Proper Motorcycle Brake Fluid Maintenance FAQ

[totalmotorcycle]

Proper Motorcycle Brake Fluid Maintenance FAQ


The average person that rides a motorcycle has faith that when they pull on a brake lever the brakes will work. This is a lot to ask of something that many people do not service often. The frequency that a motorcycles brake system should be serviced depends on the types of riding, brake pads and systems, and the type of fluid that is used. The average street rider, sports bike or cruiser, will not put nearly as much stress on a brake system as someone that is riding on a race track. The novice track day rider will not be able to input as much heat and strain on a brake system as an expert racing around the same race track. The point of bleeding the brakes is to release the buildup of oxygen that has accumulated in the brake system from the heating of the fluid, which creates moisture when it cools.

Understanding brake fluid
Brake fluid comes in four different forms, DOT 3, DOT 4, DOT 5 and DOT5.1. U.S. Department of Transportation Federal Motor Carrier Safety Administration Standard No. 116 puts the regulations and standards on brake fluid used in the USA. The heat breakdown for all each fluid is one of the main characteristics that sets them apart. The standards for brake fluid boiling points have to be regulated to avoid fluids vaporizing in end users’ brake lines. Vaporization in the brake lines causes a negative effect on hydraulic pressures, leading to catastrophic brake failure.

Listed below are the minimum boiling points stipulated by the Federal Motor Carrier Safety Administration:
Dry boiling point Wet boiling point
DOT 3 205 C (401 F) 140 C (284 F)
DOT 4 230 C (446 F) 155 C (311 F)
DOT 5 260 C (500 F) 180 C (356 F)
DOT 5.1 270 C (518 F) 190 C (374 F)

DOT 3, DOT 4 and DOT 5.1 fluids are non-silicone based formulations, but DOT 5 is a silicone based formulation and cannot be mixed with any of the non-silicone based formulations in any manner. DOT 3, DOT 4 and DOT 5.1 brake fluids are hygroscopic (water-absorbing) fluids, therefore they also have to have anti-corrosive materials added into their manufacturing. The anti-corrosive additives in these brake fluids are one of the main reasons that brake fluids will lift paint off surfaces, so when bleeding your brakes make sure to keep soapy water handy for a quick cleanup.

Brake Bleeding
When starting to work on your motorcycle it is always best to consult the owner’s manual to ensure that you have all the proper tools and protective safety equipment. Brake fluid can cause skin irritations and should never come into contact with your eyes, so be sure to have gloves and eye protection. Brake lines are pressurized and the fluid will travel a distance if a line is opened and not covered.

There are many different methods of brake bleeding: vacuum bleeding, pressure bleeding, hand bleeding or gravity bleeding, but the same principles will apply to each one. First, brake fluid has chemicals that can remove paint and ruin your bike, so cover the bike with some old towels where you will be working and have one towel that is damp with water for a quick cleanup. Next, check the fluid reservoir and add fluid, this would be a good time to draw out all the old fluid already in the reservoir and replace it with new fluid. Removing the old fluid is as easy as taking a few disposable clean towels or rags and sopping out all the old fluid. Remember that if you are adding fluid, to install the correct fluid and not to add any silicone based fluid in with non-silicon based fluids.

When bleeding a system, the caliper furthest from the master cylinder should be the first to be bled. Find the bleeder screw and size it with the proper-sized wrench. Set the wrench and install a clear hose over the bleeder to keep the fluid from dripping on the caliper and wheels. Pump the brake lever to ensure pressure in the lines, now hold the brake lever and slowly open the bleeder screw. Do not release the brake lever during this process until you close the bleeder screw. Once the bleeder screw is closed and the brake lever is released, pump the brake lever up again. When pressure is felt on the lever, you are ready to bleed the line again. This process should be repeated until the clear line has fluid with no bubbles out of the bleeder screw.
Caution: Make sure to keep checking and adding fluid to the reservoir to ensure that there is no air going into the master cylinder, which would result in you having to start the process over again. Also, check the clear hose attached to the bleeder screw to ensure there is not any air coming into the line that way, making the clear bleed line seem as if there is still air in the brake system.
Once the furthest caliper has been bled, now move on to the next-furthest brake caliper from the master cylinder and repeat the above bleeding process. The brake master cylinder should only be bled if there is a brake-pressure issue still existing. Master cylinder bleeding is slightly tricky and could get very expensive if done wrong, therefore, a trip to a shop may be a smart bet if you are not comfortable with this process.

Frequency
Brake fluid maintenance is definitely something that is overlooked more often than it should be. When the brake fluid in your reservoir starts to get dark, that is a sign that it is breaking down, losing its viscosity and getting contaminated with moisture. This is the first sign that the fluid needs to be changed. If you are a track day person or racer, your fluid is often put under extreme conditions, so the brakes should be bled often and fluid changed once a race weekend, to be safe.

[slimcolo]

Double post Mike?

[totalmotorcycle]

Thanks, fixed!

Mike

[vennyroger]

Check your brake fluid level. If you notice that the level is low have your entire brake system checked repeatedly. It is much important regulate the engine on regular basis.