Need help with plating instructions

philrock · Post by **philrock** » Mon Aug 17, 2015 2:53 pm

I’m restoring a 1966 CB77, and many plated parts are in bad shape. Some could be restored by just plating, and some would require a lot of TLC before plating.

I’m not a real stickler on OE parts, but I do like the appearance of the OE bolts with no head markings. On bolts that are not normally visible, I will probably just get Class 8.8 bolts from the hardware store, even though they will have markings on the heads. I know many NOS bolts are probably available, but I imagine they are more expensive than getting my originals plated.

On plating, I’m concerned about hydrogen embrittlement – especially on heavily loaded or critical parts like brake linkage, center stand pivot bolts, fork tube top bolts, head nuts, motor mount bolts & nuts, etc. I’ve certainly had bad experiences before in this regard. On previous projects, I did not specify baking after plating – maybe I should have?

Any suggestions on instructions for zinc, cad, and chrome plating of critical / high strength parts would be appreciated.

G-Man · Post by **G-Man** » Tue Aug 18, 2015 8:30 am

Phil

I use a zinc plater who does work for Rolls Royce Aerospace and spoke to them about hydrogen embrittlent. They didn't see the need to bake the parts.

I would be interested to know your experience with hydrogen embrittlement as it is a concern. I do know that 'black' bolts lose their original classification once plated so your 8.8 bolts will be classed as 4.5 after the zinc process.

To my knowledge, Honda did not use cadmium plating in this era. Just clear or yellow (gold) passivated zinc. Cadmium plating is banned in Europe because it is classed as a heavy metal.

Gold passivate was often used on carburettor and electrical parts but, even then in a rather hapazard way. I have identical NOS parts with different types of passivation.

The people I get to do my chrome plating will not do triple chrome as they say that the copper produces galvanic corrosion issues with the steel substrate.

G

philrock · Post by **philrock** » Tue Aug 18, 2015 9:41 am

G-man,

I once welded up a go-kart bumper from 4130 and had it zinc plated. The welds and adjacent material were almost as brittle as glass. Same story with a large black oxide setscrew I had zinc plated.

I have used zinc plated socket head cap screws from McMaster-Carr with no problems. I presume these have been properly treated post-plating.

Are OE bolts on Hondas class 8.8?

G-Man · Post by **G-Man** » Tue Aug 18, 2015 5:39 pm

Phil

Not sure on standard bolts. I would guess that the spindles and head bolts were a higher grade but you never know. Some had markings but not easily recognisable, to me, at least.

Interesting experience. I wonder if the embrittlement is dependent on material thickness? I might test some of my parts.

G

rrietman · Post by **rrietman** » Tue Aug 18, 2015 6:54 pm

pretty good thread on home zinc plating on this forum from a couple years ago. I've been doing it myself ever since. lots of discussion on to bake or not to bake. spokes need it, bolts/etc not so much. I have home plated LOTS of stuff, including spokes (baked and not baked) and never really can tell the difference.
Randy

G-Man · Post by **G-Man** » Tue Aug 18, 2015 7:06 pm

Randy

Thanks! Have you tried testing the spokes for bending or tensile strength with and without baking?

I wonder if those after market spokes are baked?

G

rrietman · Post by **rrietman** » Tue Aug 18, 2015 11:03 pm

G; never done any testing. not really sure how one would go about it? I have unbaked replated spokes on bikes with four years of riding on them, including retuning/tightening /etc with no failures or problems at all. same results with the baked items.
Randy