ones are at end of life.
Last edited by Retro78; Jul 7, 2008 at 12:42 AM.
Thread Starter
Instructor
Joined: Jun 2008
Posts: 149
Likes: 0
I am going to restore the bumper. I can't afford to replace everything that is a little worn or needs TLC. If I did that I should just buy a new vet.
Thanks for the info and reponses, they are appreciated.
-K
Thanks for the info and reponses, they are appreciated.
-K