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Braking PointCheap Street Brakes That Actually Work From the February, 2009 issue of Chevy High Performance By Wayne Scraba Photography by Wayne Scraba
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 Stock wheel cylinders for...  Stock wheel cylinders for GM applications usually measure 3/4 or 7/8 inch. Use the 7/8-inch pieces. Raybestos and other replacement parts companies have a cross-reference chart in their catalogs that lists wheel cylinder sizes. The 7/8-inch size is stock on many vintage Chevys. You can find slightly larger wheel cylinders (i.e., 15/16 inch) by looking at early station wagon listings.  All early GM 9-1/2-inch drum...  All early GM 9-1/2-inch drum brakes use a four-bolt mounting arrangement to attach the backing plate to the rear axlehousing. Later-model GM 9-1/2-inch drum backing plates make use of a two-bolt system. The early plate is preferable. Early backing plates also use two 1/4-inch bolts to hold the wheel cylinder to the backing plate, while two-bolt versions use a simple clip. Turbo Buick racers have found that when you really lean on the back brakes (with larger wheel cylinders and long shoes), the two-bolt backing plates can bend. See the accompanying sidebar for a list of cars and trucks that may have the four-bolt backing plates.  Instead of using a common...  Instead of using a common hardware-grade 1/4-inch bolt and lock washer to fasten the wheel cylinder to the backing plate, we found that an ARP PN 100-7502 12-point steel valve-cover bolt works perfectly.  The primary and secondary...  The primary and secondary shoes on a stock GM rear brake system are two different sizes. The contact patch of the primary (leading) shoe is smaller (shorter) than the secondary shoe. Racers with turbocharged Buick Grand Nationals have found that you can dramatically increase the holding power of the back brakes by using a long shoe on the primary (front) side of the brakes. This step requires two sets of shoes for the application, using the long shoes for both the front and back of the brake. It fits, and its not expensive, even when you factor in the price of buying two sets of linings.  Most jobber linings are bonded...  Most jobber linings are bonded only. Riveted shoes cost a bit more, but the added security of rivets is a good idea. Bendix offers them under its Premium replacement line. Dont worry about trick linings. Instead, use a set of good old-fashioned asbestos-free conventional linings. Remember, sintered metallic shoes work best when hot, while conventional shoes work better when cold. Obviously, the cold launch on a drag car doesnt warrant the use of semimetallic models.  Theres a trick...  Theres a trick of the week floating around that states you should use return springs from a Cadillac on a Chevy that sees use on the dragstrip. Not so. In our research, we discovered that a good old-fashioned Raybestos replacement spring kit for a standard 9-1/2-inch early brake is all thats required. According to the brake pros, the type of return spring has little to do with brake performance. Dont toss out all of your springs when disassembling brakes. You might need a few of the less taxed springs for the final assembly.  At the back of the backing...  At the back of the backing plates is this knockout slug. Its purpose is to provide access to the brake adjuster star wheel on drums with self-adjusters. Once you remove the knockout slug (a few swift blows with a hammer and a chisel accomplish the job quickly), be sure to remove all metal chips inside the backing plate. Most brake spring kits include a rubber plug to fill the knockout hole in each backing plate.  This is the star-wheel brake...  This is the star-wheel brake adjustment mechanism. Once the brakes are assembled, insert a thin-blade screwdriver through the new access hole in the backing plate to hold the adjuster lever away from the star wheel (while backing off the adjuster screw until the brake is free of drag). Once youve backed off the adjuster, make a few stops (forward and reverse) with the car to balance the adjustment of the back brakes.  If you start from scratch...  If you start from scratch on a brake job, keep in mind that the actual brake levers you use are sided. This means that certain levers are right-side specific, while the others are left-side specific (sides viewed from the drivers seat). To solve the confusion, most small parts such as levers are stamped R for the righthand or passenger side. Backing plates are similarly sided. Remember that the hole for the parking-brake cable faces the front of the car. This is important, even if you leave the parking brakes off the car.  All early GM brakes use an...  All early GM brakes use an iron drum. Unfortunately, theyre heavy. And when it comes to racing, reducing unsprung weight can have a significant effect on quarter-mile performance. The solution is simple. Swap the iron drums for a set of finned aluminum drums from late-70s to mid-80s GM rear-wheel-drive cars. A set of aluminum drums can remove 10 pounds of excess baggage from the rear of the car, and theyre a direct replacement. When you try to fit the OEM drums or aluminum drums to a rearend using an aftermarket axle, youll find some small clearance problems. Basically, the axle hole in the center of the drum (the register bore) must be enlarged. The work can either be done by hand (using a small die grinder) or enlarged at a local machine shop. Use your aftermarket axle register as a guide.  This is where youll...  This is where youll find another clearance problem. Typically, larger-than-stock-diameter wheel studs are used in almost all applications incorporating an aftermarket axle. Basically, the wheel stud holes must be enlarged for use with these studs. The original-equipment stud on these cars is either metric or 7/16 inch in diameter. Studs used with aftermarket axles are 1/2 inch minimum. You can do this yourself or have a machine shop enlarge the holes to fit your studs.  This is what the completed...  This is what the completed backing plate looks like with all of the hardware installed. We should point out that our backing plates were glass-beaded, then powdercoated gloss black before the reassembly began. Meanwhile, we had the drums glass-beaded and clear powdercoated. The purpose wasnt completely visual. We personally like working on clean cars. The powdercoat simply makes cleaning easier. And its not expensive. Millions of Chevys have been built with 9-½-inch drum brakes on their rear axles. Improving the stopping power of these cars usually means fabricating components and/or spending big bucks to change over to four-wheel discs. But what if we told you its possible to improve the stopping power of any Chevy with 9½-inch rear drums simply by juggling junkyard parts and inexpensive jobber hardware? The results might surprise you, since the idea was spawned by the Turbo Buick bunch, NHRA Stock Eliminator racers, and fellow hot rodders. What youll see here revolves around a selection of original-equipment GM components (backing plates, drums, small hardware) and corner auto parts store pieces (shoes, return springs, wheel cylinders). Youll also find that the final result not only stops well, it looks good, too. If you have a Chevy with drum brakes on the back (and you dont have deep pockets), then you owe it to yourself to check out the information here.
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