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CRG Research Report

1967 Camaro Metallic Brakes

© 2012-2013, Camaro Research Group

Primary Author -
NOT Reviewed by the CRG
Last Edit: 05-Feb-2013
Previous Edit:
Original Release: 05-Feb-2013

Index

Introduction

1967 Camaro Brake RPOs
  RPO   Description                       Cost    Qty sold 
 ----- -------------------------------- --------  --------
  J50  Power brakes                      $42.15    24,549 
  J52  Brakes, Front disc                $79.00    14,899
  J56  Brakes, HD front disc with
       metallic-faced drum rear
       (J50 & J52 mandatory with J56)    $26.35       205
  J65  Brakes, special metallic
       facing (front and rear)           $36.90     1,217
This article has been written to shed light on two special brake packages that, up until now, have been largely ignored. Very little written detail was found while researching the subject, even in original GM literature and documentation. It seemed odd that the topic of the 4-wheel disc package in '68 and '69 was well covered and had an avid group of followers, yet the earlier special brake packages were pretty much absent from all conversation. Personally, this seemed a bit like opening a book and starting at Chapter 3. My personal frustration set me off on a quest - a quest to satisfy my thirst for knowledge for two brake packages that are both extremely rare and limited to the first year of production; the year 1967.

This article describes the original components and applications for the 1967 Camaro metallic brake options, identified by the factory Regular Production Option (RPO) codes of J56 and J65.
RPO J56 was a heavy-duty brake option for the Camaro available only on the '67 Z-28. Like the RPO J52 disc brake package (an available option on any Camaro model), J56 consisted of front discs and rear drums. However, J56 added heavy-duty features to these components. According to Chevrolet records, a mere 205 examples were sold that year. However, since Z-28 production quantities only totaled 602 for '67, that equated to slightly more than a third of the total.
RPO J65 was also a heavy-duty brake option, but for drum brake cars. It consisted of both front and rear drums with special metallic shoes. It was also a relatively rare option, ending up on only 1,217 Camaros.

 

RPO J56 (disc/drum)

The Z-28 was a model developed by Chevrolet to make the Camaro eligible for road racing activity in the recently formed Trans-Am series, run by the Sports Car Club of America (SCCA). The Camaro would be competing with other similar pony cars from rival manufacturers on road courses that exacted high demands from suspension, drivetrain, and braking components. Since the Camaro was a brand new model in 1967, it was vital to GM that a car capable of holding its own against stiff competition was available to interested purchasers. Remember, Ford fully backed its racing teams back then and GM did not, at least not monetarily. A brake package that went beyond the abilities of the production J50/J52 combination was deemed necessary. This is where the J56 package comes in.

The Hugh Heishman-owned '67 Z-28 with driver Johnny Moore. This road racer is exactly the type of car that the J56 brake package was designed for.
1967 Moore race car

RPO J56 had been (and continued to be) a heavy-duty performance brake option on Corvettes prior to the introduction of the Camaro in 1967. When the new Z-28 model became available at the very end of December 1966, a Camaro-specific J56 brake package was made available for it as well. However, because the Corvette used 4-wheel disc brakes on all models, the Camaro J56 package was different than the Corvette J56. It combined the features from the Corvette discs with components from proven heavy-duty drum systems.

J56 Front Discs

The J56 package used the standard Camaro 11-inch disc brake calipers but added Pyroceram heat insulators on each of the four pistons. Under hard braking conditions, the ceramic insulators provided an effective heat barrier between the pad and the brake fluid. Thus, they reduced the likelihood of brake fluid boiling, which was a crippler of braking performance. These insulators had been proven on the Corvette racing program the year before and the technology was easily transferred over to the Camaro.

An original, unrestored J56 front brake caliper for a '67 Z-28 (front). Pyroceram heat insulators were attached to each brake piston with a Phillips head screw countersunk into the center. Compare to the standard J52 piston (rear).
J56 caliper
The above photo shows an exploded view of a J56 brake caliper. The large spring slips over a boss on the back side of the brake piston. The seal (in front) goes on after the piston has been installed.
J56 caliper
The difference between a standard J52 (right) and a J56 (left) disc brake caliper are these special pistons with black ceramic heat insulators. The heat insulators were essential for success on road race courses and road racing was the reason for the existence of the Z-28 in the Camaro lineup.
J56 pistons
A comparison of the standard '65-66 Corvette brake piston (left) versus the 67 J56 piston. The J56 piston has a much thicker black heat insulator. The piston and caliper were also redesigned in 1967 to eliminate the center piston guide. The stock 67-68 Camaro brake piston was all metal, with no insulator.
J56 pistons

Metallic brake pads were not provided for the front disc calipers on J56-equipped Camaros. Chevrolet wording for the J56 option was as follows: "Heavy Duty Front Discs With Metallic Lining Drum Rear". No service replacement metallic disc brake pads were ever cataloged in Chevrolet parts books (except for Corvettes), whereas the metallic rear drum brake shoes were readily available for all models via service replacement. The way the Camaro J56 option was specifically worded, along with the fact that Corvette 11.75-inch diameter metallic pads were cataloged while Camaro 11-inch diameter metallic pads were not, is supporting evidence that Camaro metallic front pads were never factory issue. As an added note, on a Z-28's window sticker, J56 is simply noted as "Heavy Duty Brake". The word "metallic" is conspicuously absent.

Page 2 from the Z-28 introduction letter, dated December 9, 1966. It tentatively shows J56 as a mandatory option, which turned out not to be the case. What should be noted is that the J56 package was available for the Z-28 from its inception. This was important, because many of the first Z-28s went directly to road racers who were trying to get their cars prepared for the Trans-Am road races that began in early February.
Intro Letter

In speaking with former Z-28 road racers that campaigned cars during the '67 Trans-Am season, it has been discovered that an upgrade to the J56 disc/drum brake package was made available that year. Specially modified Camaro calipers were produced for use with the stock 11-inch rotors and were machined to accept the HD Corvette metallic brake pads (p/n 5468882). [Note: These special Corvette pads absolutely will not fit into stock Camaro or Corvette calipers unless the calipers are machined to accept them.]

These Corvette brake pads used two cotter pins for retention rather than the large single pin in the middle. They also had stiffer backing plates that served to reduce the vibrations feeding back into the pistons and causing air leaks into the brake system. These specially machined Camaro calipers were available through the parts department as part numbers 5468886 and 5468887.

Interestingly, these 886 and 887 calipers are listed under the "Special Service Parts" heading of the 1968 Z/28 brochure. Chevy also made a blueprint available to race teams who wanted to machine their own Camaro calipers to accept the Corvette metallic pads.

Talk about rare, here's an original J56 racing caliper. The photo illustrates the use of two cotter pins to retain the flanged, metallic brake pads sourced from the Corvette parts bin. The pads in the photo happen to be Raybestos replacements but they are identical in every way to the Corvette pieces made by Delco-Moraine.
J56 racing calipers
NOS Delco-Moraine metallic brake pads for J56 Corvettes and also J56 Camaro (when the front calipers are machined to fit). The backing plate is Inconel, which is resistant to warping/distortion at extremely high temperatures.
J56 NOS pads

1967 Z-28 J56 caliper shown with the GM-supplied drawing detailing how to modify calipers to accept the Corvette J56 brake pads for road racing competition.
J56 caliper
This photo shows the outer half of a front disc brake caliper (casting number 5455533). The area circled in red shows the day of the calendar year (Julian date) when the part was cast. Brake calipers only indicate the day they were cast, not the year. In this particular case, it was cast on the 37th day of the year.
J56 caliper date
With the same caliper flipped around 180 degrees, we now see what the inner half of the front disc brake caliper looks like (casting number 5455530). Again, the area circled in red indicates the location of the casting date - the 89th day for this half. These are a matched pair of castings from a one-owner Z-28 built in July of 1967.
J56 caliper date

J56 Rear Drums

For the rear drum brakes, metallic linings from heavy-duty drum brakes were used. The metallic brake rear axle assemblies (which included brake drums and brake hardware) were unique and thus had unique 2-letter application codes. (Both the J56 and J65 options used the same axles). On the metallic brake shoes, the lining was bonded on, whereas on normal production brake shoes the lining was riveted on. This has been found to be standard Chevrolet practice with metallic brake shoes. The size remained constant between Camaro metallic and non-metallic rear brake shoes, 9-1/2" x 2".

Rear brake drum removed from the passenger side of a J56-equipped 67 Z-28. [Note: The top-right light blue spring has been replaced and should be light green]
J56 rear drum
Close up view of the segmented GM metallic brake shoe, as installed.
J56 rear drum

Backside of the 9-1/2" x 2" metallic rear brake shoes. A part number of 5462922 is stamped into the backside. What almost appear to be round rivet heads are actually a bit of the brake lining that fits down in the small holes to help keep the bonded-on brake lining material in place and also more precisely locate the individual segments.
J65 brake shoes

Besides the metallic brake shoes, the brake shoe springs and brake drums were unique as well. The metallic brake shoe springs are different because they are designed to handle the higher temperatures associated with hard brake use. [Future research hopes to determine if these springs have larger diameter wire and/or more windings than their stock counterparts]

The metallic brake drums carried the same casting number as the normal production part but they are not the same and are listed as a different part number in the parts book. This was due to the fact that the friction surface inside a metallic brake drum was ground to a finer (smoother) surface finish than a standard production brake drum. The Chevrolet Chassis Service Manual specifies it as a 20 micro-inch finish (a standard brake drum finish would be 80 micro-inches or less). The purpose of this finer surface finish was to help the metallic shoe have an easier time seating or "bedding-in" to the drum.

Chevrolet had been experimenting with metallic drum brake components for 10 years prior to the Camaro's introduction. Thus by that time, they were pretty highly developed. What was new to Chevrolet was figuring out how to mix in front disc brake calipers with drum brakes on the rear. The challenge was having the brake modulation be predictable, plus optimizing the overall braking effectiveness. This was not only a challenge that needed to be solved for production cars, but it was a challenge for people who were going to race the cars as well. The components for the disc/drum system that led to successive wins at the end of the '67 Trans-Am season are shown below.

Part of the Camaro Chassis Preparation sheets provided to racers by GM.
Prep sheet

Here is a photo of Mark Donohue's '67 Z-28 road racer. Besides using the J56 metallic brake linings inside the rear drums, racers like Mark often drilled the drums and backing plates to help dissipate the built up heat that caused braking performance to suffer.
Donohue's rear drums
A Word About Brake Drums
All brake drums were (and still are) a composite design; the drums are centrifugally-cast in rotating molds. The web (stamping) is inserted in the mold first, then molten iron is poured into the rotating mold to form the cast portion of the drum. On Corvette drum brakes ('63-'64), the web on standard and J65 drums is .110" thick, and on the all-out J56 system, the web is .130" thick, usually with an "X" stamped in it for identification. All research indicates that the J56 and J65 rear brake drums used on the '67 Camaros were identical to the standard version (including the same web thickness) and only differed by virtue of the finer surface finish inside.

 

RPO J65 (drum/drum)

RPO J65 had been a heavy-duty drum brake option on all Chevrolet models prior to the Camaro coming out in 1967. The J65 brake option was available on all SS Camaros for the entire model year of 1967. It was available for that one model year only and was discontinued for 1968. J65 was available with or without J50 power assist. Essentially, the J65 option provided more braking performance over the standard drum/drum package for those people who did not want to pay the extra money for the J52 discs or who were untrusting of the relatively new (to GM) disc brake package. You have to remember this was a different era. This was why things such as 3-speed manual transmissions on the column were still available - to accommodate the desires of (typically) older drivers who were more comfortable with the technology of the cars they learned to drive in.

According to Chevrolet sales literature, J65 metallic brakes were supposedly only available on SS cars. However, CRG research has found the J65 option on some L30/M20 (327 4bbl, 4-speed) models, including one with GM of Canada documentation, and we believe the J65 brakes were a legitimate option for them as well.

With the front brake drum removed, you can see that the J65 brake shoes are very similar to the rear shoes described in the J56 section, however they are 1/2" wider, measuring 9-1/2" x 2-1/2".
67 front brake drum
Backside view of a J65 front brake shoe showing the attachment detail and a part number of 5462921.
67 front brake shoe
Front brake drum used on all drum-equipped Camaros. The presence of a mold number (W-16X in this case, top of drum) and casting number (3841198, bottom of pic) is the same with either standard drum brakes or J65 brakes.
67 front brake drum
The finned front brake drum (casting number 3853549) that replaced the J65 package in 1968. It was standard for all SS and L30/M20 cars that year.
68 drum

For 1968, the J65 metallic brake package was discontinued and all SS and L30/M20 models received finned front brake drums as a standard part of their drum brake package. Not only did the fins aid heat dissipation, they also acted to strengthen the drum against heat distortion. All remaining Camaro models (L6 cars and 327's except L30/M20) with drum brakes soldiered on with non-finned brake drums on all four corners.

All '67-'69 Camaros used the 3841177 rear brake drum casting and this was never a finned unit. The only unique part used was the 3841177 drums installed on the '67 J56 and J65-equipped Camaros that had a finer inner surface finish.

1967 Drum Brake Components
 Spring, Brake Shoe Pull Back
    3855378   Primary - Front & Rear - 4.25" long   [with J65]
    5462970   Primary - Front & Rear - 4.25" long   [w/o J65]
    3855379   Secondary - Front & Rear - 3" long   [with J65]
    5462958   Secondary - Front & Rear - 3" long   [w/o J65]

 Spring, Brake Shoe Automatic Adjusting Lever
    5462097   Return - Front & Rear [with J65]
    5461984   Return - Front & Rear [w/o J65]
    3824720   Override - Front & Rear [with J65]
    5462264   Override - Front & Rear [w/o J65]

 Brake Shoes, Metallic
    3845291   Fronts, J56 - set of 4
    3830635   Rears, J56 - set of 4

 Drum, Front Brake
    3845282   [with J65]   casting # 3841198 (w/finer surface finish) 
    3845258   [w/o J65]    casting # 3841198

 Drum, Rear Brake
    3841188   [with J56/J65] casting # 3841177 (w/finer surface finish)
    3841176   [w/o J65]      casting # 3841177
 

Master Cylinders and Rear Brake Line Valves

Complete information about master cylinders and brake boosters is located on the Chassis information page, but here is basic information.

All first-generation (1967-1969) Camaros used Delco Moraine master cylinders. The casting number was on the side of the disc brake master cylinder and for model years 1967 and 1968 this number was 5460346. All '67-'69 drum brake cars used the 5452310 casting except 1967 J65 cars, which used the 5461862 casting. It is very easy to visually tell the difference between a factory disc brake and drum brake master cylinder. The disc brake master cylinders are wider looking and use two bail clips to hold the cap down. The master cylinder for a drum brake car has a narrower body and uses a single bail.

Date codes on master cylinders are "hit and miss". If one is present, it will be on the driver's side and will be a 1, 2, or 3-digit number representing the day of the year. No year would be indicated. The application code for the master cylinder was stamped on a small semi-circular pad on the front of the casting. The code for the J65 brake package with power assist is unknown. CRG research has so far failed to turn up any surviving cars with the J50/J65 combination and GM documentation also failed to provide the code. If you know of any cars which could help unlock this mystery, please contact me.

J65 master cylinder is shown above. Power-assist was available with J65. The J65 casting number is 5461862 and it is viewable from underneath on the side facing the engine. The application code is by the yellow paint spot on the front of the master cylinder.
master cyl
Chevrolet used the 5460346 master cylinder all power disc brake cars. The photo shows the wider disc brake master cylinder with two bail clips on the cap.
master cyl

GM documentation doesn't fully correlate with actual observed usage of the rear brake line valve. Essentially, what has been observed on J56-equipped Z-28s is that the Norwood cars used the rear brake pressure regulator valve and the Los Angeles (Van Nuys) cars did not.

For J65-equipped cars, the usage has the same pattern - the Norwood cars used the regulator valve and the Los Angeles cars did not. Exactly why the two factories did this two different ways will probably never be known. The GM photo with caption below implies the valve is only used on air-conditioned cars but that is simplistic and only partially true.

Rear brake line valve is mounted on the subframe under the driver's door.
rear valve
 

Replacement Metallic Brake Shoes

Service Replacement Brake Shoes

Pardon the pun, but the metallic brake shoes "wear like iron". Additionally, the front brakes do most of the braking. Hence, original rear metallic brakes been found still in place on many original J56 and J65 cars. Replacement metallic brake shoes for the front and rear were available through the Chevrolet parts department and obviously the rigors of racing would have worn out original shoes far faster than those used on street cars. Replacement shoes were sold as a set of four to a box, with two being needed for each rear wheel. The front metallic shoes were P/N 3845291 and the rear metallic shoes were P/N 3830635. Again, the fronts and rear were very similar, with the fronts being 1/2" wider.

Set of four rear metallic brake shoes that make up P/N 3830635. The two with less lining material pads are the leading or primary shoes (which face toward the front of the car) and the two with more lining material are the trailing or secondary shoes.
J56 shoes
Rear metallic brake shoes oriented as if they were installed left side of the car (The front of the car would be to the reader's right).
J56 shoes
Leading metallic brake shoes show original ink stamps stating "Delco 101 F.F.". Trailing shoe ink stamps state "Delco 102 EE". The periods are not always used after the letters EE or FF.
J56 shoes dates

The instruction sheet that comes in the box of Chevrolet replacement metallic brake shoes.
Shoe instructions
The washers that come in the box of Chevrolet metallic brake shoes. The yellow instruction sheet describes their intended use. The washers are .625" O.D, .250" I.D. and .030" thick.
Washer instructions

Aftermarket Metallic Brake Shoes

As might be expected, there were some aftermarket companies that also made metallic brakes including shoes very similar to the Chevrolet offerings. Two such companies were Lakewood and Velvetouch. [Note: Velvetouch brakes were marketed and sold by Lakewood Industries prior to 1973 before becoming two separate entities.] Other companies included the Raybestos and Grey Rock brands. Although the Chevrolet pieces are quite good, some people just gravitate toward aftermarket products if they have a choice. No doubt many owners replaced GM brake parts with others available through their neighborhood parts store or speed shop. While this is getting us a little off course in terms of the intent of the article, I felt it might be of interest to some readers to see what else was available and what some original GM components may have been replaced with.

The Lakewood version of Camaro brake shoes is segmented but not the same way as the Chevrolet parts. These are NOS and are no longer available.
Lakewood J56 shoes
J56 shoes 2
 

Summary

The '67 Camaro heavy-duty brake options are a subject that has not previously been given much thought in the Camaro hobby. The JL-8 4-wheel disc brake package of '68 and '69 seems to get all the glory but it is part of a larger story, the next chapter if you will, of the groundwork laid down by the metallic brake packages for the '67 model year. It is hoped that this report has given the reader a better understanding that these were well thought out and developed packages and the J56 brakes in particular had a legitimate, albeit short, racing pedigree. They truly were a very special part of the Camaro performance legacy.

Acknowledgements

The author would like to acknowledge and thank the following people who contributed information to this article: Robert Lodewyk, Allan Mason, Troy Criscillis, Fred Hucke, John Hinckley, Hugh Heishman, Gary Morgan, Bob Morton, Ted Muneno, Ron Shaw, Pete Sande, and Phil Bate.

You readers can help serve to improve any future revisions of this report. We would appreciate verification of individual brake parts, master cylinders, body broadcast codes, chassis broadcast codes or any other items that you feel may provide pertinent information on the subject. Digital photos of these same items are greatly appreciated as well as they serve to expand our knowledge of what is and is not correct for these cars.

 



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