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Brake issues. How do i bleed a metering valve??

Discussion in 'The Hokey Ass Message Board' started by tankwilson, Apr 11, 2010.

  1. tankwilson
    Joined: Oct 12, 2004
    Posts: 1,148

    tankwilson
    Member

    Hey guys. Just put a dual master cylinder and front disc brake kit on my 49 plymouth. Ran all new lines.. installed a 2 psi valve in the front and my new MC came with a 10 psi valve built in. Bought the MC kit from ECI and they also sold me a hold-off/metering valve for the front. Installed it on my front cross member and ran a line off to each front. Bleed the brake lines last weekend. Everything went well. Drove the car home from the buddies shop today and it doesn't seem to stop as well as i had hoped. The brake pedal feels great just doesn't stop that fast.

    Did I have my metering valve setup right? Is is upside down? Do i need to push the button when manually bleeding? It almost seems like the fronts aren't kicking in as hard as they should. Here is a pic below of the metering valve and the link below that is my tech article on a plymouth site.

    Thanks
    matt

    [​IMG]



    http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=18541
     
  2. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    Where is your MC? Is it above, at or below the front calipers level? A 2# residual valve is only used on the front disc to prevent siphoning fluid from the caliper(s) back to the MC when the MC is below the caliper level.

    Is this the metering valve?

    EC-526

    [​IMG]

    When you depress the MC, the pin in the metering valve should move (either in or out). To easily bleed the front system, you would manually actuate the valve the same way while bleeding.

    This is a DISC/DRUM MC (only rear port has 10# residual valve)?
     
  3. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,589

    V8 Bob
    ALLIANCE MEMBER

    The purpose of the hold off or metering valve is to "hold off" front pressure until system pressure reaches about 100 psi, so the brakes might not feel real good during low pressure stops. I wish these brake companies would stop pushing the sale of metering valves, as they really don't belong on custom brake systems, IMO. I would remove it, but that's your call.
    To bleed a system with a metering valve, you have to push the button in to bypass the hold off feature while bleeding.
    Normally these valves lay horizontal, so I doubt orientation has any effect on operation.
    Bob
     
  4. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member



    Source- http://rpmautodover.com/mccv3.htm

    I for one wish the brake companies would educate people more in the theory, operation and need for valving. There are a few sites that valving description is incorrect.
     
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  5. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,589

    V8 Bob
    ALLIANCE MEMBER

    KULTULZ,
    Your information is not correct. Metering valves are/were NOT required nor found on all disc/drum systems, but were installed either alone or part of combo valves on SOME vehicles, and were the result of hours/days/weeks of dynamic brake testing on particular vehicle platforms, not just blanket theory. They can produce/result in more aggressive rear braking, something you do not always want. One simple rule-the axle that slides LEADS! Having the rears act like a rudder is pure BS. That's not what happens. You always want the fronts to slide before the rears-ALWAYS.

    The use of factory style combo or independent fixed prop/metering valves on custom brake systems is a crap shoot at best, because they were all designed for particular vehicle weights, wheel bases, weight transfers, tire sizes/designs, etc etc etc.

    The best thing to use is a simple adjustable prop valve on a custom disc/drum or disc/disc system, along with 10 lb residuals to drums, and 2 lb valves to discs ONLY when the master is lower than the calipers. IMO
    Bob
     
  6. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    Please give me an example. Now I admit that I am more familiar with FOMOCO, but please give me an example of OEM disc/drum systems without a metering valve and/or a proportioning valve.
     
  7. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,589

    V8 Bob
    ALLIANCE MEMBER

    Metering valves were popular in the late 60's/early 70's, went away, then came back on a few cars because of "pedal feel" until 4-wheel ABS became the norm in the 90's, which made prop and metering valves obsolete. There were many cars I worked on over the years that did not have metering, Fords included, but can't remember all. I do know my '85 and '88 T-Birds did not have them. as well as my '88 Ranger. Just go out to a bone yard, pop some hoods, and see for yourself.
    I'll say it again-you don't want to install things in a custom brake system that complicates and/or could cause problems. KISS, and use only an adjustable prop valve along with necessary residuals. IMO.
    Bob
     
  8. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    Go pop a hood. Expected answer.

    FYI- The cars you gave as examples do have valves.

    Before offering advice on something as safety related as brakes, (especially modifications), it is important to be well informed on the subject.
     
  9. chop32
    Joined: Oct 13, 2002
    Posts: 1,077

    chop32
    Member

    Just to make this interesting...
    Some disc/drum '68 Camaros have a factory "hold off" valve in the rear brake line only. The research I have done (on Camaros) indicates that they were only installed on Big Block cars and some cars with A/C due to the extra weight on the front end.
    It seems to me that their reasoning was to keep the rear wheels from locking up first when the weight bias shifts to the front end during hard braking?
    Not trying to get in on the arguement, just presenting another way that the factory once used these valves.
     
  10. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    Good point. Also on vehicles such as an SUV, this same type of valve (measures vehicle trim height) will also vary rear brake pressure so as not to lead to a rear wheel skid condition when there is light/or no load.
     
  11. mikeco
    Joined: Nov 3, 2008
    Posts: 393

    mikeco
    Member
    from virginia

    Perhaps you should check out Bobs info he knows what he's talking about!!
     
  12. TERPU
    Joined: Jan 2, 2004
    Posts: 2,209

    TERPU
    Member

    Just be sure you have the front chamber going to the right half of the car. Without seeing how the master is oriented I can't see if you have the lines crossed. I have put in a few dual chambers in my cars and I once got the lines backwards and it had a pedal feel much like what you describe. As for the metering block lose it, you don't need it. Residual valves are good, but a metering block is not needed on a common drum/drum or disc/drum deal with their respective master cylinders. The Master cylinder will take care of that most of the time. I always use this guideline now- the chamber closest to the pedal goes to the front because it gets the pressure first, the one farthest away from the pedal goes to the rear.


    Good luck,
    Tim
     
  13. ECIGUY
    Joined: Feb 24, 2009
    Posts: 111

    ECIGUY
    Member

    You do not have to hold the button in on a metering valve, only on some combination valves. Leave everything just as it is. Take the car someplace where you can play around without pissing off the natives, take it to 35-40 mph and bring it to a normal stop. Repeat a couple of dozen times and the brakes will get better. Will also get better with driving time. We supply the medium grade semi-metallics so they do take some break-in time and a little more leg than the el-cheapo's.
    You didn't say anything about what was done to the rear brakes, but if you rebuilt them chances are pretty good that the shoes don't fit the drums real well, most of the friction material that comes into the country doesn't. Draw some lines the length of the shoes with a magic marker, drive it a while and check the lines. May have to hand sand the shoes a touch to get them to fit better. If they are close driving it will wear them in.
     
  14. tankwilson
    Joined: Oct 12, 2004
    Posts: 1,148

    tankwilson
    Member

    Thanks guys but i think i am more confused than i was before. Can i push the pin in and run it that way to see if that will make the fronts kick in sooner??

    thanks
     
  15. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    He may know what he is talking about but he is not too accurate when it comes to brake theory.
     
  16. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    :eek:

    WHAT???

    What is the difference between a free standing metering valave or one found in a combination valve? You move the pin manually while bleeding to allow it to open freely while bleeding. A pressure bleed does not require it to be manually opened.


    I for one wish the brake companies would educate people more in the theory, operation and need for valving. There are a few sites that valving description is incorrect.

    NOTE: It seems these aftermarket brake companies do not have the technical materials to give information to customers.
     

    Attached Files:

  17. KULTULZ
    Joined: Apr 10, 2007
    Posts: 328

    KULTULZ
    Member

    Do not worry about the pin. Are you absolutely positive that the fronts have been bled properly and the calipers have no pocket of air (this may having to pivot the calipers on the mounts so that the bleeders are pointing straight up)?

    Brake pedal feel and height (on a disc/drum installation) is determined by the rear brakes. They have been adjusted properly? As mentioned, does the shoes pad arch match the arch of the drum? If new, they may take a few miles to seat properly. Did you perform several medium to hard stops to seat the front pads?

    And what is with the 2# residual valve (I guess) on the front circuit? Where is your master cylinder located?
     

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