Horseless Carriage Education
Technical Articles

Choosing the RIGHT Shackle Bolts

 
Author: Harold Sharon


     Concern has been raised over the choice of material for shackle bolts for spring eyes. His comment was that by choosing a soft bolt material, the spring eye would wear less.

     The design of shackle bolts for the lower priced cars is an atrocity. The load is intense. The metals are steel-on-steel. There is no lubrication provision except an occasional oil can applied to the end of the bolt. Oil is of very short life in such a joint. There isn't enough motion for hydrodynamic lubrication.

     But back to the choice of material; the reader will readily recognize that there is dirt in the joint. The essence of a lap is that grit imbeds in the soft material, and this dirty grit then slides against the hard material. If a problem well defined is half solved, you're on the way to solving this one. (WHy does babbit last so long in the engine, yet the crank wears?) You need hard bolts in the spring eye, both for strength, and to MINIMIZE wear on the spring eye.

     If you have a lot of spring eye wear and you don't want to tear things apart, there is what I call a "5 year fix". Clean the eye in the spring surgically clean. Put steel-filled Devcon in hole along with polished rod of same diameter as bolt. Rod has release agent on it ! Set rod to original hole location. Keep warm for 24 hours, then remove rod. Install new bolt, preferably one with a very smooth body. Use anti-seize as the bolt lube. It will last for quite a few years.

     Please remember, I do not guess! This will work.

     If the Devcon makers knew of the many places I've used their stuff, they'd have me write a book!

For more of Harold's Great technical knowledge, check out His Book

 

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