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Brake bleeding - How To

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Jeff:
Bleeding brakes is simple.  Time consuming, tedious, but simple. You don't need anything fancy to do it, here are some instructions.  This is MY method.  It may not be yours.  I have had years of good results with this.  It is not the only means, but again, mine which I shall share with you...

Required materials:
Brake Fluid - Personally, I recommend silkolene pro-race 2000 from silkolenestore.com
Phillips screwdriver or other tool (as required to open reservoir)
8mm wrench (or other tool) to crack bleeders
Clear rubber hose (fuel line works fine) 12+ inches long
Water bottle with a couple inches of water in it
Rags.  Plenty of rags

Before you start bleeding or touch anything, there are a few things you should know and consider.

1.  Always clean fittings and caps BEFORE removing them.  Brake fluid does not like dirt...  
2.  NEVER shake a bottle of brake fluid.  It's oil, you're not going to "mix" anything.  All you're going to do is add tiny air bubbles to the fluid, which is exactly what you're trying to remove
3.  Brake fluid will remove paint and melt certain plastics.  If you get any on your plastics, get wiping IMMEDIATELY.
4.  NEVER pump the master cylinder without something between the calipers (preferably a rotor, but a similar diameter flat piece of wood or metal will work).  The pistons may pop out of the caliper.  If they do, don't jam them back in.  The caliper will need to be disassembled and reassembled, but that's another article...
5.  Adjust your brake lever OUT so that you can get the longest stroke available while bleeding.

All steps beyond this point assume you have the lines installed correctly and the calipers back on the bike, or a suitable block between the pads.

Initial bleed:
This is done like when you are swapping lines and have tons of air in the system.  This is the first step in fully bleeding the brakes, and requires "fine bleed" and "overnight bleed" to completely finish the project.

1.  Open the reservoir and top it off with fluid
2.  Attach the hose to the bleeder of one caliper.  Run the other end of the hose into the water bottle, keeping the end IN THE WATER.
3.  Open the bleeder valve slightly (you don't need to remove this or open it like 3 turns.  1/4-1/2 turn should suffice)
4.  Pump the brakes slowly.
   a.  You should see air bubbles coming out in the water which indicates you are removing air.
   b.  The purpose for the water here is to prevent air from sucking back into the brake system.
5.  Eventually you will see fluid coming out of the caliper bleeder.  MAKE SURE you keep the level of fluid up in the reservoir so you don't add air, or you've set yourself back to step 1.
6.  Keep pumping.  Run a full reservoir through the line.
7.  Close the bleeder valve
8.  Repeat on other side

Fine Bleed:
This step assumes you have a majority of the air out of the system.
1.  Open the reservoir and top it off with fluid
2.  Attach the hose to the bleeder of one caliper.  Run the other end of the hose into the water bottle, keeping the end IN THE WATER.
3.  With small short strokes, pump the lever until it is firm.
4.  Squeeze the lever firmly.
5.  Crack open the bleeder valve momentarily and then close it.  This should be done while the lever is pulled in and NOT RELEASED.
6.  Release the lever and repeat steps 3-5 until you get 3 or more full strokes with NO evidence of air bubbles.
7.  Repeat for other side

Overnight Bleed:
Assumes you have given your best attempt to remove all air from the system.

Using a zip-tie or strong rubber band, zip or wrap it GENTLY around the brake lever & clip-on to open the brake system.  You DO NOT need to crank it hard!!!  All you need is an open path for air to flow.  Leave this sit overnight, or for 24 hours if possible.

The change in temperature will cause slight expansion/contraction of the fluid and will move the tiniest air bubbles up to the top and out into the reservoir where they will do no harm.

Before you remove the rubber band / zip tie, take a small wrench/pencil/object and tap the lines from the caliper all the way up to the reservoir.

Wrap-up:
If you've just replaced the pads or rotors, the lever might not feel dead solid, and this can be attributed to the pads/rotors not being bedded in to each other.  Bed the brakes in and bleed again as required.

Christian:
Nice write up Jeff. I am putting on my S lines and installing new SBK3 pads from Rick this week. :)

DaBeachBum:

--- Quote from: Christian on August 01, 2004, 12:06:15 PM ---Nice write up Jeff. I am putting on my S lines and installing new SBK3 pads from Rick this week. :)

--- End quote ---
Christian, can you pleeez post pics of your install step by step? If not, at least a written synopsis? 8)

Christian:
If I remember to take the camera into the garage I will.

Christian:
I received the pads today from Rick and they do look sweet! :)

Can't wait to get these bad boys on there. Next step, install them and the new SS brake lines, change oil and filter and have the front suspension rebuilt with .95 racetech spring before Pocono-FUSA on the 14th.  :-[

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