Register now to get rid of these ads!

Projects Brake system question

Discussion in 'The Hokey Ass Message Board' started by 1oldtimer, Jul 10, 2016.

  1. Ok, it seems my '54 panel and the '60 Lark need a metering valve (hold off valve) in the front disc system. Both feel as if the front brakes are doing all or most of the stopping. I have a few valves and I have a question. The valve has 3 ports, 1 in and 2 out to each side...... can I cap 1 out and just run it inline like a res valve?. I don't want to remove the stock tee fitting on the Studebaker and to me in theory it should work the same as a tee or inline. On the panel I plumbed the whole system so replacing the tee is no big deal.

    Here's the valve:
    [​IMG]

    and the system the way they recommend it:
    [​IMG]
     
    Last edited: Jul 10, 2016
  2. i thought those valves were to keep both SIDES equal.
     
  3. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,905

    Kerrynzl
    Member

    The simplest metering valve is a pair of vice grips on the front brake hoses .[dont do that]

    Seriously though a brake hold off valve was used to hold off pressure to the rear brakes so the front brakes would go on a split second before. During extreme braking conditions, this valve prevented the car from getting sideways and evened out braking loads
    You need to put smaller piston diameter callipers on the front or larger rear wheel cylinders on the rear if there is too much front brake bias.
    Also on your schematic, why would you add a proportioning valve [a pressure limiying valve] to the rear circuit if there is too much front bias?
     
  4. BobMcD
    Joined: Jan 25, 2013
    Posts: 322

    BobMcD
    Member

    A metering or hold off valve allows the rear drum brakes to be applied slightly before the front discs . This allows time for the rear shoes to take up the clearance between the shoe and drum. Lack of a metering valve can cause the front end of the car to nose dive when the brakes are first applied. If you use a combination or 3 way valve, there is a proportioning valve, metering valve and differential pressure switch all in one.

    Posted using the Full Custom H.A.M.B. App!
     

  5. My car always seemed to have too much front wheel brake bias in a panic stop and my proportioning valve is also in the rear line like all diagrams show. It is set at zero and gets worse when closed. I just figured it was the inherent problem with "bigs and littles", but never knew any different. :confused:

    I always thought I should change the proportioning valve to the front brakes instead, but all the diagrams show it in the rear line. I'm a little confused. :confused:

    Thanks Kerry for that bit of info, I will be watching this post to see how it goes. :)
     
  6. Ok, first McD has it correct....rear brakes come on first (just to over come the return spring and touch the lining to the drum). Second the diagram I posted is from a brake parts places website and it the correct way to install a typical aftermarket (without using factory parts) brake setup. Third the adjustable prop valve goes in the rear line in case the rear drums come on too strong and lock up easy, then you dial it down until there's no lock up. If you setup the brake system properly you will not really need to use it.....but I install them anyways (have yet to use it). The '54 panel truck was bought with the disc kit on it already and the '60 Lark I bought a front disc kit and tandem master kit for it. The Lark used most of it's original plumbing and I want to keep it that way, the panel was re plumbed.

    That's what I'm wondering. Is there any difference between using the hold off part to feed the stock front system or is there something inside that needs to feed BOTH sides to work. I remember reading that there's just a poppet type valve (seat and spring) inside to let pressure by after it hit a certain amount to open the valve. To me that should work with one port blocked in a stock system (master to left front tee, one branch of the tee goes to the left brake hose and the other branch goes to the right side brake hose).
     
    Last edited: Jul 10, 2016
  7. There are cars that run a combo valve that has all the functions inside of it (hold off, prop, light) but those where made for factory cars (that came with disc front brakes). You can still buy a kit with these valves but they're preset for a specific car weight, so you can weed through to try to find a combo valve with the right ratings you need or run the hot rod style adjustable individual pieces.

    This page with give you an idea of what the valves are and their ratings:
    http://www.camaros.org/brakevalve.shtml
     
  8. Here's a factory metering valve with one line in and one line out.

    [​IMG]
     
  9. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 2,693

    1-SHOT
    Member
    from Denton

    image.jpeg CPP has a portional valve that has a brake light switch and a adjustable rear brake all built in. See September issue of Hot Rod page 54 and there is one on a 55 Chevy. First one I have ever seen. Frank
     
  10. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    If there is ANY topic on the HAMB, other than brake systems, that is a greater source of confusion, misinformation, superstition and lack of factual data, I don't know what it is!
    :rolleyes::eek::confused::(o_O

    Ray
     
    Montana1 likes this.
  11. Drive line angles :D
    I wish there were a "my hair is on fire" smiley face
     
    Ned Ludd likes this.
  12. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,791

    tfeverfred
    Member Emeritus

    "What's a traditional Hot Rod?"
    [​IMG]
     
    Kerrynzl and 31Vicky with a hemi like this.
  13. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    ^^^^^^^. By golly, I think you may be right .........certainly a contender for the crown. :p

    Edit: this reply was intended for 31Vicky, but Fred posted as I was composing ......however, he also has a very good answer and graphic! :)

    Ray
     
  14. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 2,693

    1-SHOT
    Member
    from Denton

  15. Ok, please enlighten us.
     
  16. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 2,693

    1-SHOT
    Member
    from Denton

    Enlighten you about what!
     
  17. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Waste of time and effort....first of all, I did not claim any superior knowledge....just observing the state of the discussion. And, my answers wouldn't persuade you or anyone else. So, do your own homework like I did. I am content to apply MY theories to my own vehicles and, so far, have had good results. :)

    Ray
     
  18. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 2,693

    1-SHOT
    Member
    from Denton

    I thought the combination valve covered a multitude of problems,Sorry just trying to help.
     
  19. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I can't speak for anyone else, but for the record, my comment that happened to appear right after your pic of CPP's item was NOT in response to that post. My post was a general comment about all the posts in this thread.

    Ray
     
  20. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 2,693

    1-SHOT
    Member
    from Denton

    Thanks Frank
     
  21. My comment wasn't geared towards your post, sorry if it seemed like it.

    Not really sure if helping someone that is doing their homework out is a waste of time or effort. But posting that it is might be.

    Anyways back to the post. The master is under the floor and there's not much room for a combo unit. Since I have all the stuff inside the combo unit already plumbed in except the metering valve I might try the in line stock one.
     
  22. Oil! :eek::rolleyes::confused:;)
     
  23. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    You are correct, of course. Snarky and unhelpful remark on my part. I apologize for that.

    It seems to me that many HAMB members feel that 'proportioning valves', 'combo valves'/ 'metering valves', etc. are required to be installed in any and all brake upgrades. Of course, that philosophy is supported by the OEM use of some of these devices and the aftermarket guys also promote them. But, several HAMBERs report no improvement with or without all the claptrap. That certainly suggests they were/are useless...at least in many instances.

    The new car manufacturers have legions of engineers and computer capacity galore. They can calculate, simulate and evaluate countless variations in the systems they design and attempt to fine tune them for the best performance over a broad range of conditions and consumer use and abuse.

    For our purposes, as home builders and hobbyists, we are usually building a vehicle for a much narrower set of operating conditions. However, we still have numerous variables to consider when selecting brake components. Vehicle weight, weight distribution, tire diameters and widths, tread design and rubber compounds, master cylinder bore, caliper and/or wheel cylinder bore, disc or drum diameter, brake shoe and/or pad surface area......just to name some.

    Then there are known typical vehicle braking dynamics. Weight transfer under hard braking, directional stability if wheels lock up, etc. I have read that the front brakes do as much as 70% of the work under hard braking, for example.

    But when you sift through all this maze of variables, it looks to me like we can reduce the considerations to a handful. We know how we want the vehicle to 'look'. i.e., big and little tires, or more equal in size, we should have some idea about it's projected weight, and so on.

    Choosing brake components that take our specific vehicle characteristics in to account, matching the front and rear brake types and sizes, and MC bore size chosen accordingly, should make it possible to assemble a system that does not need auxiliary devices in order to function effectively.

    In my opinion (and experience) the system could/should be assembled without anything more than residual pressure valves (if needed, depending on MC height) and tested. If there is an unacceptable brake bias (lockup), I would look to changing the wheel cylinder size, or brake diameter, to address that before I would try a proportioning valve. Similarly, if pedal pressure is too high for normal braking comfort, altering MC bore size, or wheel cylinder/caliper bore size would permit 'dialing it in'.

    Ray
     
    Last edited: Jul 10, 2016
    Crazy Steve, trollst and Montana1 like this.
  24. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,905

    Kerrynzl
    Member

    Here's some postings I made on another thread [minus the internet shitfight :)]

    Most OEM cars are calculated so that all 4 wheels share the correct proportion in everyday driving and moderate stopping in less than ideal conditions.
    The proportioning valve is then added to restrict rear brake lock-up during "Oh-fuck" moments where the drivers foot tries to press a new shape into the firewall.

    There is a lot of math involved......... Front & Rear weight bias, Wheelbase, CGH, Wheel rolling radius, Disc or drum radius, Master Cylinder diameter, Pedal Ratio, Pad or Shoe Co-efficent of friction, then finally Front and Rear Cylinder/Piston Area
    I've yet to meet a parts salesman ask any of the above questions, yet they seem to "know" what's best for your application [which they happen to be selling]

    On the race track we use more front bias in ideal conditions and more rear bias in slippery conditions [ where the front wheels will lock up long before the rears even think about helping ]

    So road cars have more rear brake bias than race cars, or you'll end up with front wheel lock-up when you try to pull up at a stop sign in the wet



    ---------------------------------------------------------------------------------------------------------------------------------------------





    The only true proportioning is done with fluid mechanics to alter the clamping pressure, or with a mechanical bias system like a "pedal box" to alter fluid pressure

    From the master cylinder all line pressure in that circuit is equalized.
    So if you brake gently , the line pressure is the same throughout the system [unless it has staggered /or dual master cylinders]
    It is at the wheel cylinders/ calliper pistons where all the clamping pressure is biased.

    With a "proportioning valve" once a pre-set pressure is exceeded a piston slides across [against a spring] and stops further increases in pressure on the rear circuit.
    Any further increases in pressure operate on the front circuit.

    Below that pre-set pressure they don't proportion at all

    Adjustable proportioning valves only adjust the spring seat pressure of the valving.
     
  25. Rice n Beans Garage
    Joined: Dec 17, 2006
    Posts: 1,658

    Rice n Beans Garage
    Member

    Try this guy, hes a wealth of info: http://www.ecihotrodbrakes.com/
     
  26. I completely agree about all the considerations and calculations that need to go into making your own braking system. I was hoping that some of that was done when putting together the system I purchased (so I wouldn't have to do it myself :)). After reading here and multiple sites, I know now that I was wrong about what metering valve is for. I also agree with the systems get over complicated with unnecessary valving, my only excuse is that the adjustable prop valve is easy to put in "just in case" and if not used (knob back out) does not harm to the system. On the Studebaker the new master and rear wheel cylinders match the stock bore sizes, so the only unknown factor is the caliper size (and rotor size). I'm now thinking of trying a larger bore size rear wheel cylinders. The caliper brackets are made for those specific calipers, which are a little odd application wise (mid 90's S10 4x4).

    Again thanks for all the help.
     
  27. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,905

    Kerrynzl
    Member

    If in doubt use the Racer's "applied research and development approach" [translated: Let's try it and see :D]
    Seriously though , there is some merit to this.
    Sometimes you cannot balance the front and rear brake bias combo, so what racers do is have twin "girling" style master cylinders with a balance bar on the pedal.
    With 2 circuits you can use a smaller rear M/C for more rear brake bias ,then fine tune it with the balance bar.

    You can buy a balance bar from wilwood and make your own. or a whole pedal box
     

  28. Kerry, I have the typical 11" GM discs on the front and 11" drums on the rear with a mid 70's Ford PU non-power master cyl. for disc/drum brakes. So, do I need to take the aftermarket adjustable proportional valve out of the rear line and put a metering valve in the front brake line like the OP shows in this diagram to lessen the front brake bias? :confused:o_O

    I think this is what this post is all about, right?

    [​IMG]
     
  29. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Pickup trucks can be a category by themselves due to widely varying weight and weight distribution. In at least one model I am a little familiar with, an OT late '90s Toyota, it had a variable brake proportioning valve mounted at the rear, with a lever on it, linked to the rear axle with a round rod. At unloaded ride height the valve lever was in one position. As weight was added to the bed, the reduced ride height moved the lever on the valve, presumable changing the brake bias in the process.

    Ray
     
  30. Interesting! I wonder how it worked in a panic situation with front end dive, wet pavement or rough terrain? :eek: This gets more complicated and confusing all the time! :confused:

    I'm just trying to figure out a simple way to adjust for front brake bias with bigs and littles.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.