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  • #16
    Lee, you said you are trying to make a prepared set up with 1.62 pistons F / 1.12 Pistons R.

    That set up has a little less that 48% front bias. Why would you choose this, meanwhile you can add more piston to the rear and use the brake bias valve to adjust the F/R balance? Wouldn't a 1.25 piston be more appropriate 59.8% R bias that will become more 50/50 when you put larger discs in the front?

    The best 50/50 set up I have found is 1.75F/1.25R with a 51% rear bias.

    Pads front to rear can be used to adjust bite and F/R lock up but when you are designing a kit wouldn't you rather use the Disc leverage to offset the piston area differences?

    A lighter smaller rotor in the rear will make the car quicker.
    Matt
    -Matt

    For Aftermarket Engine Management, Visit Electromotive Store:
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    • #17
      50/50 is a nice number that only applies to weight distribution. When a car brakes, there's a lot of weight transfer to the front axle/wheels. Especially when the car is softly suspended. So, the front wheels need more braking force than rear wheels. Don't forget that the piston sizes I mentionned where for a car with OEM fix brake valve.


      [email protected]

      1969 2002 racecar
      1989 M3 racecar
      e39 Touring

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      • #18
        I think I can answer my own question...

        Since a car needs a lot more Front brake versus rear, 48% is still fine.

        Ironhead, you have 46% R bias, where did you end up setting your bias valve?

        Matt
        -Matt

        For Aftermarket Engine Management, Visit Electromotive Store:
        http://www.electromotivestore.com

        Own a shop and need a better website?
        PM me or Visit http://www.shop-websites.com

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        • #19
          Not sure I entirely understand some of what you are saying......

          Are you saying that with equal line pressure, my rear brakes are doing 46% as much braking as the rears? That sounds about right....

          As far as the prop valve, it is the "knob" kind so it is hard to say where it is adjusted. For most conditions, it is adjusted so that when the front wheels begin to lock, the rear system has roughly 55% the line pressure the fronts have...

          This is hard to explain though. The way the prop valve works, it does not begin to reduce rear pressure until the braking effort increases. During light pressure on the pedal, the valve keeps pressure even front and rear....

          If I step HARD on the pedal (car not moving), harder than would lock the brakes if the car was moving, the prop valve reduces rear line pressure to less than half what the front system has.....

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          • #20
            Guys,,, I know this may start alot of sh*t but I have both kinds.
            I have AP on my BTCC car, and Wilwood on my silver race car.
            I have seen NO discernable difference in ANYTHING between the two other than A) cost,,, and B) Pad availablility.
            The Wilwood Superlite is the 100% most common pad in all of motorsports.
            EVERYONE makes pads for it,,, and its most likely the absolute cheapest pad they sell,,, simply because its the most common.
            So having an E30 M3,,, the absolutely least common car one can imagine,,, you finally get the "most" common pad shape in all of racing brake pads.

            My pad & rotor costs dropped so much when I built my Wilwood setup that relative to staying with stock brakes,,, it will 100% recoupe in under 5 years.

            I know AP is sexy,,, Alcon is sexier yet,,, but with the new crop of Wilwood calipers (not 10 years ago Dynalites that everyone bases their reputation on),,, is excellent and I'd put them up against pretty much anything up to almost double their cost.

            I now use EVERYTHING from Wilwood,,, the calipers, rotors, pads, fluid.
            No problems, no issues, no compromises. I have not looked back ever.

            Just my humble opinion.
            Cheers
            jimmy
            jimmy p.
            87 E30 M3 Prodrive British Touring Car
            88 E30 M3 Zinnoberot - Street
            88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
            92 E30 M Technic Cabrio - S14 POWERED!
            98 318Ti M44, Base - Morea Green
            04 Ford F350 - V10

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            • #21
              Jimmy's excellent work.
              SL6R clampers and GT 11.75" x 1.25" (300mm x 32mm) rotors.



              [email protected]

              1969 2002 racecar
              1989 M3 racecar
              e39 Touring

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              • #22
                Ironhead, I was asking about where your bias valve is adjusted to.

                You answered my question.

                THANK YOU EVERYONE!

                P.S. Lee: Your kits look great, I have to build my own kit to get engineering credit for school though.
                Last edited by Matts M3; 12-28-2007, 11:16 PM.
                -Matt

                For Aftermarket Engine Management, Visit Electromotive Store:
                http://www.electromotivestore.com

                Own a shop and need a better website?
                PM me or Visit http://www.shop-websites.com

                Comment


                • #23
                  Matt

                  You will have fun designing your own kit.


                  [email protected]

                  1969 2002 racecar
                  1989 M3 racecar
                  e39 Touring

                  Comment

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