Horseless Carriage Education
Technical Articles

Protecting Screw-On Hubcaps

 
Author: Harold Sharon


I've made a few screw-on hubcaps for friends recently. It's a bit of a mystery why these things fall off while on tour, but it keeps me busy at the lathe! I suspect that wear, over the years, and perhaps some over-tightening, has made the fine threads a tenuous engagement. There is, however, an easy fix. Clean both the male and female threads thoroughly. Gasoline and a toothbrush will do nicely. Get a tube of silicone "gasket-maker". Any of the several specialized colors will do. Paint a few stripes of it along the male threads, and a few along the internal threads. Don't overdo it. Screw the hubcaps on in the usual manner and let the stuff set overnight.

If you don't have the special spanner wrench to remove these hubcaps later, a rubber strap wrench will usually do nicely.

I learned this trick at motorcycle racetracks many years ago. These guys want to remove axles, sprockets, etc several times in the course of a day. The vibration environment is severe, and they just daubed silicone on each threaded assembly. Even if the prevailing torque of the tightened nut came loose, the fastener would not continue to drift off. Yet, the fasteners came off easily with ordinary wrenches.

Do not use Loctite "thread locker", even the lowest strength, unless you plan to heat them to 350 degrees next time you try to remove them. Also, do not use the ordinary household silicone; it's an entirely different curing chemistry, and will just about never cure inside the threads.

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