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  1. #1
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    why doesnt anyone vacuum bleed their bikes?

    manual bleeding cars is basically not done anymore.. just takes too long, and does too poor of a job! in terms of design, bike brakes are nearly identical to car brakes, except with 1/4th the components.. seems like we could vacuum bleed them too, but no one seems to?

    my hayes9's need a bleed finally (been months without so much as touching them! ). lbs was nice enough to give me a hayes bleed kit.. but it seems like i could turn it into a 30 second job with a vac pump.

  2. #2
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    Yup, sure could.
    Just need the right fittings to plug the vacuum hose into and you're on your way.

  3. #3
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    Have done it with Shimano's drawing through the caliper, havent tried with others going through the master. Avid kit is a sudo suck with the dual syringe.
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  4. #4
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    Quote Originally Posted by tomsmoto
    ...in terms of design, bike brakes are nearly identical to car brakes, except with 1/4th the components..\
    They are? I have not seen a mtb brake with vacuum power assist, ABS or f/r basis valves.
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  5. #5
    Meh.
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    Replace the squeeze bottle with a big syringe. Just push fluid through from the caliper to the top.

  6. #6
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    Quote Originally Posted by shiggy
    They are? I have not seen a mtb brake with vacuum power assist, ABS or f/r basis valves.
    you bet. one piston pushing another at a different ratio. a master and a slave, with a reservoir.

    the abs and valves are independent systems that really have no effect on the function or operation of the main system. power assist is mechanical, not hydraulic.. its similar to having a buddy help you squeeze the lever.

    but nice try to call me out on it

    will, that was my original idea.. but im having a strangely hard time finding anything bigger than a 15ml syringe locally!

  7. #7
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    Quote Originally Posted by tomsmoto
    im having a strangely hard time finding anything bigger than a 15ml syringe locally!
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  8. #8
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    Quote Originally Posted by tomsmoto
    you bet. one piston pushing another at a different ratio. a master and a slave, with a reservoir.

    the abs and valves are independent systems that really have no effect on the function or operation of the main system. power assist is mechanical, not hydraulic.. its similar to having a buddy help you squeeze the lever.

    but nice try to call me out on it

    will, that was my original idea.. but im having a strangely hard time finding anything bigger than a 15ml syringe locally!
    Disconnect any of the above on your car and see how well your brakes work. They are not independent systems.

    If you can not find a large syringe you are not really trying. They do not have to human medical grade. (that is a hint)
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  9. #9
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    car brakes work from a small piston actuating a large piston, hydraulically. bike brakes work from a small piston actuating a large piston, hydraulically. you know what im saying man. its a similar system.

  10. #10
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    Quote Originally Posted by shiggy
    If you can not find a large syringe you are not really trying. They do not have to human medical grade. (that is a hint)
    Your always on a Easter schedule.
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  11. #11
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by tomsmoto
    car brakes work from a small piston actuating a large piston, hydraulically. bike brakes work from a small piston actuating a large piston, hydraulically. you know what im saying man. its a similar system.
    Similar, yes, but that was not your original claim: "...bike brakes are nearly identical to car brakes, except with 1/4th the components..."
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  12. #12
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    alright man, you're the winner of the internets. congratulations

    ill give the vac bleed a try in a few minutes and report back how it works out. thanks guys.

  13. #13
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    Magura has (had) a shop bleed kit that was pretty similar (note, similar, not same) to an automotive vacuum bleed system. Big syringe and a giant c-clamp with big rubber pads to seal off the master cylinder with the top off. But you push the fluid from the caliper to the open master.

    I actually just bled a shimano system the other day using a syringe to suck fluid down from the master cylinder and enlisted a spare mechanic to keep the fluid level in the lever. Having the second person keep any air from getting sucked in made for a quick and complete bleed.

  14. #14
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    Quote Originally Posted by tomsmoto
    I'm having a strangely hard time finding anything bigger than a 15ml syringe locally!
    Try an animal feed/supply store.

    (No extra charge for correcting your spelling on the quote.)
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  15. #15
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    im sure the punctuation difference between im and i'm makes the whole thing down right impossible to read. thank you. no feed stores here

  16. #16
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    Quote Originally Posted by tomsmoto
    im sure the punctuation difference between im and i'm makes the whole thing down right impossible to read. thank you.

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  17. #17
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    Another option for a syringe is a Mix-Mizer avaliable at most auto parts stores and Wal-Mart near the gas cans, costs ~$3.

  18. #18
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    Quote Originally Posted by tomsmoto
    car brakes work from a small piston actuating a large piston, hydraulically. bike brakes work from a small piston actuating a large piston, hydraulically. you know what im saying man. its a similar system.
    Dude, you were very clear for people who are familiar with cars. But its the internet, and theres always gotta be someone who has to say "well actually...."

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  19. #19
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    Quote Originally Posted by tomsmoto
    no feed stores here
    Tractor Supply?

    With cars, I always avoided using a vacuum bleeder if a pressure bleeder was available, just too hard to keep air from being sucked in around the threads of the bleed fitting.
    Seems to me that bikes being what they are you could easily work the lever and the bleed screw to finish the process.

  20. #20
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    Quote Originally Posted by tomsmoto
    manual bleeding cars is basically not done anymore.. just takes too long, and does too poor of a job! in terms of design, bike brakes are nearly identical to car brakes, except with 1/4th the components.. seems like we could vacuum bleed them too, but no one seems to?

    my hayes9's need a bleed finally (been months without so much as touching them! ). lbs was nice enough to give me a hayes bleed kit.. but it seems like i could turn it into a 30 second job with a vac pump.
    I always had the worst time vacuum bleeding brakes on my cars. Everytime I cracked open the bleed nipple, I would draw air from the fitting and not from the system. I had better luck with the check-ball style bleed nipples and bleeding them the traditional way.

    9/10 times though, I would invariably get a MC leak by using the pedal becuase the piston travels into a part of the bore that it can't while the system is pressurized...torn MC seals.

    I only ever had great success with the pressure style bleeders that are connected to the resevoir cap and pumped up.

    I tried to vacuum bleed my MTB brakes and experienced the same "suck air from partially open fitting" rather than from the MC. I also need to re-bleed my Strokers after only 2 months...the rear has gone spongy *again*. Personally, I'm ready to throw them in a lake and get some XTs.

  21. #21
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    Quote Originally Posted by Konish
    I also need to re-bleed my Strokers after only 2 months...the rear has gone spongy *again*. Personally, I'm ready to throw them in a lake and get some XTs.
    If your bleeding your Strokers every 2 months there is something not right someplace, what issues are you having??

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  22. #22
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    Caution;  Merge;  Workers Ahead!

    Quote Originally Posted by tomsmoto
    manual bleeding cars is basically not done anymore.. just takes too long, and does too poor of a job! in terms of design, bike brakes are nearly identical to car brakes, except with 1/4th the components.. seems like we could vacuum bleed them too, but no one seems to?
    Manual bleeding of brakes is still done when race teams are looking for the highest performance out of their brakes...

    check out this thread from the z06 forum... http://www.z06vette.com/forums/f8/mo...12/index2.html

    ive manually bled brakes on cars and motorcycles for 15 years and have never had a problem.

  23. #23
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    Quote Originally Posted by tomsmoto
    you bet. one piston pushing another at a different ratio. a master and a slave, with a reservoir.

    the abs and valves are independent systems that really have no effect on the function or operation of the main system. power assist is mechanical, not hydraulic.. its similar to having a buddy help you squeeze the lever.

    but nice try to call me out on it

    will, that was my original idea.. but im having a strangely hard time finding anything bigger than a 15ml syringe locally!
    Sure about that? Many German autos use hydraulic assist for the brake boosting. It's kind of a cool system and retains power assist for some time/cycles even after the engine is shut off by way of a pressure accumulator with typically a nitrogen charge.

    Quote Originally Posted by shiggy
    Disconnect any of the above on your car and see how well your brakes work. They are not independent systems.

    If you can not find a large syringe you are not really trying. They do not have to human medical grade. (that is a hint)
    Disconnecting your ABS completely, as in unplugging it will only affect it at lockup, meaning you will have lockup. Bypass it hydraulically and your brakes will work fine, though you will lockup when conditions dictate. I have done this very thing on old Audis that came factory stock with "ABS OFF" controls, as well as retrofitting ABS OFF controls in other models, as well as bypassing faulty hydraulic pump units into their conventional counterparts.

    ABS only works when the electronics sense a lockup, dictated first by an extreme variance between the rotating speeds of one or more of the "channels" or wheels. Thankfully, computers got faster and they get closer to lockup now. The other method in which ABS pumps have been made to work is for brake assist, which my car has also. WHen a panic stop takes place, it can assist and add more braking, as human error typically means the driver can produce more force, but in an emergency situation, does not or can not.

    Again, this will not affect the brakes not working. Bypass this and you'll get tons of warning signs, but as a failsafe, these braking systems will still work when the electronics or the hardware malfunctions, short of a blockage or a leak.

  24. #24
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    The syringe from the caliper method works fine, at least on my brothers XTs. I got the syringe from Orchard, but you can vacuum bleed shimano brakes without one:

    1. Fill reservoir.
    2. Attach tubing to bleed nipple
    3. Squeeze brake fluid bottle and hold
    4. Attach the other end of the tube to the nipple on the bottle
    5. open bleeder and let the bottle expand and poof, you're vacuum bleeding the brakes.

  25. #25
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    I wouldn't say every 2 months as I've only had them for about that long...maybe a bt longer. The rear has gone spongy again...can touch the bar with the lever. I was having problems bleeding the rear brake on the intial setup so it may be a persistent problem from the beginning. As far as I can tell, no leaks in the system so I'll just try the simplest solution first.

    The other thing is that these brakes just won't shut up. Tried different pads, aligining with a feeler guage, eye balling it, lever method...everything. I think the rotors have more to do with it than anything. They are the stock 8" rotors and are pretty flexible. More to the point they seemingly change shape (i.e. warping) as I ride. I know for sure they are no longer flat which makes tuning these brakes....fun.

    Bottom line, if I see a good deal on XT brakes and levers, the Strokers are gone!

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