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Greetings and welcome back to Project '63, Late Great Chevy's 1963 Impala SS car. In our last installment, we added front disc brakes to create more "whoa, before we go." This month we're adding even more braking to the '63 by installing PIN 563178 (rear disc brake conversion kit). This rear disc brake kit, along with the front disc brake conversion we did last month, will give '63 of stopping. Like the front conversion, this kit is a direct replacement for 1959-1964 drum brakes on full-size Chevrolet models (it's a bolt-on) with no modifications necessary.
Time Frame: Approximately 5 Hours
We will be starting on the left rear side (driver's side) of the car. The procedure is the same for the opposite side. Jack up the car and place it on jack stands under the rear end. Let the jack down until the rear end contacts the stands and shake the car. Since PFA (Pressure is equal to force divided by area), you don't want to test this equation by having your pride and joy fall on you. Be sure the car is supported safely. Most of the time, I keep the jack under the car for an additional measure of safety.
Image 1: Next, remove the wheels and the drums from the rear axles. You might have to back off the brake shoes with an adjusting tool, like we did with the front brakes, before removal of the drums (Photo 1a). Remove the brake shoes and hardware using the brake spring and retainer tools (Photo 1b). A word of caution... brake shoe linings (the friction material bonded or riveted to the brake shoes), especially old ones, contain asbestos. The use of a dust mask is a good idea when dealing with brake linings. If you have any questions or would like more information on the removal, turn to the brake section of your shop manual; it's an excellent source for additional step-by-step instructions. I found this information referenced under section 6 in the 1963 shop manual supplement (P/N 517063) as well as the 1961 car shop manual (P/N 517051) (Photo 1).
Image 2: Now remove the emergency brake cable end from the brake shoes; this is an easy task by relieving tension on the retaining spring with the cable. The cable will be loose in the retaining end of the shoe. Just turn the cable so it will slip out of the interlocking tabs on the brake shoe and release the spring. With the brake shoe detached from the cable, set the shoe aside. The cable also attaches to the brake backing with a "finger" clip. We will not be reusing these cables, as new ones are included in the kit. Using your pliers and a screwdriver, push the "fingers" inward from their spread position and at the same time gently pull on the cable with pliers. Using side cutters, cut the brake lines near the wheel cylinders. The lines will not be reused with the disc brake kit, so you can save yourself some time by just cutting the old lines and moving them out of your way. If you have reasons to do so, you could use your line wrench set and remove the brake lines from the wheel cylinders. However, chances are quite good that the old lines will not remove easily (Photo 2).
Image 3: Locate the four studs and nuts holding the backing plate to the axle flange. Remove them with a 9/16" socket wrench. Once this is done, your backing plate should be loose and ready to be removed, along with the axle assembly. If you have the luxury - rent, borrow, or buy an axle puller to remove the axles from the rear end housing. If you're not fortunate enough to obtain an axle puller or you're an exhausted writer trying to do a job the way most folks will, using your large hammer, flog away at the inboard side of the backing plate until it and the axle come loose. Manually grab the axle and remove it from the housing. The axle WILL be covered in a lovely mess of oily filth, wipe it off and set the axle aside (Photo 3).
Image 4: Remove and discard the backing plates, or you can keep them for in case you decide that you don't like the superior stopping power this kit has to offer and you want to re-install the old drum brakes. The four studs on the axle retaining flange will be replaced with new bolts to hold the caliper bracket in place. Using a hammer and socket, drive the studs out of the axle retaining flange. The top two and the bottom rear studs will be 1 1/4" bolts while the bottom front stud will be a 1" bolt (Photo 4).
Image 5: Parts Clean-Up and Assembly There is a thin gasket on each axle mounting flange of the axle assembly. If this gasket is torn, replace it with PIN 563026. I had access to a bead blaster so I took the liberty of cleaning up my axles with the blaster, then greased them. A wire brush or wheel will work just as well, especially if you are not going to need new axle bearings. The rear axle bearings in Project '63 were shot (now is a great time to check your bearings for any sign of grinding, wear, or any sign of extra play in them before reassembling the components). DO NOT use a bead blaster on new or reusable bearings. This WILL destroy them! Because the axle bearings on Project '63 were worn, we sent the axles to a machine shop and had new bearings (PIN 521012) installed (Photo 5).
Image 6: This kit comes with new wheel studs to compensate for the difference in thickness between the rotors and the old brake drums. You will find two different size studs in this kit - PIN 610-259 are used on 1958-60 cars and PIN 610-156 are used on 1961-64 cars. Using a hammer and socket, drive the original studs out of the axle flange. The new studs can be installed using the stock lug nuts turned upside down. Add a little lube when installing the new studs (Photo 6b).
Image 7: Installing the Brackets: The brackets should be oriented so the bushings face to the inside of the car, away from the wheel. Mount the bracket so the "C" opening faces to the rear of the car. Install the bolts from the flange side before you install the axle back into place (Photo 8). Once in place, it will be virtually impossible to install the bolts from the wheel flange side, so ensure all four bolts are in before you slide the axle in and secure it in the rear housing as shown in Photo 8a. The heads should be facing out toward the wheel flange and the threaded end should face inward to the center of the car. Use a block of wood and a hammer to drive the axle into place (Photo 8a). A lock washer and nut are used on each bolt to hold the brackets in place. Once in place, move the flat washers, which also serve as spacers, so they sit as flat as possible. With the axle in place, torque the bolts to 45 foot-pounds (Photo 8c).
Image 9: Installing the Rotors: Clean the rotors with lacquer thinner or a solvent to remove a coating known as Cosmoline; Cosmoline is a waxy coating used in the shipping and storage of brake rotors and drums. You must remove all of this coating before the rotors can be used. The rotors are interchangeable; slide the rotors over the studs as shown. The rotors will have two sets of five holes drilled in them; use the smaller diameter holes for this application (Photo 9).
Image 10: Installing the Calipers: Unlike the calipers designed for front brakes, these rear calipers come without provisions for emergency, or parking brake cables (Photo 10a). Just like the calipers we installed on the front of Project '63, these calipers come loaded with everything needed for installation. This kit includes a brake lever arm, return spring, banjo bolt and washers, with shims and sliders or anchor brackets. The calipers are shimmed so the use of disc brake quiet is not necessary (Photo 10b). Each caliper is marked left or right. Take the appropriate caliper, remove the sliders by pushing outward on them, apply a bit of anti-seize compound to the threads, and mount them onto your newly installed brackets (Photos 10c and 10d). Be sure not to contaminate your brake pads; if you do, just wipe them down with a clean cloth and brake cleaner. Use a 3/8" hex socket wrench and tighten the caliper bolts to approximately 40 foot-pounds. If your torque wrench is out of commission, use a 3/8" hex wrench and tighten by hand like you really don't want it to come loose (Photo 10).
Image 11: Once mounted, make sure that one copper washer is on each side of the "Banjo" block (Photo 11a). The Banjo bolt allows brake fluid to enter the caliper. Do not tighten the Banjo bolt at this time. It's now time to install the opposite side brackets and caliper - do it just like you did on this side. We'll then move on to the brake line installation (Photo 11b).
Image 12: Installing the Brake Lines: Install the brake lines as shown. The longer one goes on the left and the shorter one goes on the right side. To make this task easier, remove the clip holding the block onto the rear axle housing assembly (Photo 12a). Thread everything together, securing your lines in the factory clips welded to the axle housing using a 9/16" socket to tighten the banjo bolts and a 3/8" - 7/16" line wrench to tighten the line nuts (Photos 12b, 12c, and 12d).
Image 13: Now that the lines are in (here's an important step), remove the return spring from the back of the emergency brake lever on each caliper. Use pliers to rotate the lever forward five times (Photo 13). You will notice different levels of resistance and travel as you do this. This brake lever is connected to an eccentric in the center of the caliper. When you move this lever forward repeatedly, it wears the eccentric out and sets the adjustment for the emergency brake to function. Failure to comply with this step will prevent your new disc brakes from working. Re-install the springs so the new brake cables can be installed.
Image 14: Installing the Brake Cables: The new shrouded cables have a ball connector on one end and barrel connectors on the other. Connect the ball side to the emergency brake lever and slide the cable end in as shown (Photos 14a and 14b). The barrel side goes through the stock bracket on the frame (Photo 14c). Using the connectors, attach one to each shrouded cable. Remove the existing brake cable and attach the new cable to the original yoke (Photo 14e).
Image 15: Using the emergency brake cable for 1959-1964 full-size Chevrolets, adjust the nut in the center of the "C" loop until your emergency brake gets nice and tight with about 1/2" travel (Photo 15). When this is achieved, your brake cable is adjusted. Now is a good time to evaluate your rear brake hose condition and replace if necessary. Ask for rear brake hose PIN 520089.
Image 16: So there you have it! The rear disc brake conversion is complete in the comfort of your own garage, carport, or driveway. Next up, we'll connect the entire front and rear disc brake system, and we'll install a brake booster, master cylinder, and valve.
Jan. 2008