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Discussion Starter #1
The brake bleeding procedure is to pump the lever/pedal, hold lever/pedal and then open bleeder valve and then tighten, I think before end of travel. You're not supposed to pump the lever/pedal when bleeding as this may draw air back into the system. Well as long as the hose is full of fluid does it really matter? I mean couldn't you just pump away and then tighten? Or does this cause air maybe to be drawn into the system from around the threads?
 

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Discussion Starter #3
Yep I've heard about em. That means I guess draining the system and replacing the bleeder screws on the calipers and I guess the masters as well. Doesn't sound like fun.
 

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Well I just swapped the bleeders on the Calipers and Clutch slave, very little fluid actually leaks out so I only needed to bleed them which, by their design, is easy enough, although I did take the opportunity to change the fluid anyway, which I like to do every year.

Whole job, including changing the fluid and removing the rear caliper to get the bleed point higher up probably took me between 1-2 hours (including Beer-breaks ;) ) and the speedbleeders are not expensive but save a whole load of time for future bleeding and fluid changes, besides my rear brake bleeder never sealed very well and there was always some seepage into the rubber cap, which is all fixed now. :)
 

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grendels_arm said:
The brake bleeding procedure is to pump the lever/pedal, hold lever/pedal and then open bleeder valve and then tighten, I think before end of travel. You're not supposed to pump the lever/pedal when bleeding as this may draw air back into the system. Well as long as the hose is full of fluid does it really matter? I mean couldn't you just pump away and then tighten? Or does this cause air maybe to be drawn into the system from around the threads?
Yes you can. i like to keep the bleeder hose and container elevated above the valve. So if there is air it will tavel up the tube.

I guess its possible it can be drawn in from the treads, but ive never has a problem.
 

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grendels_arm said:
The brake bleeding procedure is to pump the lever/pedal, hold lever/pedal and then open bleeder valve and then tighten, I think before end of travel. You're not supposed to pump the lever/pedal when bleeding as this may draw air back into the system. Well as long as the hose is full of fluid does it really matter? I mean couldn't you just pump away and then tighten? Or does this cause air maybe to be drawn into the system from around the threads?
Sam,

Air moves a lot easier than fluid. I say the probability of air getting sucked in through the threads is still there, but not as bad as using a MightyVac.

-Fariborz
 

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Discussion Starter #7
Whadayamean not as bad as using a Mityvac? You mean a Mityvac is likely to let air in?
 

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Discussion Starter #9
Maybe it was his bleeder screw. Anyway I use the hose and container method. I just don't like messing with brake fluid at all. Plus I always seem to see microscopic air bubbles when I bleed. Can't tell if this is "normal" or not. They seem to never stop sometimes. Anyway my rear brake is fine. But I want to do it again since I wasn't holding down the lever when closing the bleeder valve. If anything i'll gettingt he Speedy bleeders.
 

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Simple. Very simple.

A vacuum pump works best.

No pump? Hook a tube to the intake manifold of your car. Instant 28" hG vacuum bleeder.

Just open the bleeder a touch and you'll bleed it out nicely. No pressurization from squeezing the lever, no micro bubbles in the lines and calipers from the pressurization.

The whole thing will cost you $2. Don't run a whole quart of fluid through the thing though. Catalytic converters don't like it.
 

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Hate the vacuum bleeders. Stopped using them, as I never could get a decent bleed with them. Hose in bottle method...and just pump away....rock hard lever. Works every time. No vacuum-induced bubbles on the bleeder valve to confuse things, IMO.
 

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I use a large plastic syringe (like they sell at pharmacies for clearing out noses and so on, Not the "injection" type).

Fill that with brake fluid and connect with rubberhose to the bottom bleeder valve. Empty part of the reservoir and then push the bubbles/brakefluid towards the reservoir.

If you do a "normal" bleed, your forcing the bubbles DOWN, but they want to go UP.
Using my method, I´m forcing everything UP. Incl the bubbles.

It took me 2 minutes of bleeding to get all the air out of the system after replacing my master brake cylinder with a radiell unit (incl hooking everything up). Beat that with a vacuum bleeder...

//amullo
 

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Discussion Starter #13
I may try Amullo's method at some point but for right night want to stick with the hose in bottle method.

"Old" guys. Getting confused. I'm thinking the microscopic bubbles I sometimes see are because I pump away using the traditional method instead of holding in the lever after each time.


OldBaldy you mention pump away. You mean pump then tighten the valve after each time right?

OldFart you mention just crack open the bleeder valve and avoid the pressure. Can I do this without the intake manifold method? I guess you're saying this is needed?
 

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Bleeding like this works for me. I have never had good results with pumps and stuff. I do like my bleeder ball though.

For front brakes:
Pump lever until you get some kind of resistance. Squeeze and hold the lever. Open the bleeder screw and allow the lever to fall. Close bleeder screw just short of bottoming the lever. Release lever and repeat.

Don't allow the fluid level to get too low or you'll have to start over.

Oh yeah, this is important. Adjust the lever so that it's at its max travel.

Rear brakes:
Same for the front, except remove the caliper and wedge a piece of wood between the pads. I've found that two popcicle sticks is about right (this would depend on how worn the pads are). I hold the caliper with the bleeder pointed up in one hand, open and close the bleeder with a wrench with the other, and pump the brake pedal with my right knee.

Unfastening the reservoir from the frame and moving it to the outside of the frame helps when filling it.

I hang the bleeder hose in a container, but I don't submerge it in fluid. I think the idea behind submerging the hose end in fluid is so that you don't have to close the bleeder screw before you release the lever. Instead of sucking air back into the system, it sucks fluid with the air (IMO). I find that closing the bleeder screw before releasing the lever works fine.
 

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Discussion Starter #15
Yep Paulo that's the method I'd figure I'd use. The rear brake is a bit frustrating as the hose I got from Home Depot and therefore wanted to stay rolled up. Therefore not wanting to stay in the fluid. Next tiime I'll use duct tape and tape it to the container. The thing you gotta watch about removing the rear master resovoir is that it will tip over. I'll tape that to the side of the bike to hold it in position if I have to.


Anyone do the holding the lever/pedal overnight with a rope or something? Some people mention this helps to keep the lever firm. But I've heard some people say it doesn't do a thing.

Brake bleeding is like choosing oil.
 

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grendels_arm said:
...
Anyone do the holding the lever/pedal overnight with a rope or something? Some people mention this helps to keep the lever firm. But I've heard some people say it doesn't do a thing.
In my view it does NOT do a thing.

If there is any air in the system by pulling in the lever and keeping it in that position, you simply put the air under a lot of pressure. Most of air molecules are Hydrogen and Oxygen. Under pressure they may condense back into water (moisture). Once air (gas) turns into water (liquid) it will give you the sensation of a firmer lever for the duration that the water temperature stays way below its boiling point. Once your brakes get hot, that water will turn back into air and the lever will have the same exact feel (mushy) as if there was air in your system.

-Fariborz
 

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Discussion Starter #17
Interesting. So basically you may get the firmer feel for awhile but it'll go away. But doesn't seem like there is any harm done.

I would think the theory behind all this is people expect that putting pressure on the hydraulic system overnight will caught any remaining air bubbles to rise up in the master cylinder. However not sure if they would do that if the cap was on overnight.
 

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grendels_arm said:
Interesting. So basically you may get the firmer feel for awhile but it'll go away. But doesn't seem like there is any harm done.

I would think the theory behind all this is people expect that putting pressure on the hydraulic system overnight will caught any remaining air bubbles to rise up in the master cylinder. However not sure if they would do that if the cap was on overnight.
Sam,

I think that is an unsubstantiated folklore!

When the lever is pulled, the piston/plunger in the brake master cylinder is in front of the bleed hole to the reservoir. There is no way for the air bubbles or the brake fluid to go back into the reservoir, regardless if the cap is on or not!

As far as regular air bubbles created during normal operation of the brake making it back to the reservoir is concerned, the reservoir cap has a rubber seal that can expand or retract. So if air bubbles can make it to the reservoir the rubber seal will compensate for the change in the fluid volume.

-Fariborz
 

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Fariborz said:
Sam,

I think that is an unsubstantiated folklore!

When the lever is pulled, the piston/plunger in the brake master cylinder is in front of the bleed hole to the reservoir. There is no way for the air bubbles or the brake fluid to go back into the reservoir, regardless if the cap is on or not!
-Fariborz
maybe the idea is to compress the air bubbles so that they are small emough to travel up to the top, then when you release they move up into the resivour.
 

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DanTheMan said:
maybe the idea is to compress the air bubbles so that they are small emough to travel up to the top, then when you release they move up into the resivour.
Dan,

As I said earlier, personally I think that is all an unsubstantiated folklore. The lever feels firm right after the pressure is removed from the overnight strapping of the lever. In little to no time once the pressure is removed the feel would go back to what the lever would have felt if the lever was not pulled in overnight.

-Fariborz
 
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