Brake Line Bleeding Guide

Excerpts from the Garage message board:

Brian Wottowa -
1. Buy some high quality DOT 4 fluid and top off your reservoirs. Top them off periodically during this procedure. Do not spill any fluid on your bike cause it will eat your paint off. The front brake reservoir tends to spit fluid out the top during this process so make sure you place a bunch of rags around it to catch the fluid.

2. Put a short section of hose on the bleed valve on the brake caliper. Put a jar or other suitable container on the other end to catch the runoff. You'll need to move the hose and jar around to each caliper as you work on them.

3. Use a 10 mm to open the bleed valve while simultaneously squeezing the lever (or pedal). About 2/3 of a turn on the wrench will do it. Fluid should run out of the hose at this time. When you squeeze to within 3/4 of your full lever throw, use the wrench to close the valve. It is important that you close the valve before hitting full travel on the lever. Release the lever and repeat the process (squeeze lever, open valve, close valve, release lever) until the fluid runs with no bubbles and the lever is firm. You'll be amazed how firm you can get your system. Don't forget to periodically top off you reservoirs. And do not under any circumstances release the lever or pedal with a bleed valve open. This will pull air back into your system.

This is the order I bled mine in:

1. front left
2. front right
3. front left again
4. front right again
5. back

Martin Gibson -
You can make a bleeder resevoir fairly easily by taking a glass jar (preferably clear) with a lid (preferably threaded, screw on type). Put a hole in the jar lid just large enough to get the hose through. Put a small amount of brake fluid in the jar. Screw the lid on the jar and push the hose end into the brake fluid at the bottom of the jar and put the other end of the hose onto the bleed valve. By doing this you will limit the chances of sucking air back into the brake lines. It's really handy if you're doing the job alone. If you have another lid to fit the jar, you can remove the lid with the hole in it and put the other one on to preserve the fluid for future use (as long as it's clean) or to reuse just for bleeding brakes. It will also works on any other machines you have that have hydraulic brakes and clutches.

Emrah -
Saw the reply/instructions on how to bleed brakes. While this way WILL work and there is absolutely nothing wrong with it, it is a big misconception that you have to shut the bleeder valve between every pump/squeeze of the lever. People do this on their cars too. Pump. Open/Close. Pump. Open/Close. You really don't need to do this.

As long as you've got fluid flowing through the bleeder tube, you can just keep pumping/squeezing the lever. Just make sure the reservoir stays topped off. If you bleed it dry, you'll have to start all over again.

If you don't believe me, just watch the fluid going down through the (clear) tubing that you should use to bleed with. You pull the lever, a bunch of fluid drains out. Now, watch the air bubble SLOOOOOWLY go back up the tube. Yes, air will travel back up, but it takes it so long, you can just keep pumping away and force more fluid out (and the air with it). As long as fluid is going down the tube, no air can get back up into it.

Try it, you'll see for yourself. Oh, and that garbage about "pressure bleeding" that every car mechanic with his name embroidered on his shirt seems to talk about, Faggedaboutit. If you pump away (with the bleeder closed) to "pressure it up", all you're going to do is aerate the perfectly-fine fluid.

 


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