bleed brakes

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Locking up the front brakes? I don't think that is something you really want James. Could you please clarify. I am guessing you want to know how to avoid this from happening or you aren't sure how this lockup could have happened.

 

Robert, based on the title of the thread I believe nnyxmfan is trying to avoid the lockup situation by cleaning his Master Cylinder, flushing the lines, and putting in new fluid.

Your bike has dual disks. On the top of each Slave Cylinder (the hydraulic part of the caliper) is a bleed screw. It should have a little rubber hat on it, but many do not. Get a length of clear tubing to fit over the nipple on the bleed screw and put the free end in a container to collect the fluid. Open the nipple with a wrench. Do both sides.

Remove cover on Master Cylinder. Take wife/girlfriend/boyfriend for a night on the town. Have fun, tomorrow morning the Master Cylinder and lines should be drained.

When I did mine I also pushed the caliper piston back into the Slave Cylinder to expell that fluid, and to make room for new pads. I recommend you do the same, including pads unless there is a lot of life left on the old ones.

Remove brake lever, mirror and brake light switch. Remove banjo bolt which attaches brake line to Master Cylinder. Remove Master Cylinder. Disassemble the Master Cylinder. Mine has a dust cover with the end of the plunger showing through it. After removing the dust cover you can get to the circlip which holds the guts in.

Remove all the gook from Master Cylinder. Only use brake fluid as a solvent. I used a toothbrush with brake fluid rinse to get all the bits out. Use a fine wire to clean the tiny orifice in the bottom of the fluid resivoir. Be sure not to nick the bore the piston slides in.

Reassemble the Master Cylinder (this is a good time to put in a rebuild kit). Put back on bike and reattach brake line. Put on switch, mirror and brake lever.

Close bleed screws on calipers. Fill Master Cylinder with NEW DOT 3 brake fluid that has never been in anything but the container it was sold in. Set cover on Master Cylinder but do not screw down. The cover will keep fluid from squirting 30 feet across the room but you need to be able to remove it to refill the Master Cylinder several times.

Open one bleed screw (remember, you have a hose on it going into your waste container) slightly. Gently squeeze the brake lever. Tighten bleed screw. Gently release lever. Repeat until there are no air bubbles in the fluid. Top off master cylinder as required to keep from pumping air into the system.

Repeat other side.

Gently apply brake several times to close the calipers. Make sure to keep fluid in the Master Cylinder.

Ok, easy part is done.

There is no air in the caliper Slave Cylinders. All the plumbing going to them on the other hand is probably full of bubbles. Your brake lever probably feels like it is pressing on a sponge.

Over the next few days those bubbles will work their way to the top of the system and up into the resivoir, rise to the surface - and break. To speed this along give the lever a couple squeezes in the morning and again in the evening. Make sure to keep that Master Cylinder full.

On the third day bleed the calipers again just to be sure no air got down there.

Your lever should now feel nice and firm. DO NOT OPERATE BIKE IF BRAKE DOESN'T FEEL FIRM. Bleed again, or get help.

Aren't you glad you're doing this in January when it's too miserable to ride anyhow?

Someone will hop in now and tell you about something called speed bleeders, which make the bleeding part much easier.

 

Thanks for fielding the question MiCarl. I guess I'm pretty dense, I didn't even think about the thread title. Nice write-up, I'll bet our buddy James gets his system bled quickly.

 

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Sure I will tell you that I ordered a set of speed bleeders for my Ford pickup, those brakes are a real pain to bleed!!!!
I'll tell you how they worked out as soon as I know.
meanwhile here's the link

http://www.speedbleeder.com/

You can decide for yourself.
I wont guarantee that these really work like the mfgr says.... but if they do, it will mean a lot simpler job of bleeding brakes!

When I rebuilt my brake system on my bike, the bleeding was actually quite simple!
The only thing I would add to the instructions above, is I left my bleeder screws open when I 1st filled my system and let gravity help to fill the system at 1st then I closed them. I did this a couple of times once before I expanded the pistons and then after bleeding the 1st time then I let the system set for a while and blead them again. That took care of it for me.

 

What I do:

Remove the Master Cylinder cover.

Sop up as much of the old brake fluid in there with paper towels. CAREFUL not to get any on the paint. There is NO NEED to flush the old crap through the system.

Make a fluid catch bottle. Add some clean brake fluid to the bottom, enough to cover the end of the hose.

Add clean DOT 3 or DOT 4 fluid to the resevoir.

Start at the caliper farthest away from the Master cylinder. Put bleed hose on bleeder screw. Use correct size box end wrench (I think mine was 8mm).

Pressurize the brake lever slowly and hold it in and then crack the bleeder valve.

Now pump the lever slowly and watch the fluid until it starts to come out clear.

When it starts to run clear, hold the brake lever down and tighten the bleeder valve.

Check the brake fluid level. DO NOT let it run out or you will have to start over again.

Continue to pressurize the system and cracking open the bleeder valve. Only open the bleeder valve when the system is pressurized.

You may not have a good feel at the lever until both sides are done, so switch to the other side and repeat.

At the end of doing the 2nd caliper, if you still do not have a good feel at the lever, you may have some air trapped in the system. When this happens I usually tap the MC, the calipers and any joints in the system with a wrench to dislodge the trapped air.

There is also an adjustment at the lever to take up the free play. Make sure that this adjustment is correct and that it also is not contacting the MC piston with no pressure applied. You need some free play there.

When you had a good feel at the lever, fill the resevoir and reinstall the cover.

Phil

 

Buy the speedbleeders and replace the bleed screws on the calipers - there's two or three companies that make them and/or market them, but no matter - they're worth the money.