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Old 04-29-2019, 03:06 PM
Nicholas Studer's Avatar
Nicholas Studer Nicholas Studer is offline
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Default Unity Spotlight Disassembly and Repair

My 1969 Stoner-Chevrolet "Crash Wagon" ambulance ( has two Unity S-6 post-mount spotlights. Unfortunately, when I got the car they were in sorry shape. Besides some pitting and dulling of the chrome from "storage" in a field for probably 20-30 years, the handles spun freely without any movement of the head. The sealed beams were rattling around in the heads, as the cheap steel clips had rusted away inside - a common problem.

Internet research found me this thread at the 67-72 Chevy Truck forums: "markebo1" kindly photographed complete disassembly of these vintage Unity S6 lights and provided step-by-step intructions and pointers/tips. Having never done it before - it actually went fairly well. is a 1980s video from Unity that is very helpful as well.

1. I found the headpost housings and handle assemblies were PACKED with old, dried grease. I literally poured it out. I suspect someone at McDonnell-Douglas had been inside them at least once after the factory installation. One of them had a more liquid grease mixed in.
2. Due to this, the brass driven gear in the handle assembly of both had failed and multiple teeth had been sheared off. This is how the handle could rotate freely - the teeth on the pinion just rotated by without engaging anything. I ordered two of these from Unity and replaced them, resolving all mechanical problems.
3. I polished the chrome with the usual Chrome polish with a fair bit of staining left behind. I used the "aluminum foil and water" tactic with great results, it even filed down the raised blemishes. Here's one video:

I'm fairly happy with the results. These things make a lot more sense once they're apart, give it a try!
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