C3 Brake Backing Plate Color

**Terry M.** · November 25, 2006, 12:35 PM

Re: C3 Brake Backing Plate Color

For years the service replacement brake dust shields were yellow. I suspect Tripoli's book shows the drawing with all the updates -- when reading engineering drawings one needs to determine when the entry was made. If the entry was made after the year you are interested in one should disregard it.

Original 1968-1972 brake dust shields are silver. Some other years are silver also, but since I don't claim specific knowledge of those years I confine my remarks to what I know.

**Chuck S.** · November 25, 2006, 12:38 PM

Re: C3 Brake Backing Plate Color

Kent, this just goes to show that for every vendor's part you buy, you should do what you have done...compare it to the original, and ask questions if they don't match up exactly. If the vendor doesn't have anything to sell but zinc dichromate, most of them are going to say it's original for everything it will fit.

Joe can straighten us out if I'm wrong, but your 69 backing plates, like those on my 70, should be plain zinc...actually, I believe they were stamped from galvanized sheet stock (cut edges of the exposed steel were rusty). Close examination of one set of my backing plates (maybe it was the rears) revealed "large crystal" galvanizing in the finish. Silver zinc plating is as close as you're likely to get restoring them, and they should judge OK if they are silver zinc or cad plated.

Baer's sells good reproduction backing plates that they represent as identical to the originals, but I would prefer to restore originals if they are in otherwise good shape. Incidently, to my knowledge, Baer's was the last source for REAL NOS (identical to the originals, stamped with correct part numbers) for the zinc finished backing plates until their stock was exhausted. Papa Baer must have cornered the NOS backing plate supply.

The gold dichromate washed backing plates started after 70, and are correct for following years. Without researching it, I don't know exactly when the change occurred, but I think 71 or 72 started the gold backing plates.

**Chuck S.** · November 25, 2006, 01:04 PM

Re: C3 Brake Backing Plate Color

"...The gold dichromate washed backing plates started after 70, and are correct for following years. Without researching it, I don't know exactly when the change occurred, but I think 71 or 72 started the gold backing plates."

I was unaware of Terry's post when I started typing...He's correct; per the 70-72 TIM&JG, the gold backing plates started after 72.

**Stephen B.** · November 25, 2006, 02:02 PM

Re: C3 Brake Backing Plate Color

My 70 has silver backing plates. They appear to be original even though the car has over 300,000 miles. I was pressure washing the chassis yesterday in preparation for judging. Bunky

**Stephen B.** · November 25, 2006, 02:02 PM

Re: C3 Brake Backing Plate Color

My 70 has silver backing plates. They appear to be original even though the car has over 300,000 miles. I was pressure washing the chassis yesterday in preparation for judging. Bunky

**Joe L.** · November 26, 2006, 01:41 AM

Re: C3 Brake Backing Plate Color

Kent----

In general, I do think that 1968-72 disc brake backing plates were "silver". However, there were exceptions. My original owner 1969 was originally delivered with front backing plates that had the "gold" irridite overplate. I am 100% sure of this. It may have been the only 68-72 ever built this way, but I know there was one. They are no more, though. I had them replated with clear (silver) zinc. So, I made the car non-original "in order to make it original". Not really, though. I never liked the front gold, rear silver combination, even if that's how the car was originally built.

The rear backing plates on my car were definitely silver from the get-go. However, they were not zinc plated---they were made from pre-punch galvanized material. Absolutely, positively. I believe that most of these original rear backing plates were so-finished. However, most folks mistook this for zinc plating and that's how most of these are restored (as Chuck mentions, it's the only really practical way to refinish these, anyway, and few will know the difference).

So, why were the fronts and the rears finished differently (even if both the fronts and the rears are silver)? Well, the front shields were always a Chevrolet part number. However, the rear shields were a Delco-Moraine part number (that's also the reason that the Delco-Moraine logo only appeared on the rear shields and never the fronts). So, the rear shields were made to a Delco-Moraine specification and that specification, apparently, either specified or allowed as optional, the use of pre-punch galvanized material. The Chevrolet specification for the front shields, apparently, never specified or allowed the use of pre-punch galvanized material and required a zinc plate. The manufacturers of the front and the rear were probably different, too. In fact, the fronts were almost certainly manufactured for Chevrolet by an outside manufacturer. The rears may have been manufactured internally by Delco-Moraine or by an outside supplier to Delco-Moraine.

Later in the C3 period, I think that Chevrolet "took over responsibility" for manufacture or procurement of the rear shields, even though the part number did not change. At that time the finish went to zinc with irridite overplate for BOTH the front and rear shields (AND the Delco-Moraine logo disappeared from the rear shields).

**Joe L.** · November 26, 2006, 01:41 AM

Re: C3 Brake Backing Plate Color

Kent----

In general, I do think that 1968-72 disc brake backing plates were "silver". However, there were exceptions. My original owner 1969 was originally delivered with front backing plates that had the "gold" irridite overplate. I am 100% sure of this. It may have been the only 68-72 ever built this way, but I know there was one. They are no more, though. I had them replated with clear (silver) zinc. So, I made the car non-original "in order to make it original". Not really, though. I never liked the front gold, rear silver combination, even if that's how the car was originally built.

The rear backing plates on my car were definitely silver from the get-go. However, they were not zinc plated---they were made from pre-punch galvanized material. Absolutely, positively. I believe that most of these original rear backing plates were so-finished. However, most folks mistook this for zinc plating and that's how most of these are restored (as Chuck mentions, it's the only really practical way to refinish these, anyway, and few will know the difference).

So, why were the fronts and the rears finished differently (even if both the fronts and the rears are silver)? Well, the front shields were always a Chevrolet part number. However, the rear shields were a Delco-Moraine part number (that's also the reason that the Delco-Moraine logo only appeared on the rear shields and never the fronts). So, the rear shields were made to a Delco-Moraine specification and that specification, apparently, either specified or allowed as optional, the use of pre-punch galvanized material. The Chevrolet specification for the front shields, apparently, never specified or allowed the use of pre-punch galvanized material and required a zinc plate. The manufacturers of the front and the rear were probably different, too. In fact, the fronts were almost certainly manufactured for Chevrolet by an outside manufacturer. The rears may have been manufactured internally by Delco-Moraine or by an outside supplier to Delco-Moraine.

Later in the C3 period, I think that Chevrolet "took over responsibility" for manufacture or procurement of the rear shields, even though the part number did not change. At that time the finish went to zinc with irridite overplate for BOTH the front and rear shields (AND the Delco-Moraine logo disappeared from the rear shields).

**Dennis D.** · November 26, 2006, 10:04 AM

Re: C3 Brake Backing Plate Color

Haven't read an answer to the other part of the question, so I'll give it a shot. When I rebuilt the suspension on my 70, I took various parts to a local restorer. He sent me to the plater he uses for his top flight and gold awards. He insisted all the dust shields was silver as stated here, however, the front caliper mounts,(support), were gold,(irridate?). Maybe the reason for your "mixed info".

**Dennis D.** · November 26, 2006, 10:04 AM

Re: C3 Brake Backing Plate Color

Haven't read an answer to the other part of the question, so I'll give it a shot. When I rebuilt the suspension on my 70, I took various parts to a local restorer. He sent me to the plater he uses for his top flight and gold awards. He insisted all the dust shields was silver as stated here, however, the front caliper mounts,(support), were gold,(irridate?). Maybe the reason for your "mixed info".

**Chuck S.** · November 26, 2006, 02:49 PM

Re: C3 Brake Backing Plate Color

The gold zinc dichromate is correct for the caliper mounting brackets...I'm pretty sure Joe didn't mean he made those silver too; he was only talking about the "mis-matched" brake back plates. Somehow, I have this "deja vu" feeling I know exactly how Joe thinks on that kind of stuff.

**Chuck S.** · November 26, 2006, 02:49 PM

Re: C3 Brake Backing Plate Color

The gold zinc dichromate is correct for the caliper mounting brackets...I'm pretty sure Joe didn't mean he made those silver too; he was only talking about the "mis-matched" brake back plates. Somehow, I have this "deja vu" feeling I know exactly how Joe thinks on that kind of stuff.

**Joe L.** · November 26, 2006, 02:57 PM

Re: C3 Brake Backing Plate Color

Chuck and Dennis-----

Yes, my front caliper brackets were always irridite ("gold") over-plated. I had them re-finished as-original. They actually came out absolutely PERFECT.

**Joe L.** · November 26, 2006, 02:57 PM

Re: C3 Brake Backing Plate Color

Chuck and Dennis-----

Yes, my front caliper brackets were always irridite ("gold") over-plated. I had them re-finished as-original. They actually came out absolutely PERFECT.

**Kent Greimel** · November 26, 2006, 05:27 PM

Re: C3 Brake Backing Plate Color

You guys have been a huge help, thanks for all the info!

Kent

C3 Brake Backing Plate Color

C3 Brake Backing Plate Color

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Debug Information