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Author Topic: JL8 / J56 4-wheel disc racing brakes  (Read 1103 times)
Jon Mello
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« on: May 04, 2013, 05:30:19 PM »

Beginning in the 1968 racing season, the Camaro was homologated (passed the criteria for acceptance) with the SCCA to be able
to use a 4-wheel disc brake package in Trans-Am and A-Sedan events. This brake equipment was adapted primarily from already
existing Corvette brake components. The calipers were the cast iron Delco-Moraine Corvette units and these were the heavier duty
J56 pieces that had 3/4" thick heat insulators on the brake pistons and that used two cotter pins to retain the brake pads rather
than the single pin in the middle. The top of the caliper was milled down to remove the single pin boss because it interfered with
the top of the flanged brake pads and was unnecessary. The inner half of the front calipers had a single brake hose inlet boss where
Corvettes (typically) had two bosses. Here are some of the rare front calipers from Robert Lodewyk's collection.
« Last Edit: May 05, 2013, 12:25:22 AM by Jon Mello » Logged

Jon Mello
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Jon Mello
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« Reply #1 on: May 04, 2013, 05:35:08 PM »

Another photo of Robert's calipers.
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Jon Mello
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« Reply #2 on: May 04, 2013, 05:38:19 PM »

Closer view from the top.
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Jon Mello
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Jon Mello
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« Reply #3 on: May 04, 2013, 05:50:44 PM »

A look at the 3/4" thick J56 brake pistons outside the bore of the caliper. (Jon Mello Collection)
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Jon Mello
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« Reply #4 on: May 04, 2013, 05:52:24 PM »

A view of the insulator removed from the metal part of the piston. (Jon Mello Collection)
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Jon Mello
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« Reply #5 on: May 04, 2013, 05:55:30 PM »

A comparison of the '66 and early '67 Corvette J56 piston with its 3/16" insulator in comparison with the part that superceded it. (Robert Lodewyk photo)
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Jon Mello
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« Reply #6 on: May 05, 2013, 01:03:32 AM »

The piston bores in the Camaro and Corvette calipers are the same size They both use a 1-7/8" (1.875") piston.
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Jon Mello
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Jon Mello
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« Reply #7 on: September 20, 2014, 12:25:45 AM »

Here's an NOS set of Delco J56 heavy duty brake pads. The full set of four is part number 5468882, while apparently each individual
pad is labeled as part number 5468883. The set includes the four necessary cotter pins in an envelope, p/n 5474322 and an instruction
sheet indicating how to precondition them for the best braking performance. The backing plates on these pads are made with Inconel,
an expensive, high-temp alloy that was more resistant to warpage when they got hot, unlike steel.  Inconel is a non-magnetic material.
The thickness from the back of the backing plate to the front surface of an NOS brake pad is 1/2" (.500").           (Jon Mello Collection)








The cotter pins are around 4" long and are 1/8" (.0125") in diameter.








Instruction sheet p/n 5474920



Warning: Preconditioning of this material is necessary to
obtain maximum effectiveness. After relining the brakes,
drive the car for approximately 1/2 mile at 1/2 throttle
with the brakes held on enough to maintain a car speed
of 15 to 20 MPH.
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Jon Mello
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