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Before I do something stupid, like sell them or send them in as cores or put them back on the race car they came off of, can anyone help with the correct casting numbers on a set of rear J-56 calipers???? many thanks in advance!!
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Re: j-56 caliper casting ##
Howard-----
J-56 caliper castings were the same as non J-56 for any given year model. The rear J-56 finished caliper halves were exactly the same as non-J-56; there was no difference, at all, for J-56 rear calipers as compared to non-J-56. The pistons, of course, were different for all 67-75 J-56.
The front J-56 calipers for any given year simply had the pin boss machined off. They were otherwise the same as non-J-56. Anyone can convert a non-J-56 front caliper to a J-56 by machining off the pin bosses and adding the 1/8" holes on either end for the long cotter pins and it will be absolutely undetectable from the originals; that's just how Delco-Moraine originally manufactured them.
For 65-66 (and POSSIBLY very early 67), ALL caliper half casting numbers began with "546"; these castings have integral piston guides cast into the rear of the bores;
For 67-about 1973, ALL caliper half casting numbers began with "545"; no piston guides;
From about 1974 to 1982, ALL caliper half casting numbers began with "547"; no piston guides.In Appreciation of John Hinckley -
Joe
were the J56 pistons of a different diameter? If so could I have the specs?
I never have had a set of these to compare
Thanks
jerComment
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Re: Joe
Jerry-----
J-56 pistons, front and rear, were exactly the same diameter as non-J-56 pistons. For 65-66 (some folks say that a few J-56 cars were made for 65 and that's the only reason I include 65 for J-56), the J-56 pistons were EXACTLY the same as non-J-56----both had Pyroceram insulators and piston guides. For 67-75, the 2nd design J-56 pistons were used. These had a thinner aluminum piston, thicker Pyroceram insulator, and NO piston guides.In Appreciation of John HinckleyComment
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Re: Joe
Thank you Joe. I read this incorrectly and was surprised"The pistons, of course, were different for all 67-75 J-56." ASSUMING that you meant a different bore....no J56s in my shop
jerComment
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Re: Joe
Jerry----
Yes, I just meant that the 67-75 J-56 pistons were different than the 65-66 pistons and that the 67-75 J-56 piston were different than the 67-75 non-J-56 pistons. The diameters of all of the pistons used from 65-82 was exactly the same (fronts, of course, are different than rears). The same seals and boots were used for all pistons, J-56 or otherwise.In Appreciation of John HinckleyComment
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Re: j-56 caliper casting ##
Joe; Were not the original frt. J-56 cal. unique with a different number on them. I have a set of orginal's with, starting 545 but the print is very small and not in a straight line. The number's are like curved. johnComment
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Re: j-56 caliper casting ##
John----
The J-56 FINISHED front caliper halves were, indeed, unique and had unique part numbers (not found on the caliper halves, themselves). However, these FINISHED caliper halves were made up from the same castings as non-J-56 calipers.
If you look at the top of the J-56 front caliper halves, you will note where the pin boss was machined off. I have seen many original J-56 calipers and every one showed evidence of this. Also, I have some NOS J-56 caliper halves [none for sale] and each of these shows evidence of the machined off pin boss. Think of it this way: if GM had used special castings for J-56 front calipers, then why would they have included a pin boss which subsequently had to be machined off?
1965-66 (and POSSIBLY very early 1967)---all caliper half casting numbers, front and rear, begin with "546"; the same castings are used for both J-56 and non-J-56;
1967-about 1973---all caliper half casting numbers, front and rear, begin with "545"; the same castings are used for J-56 and non-J-56;
about 1973-1982---all caliper half casting numbers, front and rear, begin with "547"; the same castings are used for J-56 and non-J-56.
For the 72-74 period, there MAY have been a mixture of "545" and "547" castings used on any specific car.In Appreciation of John HinckleyComment
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