1972 - BRAKE ROTOR SHIELD

[Jerome E Pederson]

What color are the brake rotor shields; yellow or silver?

The JG says cadmium (dull) or zinc plated. However, my late '72 has yellow/gold color shields. Is there any possibility that these are correct for my car?

The JG manual also says chromate dip over zinc plate. Would this process create a yellow/gold color?

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

The two citations you reference from the TIM&JG are contradictory. Please let me know on what pages you are finding them, so that we can clarify future editions.

Yes, chromate dip is a yellow/gold color. The brake dust shields for your 1972 should be a dull silver color. The fronts were plated, and the rear stamped from galvanized sheet.

Later (well after 1972) the service replacement shields, and I believe some production shields, where a yellow/gold color. My guess would be someone replaced the shields during the cars life.

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

The two citations you reference from the TIM&JG are contradictory. Please let me know on what pages you are finding them, so that we can clarify future editions.

Yes, chromate dip is a yellow/gold color. The brake dust shields for your 1972 should be a dull silver color. The fronts were plated, and the rear stamped from galvanized sheet.

Later (well after 1972) the service replacement shields, and I believe some production shields, where a yellow/gold color. My guess would be someone replaced the shields during the cars life.

[Jerome E Pederson]

Re: 1972 - BRAKE ROTOR SHIELD

Terry,

1970-72 Corvette Technical Information Manual & Judging Guide (Fourth Edition)

Page 104, last paragraph.

Brake Backing Plates

"original brake backing plates were dull cadmium or zinc plated; however, the latest Chevrolet prints have specifications calling for a chromate dip over zinc plate."

Please let me know if I have errored or if chromate dip over zinc plate is an alternative coating and thus a yellow/gold color.

Thanks

[Jerome E Pederson]

Re: 1972 - BRAKE ROTOR SHIELD

Terry,

1970-72 Corvette Technical Information Manual & Judging Guide (Fourth Edition)

Page 104, last paragraph.

Brake Backing Plates

"original brake backing plates were dull cadmium or zinc plated; however, the latest Chevrolet prints have specifications calling for a chromate dip over zinc plate."

Please let me know if I have errored or if chromate dip over zinc plate is an alternative coating and thus a yellow/gold color.

Thanks

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

What that is trying to say is that the original were dull cad or zinc (dull silver) the latest prints (which I think was in the late '70s or early '80s) show chromate dip. That sentence is saying the same thing as I said in my earlier post, but uses fewer words. Perhaps that economy of words leads to confusion, but it does explain why your car has yellow backing plates, why there are NOS examples in yellow, and why those of us who are long in the tooth can remember buying backing plates from the Chevrolet parts department that came yellow.

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

What that is trying to say is that the original were dull cad or zinc (dull silver) the latest prints (which I think was in the late '70s or early '80s) show chromate dip. That sentence is saying the same thing as I said in my earlier post, but uses fewer words. Perhaps that economy of words leads to confusion, but it does explain why your car has yellow backing plates, why there are NOS examples in yellow, and why those of us who are long in the tooth can remember buying backing plates from the Chevrolet parts department that came yellow.

[Chuck S.]

Re: 1972 - BRAKE ROTOR SHIELD

Terry, I thought the 72s were dichromated, but I've been wrong before. Why would the 70-72 TIM&JG waste valuable space to tell you irrelevant information about later years' drawings/parts?

[Chuck S.]

Re: 1972 - BRAKE ROTOR SHIELD

Terry, I thought the 72s were dichromated, but I've been wrong before. Why would the 70-72 TIM&JG waste valuable space to tell you irrelevant information about later years' drawings/parts?

[Terry M.]

[Terry M.]

[Chuck S.]

Re: 1972 - BRAKE ROTOR SHIELD

I apparently arrived at that idea from other sources since my impression predates the Fourth Edition...I guess I can't blame my ignorance on the TIM&JG, Apparently my other sources were no less clear than the Fourth edition.

Maybe the Fourth Edition should read: "...original brake backing plates were dull cadmium or zinc plated. Added: Judged cars are often observed with replacement brake backing plates that are gold dichromate finished since these were sold as service parts for many years."

Actually, one pair of backing plates (I believe the rears) is zinc galvanized and not plated, but you'll never see galvanized on a restored car. Galvanizing is way past the trouble of duplicating when the TIM&JG says they were plated.

[Chuck S.]

Re: 1972 - BRAKE ROTOR SHIELD

I apparently arrived at that idea from other sources since my impression predates the Fourth Edition...I guess I can't blame my ignorance on the TIM&JG, Apparently my other sources were no less clear than the Fourth edition.

Maybe the Fourth Edition should read: "...original brake backing plates were dull cadmium or zinc plated. Added: Judged cars are often observed with replacement brake backing plates that are gold dichromate finished since these were sold as service parts for many years."

Actually, one pair of backing plates (I believe the rears) is zinc galvanized and not plated, but you'll never see galvanized on a restored car. Galvanizing is way past the trouble of duplicating when the TIM&JG says they were plated.

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

"Actually, one pair of backing plates (I believe the rears) is zinc galvanized and not plated, but you'll never see galvanized on a restored car. Galvanizing is way past the trouble of duplicating when the TIM&JG says they were plated."

Yep, you are quite right. The rears were stamped from galvanized sheet, which is exactly what that low mileage car showed, but what is galvanizing? -- It is either a dip in molten zinc (hot dip galvanizing -- like old-school garbage cans) or a zinc plating operation (electro-galvanizing). I believe the front backing plates were zinc plated after forming, and the rears formed from already zinc coated (how's that for choosing a word? ) sheet stock -- Armco, like the roadside barriers, was the brand in one case. And the end result is pretty much the same -- they were plated, fronts after forming and rears before forming. Like you I doubt too many people will go through the effort to achieve the level of detail this discussion centers around -- and for how many points at what cost?? Do the points per dollar, even if one could figure out the technology.

[Terry M.]

Re: 1972 - BRAKE ROTOR SHIELD

"Actually, one pair of backing plates (I believe the rears) is zinc galvanized and not plated, but you'll never see galvanized on a restored car. Galvanizing is way past the trouble of duplicating when the TIM&JG says they were plated."

Yep, you are quite right. The rears were stamped from galvanized sheet, which is exactly what that low mileage car showed, but what is galvanizing? -- It is either a dip in molten zinc (hot dip galvanizing -- like old-school garbage cans) or a zinc plating operation (electro-galvanizing). I believe the front backing plates were zinc plated after forming, and the rears formed from already zinc coated (how's that for choosing a word? ) sheet stock -- Armco, like the roadside barriers, was the brand in one case. And the end result is pretty much the same -- they were plated, fronts after forming and rears before forming. Like you I doubt too many people will go through the effort to achieve the level of detail this discussion centers around -- and for how many points at what cost?? Do the points per dollar, even if one could figure out the technology.