Today I did the rust repair and final painting of the differential. The first thing I did was to give it a quick final cleaning using Simple Green to remove and grease on the surface from handling and working with the differential case since I last cleaned it. Prior to introducing and water I replaced the fill and drain plugs, the breather, and taped off the axle openings to keep water from getting inside.
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Before painting I used an acid etch to brighten up the aluminum front of the differential. I used an Eagle One Mag Cleaner which is designed for rough-finish aluminum wheels. I donned my safety glasses and heavy rubber gloves (this is acid, after all) and sprayed the aluminum liberally.
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Per the instructions, I waited thirty seconds while the acid did its etching on the aluminum, which caused a fairly vigorous foaming.
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Then I washed it off very thoroughly with water.
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Then I turned my attention to the rest of the differential. The case itself had several rough areas where the original paint had worn off and surface rust had set in. I had previously used a wire brush to remove and loose material. Before painting, I sealed the remaining rusty areas using Eastwood’s Rust Encapsulator product, which is supposed to seal in rust and neutralize its ability to deteriorate any further. I bought a quart can for $19 and applied it using a regular paintbrush.
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There was a lot of rust around the edges of the axles, presumably from the finish being chipped by rocks and stones kicked-up by the tires. I painted over all of those areas with the encapsulator.
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There was also surface rust around the welds at the rear of the “pumpkin,” which I painted over.
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I rotated the differential to point down so I could access the areas underneath, and completed sealing over all of the rust areas.
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After allowing the Rust Encapsulator to dry for four hours, as recommended by the instructions on the can, I prepared for the finish coat of paint. I masked off the aluminum part using heavy-duty foil and some painter’s masking tape. You can tell Thanksgiving is on my mind already!
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Then I removed the plugs. The paint I used is Eastwood’s aerosol Chassis Black, which was $13 for the can.
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I applied two coats, waiting 20 minutes between coats.
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Then I rotated the differential up again in order to apply two coats to the areas I had missed.
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After allowing the paint to try for several hours, I moved the differential into the garage to dry over night. I removed the masking from the aluminum area.
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Overall I’m pleased with the results, particularly compared to the way it looked when I pulled it off the car.
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