67 J56 Calipers

[Tom B.]

Are the 67 J-56 Calipers the same from front to rear?

[Michael W.]

Re: 67 J56 Calipers

No, but they're not the same on any year or J56 or not. Different piston sizes for one thing.

[Richard M.]

Re: 67 J56 Calipers

Different F to R with same casting numbers as a non-J56 system. Machining was different on the fronts. Below is a copy paste of some info I collected some time ago when Jim Gessner sent me on a look see of a '67 for one of his clients in California.

.........
All references tell me that ONLY the fronts had the dual pin calipers. The 1967 JG, and Noland's C2 Guide say things like......"J56 requires J50 PB, and includes dual-pin front calipers and a proportioning valve......."

Nothing ever mentions rears having dual pins, and it makes sense, because why would they design a proportioning valve to reduce rear brake pressure when everything is up front to do the job anyways.

J56 HD Brakes. These are the numbers below that I recorded.

LF inner 5465954
LF outer 5465952

LR inner 5465954
LR outer 5465952

RF inner 5465902
RF outer 5465904

RF inner 5465902
RF outer 5465905

But the castings were the same for Non-J56. J56 calipers were made by the machining off of the center pin bosses , and drilling for the 2 big cotter pins and machining bigger bores, and different(bigger) pistons were used. The higher resolution pics are enclosed. Sorry some are blurry.

The rear calipers are not "dual pin" therefore only the fronts are J56.

It should also be noted that the J56 Proportioning Valve is missing from the brake system, normally mounted below the Differential Pressure switch.

This is from a Joe Lucia post 10 years ago......https://www.forums.ncrs.org/showthread.php?15958-j-56-caliper-casting&highlight=J56%2A

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.

Here are some of the photos of the calipers.

P4030164.jpgP4030167.jpgP4030168.jpgP4030169.jpgP4030170.jpg

P4030159.jpgP4030160.jpgP4030161.jpgP4030167.jpgP4030168.jpg

P4030030.jpg

[Wayne M.]

Re: 67 J56 Calipers

Slightly OT, as we're discussing caliper castings; but a Q about brake units (shoes [pads] & especially the backing plates) on the rear J56 calipers.

In Corvette News,Vol 9 # 4, describing the (new) HD braking, says the linings are bonded (ie. not riveted) to the backing plate. Mentions the plate is " a tough wrought nickel alloy, able to maintain strength at elevated temperature". I believe this is alloy is called "Monel" (very expensive). You may note the orange stamping on the edge of the friction material "903FF" which is the same as found on the front and rear brake "units".

5452515 J56 rears $150 , then $140 no bids 5452510 orange ink stamp.jpgNOS J56 rear pads 5452510_903FF $338.JPG5470991.jpg

[Patrick B.]

Re: 67 J56 Calipers

I doubt that the rear flat backing plates are made of the same alloy as the front bent backing plates, but the J56 friction material front and rear was noticeably much heavier than normal friction material perhaps because of a high copper content. At least that was my memory of J56 systems on 70's B/P SCCA race Corvettes that I worked on.

[Richard F.]

Re: 67 J56 Calipers

J56 pistons are the same diameter as regular ones. I believe the backing plate material on the J56 pads is Inconel. Back in the day, it was some kind of regulated material which required you to turn in old pads in order to get new ones. Recently I heard mention on an F1 race that Inconel is much used on those cars, including for the exhaust headers.