Sounds funny, your hardware hanging with mixed company, but improper plating techniques can cause a dangerous problem called hydrogen embrittlement: That’s when the chemical action of the plating process causes hydrogen gas to be trapped in the fastener, leaving it with a fraction of the strength it once had.
True story: I encountered hydrogen embrittlement in a box of 3/8” diameter allen-head bolts years ago that were so fragile I could break the heads off with a two-finger twist of a 6” long wrench. Lucky for me I discovered the problem before sending the vehicle on its merry way. A tip of the hat goes to Gardner-Westcott who performs its own polishing and plating, and has total control over this sensitive operation.
When you think about it, when customizing or rejuvenating a vintage streetbike, our goal is to create motorcycles that are cosmetically appealing and structurally sound. Using heat-treated steel fasteners from a trusted source is an excellent strategy. That said, for areas where moderate strength and high corrosion resistance are the primary goals, Havrinche suggests using stainless-steel fasteners on lower-stress areas such as engine and transmission covers.
Speaking of corrosion resistance, it’s usually a good idea to either lubricate the threads or add a little thread-locker to slow the growth of corrosion between the fastener and the part. That said, always check the appropriate service manual first for any unique requirements to assembly, such as using a specific thread locker or lubricant, or nothing at all on the fastener in question.
Now you have a little information about a very complex subject. Consider maintaining an inventory of trusted hardware for those custom and vintage bikes you’re building. Walking over to your Parts department to get a fastener you can trust is quicker and smarter than making a separate trip to the local home improvement store for fasteners from unfamiliar manufacturers.
This story originally appeared in the July 2012 issue.