SuzukiHayabusa.org
GENERAL => ROAD COURSE => Topic started by: BATTMAN on March 10, 2008, 06:28:58 PM
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Whats your technique to bleeding brakes? I got new brake lines and i have a small bubble in them. They work great when i bleed them, but then when i start to ride i feel the air bubble and then i have to pump them once and then the pressure comes back.
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I have a vacume pump bleeder, works great. Put the hose on the bleeder valve, pump up the bleeder and crack the valve. I have been putting some 30w oil around the thread of the valve to keep air from comeing in that way, works great amazing how many little air bubbles it gets out.
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Do you have a pic of the pump you have. Ive been using one of those gravity fed bottle bleeders. It takes forever that way. I think I am getting air in the line from the valve.
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Looks like this pic. Pulls vacume through a cup and that is where the fluid goes. Put some oil around the valve to keep it from sucking air.
http://www.webbikeworld.com/Motorcycle-technical-articles/bleeding-motorcycle-brakes/bleeding-motorcycle-brakes.htm (http://www.webbikeworld.com/Motorcycle-technical-articles/bleeding-motorcycle-brakes/bleeding-motorcycle-brakes.htm)
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I use a Mityvac vacuum bleeder, but to be honest I only use it to get the new fluid into the system. It takes forever to get the air out using the Mityvac, partly because I can't seem to get a good seal at the bleed nipple, and nothing generates false bubbles like a vacuum and a leaking seal. Now I just use the brake lever pump technique, and it doesn't generate false bubbles.
-PR
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I just have to seal the valve better. Thats where i am getting the bubbles from.
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if you can let it set for a couple days do this... take a zip tie and compress the brake lever to the grip.. leave it for a day or two compressed with the res. cap off and the air will bleed off. you will be surprized how much better it is compared to what you thought was a good. i always use this method as the mighty vac sucks air around the bleeder and creates more trouble than its worth.
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if you can let it set for a couple days do this... take a zip tie and compress the brake lever to the grip.. leave it for a day or two compressed with the res. cap off and the air will bleed off. you will be surprized how much better it is compared to what you thought was a good. i always use this method as the mighty vac sucks air around the bleeder and creates more trouble than its worth.
I read an article recently about how brake fluid loves to absorb moisture, even from the air. And you do not want water in your brake system. The Suzuki manual even recommends refilling with a fresh bottle of brake fluid.
-PR
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if you can let it set for a couple days do this... take a zip tie and compress the brake lever to the grip.. leave it for a day or two compressed with the res. cap off and the air will bleed off. you will be surprized how much better it is compared to what you thought was a good. i always use this method as the mighty vac sucks air around the bleeder and creates more trouble than its worth.
I do the same thing. Usually, the lever is 'rock' by morning!
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Do you have the valve open as well? Or do the bubbles come out through the reservoir.
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Valves closed, air eventually seeps to reservoir.
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Ill give it a try. Thanks
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I let it sit overnight....the brake peddle is hard now. It worked great.
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if you can let it set for a couple days do this... take a zip tie and compress the brake lever to the grip.. leave it for a day or two compressed with the res. cap off and the air will bleed off. you will be surprized how much better it is compared to what you thought was a good. i always use this method as the mighty vac sucks air around the bleeder and creates more trouble than its worth.
I read an article recently about how brake fluid loves to absorb moisture, even from the air. And you do not want water in your brake system. The Suzuki manual even recommends refilling with a fresh bottle of brake fluid.
-PR
That doesn't make a whole lot of sense, if brake fliuid loves to absorb mositure, then why would we want any?
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tried the gadgets but i prefer the old fashioned pump the lever/open the valve method.
It gives me the best results.
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if you can let it set for a couple days do this... take a zip tie and compress the brake lever to the grip.. leave it for a day or two compressed with the res. cap off and the air will bleed off. you will be surprized how much better it is compared to what you thought was a good. i always use this method as the mighty vac sucks air around the bleeder and creates more trouble than its worth.
I read an article recently about how brake fluid loves to absorb moisture, even from the air. And you do not want water in your brake system. The Suzuki manual even recommends refilling with a fresh bottle of brake fluid.
-PR
That doesn't make a whole lot of sense, if brake fliuid loves to absorb mositure, then why would we want any?
What he is trying to say is that as you use your brakes and compress the fluid it breaks down and (just like oil) looses viscosity. When it is at less than consistant it takes the form of water and absorbs more water in the usage but if your res is sealed and no air or moisture can get in you are fine but you still need to bleed the system dry and change the fluid periodically!
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When I first got started in the racing business, I was the brake guy for a sports car team.... brakes have always been my specialty I guess. Going fast only gets you so far, being able to stop and do it all over again is just as much fun!
Here is a post I wrote for another bike site a few years ago... well, many years ago.
http://www.zrxoa.org/webpages/techinfo/brake/bleedbrakes.html
Please let me know if you have any questions or comments!
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Let me clear up some misconceptions...
First - if you are not 100% comfortable working on your brakes, please PLEASE bring it to a shop and have them do it for you.
Brake fluid is hygroscopic which means it likes to absorb moisture. It can suck moisture from the air, through regular rubber hoses, condesation air pockets, etc. The more moisture it absorbs, the lower the wet boiling point of the fluid (thus reducing its thermal capacity). Most brake fluids are rated for dry and wet boiling points. Dry is practically meaningless except for the first day after being installed (maybe). All non-silicone (non DOT 5.0) fluids are also very caustic and will ruin your paint and the finish on metal. Water is the best barrier - so I recommend a wet towel to protect to painted surfaces.
Bubbles are very hard to completely remove - I usually do a combo of mity vac and old fashioned manual bleeding, especially for new brake line installations. I don't use a pressure bleeder on bikes because the reservoir is too small and its easy to mess up and introduce air accidentally. YRMV. First, gently rap the caliper, fittings, brake lines, and banjo bolts from the bottom up with a small wrench like the 8 or 10mm one you have in your hand for the bleeder nipple. Then bleed a full reservoir of fluid (don't let the reservoir run dry and expose the feed port at the bottom to the air) through each caliper.
When cracking the bleeder nipple, I hold pressure on the brake lever, then gently crack the bleeder open only as far as needed for fluid to come out. Don't swing the bleeder open 360 degrees. You can also seal the threads around the bleeder with some wheel bearing or axle grease to prevent air from getting past where the threads go into the caliper.
It just takes time and patience, and probably the better part of a bottle of fluid for the front brakes.
Wrapping a zip tie around the front lever forces the air bubbles to come together and make a larger bubble which is easier to bleed out. The pressure in the system is working for you. Don't release the lever the next day, squeeze it, and then bleed both calipers.
Finally, make sure to use fresh crush washers - the suzuki ones are excellent - I prefer them to the replacement ones from most companies. Mkae sure the banjo bolts have the correct torque on them, but don't over torque. Air likes to accumulate at the fittings - both at the calipers and at the master cylinder. and also at the top of the pistons and at the bleeder nipples.
The last resort is to remove the calipers and most of the fluid from the master cylinder. Do not disconnect the calipers though, just unbolt them from teh forks. Then use a piece of wood to force the pistons back into the calipers. This is a cheap reverse bleed and will pust the fluid back up to the master cylinder and should bring all the air wil it. Make sure to clean the calipers first, you don't want to push nasty dirt past the seals and add contamination to the fluid or possibly damage the seals. Cleaning the calipers is whole new thread LOL.