C3 Brake Caliper Casting Date

[Tom R.]

How are casting date codes read on brake calipers?

[Patrick H.]

Re: C3 Brake Caliper Casting Date

Tom,

The thought is that they are not casting dates. If you look on the machined surfaces on the top of the caliper you will see tiny stamped numbers, which are a date code like the one stamped on the port side of the master cylinder.

Patrick

[Tom R.]

Re: C3 Brake Caliper Casting Date

I noticed the service placement calipers had an L or R stamped in that machines area so look at those on the car and did not see a stamp as you describe. What does that suggest...service replacement?

[Joe L.]

Re: C3 Brake Caliper Casting Date

I noticed the service placement calipers had an L or R stamped in that machines area so look at those on the car and did not see a stamp as you describe. What does that suggest...service replacement?

Tom------

It's hard to say. These calipers were used in PRODUCTION from about 1973 through 1982. They were, of course, also used for 1973-82 SERVICE. However, they were also SERVICE for 1965-72. So, considering how long they were being manufactured, there were LOTS of these that were sold in SERVICE. Consider that before the introduction of stainless steel lined calipers, a new GM caliper half was the only cure for a damaged bore. Even after the introduction of stainless steel lined calipers, many mechanics continued to use GM caliper halves for SERVICE, especially Chevrolet dealership service departments. As far as I know, though, I don't think that GM ever offered the 65-82 style Corvette calipers as complete, new units----only the caliper halves and separate internal parts were available.

While the 65 to E67 calipers and L67-72 calipers were cast at GM foundries, I believe these later calipers were cast at an outside foundry. The 2 earlier series castings were malleable iron while this later series was gray iron.

[Patrick H.]

Re: C3 Brake Caliper Casting Date

The key is that the numbers on the side - other than casting numbers - don't really matter.
And, the dates are almost impossible to see, even when off the car. So, as long as the casting numbers match what the car should have, I would consider them correct and reusable for that car.

[Gary J.]

Re: C3 Brake Caliper Casting Date

Tom, if you were to send the calipers out for rebuild be sure you ask for your calipers back. If not you may get some missed match set.

[Tom R.]

Re: C3 Brake Caliper Casting Date

Tom, if you were to send the calipers out for rebuild be sure you ask for your calipers back. If not you may get some missed match set.

Have already done the math concluding the cost is not worth saving them. What I concluded after Patrick's and Joe's comments is that the configuration of the four calipers are too dissimilar to be a set and therefore original to the car. They are lip seal but not OEM calipers.

I have also concluded that these are not original to the car. This was the intent of my original query above...casting date code! The two rusted calipers are what came off the car while the painted caliper is the rebuilt, sleeved O-ring caliper.

A stamp code, as Patrick intimates, to me is a caliper assembly code and if it's missing, leads again to the same conclusion...not original to the car.

My question has to to do with the casting date code...nothing more. Four digits, three digits so how is this interpreted, week with digit for year; or day of the year and digit for the year?

[David B.]

Re: C3 Brake Caliper Casting Date

From Product information Manual: The caliper build date is stamped on the lower side of one of the caliper outboard ears. The build date is either a four or five digit number.
Examples: 4 2 3 4 4 = 1974 234 = 234th day of year or 2 8 2 7 4 282 = 282nd day of year 74 = 1974

[Patrick H.]

Re: C3 Brake Caliper Casting Date

My question has to to do with the casting date code...nothing more. Four digits, three digits so how is this interpreted, week with digit for year; or day of the year and digit for the year?

Tom,

As I mentioned previously, current thinking is that they are not date codes. Mold ID possibly, or internal code, but based on original cars with original calipers, they do not seem to have any relationship to a date.

Patrick

[Edward A.]

Re: C3 Brake Caliper Casting Date

Just thought I would add this into this conversation since I had already cataloged it. A 1979 built in May/June 79 with original brake components. I had to replace the calipers but chose to keep the originals. Here is a breakdown of the casting numbers and the 3/4 digit codes.