Brakes

Brake Fluid

• Brake Fluid - DOT 4 Recommended

The three main types of brake fluid now available are DOT3, DOT4 and DOT5. DOT3 and DOT4 are glycol-based fluids, and DOT5 is silicon-based. The main difference is that DOT3 and DOT4 absorb water, while DOT5 doesn't. DOT 5 should not be used with any of the others as mixing of glycol with silicone fluid may cause severe corrosion due to trapped moisture in the glycol based fluid.

As a DOT3 or DOT4 brake fluid absorbs water, its boiling point decreases. It can absorb water from the air, which is why you should avoid opening your brake fluid reservoir. For the same reason, you should always keep containers of brake fluid tightly sealed.

DOT5 fluid does not absorb water. This means the boiling point will remain relatively stable, but it also means that any water that does get into your brake system will tend to form pure water pockets, which could cause brake corrosion.

Two other important things about brake fluid: DOT3 and DOT4 eat paint, so don't spill either of these on your car. Also, none of the different types of brake fluid should be mixed. They can react badly with each other and corrode your brake system.

One of the important characteristics of brake fluid is its boiling point. Hydraulic systems rely on an incompresaible fluid to transmit force. Liquids are generally incompressable while gases are compressible. If the brake fluid boils (becomes a gas), it will lose most of it's transmit force. This may partially or completely disable the brakes. To make matters worse, the only time you are likely to boil your brake fluid is during a period of prolonged braking, such a drive down a mountain -- certainly not the best time for brake failure!

Brake Rotor Wear Levels

DaddoCFL:

The discs on this bike don’t really have wear indicators. The front rotors are 5mm. when new with a replacement wear limit of 4.5mm.

The rear rotor is 6mm. out of the box with a wear replacement limit of 5.5mm.

It was not unreasonable to assume that a visual wear indicator be cast into the rotors, but a technician will always go by the actual disc thickness.

Brake System -- Preventative Maintenance. - DaddoCF

Why would you want to replace the fluid in your motorcycle’s braking system at least once a year?

Brake fluid has an affinity for moisture. That is to say, that it will readily absorb water vapor from the air (hygroscopic). As the percentage of water in your brake fluid increases over time, the potential for serious problems in the performance of your brakes increase as well. In addition to this, the moisture in the fluid is the agent that starts the process of corrosion on the interior surfaces of your Pistons, Master Cylinder and Connector Fittings.

Now I understand that no one enjoys the prospect of bleeding brakes, let alone replacing all of the fluid in both the front and rear systems. Sure it can be a nasty, messy job that at times will allow you to run through your vocabulary of descriptive terms that we don’t use around children or ladies. But, there is an easy and almost painless way to put this important maintenance job behind you.

The use of a vacuum pump brake bleeding system will make your life a lot easier when it comes to bleeding your brake lines, or with respect to this project, purging the system and completely replacing the old fluid. There are a lot of low cost vacuum pump systems available. I use a Mityvac system ($25 buckos from AutoZone, although they are available through almost any auto supply house, including sources like Harbor freight). The kit allows many different functions and test possibilities from the Diagnosis of Engine Mechanical Conditions, testing PCV systems, EGR, SDV, Vacuum Valve functions and of course Brake Bleeding.

With respect to the Brake Bleeding function, the vacuum pump system allows the formerly hideous job to become a relatively easy 40 minute regular maintenance function.

Most of these kits contain a hand pump with attached vacuum gauge, a container to accept the used brake fluid (this container is attached to the pump on some models and separate and connected via a length of plastic tubing on others), several lengths of clear plastic tubing, an assortment of various connectors which will facilitate the various tests that the unit is capable of.

The unit functions as a brake bleeder by creating a vacuum inside the empty fluid container, which will draw fluid from the brake bleeder valve through an attached length of the plastic tubing.

Process:

1. Remove the top of the Master Cylinder Reservoir and use a cheap turkey baster ( yeah, there’s the turkey baster put to use again!) to remove as much of the old brake fluid as you can. Then refill the reservoir with fresh fluid. Place the top back onto the reservoir loosely to allow refilling as needed. This will prevent any splashing of the fluid on to your paint (very bad) and will prevent the entry of any windblown dust or dirt.

2. With the pump assembled according to the manufacturer’s directions, select a clear hose that will fit snugly over the end of the bleeder valve of the brake caliper piston’s bleeding valve (You will need to do this twice on an 1100’s twin front calipers).

3. Using the pump, create a vacuum inside the fluid container and the clear hoses. If the vacuum starts to drop after a few seconds, you may have an air leak. Make sure that the tubing connection at the valve is clean and free of any grit, or you may need to grease the threads or sealing flange of your receptacle container.

4. With a working vacuum in the kit (about 8 to 15 lbs.), crack the valve open until you notice the old fluid coming out of the brake system. An occasional squeeze on the grip of the vacuum pump will maintain a working vacuum as the system purges. From time to time during the process, close the valve and check the fluid level in the reservoir, You don’t want to let the fluid drain down to the bottom as you will then suck air into the top of the system. If you have help while you are doing this, a second person can monitor the fluid level in the Master Cylinder for you and from time to time, add additional fluid as needed during the process.

5. There is no 5. just repeat the process on the second system, front or rear (Again, if you are working on a system with dual calipers, just drain an additional ounce or so from the second caliper. This will purge all of the fluid in that branch of the line from the “T”.

The vacuum bleeding method also makes short work of the occasional brake bleed as the continuous draw of fluid tends to do a more efficient job of removing small bubbles from the lines.

Now. . . Clean up and go for a ride!

Brake Bleeding

• Another Bleeding Technique - Push Fluid UP! - greenhell07 posted:

When I was installing my Apes I had to bleed the front brakes as well. Having a second pair of hands is a big help (wife, buddy etc).

A local shop gave me the tip. His explanation was this: Since air rises in the line you're giving it a boost by forcing the air to rise to the top of the master cylinder instead of trying to pull the air down. That's why it is such a pain in the AIS trying to suck the air down and out of the line.

1. Take the master cylinder cover off so you can see the fluid.

2. Get a large syringe with some clear tubing. About 5-6" would be good

3. Attach clear tubing to the bleeder

4. Fill syringe with brake fluid

5. Gently push on syringe as you force the brake fluid in.

You should have seen the air bubbles come popping out the top

For me, bleeding the line took about 20 minutes. Not the hour or longer others have reported.

• Another trick on "pushing" fluid up: Bweland) - use a restaurant squeeze ketchup/catchup (no arguing please) bottle - fill with brake fluid, insert and squeeze it up - looks like it would do a better job that syringe.

Where to get large Syringe?

"I went to Walgreens and they gave me the two largest syringes they had. They were big but not as big as I'd like have had."

"I had to go to Tractor Supply for a couple of items, and looked in the animal vaccination area and they carry some pretty big syringes that look like they would do the job. Real cheap too."

• TimB's Variation on Push Up!: I bought a $10 oil can (old fashioned one with a pump handle), filled, primed, connected it & the clear tube to the bleeder & pumped it up the line. Have some help so as to not pump the fluid out of the M/C & onto your bike.

Speed Bleeders

Available from multiple souces

Speed Bleeders: Size is: M8 X 1.25 rear (1 needed) and M7 X 1.00 front (2 needed)

V STAR 1100 Riders Forum