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Bleeding the Brakes
According to brake specialist Bill Cummings, air in the brake lines results in a spongy brake pedal. Moreover, the air contains moisture that can corrode the braking system from the inside -- or create a vapor-lock in the presence of heat.
For bleeding brakes, Bill prefers the "gravity bleeding." This is a simple method for bleeding brakes, especially if you're working alone. Just open the bleeder valve and allow the fluid to drain out for a couple of minutes into a catch-container. Then close off the bleeder. Repeat on the other side.
- If you're working with a new brake kit, the pistons will be fully compressed into the calipers. In that position they will prevent the flow of fluid to the bleeder screws. Depress the brake pedal a few times to seat the pistons against the brake pads.
- Make sure the master cylinder is topped off with fluid. Leave the lid for the fluid reservoir removed while you bleed to allow the fluid to flow freely.
- Important: Brake fluid will cause severe damage to your paint. Use extreme caution to prevent the fluid contacting your paint.
- Important: Always dispose of brake fluid, and other automotive fluids responsibly.
- Place a clear hose onto the bleeder screw.
- Release the screw with a line wrench. At first there will be some air bubbles in the fluid. When these air bubbles stop and a steady flow of fluid escapes for a couple of seconds, close the bleeder valve and move on to the next wheel.
- If you're bleeding all four brakes on the car, start with the wheel farthest from the master cylinder and work towards it. In our case, we only need to bleed the front two brakes because we didn't touch the back brakes.
- When the brakes have been bled, top off the fluid in the master cylinder.
- Important: Keep close watch of the fluid level inside the master cylinder. Always keep it at least 1/3 full so no air gets into the lines.
To test the brakes, start the car and make a few applications of the brake pedal. If you have a "hard" pedal, you bled the brakes correctly. If the pedal feels spongy, repeat the bleeding process from start to finish until you get the hard-pedal feel.
In the segment that follows, Andrew and Bill test the system and install new front wheels and tires to go with the new brake system.
Note :
These steps are general guidelines. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of repair-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and Note that come with your kit or replacement parts.
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