Bench Bleed the Clutch Master Cylinder?

Discussion in '40- & 55-Series Tech' started by greytandy, May 20, 2007.

  1. greytandy

    greytandy

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    I'm installing a whole new master/slave cylinder system for the clutch, and have read references to "bench bleeding" the master. What exactly is this? Is it necessary? Thanks.
     
  2. pbgbottle

    pbgbottle Forum Lifer

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    bench bleeding

    :grinpimp:
    becnh 1 (Medium).jpg becnh 2 (Medium).jpg
     
  3. Pin_Head

    Pin_Head

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    "Bench" bleeding is not necessary, although it is useful if you are working alone. Clutch masters bleed well by just cracking the bleeder on the slave and letting gravity do the work. If there is air in the master after bleeding it, you can just loosen the nut on the line on the master and squirt some brake fluid into a shop rag, then tighten it before sucking air back into the master. This is a two person job.
     
  4. greytandy

    greytandy

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    Thanks guys. The master cylinder and slave cylinder are all "connected" by the same hydraulic fluid, right? So, why would the master need to be bled separately? It seems to me all the air would be released from the slave since it's all the same fluid. Just wondering what I'm missing.
     
  5. F-junker

    F-junker

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    One for the front disc brakes and one for the rear. The picture up above is as good a discription as it can get. You want to make sure to get ALL of the air bubbles out of the cylinder.
     
  6. pbgbottle

    pbgbottle Forum Lifer

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    i bench bled my last brake master, but did not bother bench bleeding my clutch master, had no issues . i just gravity bled it also.
     
  7. greytandy

    greytandy

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    For a clutch, is gravity bleeding better or worse than the good old two-person loosen, push clutch, tighten, repeat technique?
     
  8. Pin_Head

    Pin_Head

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    Properly executed, the two person method is fool proof for every application, but clutch masters seem to bleed just fine by gravity.
     
  9. pbgbottle

    pbgbottle Forum Lifer

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    i just gravitly bled it because i was by myself , i just let it bleed while i did other things .such as clean up my mess :doh: i usually use the two person method .
     
  10. greytandy

    greytandy

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    Just so I know for sure, gravity bleeding simply entails letting the air slowly work its way out of the system? In other words, just simply letting it sit? No turning of the slave bleeder? How long do you normally let it set? Sorry for asking so many questions. I just want to make sure the job is done right. Thanks again. :)
     
  11. pbgbottle

    pbgbottle Forum Lifer

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    just fill the resevoir on the master crack open the bleeder screw on the slave and let it be .shouldn't take long and out comes the air ,and then see bubbles, and eventually the clean fluid, no bubbles ,something like that :grinpimp:
     
    Last edited: May 20, 2007
  12. TOR25

    TOR25

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    I was able to reach the bleeder valve with my left hand and the clutch pedal with my right. Somewhat uncomfortable but it worked.
     
  13. Avro

    Avro

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    Clutch master cylinder bleeder screw location

    Can't find the bleeder screw on my 85 bj 60 land cruiser. Can anyone help?
     
  14. mossman40

    mossman40

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    Bleeder screw should be down by your slave cylinder. Follow the lines down to the slave and look for your bleeder screw there.
     
  15. Fast Eddy

    Fast Eddy

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  16. loumar1684

    loumar1684

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    Not sure if this is the right place for this question, but perhaps someone can direct me. On a 97 fort escort wagon I have replaced both the slave and master clutch cylinders. No fluid coming out of the slave, pump clutch several times and nothing. Provided I have not ruined the Master cylinder... is this when I can open the Slave and hopefully it will gravity bleed itself and then I crack the Master line and let some fluid out and close line again?
    Please advice... newbie at this. Thanks
     
  17. Pin_Head

    Pin_Head

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    It is just a cylinder, so the fluid moves back and forth. If you want it to pump fluid, cover the outlet with your finger so the fluid doesn't get sucked back into the cylinder.
     
  18. 1969FJ

    1969FJ

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    The reason to bench bleed is because when the master is empty, and you fill it, as you push the piston , it will allow fluid and air to move around. As you add fluid to replace where it is going, air will enter again. Now, if you have those output tubes going back to the reservoir, eventually you will get equilibrium and all air will be squeezed out and only fluid will remain.

    I can suggest a real easy way to do brakes or clutch systems easily by one person. Take a look. Phoenix systems.

    Bench bleed.PNG
     
    mrboatman likes this.
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