C3 (72) AC acorn nuts

[Rob C.]

Hi all,
Cound some one tell me what type of playting they are soposed to be.
I know they are brass under. I have one that is brass and one that is silver? with brass under.

[Terry M.]

Re: C3 (72) AC acorn nuts

Tin plate on brass.

[Rob C.]

Re: C3 (72) AC acorn nuts

Thank you Terry.

[Chuck S.]

Re: C3 (72) AC acorn nuts

TIN??!! Not zinc? Not cad? What the devil were they thinking? There had to be a reason for...Tin!!!

[John H.]

Re: C3 (72) AC acorn nuts

Chuck -

The supplier probably bought lunch.

[Terry M.]

Re: C3 (72) AC acorn nuts

The coating was strictly for cosmetic reasons. The underlying brass will not corrode. All that was desired was a uniform silver matte appearance. They got it the least expensive way possible.

[Chuck S.]

Re: C3 (72) AC acorn nuts

LOL! I guess if you're going to get a zillion acorn nuts plated, it's worth saving $0.005 per acorn nut to get a siver matte finish on a corrosion resistant material.

Ah...those were the good ole days. Most of the stuff about working was grinding, but there were some bright spots: Supplier's Sales Guy: "Hey, you wanna' go get some lunch? We can talk about our new Widget...You take time to eat lunch doncha'?" Client's Engineer: "Mmmmm, yeah...I'll go to lunch with you...But, lunch isn't going to change my mind about that piece of crap Widget you're sellin'."

[Peter L.]

Re: C3 (72) AC acorn nuts

Chuck - Lest we all forget, tin plating like zinc plating was relatively inexpensive in the old days and used extensively until the price of tin jumped and then zinc plating was the winner and what's more how many AC acorn nuts are we talking about anyway. Not an expensive lunch!!!!!!!!!! Pete

[Chuck S.]

Re: C3 (72) AC acorn nuts

If tin was as effective at resisting corrosion as cadmium and zinc, and it was just as cheap, it seems like we would have heard of more parts being plated with tin. To my knowledge, this is the only automotive part I have ever heard of being tin plated...at least since the fifties; I'm not talking about the old winged radiator cap days.

In this case, it seems clear that the tin provided only an aesthetic appearance; it served no other purpose. The fact that it was being plated over brass, and brass wouldn't corrode even if the tin was worn away, makes me think tin's performance in the salt spray test wasn't comparable to cadmium or zinc. Otherwise we might have heard of more old GM manufacturing drawings with the note: "Electroplate part with cadmium to GM specification XXXXXXXXX. Zinc or Tin plating to GM specification may be substituted for cadmium."

[Terry M.]

Re: C3 (72) AC acorn nuts

Some, maybe most, dipstick tubes were tin plated back in the day. Tin over copper me thinks.

The drawings I have seen specify a GM specification for either appearance or corrosion or both, but rarely specify a plating material.

[Chuck S.]

Re: C3 (72) AC acorn nuts

Terry, it sounds like you are agreeing that tin may have been specified as an appearance finish, and not for corrosion resistance.

I can recall many discussions we've had here about "Is it cadmium, or is it Zinc?". Dale Pearman was adamant that those two finishes could not be told apart, and told the story of taking zinc and cadmium plated parts for examination by scanning electron microscope. Dale probably had some old friends with access to such high technology...academics might think it was being misused for trivial pursuits.

Someone, maybe Joe Lucia (Sorry, if not you Joe), explained that the drawings for plated parts would often allow either material to be plated, and therefore a definite call could likely not be made...it could be either. It wasn't explained if the plating was specified by drawing note text or specification number; I was only making a point with a hypothetical case.

To my knowledge, the question about the silvery finish being TIN has never come up in any of that discussion if it was a possible candidate. So, Terry, come on...give up your sources: How did anyone EVER figure out that was TIN on those AC acorn nuts? That information had to come from a GM employee in a position to know.

[Terry M.]

Re: C3 (72) AC acorn nuts

Chuck if I told you I would have to kill you.