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How To Replace A Master Cylinder

Easy Master Cylinder Replacement For Any Shark

Tom Benford Apr 25, 2007
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This master cylinder has seen better days.

All shark Corvettes have dual-reservoir master cylinders that, in effect, act as two independent braking systems. If the front brakes fail, the rears will still operate and vice versa. Obviously, this is a good thing. With age and use, the master cylinder will eventually wear out and will need replacement. Fortunately, this is a simple task that can be performed with basic hand tools. This procedure will also apply to any Corvette that uses this same basic master cylinder setup.

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A flat-blade screwdriver is used to pry the spring clamps that hold the cap and rubber gasket on the master cylinder. All sharks have a dual-reservoir master cylinder regardless of whether they have manual or power brakes.

The first step is to evacuate the brake system of all its brake fluid. This is accomplished by opening a bleeder valve on one of the front wheels and positioning a catch basin beneath it to catch the brake fluid. Be sure to use a catch basin to contain the brake fluid as you bleed the system because the fluid will eat into the blacktop of your driveway or remove the paint from your garage floor if it gets on it. Next, open the hood and use a flat-blade screwdriver to pry the spring clamps that hold the cover and rubber gasket on the master cylinder. Go inside the car and pump the brake pedal, monitoring the front reservoir to see when it is completely empty.

Close the front bleeder valve and move the catch basin to a rear wheel. Open a bleeder and again pump the pedal until the rear reservoir is totally empty. Alternatively, you can purchase and use a trigger-operated vacuum tool that is easy to use and operate for draining fluid and bleeding air from the brake system. One of these tools will set you back about $50-$90. You may also be able to borrow one from AutoZone or another auto parts store if you purchase your brake parts there.

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A good set of line wrenches, also known as flare-nut wrenches, are the tools of choice for jobs that involve working on brake or fuel lines. The opening in the wrench "box" lets the wrench pass over the line itself, and the box is made of thicker, stronger steel so it won't stretch out or break off. While you can also use open-end wrenches, they have a tendency to slip off the nut and round the corners, which may necessitate replacing the entire brake line.

When all the fluid is out of both reservoirs of the master cylinder, the front and rear brake-line connectors can be loosened with an open-end wrench and pulled free of the master cylinder. if you happen to have a set of line wrenches available, by all means use them, as they will reduce the risk of rounding the corners of the connector nuts. A gear wrench or a ratchet with socket is then used to remove the two retaining nuts and lock washers that hold the master cylinder to the brake booster (or firewall if you don't have power brakes). When these nuts are off, the master cylinder can be pulled off the two mounting studs and removed from the engine compartment. You can take this opportunity to clean up and repaint your brake booster and rusted brake lines.

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The new master cylinder installs in the exact reverse order of removal. Job Done!

Installation of the new master cylinder is the reverse of removal. Slide the new unit on the two studs and secure it with the two nuts and lock washers removed earlier, tightening them all the way. Next, the front and rear brake lines are attached to the new master cylinder.

This is also a good time to upgrade your brake fluid to Dot 4 or silicon brake fluid, which holds up better under high temperatures. Fill up the front and rear reservoirs with brake fluid and bleed the air out of the lines, top off the fluid level, and snap the cap back on the reservoir. That's all there is to it-the whole job should take well under an hour, even for a novice.



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