I am looking to verify correct numbers for 67 J56 calipers. I have a couple of numbers that I was told were J56 calipers for 67 but I not been able to verify them as they don't show up in Group 4.665A. 1st set of numbers is 5465952 and 5465954 and the other set is 5452270 and 5452273. Can anyone tell me if these numbers are not correct are they still actual J56 calipers and where they were used. Also, what then would be the correct numbers for 1967 - J56. Thanks.
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Re: 1967 J56 Calipers
Ron-----
You will not find the caliper CASTING numbers in any edition of the P&A Catalog----those catalogs will show only the PART numbers for the finished caliper halves. These PART numbers appear nowhere on the caliper halves.
The CASTING numbers for J-56 caliper halves were the same as those for standard calipers inasmuch as the J-56 calipers were manufactured from the same castings. The PART numbers for the caliper halves would be different, but, as I mentioned, those are nowhere found on the calipers.
The casting numbers 5465952 and 5465954 were used for the front calipers for 1965 through early 1967. These are "1st design" calipers. With "1st design" front caliper halves, the only difference between standard and J-56 is the fact that J-56 have the pad pin bosses machined off and the two 1/8" holes added at either end. For "1st design" caliper ASSEMBLIES, the pistons were of the guided type and used the "thin" Pyroceram insulators on the front. The same pistons were used for both standard and J-56.
The casting numbers 5452270 and 5452273 were used for the front caliper halves for later 1967 through about 1972. These are "2nd design" caliper halves. As far as the caliper halves go, the difference between standard and J-56 relates only to the machining off of the pad pin boss and the addition of the two holes, as described above for "1st design" calipers. For "2nd design" caliper ASSEMBLIES, though, the standard use pistons with no insulators on the front and the J-56 use pistons with a "thick" Pyroceram insulator on the front. The insulator and pistons are different than those used on all "1st design" calipers. "2nd design" caliper halves will have no piston guides cast into them.
For either "1st design" or "2nd design" calipers, J-56 configured calipers can be made by machining off the pad pin bosses and drilling the holes for the long cotter pins. There is absolutely no way to detect an "original" J-56 caliper half from "later modified" ones if the "conversion" is done properly. Doing it properly is relatively easy. So, there's no way to tell if either of the sets you are referring to are original J-56, or not.
For a 1967, either set would have "correct" casting numbers for either J-56 or standard brakes depending upon whther the car is an "early" or "late" car. I don't know when the changeover occurred in PRODUCTION, but I think that it was fairly early in the model year.In Appreciation of John Hinckley -
Re: 1967 J56 Calipers
Joe:
I have a pair on the bench, and I can't see any grind marks on the top of the calipers, it looks like the dual pins are cast and nor drilled in place..
Question how would a flight judge look at the J-56 option since it very rare option.
Thanks,
BillComment
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rare, but seen frequently
The bigger meets usually draw some L88's so the judges get to see the J56 brakes often enough, especially the team leaders.Comment
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Re: 1967 J56 Calipers
Bill-----
The original J-56 calipers were manufactured from the same castings as the non-J-56. So, the pad pin bosses had to be machined off and the cotter pin holes added. Every one of these calipers that I've seen (including NOS J-56 caliper halves) have shown evidence of the machined off bosses. I suppose that it's possible that if some were machined a little "deeper", all evidence of the boss would "disappear". But, it was there to begin with.
As far as the cotter pin holes go, they would have to have been added by machining/drilling of the caliper casting; there's NO way that such holes could have been part of the casting. There's absolutely no practical, or even impractical, way that could have been done.
Theoretically, it would have been possible for GM to have a different casting (and, different casting number) for the J-56 caliper halves. Such a casting could have deleted the pin boss to reduce machining. As I've mentioned, though, it could not have included the holes. However, considering the tiny number of these things ever used in PRODUCTION, it would not have made sense for them to use a special casting. And, they didn't.
What are the casting numbers on yours?In Appreciation of John HinckleyComment
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Re: rare, but seen frequently
# 5452270
BillComment
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