So, now that you understand the need behind bleeding your brakes, let us present the procedure as utilized here at team scR when we service our fleet of SC2’s. Note that unless you are replacing your master cylinder, the procedure is the same whether you have a vehicle equipped with ABS or not…
You will need the following tools:
- 10mm box-end wrench (8mm for rear drum brake units). An offset head design works best.
- Extra brake fluid (1 pint if you are just bleeding, 3 if you are completely replacing).
- 14-inch long section of 3/16 in. ID clear plastic tubing.
- Disposable bottle for waste fluid.
- One can of brake cleaner.
- One assistant (to pump the brake pedal).
Vehicle Preparation and Support
- Loosen the lug nuts of the road wheels using a 19mm socket and place the entire vehicle on jackstands. Be sure that the car is firmly supported before going ANY further with this procedure!
- Remove all road wheels.
- Install one lug nut backward at each corner and tighten the nut against the rotor surface. Note that this step is to limit caliper flex that may distort pedal feel.
- Open the hood and check the level of the brake fluid reservoir. Add fluid as necessary to ensure that the level is above the seam of the reservoir. Do not let the reservoir become empty at any time during the bleeding process.
- Begin at the corner furthest from the driver and proceed in order toward the driver. (Right rear, left rear, right front, left front.)
- Locate the bleeder screw at the rear of the caliper body (or drum brake wheel cylinder.) Remove the rubber cap from the bleeder screw – and don’t lose it!
- Place the box-end wrench over the bleeder screw (10mm for discs, 8mm for drums.) An offset wrench works best – since it allows the most room for movement. (If you do not have an offset wrench, avoid pushing the wrench head to the bottom of the bleeder screw – since the wrench may interfere with other parts during movement. Allow a standard wrench to sit near the top of the bleeder screw contact point.)
- Place one end of the plastic hose over the nipple of the bleeder screw.
- Place the other end of the hose into the disposable bottle.
- Place the bottle for waste fluid on top of the caliper body or drum unit. Hold the bottle with one hand and grasp the wrench with the other hand.
- Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so.
- Loosen the bleeder screw with a brief ¼ turn to release fluid into the waste line. The screw only needs to be open for one second or less. (The brake pedal will "fall" to the floor as the bleeder screw is opened. Instruct the assistant in advance not to release the brakes until instructed to do so.)
- Close the bleeder screw by tightening it.
- Instruct the assistant to "release" the brakes. Note: do NOT release the brake pedal while the bleeder screw is open, as this will suck air back into the system!
- The assistant should respond with "released."
- Inspect the fluid within the waste line for air bubbles.
- Continue the bleeding process (steps 11 through 16) until air bubbles are no longer present. Be sure to check the brake fluid level in the reservoir after bleeding each wheel! Add fluid as necessary to keep the level above the seam line. (Typically we repeat this process 5-10 times per wheel when doing a ‘standard’ bleed.)
- Move systematically toward the driver – right rear, left rear, right front, left front - repeating the bleeding process at each corner. Be sure to keep a watchful eye on the brake fluid reservior! Keep it full!
- When all four corners have been bled, spray the bleeder screw (and any other parts that were moistened with spilled or dripped brake fluid) with brake cleaner and wipe dry with a clean rag. (Leaving the area clean and dry will make it easier to spot leaks through visual inspection later!) Try to avoid spraying the brake cleaner DIRECTLY on any parts made of rubber or plastic, as the cleaner can make these parts brittle after repeated exposure.
- Test the brake pedal for a firm feel. (Bleeding the brakes will not necessarily cure a "soft" or "mushy" pedal – since pad taper and compliance elsewhere within the system can contribute to a soft pedal. But the pedal should not be any worse than it was prior to the bleeding procedure!)
- Be sure to inspect the bleeder screws and other fittings for signs of leakage. Correct as necessary.
- Properly dispose of the used waste fluid as you would dispose of used motor oil. Important: used brake fluid should NEVER be poured back into the master cylinder reservoir! Dispose of the fluid as you would motor oil.
Vehicle Wrap-Up and Road Test
- Re-install all four road wheels.
- Raise the entire vehicle and remove jackstands. Torque the lug nuts to 140 Nm (103 ft-lb) using a 19mm socket. Re-install any hubcaps or wheel covers also using a 19mm socket.
- With the vehicle on level ground and with the car NOT running, apply and release the brake pedal several times until all clearances are taken up in the system. During this time, the brake pedal feel may improve slightly, but the brake pedal should be at least as firm as it was prior to the bleeding process.
- Road test the vehicle to confirm proper function of the brakes. USE CAUTION THE FIRST TIME YOU DRIVE YOUR CAR AFTER MODIFICATION TO ENSURE THE PROPER FUNCTION OF ALL VEHICLE SYSTEMS!
How Often do I Need to Bleed My Brakes?
In closing, here are a few rules of thumb to help you to determine the proper bleeding interval for your particular application:
- Under normal operating conditions, and without brake system modifications, the braking system on your Saturn has been designed to NOT require bleeding for the life of the vehicle…unless the system is opened for repair or replacement. If you’re just driving around town or on the highway to work, there is no need to bleed!
- Those who choose to autocross or drive in a sporting manner may choose to upgrade their brake fluid and bleed on an annual basis – this is a good ‘start of the season’ maintenance item for low-speed competitors.
- If your car sees significant amounts of high-speed braking, or if you choose to participate in driver schools and/or lapping sessions, bleeding prior to each event is a sound decision. More intense drivers at these events may choose to skip right past this step and on to #4…
- Finally, dedicated race cars should be bled after every track session. If you choose not to, it’s your butt on the line, not ours!
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