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How To Flush and Bleed the Brakes

and Replace the Brake Fluid and Install Speed Bleeders

By Rob Robinette

Brake bleeding is covered on page P-7 in the RX-7 Workshop Manual. You need two people, one to operate the brake pedal and one to open and close the bleeder and top off the brake fluid tank (unless you have speed bleeders). Use a proper brake-line wrench for the bleeders (an 8mm wrench or socket works ok). You will need about 1 liter of brake fluid for a complete flush. Don’t spill brake fluid on painted surfaces, if you do clean it off immediately.

bleed_brake.jpg (20035 bytes)

Clear line and bottle connected to bleed nipple

To do a complete flush, start by sucking out as much of the old fluid from the reservoir as possible with a vacuum pump. To drain the clutch half of the reservoir disconnect the clutch line, it has a spring hose clamp that holds it to the reservoir. Put some paper towels below the reservoir to catch any drips and use a bowl to catch the clutch fluid. Reconnect the clutch line and then refill the reservoir with fresh fluid.

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Bleeding the clutch (driver side of transmission)

Since the hydraulic clutch shares the reservoir with the brakes you should go ahead and bleed the clutch too. The clutch nipple is on the driver side of the clutch housing. You will have to access it from under the car. A good time to do it is when you're bleeding the left front wheel.
Start at the wheel furthest (in hydraulic-circuit terms) from the master-cylinder and progress toward the closest. The correct order for the 3rd gen RX-7 is right rear, left rear, left front, right front.
Remove the brake/clutch reservoir cap. Remove the bleed nipple rubber cover and clean the area around the nipple.

Installing and Using Speed Bleeders  speedbleederanim.gif (42187 bytes)

Speed bleeders make brake bleeding an easy and quick one man job. They have a one way valve and sealed threads that prevent air from being sucked into the system during the brake/clutch pedal up stroke. If you are installing Speed Bleeders (highly recommended) just completely unscrew the original bleeder nipple and screw in the speed bleeder. You will feel resistance when the thread sealer starts to screw into the caliper. Torque the speed bleeder to only 32-40 inch pounds (about 3 foot pounds). That's like having a one foot long wrench with a 3 pound weight on it (not much torque). I stripped a speed bleeder on my dirt bike (it didn't hurt the caliper's threads though) so go easy on them. To use the speed bleeder fit a piece of clear  tubing (so you can see the bubbles and color of the fluid) over the bleed screw nipple and run the hose into a clear bottle. Unscrew the Speed Bleeder about a 1/4 turn and go pump the brake/clutch pedal and keep refilling the reservoir before it goes below the 3/4 mark. You don't need to know the size of your bleeder nipples when you order speed bleeders, just tell them the year and model of your car/motorcycle, they know what fits.

Bleeding Without Speed Bleeders

Fit a piece of clear  tubing (so you can see the bubbles and color of the fluid) over the bleed screw nipple and run the hose into a clear bottle. Ask your assistant to step on the brake with light pressure. The pedal should only be moved through it’s normal range of movement, not all the way to the floor.
Open the bleeder screw just enough to get fluid flowing, and before the fluid stops flowing, close the bleeder. If you don't do it this way you may suck air into the lines through the bleeder threads which will lead to a spongy brake pedal feel. Torque the standard bleeder nipple to 53-86 inch pounds (about 5 foot pounds).
Repeat until clean/clear/bubbleless fluid comes out. Don't let the fluid tank go below the 3/4 mark or air will be drawn into the system. It would take a lot of bleeding to get a large amount of air out of the system when it enters at the reservoir, so be careful.
Move to the next closest wheel until all are done.
Ensure you have a nice firm brake pedal before you take the car off the jacks. Test the brakes by moving the car slightly and apply the brakes and then continue to test the brakes as you begin your test drive.
Rob Robinette


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