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Brake proportioning valve...

Discussion in 'GM 6.5 Diesel Engines' started by steelydan, Sep 23, 2009.

  1. steelydan

    steelydan New Member

    161
    1
    May 29, 2008
    Mission B.C.
    1999 Suburban k2500. Does it have a load sensing proportioning valve? I have 1300lbs or so of ironer parts in the back and the brakes work much better. I know on my toyota I used to bend the linkage to give the back brakes a little more grab. I don't remember seeing a load sensing valve on these trucks.
     
  2. bk95td

    bk95td 6.5 nut job/addict

    2,548
    3
    Nov 26, 2008
    I don't think gm used those since the 80's. ABS controls how much brakes the rear gets.
     
  3. Missy Good Wench

    Missy Good Wench Wild Blonde from Cloud Mt

    1,678
    30
    Nov 19, 2008
    Newberg Oregon
    These trucks use a combination valve to control rear brakes and to set the light on the dash should pressure be lost.

    The springing or valving on some of these has issues and they stop putting enough pressure to the rear brakes.

    My 94 has the same issue but its still OK.

    If its a problem, change the Combination valve and bleed the system out.

    MGW
     
  4. Matt Bachand

    Matt Bachand Depends on the 6.5

    5,330
    4
    Jun 10, 2008
    Worcester, MA
    Probably stopping better because the rear's are actually working with weight. Your pedal will travel more as the fronts alone can't stop it before the rear's kick in.

    I have seen over-sized wheel cylinders, but have never heard from anyone who tried them.

    I saw those oversized wheel cylinders when looking at the rear disc conversion companies websites. Turbine Doc's company specifically. Give em a shot, they weren't much cake.

    Are they well adjusted? Either jack it up and adjust them, or go into a parking lot and roll backwards fairly quick, and snap the brake pedal hard about 10 times and see if its better pedal.

    Never liked drums..... audo adjust? yeah right.
     
  5. mmcna

    mmcna Recruit

    88
    0
    May 6, 2008
    land of lincoln
  6. guybb3

    guybb3 Member

    695
    1
    May 29, 2008
    Tewksbury Mass.
    You never asked me, Matt.:nono:
     
  7. mmcna

    mmcna Recruit

    88
    0
    May 6, 2008
    land of lincoln
    So do larger cylinders help?
     
  8. ghitch75

    ghitch75 livin' in the sticks

    405
    0
    May 28, 2008
    Indiana B.F.E.

    great info!!!!!......burb goin' to get a brake redo.....i have EBC vented rotors and EBC ULTIMAX pads...they will stay just new pads....all the rest will go....then the thing might stop!!!!:mad2::mad2::mad2:
     
  9. docdray

    docdray Oompa Loompa

    349
    0
    May 30, 2008
    Cleburne, Texas
    my 94 is finally beyond not repairing. have continued to readjust rears over last year, but now the fronts start to cook with load. using parking brake in emergencies, guess I gotta do something this weekend.
     
  10. Matt Bachand

    Matt Bachand Depends on the 6.5

    5,330
    4
    Jun 10, 2008
    Worcester, MA
    Good info to add to this thread!

    Any more breaking power? Any pedal change? Can you make the rears lockup easier? (easiest to tell the hard way in the snow!)
     
  11. guybb3

    guybb3 Member

    695
    1
    May 29, 2008
    Tewksbury Mass.

    Absolutely added more power to the rears. iirc I only went 1/16 of an inch bigger. Stock is 1". Need to keep the rears adjusted as you get more pedal travel if they aren't kept well adjusted. I'll look tonight to make sure of the size. I bought them from EBC brakes. When the drums are not servicable or I get more money, I'm going to rear disc. TSM is the kit I'm looking at.
     
  12. Matt Bachand

    Matt Bachand Depends on the 6.5

    5,330
    4
    Jun 10, 2008
    Worcester, MA
    Rear disc is a win/win. Not only way better stopping power, but less weight (especially on duallies!) and will actually feel more power as well as braking.

    Subtract the cost of the new drums/shoes to the conversion price, and its the way to go.

    I'm renovating my brakes next year I think. My rotors wear pattern is getting smaller and smaller, although they could probably be turned, I'd rather replace with some high performance vented rotor or something.

    You using those? :)

    With a DRW changing rotors is a nasty job with those extension hubs. I may time it with my P.S. Hub if it holds out till next year, as it needs to come apart anyhow.

    FWIW I have had absolutely excellent luck with Cermanic pads.

    I think I'll do them oversized wheel cylinders also.
     
  13. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    6,616
    294
    May 9, 2008
    ZEPHYRHILLS FL
    I just put this valve in FRANKENBURBAN yesterday as the added weight in the front end was causing a bad nose dive on braking. Also when the nose went down it would lift the rear up and the rear tires would begin to hop around and it would go either direction it wanted to. The valve made a definate improvement in braking that is noticeable.
     
  14. ghitch75

    ghitch75 livin' in the sticks

    405
    0
    May 28, 2008
    Indiana B.F.E.
    draggin' up an old ghost......just gettin' around to doin' my brakes....where in the world is the Brake proportioning valve?.....i can't find it?...on my burb btw...
     
  15. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    6,616
    294
    May 9, 2008
    ZEPHYRHILLS FL
    It mounts into the end of the ABS module.
     
  16. Joey D

    Joey D Member

    520
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    Nov 25, 2008
    I think the disc brakes will be the best thing you can do to these trucks.
    My truck stops like a corvette, well almost:D. My next thing is lose the abs controller all together and install and adjustable prop valve for the rear.
     
  17. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    6,616
    294
    May 9, 2008
    ZEPHYRHILLS FL
    I've still got the factory brakes with the ABS still functioning, and couldn't be happier. Stainless braided brake lines made a HUGE difference, along with ceramic front pads and the upgraded proportioning valve I can throw people into the windshield even towing a trailer.
     
  18. Matt Bachand

    Matt Bachand Depends on the 6.5

    5,330
    4
    Jun 10, 2008
    Worcester, MA
    Are you suggesting the old rubber has more flex to it and takes away from the front power?
     
  19. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    6,616
    294
    May 9, 2008
    ZEPHYRHILLS FL
    It made a big difference in my BURB. I know before I could bottom the pedal out when braking, now it will warp the rotors from being able to clamp down on em so tightly.
     
  20. Matt Bachand

    Matt Bachand Depends on the 6.5

    5,330
    4
    Jun 10, 2008
    Worcester, MA
    My ACDELCO front rotors are originals. 140k on them. I've put over 20,000 on a set of Ceramic pads and they still have beef on them.

    They look like shit, but smooth as glass. They are down to probably 60%-70% useable surface. They need to be turned, but such a ferminator to take off the hubs/dually adapter crap.
     

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