Saturday, February 20, 2016

Rust By Any Other Name

So now on to the results of my electrolytic rust removal 'science fair' experiment.  You'll notice that I used some extra solid copper wire to ground the hub rotating assembly to the spindle.  This was to ensure a good electrical connection between the two, ensuring the treatment would act on both.  Don't worry about any potential side effects on the longevity of the bearing, as I planned to replace them all along anyways.  This just allows me to use what I've already got for measurements and mock-ups.

Picking up where the experiment left off last last time, is the spindle immediately after the electrolysis treatment had completed:

Quite a difference!  Now that pretty black coating electroplated on it is actually not desirable, and needs to be removed.  Also note that some areas, like the rotor/wheel register don't have it.  That's because this process only acts on the rusted surfaces, and any rust that was in those areas was little more than superficial surface rust.  I chose to let the spindle soak in a mild acid solution (Distilled Vinegar) for an hour or so to soften the black coating, This was followed by a good thorough scrubbing with a small wire brush, revealing the bare metal underneath:

Now we're getting somewhere!  This is actually after a quick dip in water to neutralize any remaining acidity on the surface.  Also note that I was able to get the wheel speed sensor off, which thankfully when the bolt is no longer rusted in place, a conventional 6 point 1/4" socket will fit firmly enough over the external Torx head fastener to remove it.  However, at this point, my freshly bared and unprotected metal was rusting right before my eyes as the part dried.  I had heard it would rust within the hour, but we're talking by the second.  So I decided to speed up the process by using a hair dryer to get the water out of all the nooks and crannies.  It was both intriguing and concerning to watch the rate of 'flash rusting' multiply with the forced air drying.  This is where the Scotch Brite pads came in handy:

Holy crap nuggets!  I never thought the spindle would ever look this good again.  The flash rust was totally eliminated, leaving the surface of the part at least stable enough to take a few minutes and spray a coat or two of high temp primer on it:

So there you have it...A cheap, but admittedly more involved than anticipated, method for taking ugly rusted parts and making them look nearly as good as new without any fancy equipment.

Now, apparently pure carbon/graphite rods for the anodes will not produce the floating rust-sludge, eliminate the need to regularly clean the anodes, and doesn't require as much cleaning of the finished part either.  In other words, the whole process would be significantly cleaner and easier.  If I was de-rusting parts on a regular basis, or doing so with a large quantity of parts, this would absolutely make sense.  However, it's considerably more expensive, and much less readily available locally, than mild steel.  If I can find a few rods for cheap enough, I would certainly consider this for the other spindle, but I won't be holding my breath for that to happen.

No comments:

Post a Comment