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    Thread: Brake proportioning valve adjustment on lowered mk3 GTI?

    1. Member GTI Jay's Avatar
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      04-19-2012 01:52 AM #1
      Ok so I just recently lowered my 95 gti vr6 on neuspeed springs and changed out the proportioning valve at the same time because it was leaking badly for a while before this. So now my question is where should the lever on the proportioning valve be set to? I flushed and bled the brakes at all 4 wheels so there is absOlutly no air in the lines but I am still having a hard time locking up the wheels and if I do get them to lock up it's always the rear first. Can someone tell me which way the valve functions? In a front/rear bias whether the lever is up/down? thank you

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      04-19-2012 05:58 PM #2
      Quote Originally Posted by GTI Jay View Post
      Ok so I just recently lowered my 95 gti vr6 on neuspeed springs and changed out the proportioning valve at the same time because it was leaking badly for a while before this. So now my question is where should the lever on the proportioning valve be set to? I flushed and bled the brakes at all 4 wheels so there is absOlutly no air in the lines but I am still having a hard time locking up the wheels and if I do get them to lock up it's always the rear first. Can someone tell me which way the valve functions? In a front/rear bias whether the lever is up/down? thank you
      Adjustment bolt down in the slot, and you get less pressure at the same ride height.

      Adjustment bolt up in the slot, and you get more pressue at the same ride height.

      The type and the condition of the tires, the pavement, the brake rotors, and the brake pads will also affect when the brakes will lock up and which end of the car locks the brakes first.

      Maybe you need to replace the front brake pads with a more aggressive compound.

    3. Member GTI Jay's Avatar
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      04-20-2012 01:47 AM #3
      Thank you. So with the bolt up I'll get more pressure to the front? Or rear? And Then obviously it's the opposite way for the other direction. But currently I have hawk hps and Zimmerman cross drilled rotors on the front and in the rear I have standard rotors with autozone ceramic pads at the moment. Both installed the same time in August last summer so still pretty new. I've been thinking about upgrading both pads out for more aggressive but Im not sure where to go for more aggressive pads. Or just to go with hawk hpp.

      Quote Originally Posted by germancarnut51 View Post
      Adjustment bolt down in the slot, and you get less pressure at the same ride height.

      Adjustment bolt up in the slot, and you get more pressue at the same ride height.

      The type and the condition of the tires, the pavement, the brake rotors, and the brake pads will also affect when the brakes will lock up and which end of the car locks the brakes first.

      Maybe you need to replace the front brake pads with a more aggressive compound.

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      04-20-2012 01:58 AM #4
      Quote Originally Posted by GTI Jay View Post
      Thank you. So with the bolt up I'll get more pressure to the front? Or rear? And Then obviously it's the opposite way for the other direction. But currently I have hawk hps and Zimmerman cross drilled rotors on the front and in the rear I have standard rotors with autozone ceramic pads at the moment. Both installed the same time in August last summer so still pretty new. I've been thinking about upgrading both pads out for more aggressive but Im not sure where to go for more aggressive pads. Or just to go with hawk hpp.
      NO, at the back.

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      04-20-2012 01:59 AM #5
      Quote Originally Posted by GTI Jay View Post
      Thank you. So with the bolt up I'll get more pressure to the front? Or rear? And Then obviously it's the opposite way for the other direction. But currently I have hawk hps and Zimmerman cross drilled rotors on the front and in the rear I have standard rotors with autozone ceramic pads at the moment. Both installed the same time in August last summer so still pretty new. I've been thinking about upgrading both pads out for more aggressive but Im not sure where to go for more aggressive pads. Or just to go with hawk hpp.
      NO, at the back.

      No wonder the rear locks up first.

      You have street pads in the rear and sport pads in the front.

    6. Member OddJobb's Avatar
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      04-20-2012 06:58 PM #6
      Quote Originally Posted by GTI Jay View Post
      Thank you. So with the bolt up I'll get more pressure to the front? Or rear?
      The proportioning valve in no way affects the front brake pressure. It simply varies the amount of pressure to the rear brakes under hard braking.
      Quote Originally Posted by LG6R View Post
      I never understood this and don't take it personally because people come on here and say that all the time. But if you don't know what it is or what it does, why don't you leave it the hell alone?

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      04-21-2012 12:44 PM #7
      Quote Originally Posted by OddJobb View Post
      The proportioning valve in no way affects the front brake pressure. It simply varies the amount of pressure to the rear brakes under hard braking.
      Not exactly true.

      By limiting pressure to the rear brakes, more fluid/pressure is available for the front brakes at the same travel/pressure on the brake pedal.

    8. Member GTI Jay's Avatar
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      04-29-2012 05:20 AM #8
      Hm ok it's making sense now. I went out the other day and played with the adjustments on the lever and tried heavy braking with the lever both all the way up and all the way down and in between. And so far I'm pretty happy with it about 30% from the "up" position with my lowering springs. I'm going to go back out when it rains and see what it does on a wet surface but on dry pavement it seems like the front locks up first. Thank you guys for clarifying this for me.

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