Finished painting the axles and diffs yesterday. Very pleased with the Mastercoat products. I have used POR15 very successfully in the past but I was sold on other's reviews of the Mastercoat products and I also wanted to use a product with its own topcoat paint. Like all of these products, prep is key.
So ideally I would have powder coated these parts but I didn't want to tear the diffs completely apart to get to a bare housing that could go in the oven. And once I pulled the axles, etc. I saw that the rear axle bearings looked new. In reviewing Redline Cruisers advertisement for this 55 from only a few thousand miles ago, they went through both axles, front and rear. So, rightly or wrongly, I made the uncharacteristic (of me) decision to leave the diffs on the axles, button up the ends with gorilla tape, and to get everything sandblasted. I did pull the washers off so that the sandblasting would get as much surface as possible but otherwise that was the only other prep that I did. I also asked my sandblasting guy (also my powder coat guy) to either tape up the rotating part of the diff output or to at least stay away from that end. Well something got lost in that translation so everything was sandblasted. It doesn't appear to have hurt anything so se la vie.
After blasting I applied the metal prep with a paint brush and let it dry for a couple of hours. Where there is any remaining rust, you get some reaction and bubbling. I came back a couple of hours later and wiped those areas down with a rag soaked in metal prep which helped smooth those areas out. Lastly I used a scotch brite pad and occasionally even a wire wheel cup to smooth up some areas prior to applying the Permanent Rust Sealer. I then let the parts dry overnight before proceeding with paint.
The rest was pretty cut and dry. Two coats of the silver Permanent Rust Sealer applied approximately 3 hours apart, followed by 2 coats of the AG111 (in satin black) the next day. The AG111 is a two part system and I let it dry a little longer between coats, maybe 4 hours or so. Use a nylon/polyester brush for the Permanent Rust Sealer and a china bristle brush for the AG111. The Permanent Rust sealer is very thin; like viscosity of water. The AG111 is much thicker, like latex paint.
1/3 cup of the Permanent Rust Sealer was almost enough to do one coat on all of these parts. 3/4 cup (1/2 cup of part A and 1/4 cup of part B) was more than enough to do a coat of the AG111. I could have easily done one coat of the AG111 with 1/2 cup total but I just used the measuring cups that I had on hand.
After sandblasting:
After metal prep but before I had used the scotch brite pad
After Permanent Rust Sealer
And after 2 coats of AG111