POR-15'ing the underside, wire brush woes Options

[jandro62]

So I'm in the process of removing surface rust from the underside of the teener. I bought a bunch of marine clean, metal ready, por15, & topcoat. I'm actually getting the original blue color to come out in places! Do I strip the paint from the underside of the car also before applying the chemicals? Should I just try to remove as much of the rust & dirt under there as I can and then go at it with the chemicals?

Also, there are a couple of small (dime & nickel size) holes down there. How do I deal with those?

The only severe spots for rust etc. seem to be near the rear jacking donuts where it seems the car was improperly jacked and the metal got crunched a bit.

Will post pics as soon as camera charges.

[newdeal2]

Not sure about putting the 15 over paint but I would sand it off paintwherever possible before prep and get rid of the holes. Grind away all of the rust and crud to bare metal and weld in patches.

[Doug Leggins]

I recently painted the bottom side of my 914. I was going to paint the entire bottom side with POR15. Just to get familiar with how the product worked, I put the POR15 on an area about 8" x 18". Some of the area was taken down to bare metal and some of it still had the paint on it. I wire brushed the painted area, followed the POR15 product instructions - marine clean, metal ready, POR15. A few days later I was wire brushing the surrounding area with a drill and a cupped wire wheel and decided to test the POR15 adhesion. The POR15 applied over bare metal had pretty good adhesion. The POR15 applied over the prepped paint did not adhere very well at all - It peeled off in strips.

Others here have stated that they have successfully used POR15 over paint and it has worked well. I chose to not use the POR15 on the bottom of my car because I did not want to remove all of the paint to insure good adhesion. THe bottom of my car was in very good condition so I decided to use an epoxy primer and an industrial enamel on the bottom side of my car.

Try a test area and determine if the adhesion of the POR15 over the painted area works for you.

The test I gave it may have been a bit severe - not likely to see action like a wire wheel going at the bottom side of a car. What I did not like was the fact that once it started peeling it came off in strips up to about 3" long

[jandro62]

thanks for the info. I too have a lot of the original paint left on the underside of the car. However, I found these 3M paint stripping wheels that don't spark like a wire wheel. I'm working my way across the underside of the car. I figure the POR15 with the topcoat will be better in the long run. Also, my car is now silver, so unearthing the adriatic blue paint all over the underside leaves my car a bit odd.

[STL914]

jandro62,

Are you doing this with your car on jack stands and you on your back? I've been considering the same procedure on my '72 after seeing pics of Doug's teener here on the BBS.

[Levi]

POR15 adheres best to a rusted surface.