1966 J-56 Calipers

[scott hasko]

I have read most of the old posts here on the topic of J-56 brake calipers. My '66 has this option. I recently went under the car to check the numbers and casting marks on my front calipers as there was an ad in the Driveline advertising "Armasteel" J-56 calipers for $3,500.00/pr. My part nembers matched those in the ad, and the word Armasteel was indeed cast into the cases. These calipers had been purchased years ago and came off of a wrecked '66 that also had the J-56 option. Has anyone heard of this caliper variation? Are they indeed worth that kind of money? If I had known this I would have hung them on the wall instead of running them...

-Scott Hasko

[Bill Stephenson]

Re: 1966 J-56 Calipers

Scott,

------More knowledgeable people than me will probably post on this subject,but I have always been under the impression that the J56 calipers themselves were the same as non-J56 other than the dual pins and minor machining.I believe this to be true as I have owned several J56 cars and never noticed any differences other than the above.
------Price seems to be seriously out of whack,like really,seriously out of whack.Did I say "out of whack"?...........Bill S

[Joe L.]

Re: 1966 J-56 Calipers

Scott-----

For 1966 the J-56 front calipers were identical to the non-J-56 except for the fact that the pad pin bosses were machined off and the 1/8" holes added for the "twin pin" pad retention. The calipers were, otherwise, the same, including all casting numbers. Rear calipers were the same for J-56 and non-J-56.

The "Armasteel" embossment was cast into the outer front caliper halves only. To be honest, I've not seen this on the 65-66 style caliper castings. I've only seen it on the 67-73 style castings, but it's possible that it was used earlier. For the 67-73 style calipers, the "Armasteel" was used in many, most, or all. Actually, I'm not sure that it was used on the 67-vintage examples, but it was on the 68-73 examples. It is NOT rare.

The 65-66 and 67-73 calipers are made of the same material, whether or not the "Armasteel" appears on them-----nodular cast iron.

What are the casting numbers of the caliper halves for sale in the Driveline?

[Mike M.]

Re: 1966 J-56 Calipers

Scott: agree with bill. always felt the J-56 cars just had std caliper with ears groud off and two holes drilled per half. took a pair off a 66 i once owned and do't recall any armasteel being cast or embossed in the pair i had and got rid of. ike

[scott hasko]

Re: 1966 J-56 Calipers

Thanks for the response(s). I'd have to go back under the car to get the whole number, but they ended with numbers 270 and 273. "Armasteel" logo was cast into them in relief, and these are definitely the early design. If anyone wants mine I'll beat the price and let them go for $3,000...such a deal...

-Scott

[Dick W.]

Re: 1966 J-56 Calipers

Somewhere it seems like I remember that the J-56's also had the bakelite insulators on the pistons. That, the pins, and the machined top are the only differences I can remember. I know that I bought several sets over the years for the going core prices. I salvaged the pistons with the insulators and sold the cores to rebuilders

[Joe L.]

Re: 1966 J-56 Calipers

Scott-----

Before I provide some additional information on this, let me ask you a few more questions:

1) Do you know, for sure, that these calipers are original to the car?

2) How do you know that these calipers are the first (early) design? What specific features do they exhibit which leads you to believe that?

[scott hasko]

Re: 1966 J-56 Calipers

I do not know for certain that these were original to the car they came off of.

I classified the calipers as 1st design because they have the piston guides, and a ceramic type insulator attached to each piston...between the piston and pad backs. The insulator is attached to the piston via one screw. At least that's how I remember them. I have not had them off of the car for about 8 years.

-Scott

[Dick W.]

Re: 1966 J-56 Calipers

You deefinitely have the first design with the guides in the bores. Most, if not all, of the rebuilders when they sleeve them machine the guides out. At one time rebuilders did not even want 1st design cores.

[Bill Braun 33186]

Re: 1966 J-56 Calipers

Scott,

I have J-56s on my 66 and they are original to the car, as all Swiss Export Corvettes were automatically ordered with the heavy duty brakes. Mine do not say Armasteel anywhere - just Delco Moraine.

Bill 33186

[Joe L.]

Re: 1966 J-56 Calipers

Scott-----

Well, there are some strange things here that I don't understand. But, here's what I can offer:

The first design calipers were used for all 1965-66 Corvette and very early 1967 Corvette applications. For these applications, the standard and J-56 calipers were the same, except that the J-56 fronts had the pin bosses machined off and the "twin pin" holes added. The exact same castings were used, though. The first design calipers had the piston guides cast into the piston bores, the pistons had the guide "pins" on the rear, and the pistons used a Pyroceram insulator on the front surface. The insulators were about 3/8" thick and were attached by a single phillips head screw in the center, countersunk hole. Just to emphasize, the guided pistons and Pyroceram insulators were used on BOTH standard brakes and J-56 for 1965 through early 1967.

For later 1967 through 1975, things changed considerably. These cars used the 2nd design calipers. 2nd design calipers used no piston guides and, of course, the pistons had no guide "pins". For standard brakes, no Pyroceram insulator was used---the aluminum piston face acted directly on the brake pad backing plate.

For 2nd design J-56, the calipers also used no piston guides. The calipers were exactly the same as standard brakes except that the front calipers had the pad pin bosses machined off and the "dual pin" holes added, just like the first design J-56. The 2nd design J-56 pistons were completely different than the 1st design insulated pistons, though. The 2nd design J-56 pistons used a much thicker Pyroceram insulator on the front and the piston was greatly reduced in thickness to compensate. The Pyroceram insulator was approximately 1 inch thick on these pistons. Of course, no guide "pins" were used on these pistons since NO 2nd design piston used guide pins.

Now, here's where the part that I can't figure out comes into play. ALL of the 1st design calipers that I have seen have the following casting numbers:

front CASTINGS: 5465952 and 5465954

rear CASTINGS: 5465902 and 5465905

These are the castings that have the piston guides cast into the rear of the caliper piston bores. I have never seen the "Armasteel" script embossed on these calipers.

All of the 2nd design calipers USED THROUGH ABOUT 1972 have the following casting numbers:

front CASTINGS: 5452270 and 5452273

rear CASTINGS: 5452281 and 5452284

I have NEVER seen any of the above-referenced calipoer castings with piston guides (and, I have looked at HUNDREDS of the caliper castings). Also, none of the ones that I looked at appeared to have had the piston guides "field-removed" (the vast majority of the calipers that I looked at were "first run" with no sleeves so there was really no chance that a rebuilder had removed the piston guides anyway). For these calipers, the outer front casting, GM #5452273, usually have the "Armasteel" embossment. I've seen a few that didn't, but most do.

You report casting numbers of "270" and "273". These are the 2nd design calipers as I have described above. Most 2nd design calipers have the "Armasteel" embossment, as you report finding. However, as I mentioned, I've never seen any of the 2nd design caliper castings with piston guides. Are you certain that these calipers had the piston guides cast into the rear of the piston bores?

[Joe L.]

Re: 1966 J-56 Calipers

Bill-----

Do you happen to know the casting numbers for your caliper halves? Even just one or two of the front caliper half numbers would be helpful.

[scott hasko]

Re: 1966 J-56 Calipers

Thanks for the response Joe,

I'm certain on the part number and the insulators, since I have recently viewed them. I'd have to pull a caliper and disassemble to check again on the guides. If I get some time this Winter I may just do that to settle the issue. Is it possible that the castings are second design with the first design pistons/insulators?

-Scott

[Eugene B.]

Re: Caliper verification

Gents,
Just a quick post to document that the casting numbers that Joe published are indeed correct for 1st series DM calipers. My original '65 has these calipers.

Also for information, Lonestar Caliper will rebuild/sleeve 1st series units and leave the piston guides alone. They did mine a few months ago. Great work!

Best regards,
Gene

[Joe L.]

Re: 1966 J-56 Calipers

Scott-----

I don't see how the 1st design pistons would work in 2nd design calipers, but, I suppose that it's possible that they would. Overall, the length of the pistons is about the same and the diamters are exactly the same. If you have the 3/8" thick insulators, then you definitely have the 1st design pistons.