Midyear Corvettes went through many brake system changes. Production began with drum brakes, which were similar to those on first-generation, solid- axle Corvettes. Brake fade or loss was typical when drum brake systems became wet or excessively hot. Nothing was more unnerving than stepping down hard on the brake pedal, only to find that it did very little to halt vehicle motion.
Earlier, I touched on GM’s very special optional drum brake system, RPO J65, which was available with the big tank, road race 1963 and 1964 Corvettes. RPO J65 used segmented, sintered-metallic brake shoes with finned, aluminum, 11-inch brake drums. The finned, aluminum drums helped dissipate heat much more quickly than cast-iron drums. Ventilated brake backing plates further helped alleviate heat build-up. Unfortunately, the J65 optional brake system came with com- promises that drivers had to contend with. Temperature was still a concern, as cold brake shoes caused uneven braking until heat built up. Chances are good that very few folks work with the rare J65 option.
This Tech Tip is From the Full Book “HOW TO RESTORE YOUR CORVETTE: 1963-1967“. For a comprehensive guide on this entire subject you can visit this link:
SHARE THIS ARTICLE: Please feel free to share this post on Facebook / Twitter / Google+ or any automotive Forums or blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.chevydiy.com/c2-corvette-restoration-ultimate-brake-guide/
I cover the most common Midyear systems and possible upgrades, in order to eliminate safety concerns. Early Midyear brake hydraulic systems were very simple: A single master cylinder actuated all four brake assemblies. Wheel cylinder piston diameter and brake shoe width determined the drum brake system balance. Wider brake shoes and wheel cylinders with a larger diameter were used up front for greater braking power, due to weight distribution. General Motors used the Corvette platform for many first-run mechanical advances, and brake systems were no exception, such as the introduction of disc brakes and dual-circuit hydraulic brake systems. For the first time, Mid- year Corvettes had a power brake option. Many positive changes occurred with the braking system in the five years of Mid- year production.
The 1965 Corvettes have front disc brakes as standard equipment. Disc brakes on the Midyear Corvette are not perfect. Like any new product, problems surfaced. In spite of a few issues, General Motors used the same style caliper in place on all Corvettes until 1982. The Delco-designed Midyear disc brake caliper had four pis- tons in a fixed housing. The “fixed” calipers use four caliper pistons to apply pressure to both sides of the rotor surface. The design applied equal pressure to the rotating disc and provided excellent braking.
Brake pedal travel is relative to fluid displacement, which presents a challenge when you have 16 caliper pistons to actuate. To limit caliper piston travel, light- duty compression springs were placed behind the pistons, to keep the disc pads close to the rotor. This minimized caliper piston movement during rotor rotation and limited brake pedal free travel. The number-one concern or problem with any fixed caliper is ensuring that the rotor centerline is parallel to the caliper center- line. Centerline variations past .004 inch at the outer edge of the rotor cause a low brake pedal. Excessive brake pedal travel also occurs as caliper piston movement introduces air into the hydraulic system. The calipers become much like a little engine with the pistons pumping air into the hydraulic system.
Caliper piston seal wear was another issue, due to excessive rotor run-out. One more malady that plagued the early design calipers was corrosion of the caliper piston seal surface. When calipers leaked (and they all did) expensive housing replacement was required. In 1969, when floating calipers were introduced for all other car lines, the caliper piston seal design was changed: The caliper pistons became the seal surface, and the pistons were made of stainless steel. This meant that, in the worst case, floating caliper corrosion only required piston replacement.
As you can imagine, a lot of 1965– 1982 Corvette calipers were in the field. Additionally, in limited numbers, GM and other U.S. vehicle manufacturers used fixed calipers on their high-performance vehicles until 1968. This brought about an industry focused on repairing and enhancing the original, fixed, four- piston calipers. Early on, stainless-steel sleeves were pressed into machined original housings to restore corroded calipers. Aluminum pistons were replaced with new, improved lip seals, making them better than new. Many of these remanufactured calipers are used today with excellent results.
Brake caliper design has evolved with some crossover of fixed and floating caliper ideas. Floating calipers have square- cut caliper piston seals. The significance of the square cut O-ring seal is its adaptation to the fixed caliper pistons. As mentioned earlier, fixed calipers use lip-style piston seals for the loose-fitting pistons, which were more susceptible to excessive rotor run-out. The square cut O-rings held the pistons better than the original lip seals. Consequently, the rotor run-out concerns were not nearly as troublesome.
The caliper piston square-cut O-ring seal design has been improved to increase fuel mileage. By modifying the square- cut O-ring with a tapered edge, caliper pistons pull back very slightly when the brake pedal is released. The slight pull- back of the caliper piston relieves disc brake pad drag, thus increasing fuel mile- age. Vette Brakes and Products utilized this square-cut O-ring technology for their remanufactured calipers. You can purchase either style O-ring or lip-seal- type caliper assemblies from Vette Brakes and Products.
The beauty of the stainless-steel- sleeved calipers is that you can have your original set of calipers restored. With- out disassembly, no one can detect that stainless-steel sleeves or O-ring-style pis- tons have been installed. There are other remanufacturers, such as Stainless Steel Brakes Corporation, that do fine work making original calipers look new and ready for the NCRS judges. If you are inclined to restore your project back to Bloomington Gold or NCRS standards, make sure you have original GM caliper housings. Date codes were stamped onto the caliper housings, which are important for a correct restoration. Over the long history of the Corvette fixed caliper, many companies have made new, look- alike replacement calipers. You certainly do not want to have the calipers restored, only to find out that the calipers are not GM originals.
I do not attempt to restore or rebuild calipers. These days, there are very few original, non-sleeved calipers avail- able. The vast majority of calipers have been sleeved multiple times with new components installed. When you find stainless-steel-sleeved calipers leaking, there are a few causal factors to look for. The number-one most common factor is rotor run-out, which causes wear to the sleeves. Contaminated brake fluid con- tributes to caliper leaks, too, especially with lip-type piston seals. I have disassembled many leaking, stainless-steel calipers to inspect them, hoping that I would be able to replace the seals. No such luck. I found damaged stainless- steel sleeves every time. The fact is that the stainless-steel-sleeved, O-ring-sealed calipers should last a lifetime if rotor run-out is maintained. Periodic brake fluid flushing is also necessary to keep the calipers in good condition.
The 1965–1982 Corvette calipers are available in kit form from specialty sup- pliers. The most common kit consists of four calipers, disc pads, hoses, and rear lines. Beware when it comes time to buy replacement calipers. Many of the major discount automotive supplier chains can- not come close to the pricing from the specialty suppliers. Every time I compare prices at discount stores against specialty stores, the specialty stores win. Another concern is the discount chains may not have stainless-sleeved calipers. I have found them without stainless sleeves in new aftermarket and remanufactured calipers from the discount chain suppliers. Instead, these sources are using the cast-iron bore as in the old days. At the very least, you want the stainless-steel- sleeved calipers, whether they are new or remanufactured. I always use the stain- less-steel-sleeved, O-ring version for all of my restorations.
Don’t forget about rotor wear. Rotors wear as a result of aggressive disc brake pads and dirt. Rotors should be checked for minimum thickness before and after machining. General Motors stamped a minimum wear limit inside the rotor; please heed the allowed limit. You might think that machining the rotor removes excessive run-out. This statement would be true if the rotor is still riveted to the hub, as General Motors originally manufactured them. When front rotors are replaced, rivets are drilled out and the assembly becomes two pieces. Companies, such as Corvette Central, have replacement rivets if you desire to make the assembly one piece again.
Rear brake rotors are another story. The rotors must be removed to access the parking brake assembly. The alter- native method to access the parking brake is to press out the spindle and rotor as an assembly. When rear rotors are replaced or machined, the rivets must be drilled out. One rotor machining option is to machine the rotors on the car. On-the-car rotor machining is more commonplace today, due to the majority of front-wheel-drive cars on the road. By now, however, the majority of Midyear rear brake rotors have had the rivets drilled out. Riveting a new rear rotor onto the spindle requires major work disassembling the spindle. It really makes no sense to worry about riveting rear rotors to the spindles, unless you are planning an NCRS or Bloomington Gold restoration.
Once the rotors have been removed, check for minimum thickness, and if they are within limits, they can be machined. After machining, the rotors should be washed thoroughly with soap and water. Many shops blow off the metallic dust and slap on the spindle, ready for service. Like engine cylinder walls, the machining process leaves the rotors and drums coated with a fine metallic dust that should be removed. The dust accelerates wear, causes squeaking, and shortens rotor or drum life. I use Purple Stuff, Simple Green, or a similar type of acidic cleaner to remove dust and grease. Scrub the rotor and then wash it down well with water.
Now, the trying part begins. Each rotor should be checked for excess run- out with a dial indicator. I always knock off any high spots on the rotor and hub before installing the rotor onto the hub. Place five lug nuts on the hub and rotor assembly and tighten them with a wrench. The following photos show you how I address high and low spots that cause rotor run-out.
1963–1965 Drum Brakes
The tried-and-true duo-servo drum brake system was used on all the Mid- years. The front brake shoe is the primary shoe, with a rear, secondary shoe. The duo-servo design increases braking effort as the primary shoe drags the secondary shoe into the drum. Another first for the Midyear were self-adjusting front brakes on the ’63 to ’64, and rear brakes were self-adjusting from 1963 to 1965. When applying the brakes in reverse, a lever pivots off the secondary brake shoe and turns the adjuster wheel one position. The system worked well for those who came to a full stop. If you had a tendency to let the transmission make the transition from rearward motion to forward, brake adjustment did not occur.
Drum brake service is simple enough and requires very few special tools to address the most common problems: wheel cylinder leakage and brake shoe and drum wear. For the most part, drum brake replacement parts are inexpensive. In the past, I usually rebuilt the wheel cylinders, which have aluminum pistons with a cup-type rubber seal to actuate the brake shoe pin. The aluminum cups cor- rode and stick in the wheel cylinder bore. Water-saturated brake fluid ends up finding its way between wheel cylinder cup seals, contributing to corrosion. Corro-sion eats away at the wheel cylinder surface, leaving irregular low spots. Wheel cylinder hones are used to smooth and refinish the seal surface. In the majority of cases, honing the cylinders to remove the irregular low spots is impossible. The cylinder bore ends up oversized and allows fluid to leak past the wheel cylin- der seals. For these reasons, replacement is the better option.
If you are doing an NCRS restoration, original wheel cylinders can be restored for judging. There are companies that machine and install brass or stainless sleeves in your wheel cylinders. Apple Hydraulics machines and sleeves all brands of wheel and master cylinders. Like the calipers, make sure you have the correct Delco wheel cylinders before sending them out for service. The cost is higher, but the wheel cylinders should last the life of the car with periodic brake fluid servicing.
Unless there is a record of recent replacement, you should replace the return spring hardware. Over time, the spring loses its rate due to heat, which weakens the brake shoe hold-down and return springs. Zip Products has all the return springs, clips, and pins available in one kit, making it a simple job. The price is low enough that it is not worth cleaning the tired pieces and hoping that they do the job correctly. After 48-plus years, the self-adjuster hardware most likely is worn and in need of replacement, too.
Midyear brake drums were also Delco products, and chances are they have been changed multiple times by now. You can buy Delco replacements, but they are not Bloomington Gold or NCRS correct. Checking the drum diameter is very important for maximum brake performance and safety. The drum has a maximum safe oversize limit stamped on the outer surface. If the drum has enough material for machining, make sure the shop checks the finished diameter. Drums or rotors worn beyond limits are not safe because they can crack under hard braking. Automotive machine shops and brake specialty shops can service drums and rotors, if necessary.
When drum brakes were popular, brake shoe arc grinders were used for maximum brake shoe-to-drum contact. The arc grinder was set for the exact drum diameter, then the brake shoes were ground accordingly, to fit the drum very closely. The beauty of the brake shoe arc grinder was that the brakes felt good immediately; however, over time, shoes that have not been arc ground wear into the oversize drums, making better con- tact. Maximum brake shoe contact and correct adjustment is critical for minimal brake pedal travel.
Drum Brake Options
Consider changing your front drums to discs if you have a ’63 or ’64 Midyear. This suggestion is especially worth considering for any Midyear you want to drive on a regular basis. Changing from drums to discs on the front is simple with readily available kits. The rear drum brakes are fine and take quite a bit more work to upgrade. Rear disc conversions are usually done when rear wheel bearings and trailing arm bushings are replaced. All of the available kits are complete with conversion brackets, calipers, disc pads, and hardware. By far, front disc conversions are the best brake upgrade for the dollar.
Single-circuit hydraulic systems worked for years with one common pres- sure source: the master cylinder. If you have not driven an early car and experienced a brake system failure, it’s quite exciting. When a single-circuit hydraulic system springs a leak, complete brake failure occurs. Today’s dual-circuit braking systems have two, separate hydraulic systems in one unit. The front brakes are independent of the rear brakes. If the front or rear brakes experience a hydraulic leak, valving shuts down the offending side of the split system. The remaining front or rear brake system provides some stopping power. Of course, if you lose the front brakes, stopping distances are much greater. Due to weight distribution, the front brakes normally do more work.
The good thing is, you can still stop if there is enough distance between you and the next car. Most brake valves are multi-purpose, diverting brake fluid flow when hydraulic system failure occurs and warning of system failure. Some valves serve a third purpose, proportioning the brake fluid pressure for the best possible brake balance.
GM brake technology was cutting edge for 1965, using a dual-circuit master cylinder on cars equipped with power brake. This early dual-circuit system had a control valve with a warning light switch. By 1966, all Midyears had a dual- circuit hydraulic system with or with- out power brakes. This is one very smart upgrade for any single-circuit hydraulic system. Brake lines require reconfiguring for the dual-circuit system, which is easily done during restoration.
Like many of the normal wear items, most master cylinders have been replaced multiple times, by now. The correct, date-coded cylinder requires a brass or stainless sleeve for sure. In that case, pack up the master cylinder with your calipers and send the whole batch away for restoration. As I mentioned earlier in this chapter, it makes sense to upgrade to a dual master cylinder. The task is easy enough with most major Corvette sup- pliers carrying all the pieces needed for quick installation.
Master cylinders leak at the rear, where the pushrod from the brake pedal forces the piston inward. Cars with manual brakes may have brake fluid stains or possibly liquid on the backside of the carpet under the dash. Power-brake- equipped Midyears with master cylinder leaks do not readily show the fluid loss. As the fluid seeps out of the rear of the master cylinder, it can end up in the booster, where the fluid causes internal damage. Master cylinder failure is gradual in most cases. Many times, the problem is noticed when waiting at a stop light, the brake pedal creeping toward the floor. If you have to wait for an extra-long light, the pedal may actually end up on the floor- board because brake fluid is bypassing the compression seals, causing the brake pedal to drop slowly. Eventually, the seals do not hold pressure at all and the pedal has a slight drag when depressed. After the slight drag, the brake pedal hits the floor. You can pump the brake pedal, and it has resistance, but the pedal just heads to the floorboard a moment later.
Brake Lines, Fittings, Hardware
Finding corroded brake lines and fit- tings is commonplace. If the brake lines are more than 10 years old, chances are all the brake lines are in poor condition. Brake lines corrode externally and internally. With all your hard work, it would be a shame to crash over the cost of new brake lines. If you are planning a body-on restoration, brake line replacement is very tough. I don’t want to say it is impossible; it can be done. Of course the lines can be modified to fit without body removal. The problem there is that it is very obvious to a potential buyer. If you decide to just lift the body enough for body mount replacement, go a little further and replace the brake lines.
Removing old brake lines is usually difficult. Either the line wants to twist off or the fitting nut is rounded off. If you want to save the lines, here are some tricks. Heat the fitting nut when replacing a front brake hose with a seized fit- ting. To avoid a small explosion, cut the flexible brake hose, close to the hose fitting. (I got a surprise the first time I heated up the fitting to loosen a line: The ensuing pop blew the rubber hose out of the hose end. No danger or damage, just a very noticeable surprise.) If you find a slightly rounded fitting nut, Vise-Grips pliers applied to the line wrench helps loosen it. Clamp the Vise-Grips onto the open end of the line wrench to prevent slippage of the wrench.
All Midyear brake lines are carbon steel with double inverted flare ends and steel flare nuts. If you plan on repairing steel brake lines, they should be double flared. Stainless-steel lines should be single flared. Under no circumstances should compression fittings be substituted for flare fittings. If you do splice a brake line, use inverted flare coupler fit- tings to make the connection. Brake system pressure is 50 to 100 psi and any leak is a problem. Besides the obvious loss of fluid, system pressure is reduced from even a small leak.
Power or Manual Brakes?
Disc brakes require additional pedal pressure to move the multitude of caliper pistons. Vacuum-diaphragm, power- assisted boosters were introduced to ease the extra pressure requirements. Power brakes also make drum brakes feel better if the drums and shoes overheat.
New 1964–1967 date-coded brake boosters with correct cadmium plating are available from all the major suppliers. Long Island Corvette Supply has a rebuilding service for your original unit, if you desire. Keep in mind that the rebuilding service takes approximately a month. With proper planning, the booster is ready for installation when you need it.
Let’s face it: We are getting soft with all the latest automotive options avail- able. Driving an early car with manual disc or drum brakes is hard to accept after cruising around in your daily driver. Converting to power brakes is routinely done with readily available parts. Brake boosters are available remanufactured and new with correct master cylinders. If you do convert to power brakes, make sure you also purchase the appropriate master cylinder.
Brake fluid is the culprit of almost all problems in the brake system. DOT 3 and DOT 4 glycol brake fluid is hygroscopic and draws water from the atmosphere. Master cylinder caps have rubber diaphragms to prevent air intrusion into the system. The diaphragm expands and contracts as brake fluid level changes. It is imperative that the rubber diaphragm seals tightly to the master cylinder reservoir. Water ends up in the hydraulic system no matter how careful you are. The worst thing to do is use a previously opened can of brake fluid that has been sitting around for many months. When you check the brake fluid, put the cap back on the reservoir as quickly as possible.
DOT 5 or silicone brake fluid is an alternative to the glycol fluid. Silicone fluid is non-hygroscopic, although moisture in the system is still possible. The use of silicone fluid is somewhat controversial because of spongy brake pedal concerns. Another concern is silicone fluid’s inability to mix with any moisture that may be present. Water in the system is in specific areas and not disbursed through- out the hydraulic system.
I use silicone brake fluid in all Midyear project cars to prevent dam- age to painted surfaces. My personal cars all have silicone fluid with no ill effects especially concerning the spongy brake pedal claim. The chance that water intrusion is an issue with proper maintenance intervals is greatly reduced. If you plan on road racing or high-speed auto crossing use the glycol fluids and change it often to limit moisture intrusion Silicone-based fluid is particularly dangerous in areas with freezing temperatures because the water freezes within the system, potentially preventing brake operation or causing component failures. DOT 5.1 glycol-based fluid is a good solution for cold temperatures.
Like the vehicle brakes, parking brakes went through numerous changes during the 1960s. The 1967 parking brake system was refined and a similar design was used until 1982.
The 1963 parking brake cable system had some trouble spots. The parking brake front cable was secured to the fiberglass floorboard. After years of use, the parking brake weakens the fiberglass floorboard, eventually tearing out the cable support. The front cable pulls on a frame-mounted lever that connects to the rear parking brake cables. The frame- mounted lever is easily damaged from road debris or improper jacking during repairs.
The 1964 model year brought a much-needed change: the front parking brake cable was mounted to the transmission crossmember. There were a couple of different rear parking brake cable configurations for the drum and disc brake cars. A much easier to use, center-mounted parking brake lever was brought into production in 1967. The center-mounted parking brake lever was easier to use, thanks to greater leverage. Throughout all the changes, two mechanical parking brake assemblies were used. The 1963– 1965 drum brake-equipped Midyears mechanically applied the rear brakes, while 1965–1967 Midyears with disc brakes had a unique, miniature drum brake system incorporated into the disc brake system.
The mini parking brake assembly worked poorly, at best. The mini drum brake shoes and cables had to be adjusted frequently for any parking brake reliability. To top it off, the brake shoes were hidden behind the rear spindle. Many parking brake shoes and hardware have been removed because of the difficulty in servicing them. Specialty tools are avail- able to service the brake shoes, but even so, the task is quite difficult.
The best policy is to replace the parking brake shoes and hardware when servicing the rear spindle bearings. I use stainless-steel hardware with steel parking brake shoes.
No matter what Midyear you own, operate the parking brake frequently. All parking brake cables have a tendency to freeze from non-use. Always adjust the parking brake shoes before adjusting the cable. In most cases, I back off the parking brake cable, leaving it loose while I adjust the brake shoes. Make sure the wheels rotate freely after adjusting the parking brake. Excessive brake shoe drag causes high heat, which possibly dam- ages the wheel seals and bearings. Of course, brake shoe wear and damage does occur and requires the dreaded parking brake shoe replacement.
Bleeding the 1963–1967 Corvette brake system is a major pain and at the very least an annoyance. The multitude of air pockets within the calipers makes it very difficult to get all the air out. Having a friend pump the brakes is an option. Expect an all day affair in the quest to get a really good, hard pedal. Today, pressure bleeding systems work well and can be purchased at a very reasonable cost. If you use a pres- sure bleeding system, you do not need anyone to pump the pedal; just pressurize the system and bleed. You can also use the pressurized bleeder to check the system for leaks. Leave the system pressurized for half an hour after bleeding the system. Any leaks can then be spotted before heading out on your maiden voyage.
Motive Products has a very reason- ably-priced brake bleeder unit that works like a garden sprayer. Be sure to buy the appropriate adapter for your Midyear’s master cylinder. After installing the adapter, the cylinder is pumped up and the bleeding begins. Another nice feature is that with the multitude of adapters available you could flush any of your other vehicles’ brake systems easily.
Brake Rotor Replacement
Step-1: Measure Brake Rotor Thickness
Using this dial caliper is not the ideal way to check rotor thickness but it gives you an idea whether to machine the rotor or not. This rotor is an original, riveted to the rear spindle with plenty of meat for machining. I measured the flat, smooth rotor at 1.256 inch thick, well above the 1.215 discard limit.
Step-2: Replace Brake Rotor
Rotor replacement starts by drilling out the factory-installed rivets. Use a 3/8-inch drill bit to remove just the head of the rivet. Use a center punch first to dimple the rivet as close to center as possible. The rivets are soft steel and using a drill press makes it much easier to cut them out.
Step-3: Punch Rivets Out of Brake Hub
Once the drilling has been finished, use a flat punch to drive out the remaining rivet shank. After the rivets have been punched out of the rotor, the remaining portion of the rivet needs to be driven out of the hub. Pushing the rivet piece out of the hub can start trouble that shows up during rotor run-out checking. Keep the punch centered; do not let it get stuck in the hub’s rivet hole. The rivet hole becomes raised if the punch gets stuck and causes one or more high spots.
Step-4: Clean Brake Rotors
Use a degreaser or brake cleaner on new, used, or machined rotors. Machined rotors have metallic dust embedded in the surface. A good cleaning with a scrub brush helps keep the disc pads healthy and squeak-free. Once the surfaces are clean keep your hands off the disc pad wear areas.
Step-5: Clean Brake Hub
Machined rotors require more rotor hub area preparation. Use a high-speed grinder with a 3M Scotch-Brite disc to knock off the corrosion and any high spots from the axle flange area. Run the grinder around the entire axle flange area in the rotor hub area until it shines. The better you prepare now the more it helps the run-out testing.
Step-6: Measure Brake Rotor Run-out
Use a magnetic or Vise-Grips base dial indicator to check rotor run-out. Set up the indicator at the outer edge to find maximum rotor run-out. Note the low spot to the closest wheel stud. Tighten all five of the lug-nuts with the flat side against the rotor to 50 ft-lbs to ensure the rotor is tight and flat against the hub.
This run-out was 0.012 at the high end. I placed a 0.005 piece of brass shim stock on the stud opposite the low spot. This can be tricky. Sometimes you have to place the shim to the right or left of the perceived low spot. Install the rotor and try the run-out check again until the run-out is 0.004 or less. Do this same procedure on new components as well as dated, hard- driven Midyear examples.
Step-7: Prepare to Install Caliper
In preparation for the caliper installation, run a 7/16-20 thread tap through the mounting plate’s bolt threaded holes. This is for a rear caliper that bolts to the mounting plate. Be extra careful cleaning these threaded holes with the rotor in place. The tap can easily bottom out against the rotor and chew it up.
Step-8: Install Piston Retainers
Use caliper piston retainers to keep the pistons in the bores until the pads are installed. Push the caliper pistons back into their bore then install the retainers. It is much easier to install the retainers when the calipers are off the car. Or the retainers can be put in place before the pads are removed. The retainers work well when it comes to replacing the disc pads to keep the caliper pistons out of the way. Apply a light coating of silicone grease to the disc pad’s back plate before slipping it into place. This caliper kit has new pins that hold the floating disc pads in place.
Step-9: Torque Caliper Mounting Bolts
Use a click-type torque wrench to torque the mounting bolts to 65 ft-lbs after the Stainless Steel Brake Corporation caliper is bolted into place. Leave the brake fluid supply hard line loose and the hose off until you torque the caliper.
Drum Brake Rebuild
Step-1: Remove Drum Brake Spring
Ah, drum brakes. Had to get out some tools that were lonely in the brake service drawer. This is one valuable brake spring removal and installation tool. Hook it on the spring, give it a simple twist, and the spring is off. Remember, these springs have plenty of stored energy and can hurt you if you are not careful.
Step-2: Replace Drum Brake Wheel Cylinder
This is what you typically find when peeling back the wheel cylinder boot: a blob of rust and corrosion formed around the aluminum cup. Today it makes sense to replace the cylinders, considering the cost of materials and labor time. Two 1/2-inch hex bolts hold the wheel cylinder to the brake backing plate from the backside. Break the hose or brake line loose before removing the 1/2-inch retaining bolts.
Step-3: Install Brake Shoes
Set the brake shoes in place as an assembly with the star wheel adjuster and return spring installed in the shoes. Make sure to install the parking brake actuator lever and E-clip in the rear shoe before proceeding.
Step-4: Install Brake Shoe Spring
Use the special installation tool to install brake shoe hold-down springs and retainers. This can be tricky since you have to place the self-adjuster lever in the shoe while installing the hold-down spring. The hold-down spring retainer fits into the special tool to aid in pushing down the retainer until the pin is far enough out to allow the retainer to be twisted. Twist the retainer a quarter turn until it sits into the retainer depressions.
Install the new primary and secondary brake shoe return springs. The spring (here) is on the primary side. The spring ends have a tendency to open up after installation, so use a pair of pliers to squeeze the spring closed.
Step-5: Confirm Adjuster Lever Operation
This short red spring is part of the self-adjuster assembly. The adjuster lever rocks downward and tightens the brakes each time the brakes are used in reverse. Make sure the adjuster lever is engaging the adjuster’s star wheel. You should be able to move the lever downward by hand to tighten the brakes.
Step-1: Remove Brake Adjuster Nut
First soak the parking brake cable with PB Blaster to help break the adjuster nut loose. Sometimes heat must be used to get frozen nuts loose and a propane torch does the job well; however, always remember you are working around a fiberglass floorboard that burns quickly.
Step-2: Connect Brake Cable to Lever
This gives you an idea how the parking brake cable connects to the lever. The caliper has to be removed to access the parking brake cable. The rear caliper brake line should be set in place before the caliper is installed. I often find this brake line incorrectly placed on top of the trailing arm. The line sits under the caliper conforming to fit alongside the trailing arm.
Step-3: Replace Parking Brake Springs
Use this special tool to remove and replace the springs for parking brake service with the spindle in place. The notches grab the spring for the contorted installation of the springs. Although feasible, this tool is no miracle device, it allows you to service the parking brake shoes. Mid America Corvette has this tool available along with all the necessary parking brake pieces.
Step-4: Restore Parking Brake Assembly
This is the condition of many parking brake assemblies found hidden under the rear spindle. Broken return springs cause a constant clicking noise as the wheels rotate. Grease on the brake shoes from incorrectly installed spindle seals is commonplace. This is why I always recommend disassembling the spindle and restoring the entire assembly.
Step-5: Remove Rivet Stud from Spindle
Someone has drilled the rivet heads off leaving the remaining rivet stud in the spindle. It seems harmless enough until the rivet stud backs out into the parking brake assembly. I always remove the entire rivet to prevent floating shrapnel from tearing up the parking brake’s internal components.
Step-6: Install Brake Shoes
This is what I like to see: New steel cadmium plated brake shoes with stainless steel hard- ware installed. Use Never-Seeze to lube the adjuster threads during assembly. As you can imagine, working through a couple of 1/2-inch holes to install the pieces is very difficult. If you can master installing the shoes with the spindle in place, shipbuilding in a tiny bottle is right up your alley.
Step-7: Set Brake Adjusters
Old-time brake adjusters that are not right- or left-specific need to be adjusted now. One side goes up to lengthen the star wheel adjuster while the other side goes down. Tighten the parking brake adjuster until the rotor does not turn, then back it off five to six clicks. The rotor should turn with minimal brake shoe drag. I usually tighten until the rotor does not turn and back off the adjuster procedure twice to set the shoes in the drum.
Step-8: Bleed Brakes
Using a pressure- pot assembly is the preferred method to bleed brakes on all Midyears. The cover plate fits tightly on the master cylinder and 15 to 20 psi of pressure is applied from the pressure tank filled with fresh brake fluid. This is absolutely the quickest and easiest way to bleed brakes.
As you bleed the brakes, clear, fresh DOT 5 silicone fluid flows from the remanufactured O-ring calipers. The hose is used to prevent spilling brake fluid. To check operation, also look between the disc pad and caliper and check to make sure the caliper pistons have come out and are pushing against the disc pads. Once in a great while, a piston sticks slightly and prevents it from seating on the disc pad.
Written by Chris Petris and Posted with Permission of CarTechBooks