EDITOR’S NOTE: This story originally appeared in the March 2007 edition of Sprint Car & Midget Magazine.

Last season I fought many different brake problems, and let me tell you, in my opinion there’s nothing worse! This month, I will be going over the best way I have found to bleed the brake system.

First things first: You will need a good, high temperature (500 degrees-plus) brake fluid. There’s many to choose from, such as Wilwood or Red Devil. This brake fluid will not break down under hard braking situations or in high temperature situations.

Now that we have established the proper brake fluid to use, it’s time to begin. I start by bleeding the master cylinder first. To do so you need to block off the feed end where the brake line comes out of the master cylinder and goes to the calipers.

You will achieve this by using an eighth-inch or quarter-inch (size may very depending on the master cylinder) pipe plug. Now that the line is blocked off, fill the master cylinder with break fluid.

Next, apply firm pressure to the pedal and crack open the bleeder on the master cylinder (the bleeder generally uses a quarter-inch wrench).

Brake bleeding is an integral part of sprint car maintenance. (James Mosher photo)

Allow the air to “bleed” out while keeping pressure on the pedal. Now tighten up the bleeder and let the pedal up slowly. Repeat this step until only fluid comes out of the bleeder.

Now, with the master cylinder bled and the pedal up, remove the pipe plug in the feed part of the cylinder and reinstall the break line.

Then it’s on to the brake lines themselves.

When bleeding the brake lines, I usually start with the rear inboard caliper first (unless you’re using a left or right rear outer brake, then start with that first instead). Block off the line that feeds the front caliper by using an aluminum -3 or -4 AN plug, unless you have a dry brake quick disconnect fitting and you can disconnect them.

Now, remove the inboard caliper by removing the two bolts that hold it to the rear end.

Raise the caliper to a level higher than the master cylinder and hold it up vertical with the feed line coming in the bottom. Now, put a spacer in between the brake pads in the caliper (I use a wrench) that is just slightly larger than the rotor.

Next, crack open the fitting from the line to the caliper and have someone slowly press the pedal down. While the pedal is down, tighten the fitting.

MOSHER’S TIP:
Always wear a quality fire suit. Fires really do happen!

Repeat this process until only fluid comes out of the line and you are sure all the air is out. Now, with the pedal up, crack the top inside bleeder screw and slowly press the pedal down. Tighten the bleeder while the pedal is down.

Again, repeat until only fluid is coming out in a steady stream. Next, go to the outside bleeder screw, crack it open and slowly press the pedal down. Tighten the bleeder screw when the pedal is down.

Make sure the bleeder screw is tight before letting the pedal back up so it does not suck air back into the caliper.

Repeat this process until all the air is out of the caliper. Remove the spacer you used to keep the pads apart in the caliper, and reinstall the caliper on the rotor.

Now move to the front caliper. Remove the plug you installed in the line and reattach the line to the caliper. As you did with the rear inboard caliper, remove the caliper and again place the spacer of your choice in between the two pads.

Hold the caliper vertical and higher than the master cylinder. Crack the line feeding into the caliper and press the pedal slowly.

bleeder screw
A demonstration of brake bleeding. (James Mosher photo)

With the pedal down, tighten the line. Again, repeat until the air is out of the line. Next, crack the outside bleeder valve and press the pedal slowly until a steady stream of fluid comes out of the bleeder screw.

When the pedal is down, tighten the bleeder valve. Repeat this on the inside bleeder next. Again, don’t stop until all the air is out of the caliper and only fluid comes steadily out of the line.

Don’t forget to check your brake fluid level as you are bleeding the system.

Remember, there are many different ways to bleed your brakes and this is the way I feel works best for me. I suggest you give it a try, and you too could be converted.

One more thing; I need to thank a few people for all their help last season when I was having brake problems myself. To those who helped me, I say “thank you!” You know who you are!

Until next month, drive hard and be safe!

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