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stuiped residual pressure valve question

Discussion in 'The Hokey Ass Message Board' started by a.y1320, Jul 28, 2011.

  1. a.y1320
    Joined: Feb 3, 2008
    Posts: 117

    a.y1320
    Member

    Hey guys I'm having some brake problems. Let me start with the parts I'm using. Speedway model a m/c. Speedway front disc setup 70's Ford rear drums. Wilwood proportioning valve, and speedway rpv 2# for the front line before the tee. A 10# rpv on the rear line.
    The problem is that after bleeding all the air out of the system I am still not making good pedal pressure. It gets worse, the front calipers will not release after pumping the brakes. The calipers will release if I open the bleeder. Adversely the rear brakes won't engage at all.
    The residual pressure valves are marked only with "in" and "out" I installed them with "in" from the m/c and "out" towards the wheels. Am I wrong? I'm freakin lost and I need some ideas. Thanks for any info.
     
  2. brigrat
    Joined: Nov 9, 2007
    Posts: 5,381

    brigrat
    Member
    from Wa.St.

    You need to back off your M/C rod for one thing. That should take care of the fronts locking up. You will however loose more pedal doing it. What is your pedal ratio and how much throw do you have?..................... You have the in & outs rite.
    You either have the wrong M/C bore and or your not throwing rod far enough into bore.
    You can try a front line mounted Hold off valve that will let rears build up a bit before fronts or install a metering valve.
     
    Last edited: Jul 28, 2011
  3. 26 roadster
    Joined: Apr 21, 2008
    Posts: 2,015

    26 roadster
    Member

    is the portioning valve in the front line?? it goes in the rear line, unless I read you wrong
     
  4. a.y1320
    Joined: Feb 3, 2008
    Posts: 117

    a.y1320
    Member

    I don't really know what the pedal ratio is. This m/c came with the pedal rod bracket and pedal assembly. I have tried backing up the push rod with no noticeable change. I can see that the piston doesn't return completely on its own. It stops about an 1/8" short. I can grab the pedal lever and pull it forward and the piston will move all the way out.
     

  5. brigrat
    Joined: Nov 9, 2007
    Posts: 5,381

    brigrat
    Member
    from Wa.St.

    Do you have a return spring on the pedal?
     
  6. dirtbag13
    Joined: Jun 16, 2008
    Posts: 2,540

    dirtbag13
    Member

    did you adjust out your rear brake shoes after installing them to where they are contacting the drums ?
     
  7. a.y1320
    Joined: Feb 3, 2008
    Posts: 117

    a.y1320
    Member

    I did adjust the rear shoes and yes the prop valve is on the rear line. I don't have a return spring on the pedal. I've never used one before. Do you think the rpv's are backwards?
     
  8. brigrat
    Joined: Nov 9, 2007
    Posts: 5,381

    brigrat
    Member
    from Wa.St.

    You have to have a spring period. Again, Yes the RPV's are correct..................
     
  9. a.y1320
    Joined: Feb 3, 2008
    Posts: 117

    a.y1320
    Member

    I appreciate the help guys. This is really annoying, I will add the spring for sure.
     
  10. Billet
    Joined: Oct 13, 2008
    Posts: 275

    Billet
    Member

    Is the male side of the rpv towards the master cylinder?
     
  11. brigrat
    Joined: Nov 9, 2007
    Posts: 5,381

    brigrat
    Member
    from Wa.St.

    The spring will only stop the fronts from locking up and may or may not help the rear........... I'll bet that if you jack the rear up, put in drive, press hard on the pedal the rear tires will still be spinning.
     
  12. dontlifttoshift
    Joined: Sep 17, 2005
    Posts: 652

    dontlifttoshift
    Member

    If you have no freeplay between the pushrod and piston in the master you will never get the brakes bled properly. You need freeplay first, then bleed again.
     

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