Question for Joe Lucia re: 1st Gen Brake Calipers

[Louis T.]

Hi Joe,

First...
Congratulations on receiving your NCRS Presidents Award. Your posts, knowledge, and opinions are priceless, and now that I have a picture, I hope I might run into you at Carlisle or some future NCRS event.

Second...
I read with great interest your April and July posts on disk brake caliper castings and have a couple of questions. I am trying to determine how "original" my old front calipers are, and whether they are worth rebuilding and putting back on my car. In a moment of haste, and poor advice, I regrettably replaced them recently with some later rebuilds from a local Corvette supplier, which I find "ugly" compared to my earlier castings (I have yet to turn in the cores). The replacements are not even black - they're grey. My late '65 convertible is a mostly correct restored driver that I wish to maintain as original as possible/practical.

The calipers I removed are very clean (and in my opinion pretty) first generation 5465954/5465952 castings which I will assume have been converted to second generation at some point in their lives since the pistons outwardly appear to be second design (no provision for insulators), so I'll assume the piston guides are long gone. There are some additional markings: (1) a large inverted "7" stamped above the casting number of each caliper half, and to the right of the casting number on each are, also inverted, respectively, the casting numbers 822, 118 (looks more like 811 right-side up), 258, and 8 (hard to tell if there were additional numbers after the 8 and filed off, or if there never were any others). What do these numbers mean? Are they date codes? Do they provide any indication as to whether these might be original to my car?

If these are not original to my car, are these first generation castings available from other rebuilders, so that I shouldn't worry about relinquishing these particular ones as cores? Or am I making altogether too much about these calipers, especially since they are not unmolested, but converted? My buddies with way more experience in the hobby just tell me to spray paint the replacements black and not to worry about it. Your input would be most appreciated.

As an aside, my rear calipers appear to be first generation, as well. How can I tell? What are the correct casting numbers?

Thanks.

Louis

[Joe L.]

Re: Question for Joe Lucia re: 1st Gen Brake Calip

Louis-----

Most of the other numbers found on caliper castings have no meaning that I am aware of which is relevent to us. They represent various manufacturing codes for which the meaning is "lost in antiquity". I believe that one of these, though, is a "date code" of sorts. In your case, this could be either the "258" or "118". I can't say, for sure, without seeing the casting. In any event, the "date code" on these calipers is really moot. That's because, assuming they are date codes, at all, they represent a julian date code without a year coding included. So, if they are a date code, the number represents only the consecutive day of the particular year that they were manufactured. Without a reference to year, the consecutive day of the year doesn't really mean too much. I've never been able to confirm that any of the other raised numbers on these castings represents a year code. The known-original castings on my original owner 1969 don't have an "8" or a "9" (which are the last digits of the only possible years that they could have been cast) to be found on them anywhere.

Some folks have reported finding another date code STAMPED on the calipers. As reported, this involves a very small, lightly stamped, coding which includes a 4 digit series stamped on one of the casting's machined surfaces. The first digit represents the last digit of the year and the last three digits represent the consecutive day of the year. Although this sort of coding system was used on other Delco-Moraine castings (some master cylinders, in particular), I've never seen it myself on a Corvette caliper. I've looked at a lot of caliper castings and I've not seen it yet. But, it may be on some. In any event, unless your calipers happen to have theses stampings somewhere on them, I don't think that there's any way to discern if they might be original to the car. However, if your car is a 1965-E1967, they are the correct calipers for the car, notwithstanding the piston conversion.

The 5465954 and 5465952 are the casting numbers used for the front brake caliper halves for the first design, 1965-E1967 calipers. If yours currently have non-insulated pistons installed, then I agree that these likely have been converted to second design configuration with the piston guides machined out. This is a VERY common conversion when the calipers are rebuilt by commercial rebuilders. It's not so bad, either, from a functional and practical perspective. The first design pistons are hard to locate and expensive. The second design pistons will work just as well for street applications and no one will know the difference. While the casting numbers can be checked for correctness with the calipers installed on the car, it is difficult or impossible to see the brake pistons. The conversion renders the calipers functionally second design, but they remain first design in most elements of external configuration.

The first design calipers, converted or not, are harder to come by than later castings. Some of the rebuilders will supply them if you ask, though. Lonestar Caliper is one that, I understand, will do this. If it were me, though, I wouldn't turn in the ones that you have.

As far as the color of the replacement calipers that you have goes, most rebuilders paint the calipers with gray or silver paint. It's become sort of an "unofficial code" for stainless steel sleeved calipers. Some rebuilders will supply the calipers bare or painted black if you request it (and, in some cases, pay an extra charge). You can just repaint the calipers as they are, though. However, this will often result in "too thick" looking paint. The calipers were originally painted a very thin, semi-flat black. However, for most folks, the correct color would be about 99% ok; few are going to inspect and discern that the paint looks "too thick", if they look at the calipers, at all.

The rear caliper castings used for the first design calipers were 5465902 and 5465905. If your rear caliper halves all have one of these numbers cast upon them, then they are first design, although they may have undergone the piston conversion, too. If so, then they are functionally second design, but externally configured as first design.

Basically, there are just the 2 caliper designs. The first design used for 1965-E1967 and the second design used for L1967-1982. However, there were two distinct versions of the second design. The first version, with caliper half casting number prefix "545" was used for L1967-about 1973. The second version, with prefix "547", was used from about 1973 to 1982. This is not a "hard-and-fast" rule since some SERVICE castings were made which had the "545" or "547" casting numbers, but first design internal configuration.

For all practical purposes, all of the castings are functionally interchangeable. Aside from the issue of "correctness of casting numbers for particular year model ranges", I find the external appearance of the calipers to all be about the same. However, there is one notable difference: the "546" (1st design) and "545" (2nd design, 1st version) were manufactured from nodular cast iron. Most of these calipers (but not all) will be seen with a "D" casting mark which represents the old Danville, IL GM foundry (which was a nodular iron foundry). The "547" (2nd design, 2nd version) caliper castings, which are the most common in the world of rebuilt calipers, were manufactured of gray iron. The nodular iron castings have a somewhat "smoother" external casting finish. The gray iron castings are a bit "rougher". That may be what you're refering to.

Very often, the outer front calipers of the 2nd design (cast #5452273) will have the word "ARMASTEEL" cast upon them in a "debossed" (indented) fashion on the lower, outer surface. This was a trade name for the nodular iron used for these castings. I've seen this on some 1st design calipers ("546"), too, but not all have it. I think that it might have been added to later 1st design units or, possibly, SERVICE 1st design castings.

[Louis T.]

Re: Question for Joe Lucia re: 1st Gen Brake Calip

Thanks, Joe.

As always, incredibly informative, and insightful.

Louis