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Brake Bleeding / ABS & Standard

Stephen Karlan (Dali Meeow)  -  dalimeeow@adelphia.net


Compendium of Bleeding Procedures

R1100 and R850 yearly maintenance requires replacing (by bleeding) the brake fluid.

WARNING: Brake fluid wrecks (eats) paint immediately and must NOT come in contact with any part of your bike. Keep it inside the brake reservoir and brake lines. You cannot clean it off fast enough to save the paint it touches; cleaning quickly will only prevent it from eating additional paint. Keep a damp towel and water handy to dilute any spills.

Perform all work with the engine off; place bike on center stand for easiest access. The front brake reservoir is located on the right handlebar and is part of the brake casting. The reservoir top measures 2-inches x 1 7/8-inches and is held on with four screws; rotate and secure the handlebar so that the top is level. Protect the bike with a large plastic garbage bag under the front reservoir and the right front bike area; place paper towels or rags on top of the plastic to capture any brake fluid that escapes. The rear reservoir is a clear plastic bottle located on the right rear of the bike; you must remove the side fairing piece to see it. When working with the rear reservoir, the right-side plastic fairing parts must be removed and a plastic bag may be taped so that it is held behind the reservoir and drapes down to protect the area where fluid might leak from the rear reservoir.

WARNING: Maintain fluid in the reservoir at all times (no air into the brake lines).

Objective: Drain the old brake fluid from the system while adding the new fluid. The reason for this yearly maintenance is that old brake fluid is potentially contaminated with some water; brake fluid is made to absorb water. Newer fluid will be drier and thereby have a higher boiling point. Bleeding the brakes also will remove any air bubbles that may be in the system. Read Method One regardless of which method you use; the rest of the methods are variations on Method One. Methods Three and Four are for experienced wrenches.

Method One:

A Mityvac(r) vacuum pump tool is designed for bleeding brakes; read the Mityvac information your receive with the tool. If you are not using a Mityvac or similar tool, the difference will be explained in the paragraphs under Method Two and Method Three. All methods will yield the same excellent result if performed properly.

This paragraph is optional, and you may follow it or not. If you don't understand why you might like to try this, then skip this paragraph and go to the next one. Optional: Replace the fluid in handle-bar mounted reservoir by using a turkey baster or other device to get the old fluid out and then fill with new fluid, and do the same with the reservoir under the seat on the right side of the bike. [Protect your paint and use something (cup/paper/rags) to catch the drips from the turkey baster, because the turkey baster will drip.] Fill the reservoirs with one of the recommended fluids. Now follow the cycle of the four basic steps.

Cycle of four basic steps: (1) Create suction at the bleeding nipple which is on the caliper, (2) Drain most of the fluid from the reservoir by opening the bleeding nipple , (3) Close the bleeding nipple while fluid is STILL COMING OUT and BEFORE the reservoir is empty, (4) Add more fluid to the reservoir and start this cycle again. Memorize step #3.

The brake nipple is located on the caliper body. Stand to the left side of the bike and look at the front wheel. The tire is mounted on the rim. The brake disc (rotor) is smaller than the rim, made of shiny metal with holes bored in it. At the one o'clock position there is a black metal caliper with the word "BREMBO" in metallic relief on the body. A rubber hose containing the brake fluid is attached to the top of the caliper. Also on the top of this black caliper is a rubber cap that covers the metal nipple. The nipple sticks up, has a hole in its center, is smooth and round at the top and the base is a six-sided bolt. Remove the rubber cap and clean the nipple before using it.. When the nipple bolt is rotated (looking down at it) counter-clockwise it becomes loose and brake fluid may flow out of the brake system through the center hole.

Position the bike and secure the handle bar so that the handle-bar reservoir is level with the ground or slightly tilted so that the hose connection is the lowest point. Using an 11mm box end wrench or socket to open the nipple may help prevent problems if it is very tight. Start on the left front caliper (furthest from the reservoir). Open the reservoir top.

Step one: Attach the Mityvac suction hose to the nipple and pump the tool to create suction. Make certain the reservoir on the tool is attached and the tool is functioning; and you might even try reading the manual for the tool. Pump the tool to create a vacuum. [Consider the following ]: You may wish to seal the nipple-hose connection area with grease so that ambient air is not sucked into the hose. In this way, if there was no air in the brake system there will be no air in the spent fluid cup. (Steve VanTwuyver's suggestion <s.vantwuyver@x400.icl.co.uk>). Many machanics don't seal the nipple-hose connection with grease because air in the spent fluid does not affect the bleeding procedure, they do not mind seeing the air bubbles because the spent fluid will be disgarded and they do not check it for bubbles, and therefore they consider greasing the nipple as an unnecessary bother.

Step two: Slowly and carefully open the nipple and observe the fluid level in the bike reservoir carefully. When you look at the hose that is attached to the nipple you will see bubbles in the hose. The bubbles are from air being sucked into the line around the nipple area as well as any air that may be in the system. Step three: When the amount of fluid in the reservoir decreases by 50%, turn off the flow by tightening the nipple (clockwise). As you are tightening the nipple, the Mityvac must still contain some vacuum , some fluid flow must be taking place so that air can not enter the system, and the reservoir must contain some fluid. Step four: Add brake fluid when 50% or more of the fluid has been vacuumed (drained, suctioned) from the bike reservoir. Repeat these four steps until the fluid appears clear in the tube leading to the Mityvac reservoir jar. When the fluid is clear, tighten the nipple and replace the rubber cap. Move to the right side of the bike and repeat the four steps until the fluid appears clear again. When finished with the right side, replenish the bike reservoir and replace the cap and screws. Several bubble removal maneuvers are sometimes used, such as tapping the reservoir with a screwdriver handle or pushing the handlebars back and forth so that any bubble in the system will work its way out of the brake line and to the top of the reservoir. Move to the rear disk and bleed the rear reservoir from the nipple on the rear caliper until the fluid is clear. Replace the rubber cap on the nipple, replenish the reservoir and replace the cap on the rear.

After the fluid has been completely replaced and all nipples are tight, check that the front and rear reservoirs are filled and secure. Make certain they are secure. Slowly pump the brake lever, then pump the foot pedal until there is a solid feel. Continue pumping the brakes for a few minutes, then recheck the reservoir level and refill if necessary. You must pump both front and rear the brakes to confirm that they are responnding with a solid feel BEFORE you ride the bike.

Note on brake fluid level: Before replacing brake pads, remove brake fluid so that it is NOT at the maximum level. New brake pads will take up some of the brake fluid space in the system; if the brake fluid is at maximum level it probably will overflow the reservoir.

Method Two:

No Mityvac is used in Method Two. This method is used by many auto mechanics who use the brake master cylinder to create the pressure needed to force fluid through the brake lines. You will not be using the suction created by the Mityvac.

This paragraph is optional, and you may follow it or not. If you don't understand why you might like to try this, then skip this paragraph and go to the next one. Optional: Replace the fluid in handle-bar mounted reservoir by using a turkey baster or other device to get the old fluid out and then fill with new fluid, and do the same with the reservoir under the seat on the right side of the bike. [Protect your paint and use something (cup/paper/rags) to catch the drips from the turkey baster, because the turkey baster will drip.] Fill the reservoirs with one of the recommended fluids. Now follow the cycle of the four basic steps.

There are still four basic steps in Method Two, but number one has been changed. The steps now read: (1) Keep the reservoir cover in place to prevent fluid from squirting up (which will create havoc with your paint) and attach a tube and jar to the caliper nipple to catch any fluid that will be drained from the nipple. Pump the brake lever to insure that the system can create pressure. Now, pull the lever gently (as in applying the brake) while you perform the next two steps. Do not allow the lever to return to its open position until the next two steps are complete. (2) Allow 50% or more of reservoir's brake fluid to drain by gradually opening the bleeding nipple at the disk caliper , (3) Close the bleeding nipple while fluid is STILL COMING OUT and BEFORE the reservoir is empty, (4) With the caliper nipple closed and the reservoir cover still in place, release the lever. Now add more fluid to the reservoir. You are now ready to start Step 1 again. Understand and memorize step #3.

Be extremely careful with the bike's brake fluid in the handle-bar mounted reservoir.

Follow the same procedure that is described in Method One. Start on the left front and bleed the fluid until it is clear in color. You must close the bleeding nipple to turn off the flow by tightening the nipple while the fluid is still coming out, and this means maintaining a small amount of pressure on the brake lever and maintain some fluid flow. If you take the pressure off the brake lever while the fluid is still coming out, you may introduce air into the brake system and this is bad. Read "Air in the System" below. [You may be able to locate a "One Man Brake Bleeder" which is a one-way valve that attaches to the bleeder nipple and prevents air from entering through the bleeder nipple. When using this, instead of opening and closing the bleeder valve, you just pump the master cylinder until the fluid runs clear and being careful to keep brake fluid in the reservoir. Do not let the reservoir run dry; this will pump air into the system.] You are finished with that side when discharging fluid is clear and caliper nipple is tight. Repeat this procedure with the front right. Make certain the front brakes are finished, the front nipples are tight, and the front reservoir cap is secure with the four screws. It is now time to bleed the rear brakes using the same procedures. Attach the tubing and jar to the rear caliper nipple and repeat the four steps with the rear brakes. Gently and carefully actuate the rear brake while releasing the nipple on the rear brake. Observe the rear reservoir closely and replenish as needed. Discontinue pumping when the fluid is clear; close the nipple as fluid is gradually flowing out.

After the fluid has been completely replaced and all nipples are tight, check that the front and rear reservoirs are filled and secure. Make certain they are secure. Slowly pump the brake lever, then pump the foot pedal until you there is a solid feel. Continue pumping the brakes for a few minutes, then recheck the reservoir level and refill if necessary. You must pump the brakes and be certain the brakes are responding with a solid feel BEFORE you ride the bike.

Method Three:

At least one BMW rider suggests that gravity will drain the brake fluid. I have not tried this, but if you attach tubing to the caliper nipple with a jar at the end of the tubing to catch the old brake fluid as it is expelled, the same four steps can be used as in Method One. Open the nipple and allow brake fluid to slowly drain out. Close the nipple and replenish the bike's brake reservoir as needed. While this may work on the front brakes, the rear may present a problem because the verticle reservoir to caliper distance is not great enough to create much pressure.

After the fluid has been completely replaced and all nipples are tight, check that the front and rear reservoirs are filled and secure. Make certain they are secure. Slowly pump the brake lever, then pump the foot pedal until you there is a solid feel. Continue pumping the brakes for a few minutes, then recheck the reservoir level and refill if necessary. You must pump the brakes and be certain the brakes are responding with a solid feel BEFORE you ride the bike.

Method Four:

Not for newbies. This method is fast and works well for experts. Once you understand the principles involved in bleeding the brakes, instead of using a vacuum at the nipples you can use pressure at the master cylinder. Prepare a heavy gauge half-liter screw topped plastic bottle with two tubes fixed into the top. One tube will be the brake fluid supply tube, which will go to the bottom of the bottle. The second tube, which will become the "power supply", will project less than 1/2-inch into the plastic bottle and will be in the top air space of the plastic bottle. Buy a spare top for the master cylinder and prepare it with the supply tube of the plastic bottle fitted through (and sealed at) the master cylinder top and projecting about an inch into the master cylinder reservoir.

The "power supply" tube will be fitted with a tire valver on the end so that, when a compressed air tire inflator is applied, air will fill it under pressure. All tube joints must be pressure tight. To use, put new brake fluid into the plastic bottle, install the modified cylinder top, and put pressure into the plastic bottle using a tire that has no more than 5 psi. As you open the bleeder, the old brake fluid is pressured out and you can easily flush all air out of the system. Keep an eye on the level in the supply bottle and be certain it does not drop too low. Close the bleeder if it comes close, otherwise you will force air into the system and will have to totally recharge the system with new fluid.

After the fluid has been completely replaced and all nipples are tight, check that the front and rear reservoirs are filled and make certain the tops are secure. Slowly pump the brake lever, then pump the foot pedal until you there is a solid feel. Continue pumping the brakes for a few minutes, then recheck the reservoir level and refill if necessary. You must pump the brakes and be certain the brakes are responding with a solid feel BEFORE you ride the bike.

Method Five:

This method is presented in the interest of being compleat; it is for experts only. If there is a large vertical drop between reservoir and nipple, and if it seems impossible to bleed the air from the system, an alternative is to pressure feed in reverse, forcing the fluid up from the calliper to the master cylinder. This is a last resort and is dangerous because of the liklihood of fluid being spilled from the master cylinder. No steps or instructions are given here. If you do not understand exactly what to do, do not attempt this procedure. Andrew Grant <Drew.Grant@btinternet.com> contributed the information for Method Four and Five.

Recommended Fluids

Use only fluids from a new, never-been-opened container. Use only fluids from a new, never- been-opened container. The manual calls for: BMW DOT4, Castrol Disc Brake, DOW ET 504 Shell Donax DOT 4, Hydraulan DOT 4. None of these is a synthetic. Use the recommended fluids. Synthetics (DOT 5) are not approved and may not be compatible with the R1100. Reasons listed for not using synthetics include foaming with the ABS, incompatibility with seals and incompatibility with other fluids (we have not tested this and do not intend to). DOT 5.1 has been recommended, and also has not been tested.

Trouble Shooting

Air in the System:

--- The brake system works with brake fluid. You push on the brake lever and this force is transmitted to the brake piston at the discs and causes the pads to grip the discs. The more you pull on the brake lever, the more pressure you put on the discs and the faster you stop. There is fluid in the brake lines that transmit this force; you cannot compress this liquid fluid. But if there is air in the brake lines, even a little, this will cause problems because air compresses. If you pull on a brake lever and there is air in the brake line, the air will compress and less force will be transmitted to the brake pads.

If you feel air in the brake lines (spongy brakes), you MUST bleed the brakes until all of the air is expelled. If air is allowed to remain in the line, it will compress when the brakes are actuated and will not give you firm and steady pressure on the pistons and pads. This will result in uneven and dangerous braking, Soft or spongy brakes feel as though they are not working because they are not working. The best procedure is to work so that no air enters the system. If it does get into the system, you must expel all air from the system.

Air in Rear Brake System

If you get air in the brake system, especially the rear brake system, you will want to start the corrective process by bleeding from the ABS nipple under the tank. Do this because air bubbles, which rise, may be trapped in the higher ABS area. Then continue with either Method One or Method Two. See: TWO OPTIONS.

Unresponsive Brakes

If you still have an unresponsive brake system after bleeding the brakes and after following the procedures recommended here, you may have water in the system or an ABS problem. Do not ride the bike. Seek professional advice.

Brake Squeak, Squeal

Cleaning the disc and pads may eliminate brake squeak, squeal. Using non-BMW pads may cause brake squeak, squeal. If your properly-installed new brake pads make noise, try stompin' on the buggers a few times (very hard braking).

Steel Braided Lines

Rubber hoses have a tendency to expand and may result in a spongy feel after much use. How much ? I don't know. Braided steel lines do not expand as much and are frequently used to give a more solid feel to brake systems.

Two Options

The ABS system has a bleeding nipple under the gas tank. You do NOT have to bleed from this nipple. Old brake fluid will be totally flushed when bleeding from both front and rear caliper nipples. Bleeding from under the tank will neither hurt nor help your brake system. The nipple at the ABS unit under the tank may be bleed before starting with the front nipples at the calipers. Some shops bleed at the ABS under the tank, some do not. Under tank bleeding is recommended by the BMW manual. However, you should bleed from under the tank if your bike experiences problems outlined in the paragraphs: " AIR IN REAR BRAKE SYSTEM" or "UNRESPONSIVE BRAKES'. If you decide to bleed from the ABS nipple under the tank, you might consider scheduling the fuel filter replacement at the same time so that you can do both jobs while the tank is off. Also remember to check the battery and air filter while the tank is off.

Brake pads may be retracted (pushed in) while bleeding the brakes. A minute amount of brake fluid will be extracted with this maneuver. There are contrary opinions about whether this procedure is beneficial. Note: The pads may be pulled in by suction when Method One is used in bleeding the brakes. Retracting the brake pads is not part of the bleeding procedure recommended in the BMW manual.

Glossary:

Brake pads
Composite material that contacts the disc (or wheel) and creates friction. This material is designed to wear, and to protect the disc (or wheel) from wearing. Pads are replaceable, maintenance items and should be checked periodically.
Brake shoe
See brake pads. Usually called a shoe when used on a drum system, a system in which the shoe (or pad) contacts the inside of the wheel to create friction and stop the vehicle.
Brakes
The whole system (reservoir, fluids, cylinders, pads, discs, etc.)
Binders
Motorcycle term for brakes. Usage: I hit the binders.
Caliper
The housing that holds the piston(s) and brake pads and is attached to the forks.
Cylinder
Usually located near the brake lever or brake pedal and is used to create the hydraulic pressure that is transmitted to the pistons. Referred to as "master cylinder".
Disc
Also called a rotor. This is attached to the wheel rim. When brake pads compress on both sides of this disc and create friction, it stops the bike. When this disc is incorporated into the braking system, the system is called "disc brakes".
Nipple
A release valve where fluid may be drained from the system. Also known as a "bleeder". Hence the term "bleeding the brakes". The bleeding takes place at the nipple, which is opened and closed by rotating it.
Piston
A round, metal, cup-shaped piece that is pushed out from the brake body by the application of hydraulic pressure . The piston exerts pressure on the brake material, which then contacts and creates friction on the disc.
Reservoir
Location where brake fluid is stored for use and where fluid is replenished during the bleeding process (after the top is removed). One is located on the right handlebar, the other underneath the right rear fairing.

Buying Tools

Mityvac(r) is a hand-held vacuum pump that attaches to the bleeder valve on the caliper and pulls brake fluid from the reservoir, through the brake line and nipple, into a plastic line and deposits the fluid into a cup built into the tool. There is a plastic model (Part NO. 7000) and a metal model. The plastic version is available from some WalMart Stores for approx. $25. Metal models cost about $60 and are available from Mac Tools (part number MV4000) and Snap-On Tools (private vendors who sell to auto repair shops and may be found in the telephone book), and from Imparts at 1-800-325-9043, part number 29900. Sears also sells a vacuum pump (about $35) and a brake bleeder kit (about $10) which work well.

Here's a list of some who added ideas, comments and corrections. (Alphabetical by first name).

Aaron Burns in Totonto, Canada <aaronb@acm.org>
Anthonie Mans in Delft, Holland <ardericc@pop.knoware.nl>
Brian Curry in Chester Springs, PA <bmwbrian@voicenet.com>
Carl Kulow near Bloomington, IN <kulowc@indiana.edu>
David R. Norton in Phoenix, AZ <norton@doitnow.com>
Drew Grant in U.K. (North East Frontier of England) <Drew.Grant@btinternet.com>
Mick McKinnon in Simi Valley, CA <bmwmick@comcast.net>
Rob Lentini in Tucson, AZ
Ross Elkins in San Rafael, CA <Madera@ricochet.net>
Stephen Powers in Seattle, WA <powers@uplex.net>

Off the record:
I talked at length with an approved BMW instructor, one who certifies BMW mechanics, and he said that pushing in the caliper will expel almost every last drop of the old fluid from the system. He also said that, with his own bike, he does not retract the brake pistons and he does not bother to bleed from the under the fuel tank (the fluid will be replaced without this step as it travels from the master cylinder to the caliper nipple). He thinks that the engineers have gone overboard and complicated an otherwise simple maintenance procedure.

What does he teach ? He teaches to bleed from under the tank and to retract the pistons. "If I don't teach it this way, I'll get fired." This is offered so that you may make your own decision for your bike.

Speed Bleeder

This new product is a one-way valve that looks similar to the standard bleed nipple at the caliper, but replaces it. It operates like the standard bleed nipple, opening when turned counter-clockwise and allowing brake fluid to flow from the nipple at the caliper. The advantage of the Speed Bleed is that it is manufactured with a check valve that prevents air from entering the brake system at the nipple. Turning the Speed Bleeder clockwise closes it, just like a standard brake nipple. This will simplify bleeding the brakes because you will not have to open and close the nipple every time you pump brake fluid out and air will not enter the system from the nipple.

Each Speed Bleeder costs approximately $8.00. The manufacturer has been accurate in determining the correct thread size; if you are not certain about sizing, ask him. You will need one Speed Bleeder for each brake caliper, and one for the nipple under the tank if you are bleeding from this ABS location.

The contact information is:
Speed Bleeder Products,
13140 Apakesha Rd,
Newark, IL  60541,
Toll free  888 879 7016
Telephone  815 736 6296
Fax  815 736 6297
eMail: speedbleeder@earthlink.net or click here for their web site at http://www.speedbleeder.com

The Speed Bleeder has operated as advertised in our limited trials. Several BMW riders are using this product, and all reported results have been positive. This author has had excellent results. When using these, ensure that (1) air is not entering the system through the Speed Bleeder's check valve, that (2) air is not entering the brake line through the threaded area between the caliper and the Speed Bleeder, and that (3) the Speed Bleeder is closed and will not permit fluid to escape at the conclusion of bleeding the brakes. A firm brake lever after bleeding will normally mean that the Speed Bleeder worked correctly. Exercise the same precautions and the same "firm brake lever" test you must make when using the standard nipple. Warning: When installing these, do not seat them too far into the caliper. They must be seated only far enough to prevent brake fluid from escaping. I have a report of one person who broke a Speed Bleeder off in the caliper.

The author has done his best to produce accurate information. However no responsibility can be accepted for any damage or injury caused by any errors or omissions in this article. Make certain you understand what is described and why it is being done. Use at your own risk.

Comments, corrections and questions may be directed to
Stephen Karlan (Dali Meeow) at (305) 255-1010
or via email at dalimeeow@adelphia.net.
Updated November 23, 2004.


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