Painting Flexible Steel and Aluminum
I painted a set of Fox Shocks for my Formula III Ski-Doo.
This gives us a couple of unique challenges.
First off is the bodies are aluminum which we paint a lot of aluminum in the snowmobile world.
Second and probably a bit more unique are the springs. What is unique is that they are steel but require flexibility.
Painting Aluminum
What is unique about painting aluminum is that it starts to oxidize almost immediately. Paint sticks to the aluminum fine, but paint has trouble with oxidation. Freshly sanded or blasted aluminum will accept paint fine.
Generally a self etch or epoxy applied within 24 hours of sanding will get great adhesion.
I used my 2k epoxy so that it would fill some previous "tool" marks. I also sandblasted them to remove some poorly applied paint.
Painting Springs
I talked to several paint reps about painting springs to get their take. What is special? Sandblasted steel needs enough fill to fill the small indentations caused by blasting called "blast profile" and the paint must be flexible due to the nature of the spring moving with bumps. I used an epoxy and applied it a bit thinner so that it could flex because epoxies by nature are not flexible. A self etch also could have been used also. I then used my Urethane Single Stage applied over the 2k within a couple of hours for better bite to the epoxy by the urethane.
Some Pictures, enjoy
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All of these parts were lightly sandblasted. The shock bodies were sanded a bit to remove the tool marks as well as possible without going through the work of filling the marks with filler product. The bases of the shocks had some polishing done to them to remove major marks from 20 years of use. I then masked the items so that threads and shafts would not receive any paint. I lucked out and some "fender washers" that I had worked very nice for hanging the shock bodies and effectively masking the inside of the shock body.
Hanging small parts is very critical to getting a good paint job. The springs received a fairly light coat of my 2k epoxy, the bodies of the shocks received a heavier coat to help fill remaining tool marks which it did nicely.
I then allowed the epoxy to flash about 2 hours and top coated with my 2k urethane with flex additive added.
We then waited about a week or so to assemble the shocks so that the paint would be set up so chemicals and oil would not bother it. These were painted to match the hood of the sled versus the solid purple that the springs were originally.
A small plug for the person who does my shock rebuilding! http://twoguyswithwrenches.com/ He will do custom work like these Fox Shocks or just rebuild your stockers and everything in between and more.