Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Anyone runing an adjustable Proportioning Valve? How do you like it?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 8_YOUR_H2, Dec 18, 2001.

  1. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

    Joined:
    Feb 20, 2000
    Posts:
    2,663
    Likes Received:
    0
    Location:
    Iowa
    I am getting ready to do the discs on my 14FF and I am thinking about upgrading to the adjustable valve. Does it go where the old one is? It dont look like it will bolt up. Any opinions? Any tips? Pro's or Con's?
    Thanks
    Brent
     
  2. pcorssmit

    pcorssmit 1/2 ton status

    Joined:
    Jan 2, 2001
    Posts:
    1,346
    Likes Received:
    0
    Location:
    Denver, CO
    I run one, its in the stock location but I had to find fittings to make it work. I plumbed the rear line in and out of it, and put a T on the front line (front line from master cyl, to T, then lines to front brakes).

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  3. michaelm

    michaelm 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    872
    Likes Received:
    0
    so you are running with no combination valve
    that can be deadly
    do a simple test,
    undo a fitting on either the front or rear system and see if you are able to apply enough brake pressure to stop your truck
    what that tests is if both primary and secondary systems in your master cylinder can be bottomed out by pedal linkage alone.
    many MCs require hydraulic pressure between the pistons to function.
    that is one of the functions of the shuttle portion of the COMBINATION VALVE
    is shuts off the system with the leak so the master will still function
     
  4. pcorssmit

    pcorssmit 1/2 ton status

    Joined:
    Jan 2, 2001
    Posts:
    1,346
    Likes Received:
    0
    Location:
    Denver, CO
    I broke a rear brake line on the last wheeling trip. Front brakes still work. Rear brake reservior in master bone dry. Pedal sucked, but it did stop good enough (on the street as well, of course I have since fixed it). I used to have a Firebird that lost the fluid in the front lines. The rear drums still worked good enough to lock the tires (not that its that hard with no front brakes). Not saying you are wrong (technically, you're prolly right), just in my experience the OE valve's are over rated.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  5. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,088
    Likes Received:
    488
    Location:
    Grand Rapids area
    The proper way to do it is to leave the combo valve in there and add an adjustable valve. The adjustable valve on reduces pressure, of course, and there's a chance that it is not even quite enough for the rear discs to begin with. This depends on the size of your rear caliper pistons and other issues with the vehicle. If the rear pressure is too high, just plumb in the adjustable valve and you are good to go. If the pressure is to low, you will have to get a different combo valve (from a 4W disc brake vehicle) or modify your existing combo valve. I have a theory that the proportioning valve can be removed from the stock combo valve, but I haven't been able to prove it either way yet.

    <font color=green>Today's Forecast: Partly cloudy with a chance of mud</font color=green>
     
  6. Triaged

    Triaged 1/2 ton status

    Joined:
    Feb 21, 2001
    Posts:
    3,808
    Likes Received:
    0
    Location:
    CA (LA/OC area)
    I want to hear about it when you take the prop valve out of the stock combo valve. I will be going to 4 wheel disc soon and it would be cheeper and easer to keep the stock combo valve.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
    <a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>
     
  7. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

    Joined:
    Feb 20, 2000
    Posts:
    2,663
    Likes Received:
    0
    Location:
    Iowa
    So the proportioning valve is only for the rear brakes?
     
  8. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,088
    Likes Received:
    488
    Location:
    Grand Rapids area
    The proportioning valve regulates the pressue to the rear brakes, based on the pressure going to the front brakes. This is to give you the proper front to rear brake bias. The front brakes pretty much see all of the pressure from that side of the master cylinder.

    <font color=green>Today's Forecast: Partly cloudy with a chance of mud</font color=green>
     

Share This Page