Brake System Design Overall Strategy


    This section is meant to be a last chapter, expanding upon what was discussed in the Brake System Design Theory chapter and the Brake System Design Component Choice chapter.

    This is a discussion recapping the primary concepts of how to increase braking force, and highlighting the magnitude of braking force increase that will be needed to match contemporary and modern vehicles.

    Expanding upon the most important things we learned in the previous discussion of Brake System Design Theory and Brake System Design Component Choice:

    Remember the lessons from the discussion on Brake System Design Theory:

      There Are Three Ways To Increase Braking Force:
      • Increase brake caliper piston area.
      • Increase rotor diameter.
      • Increase break pad friction coefficient.

      And

      Brake Bias Must Always Be Considered.
        The brake system must be balanced and built to provide the appropriate amount of braking force to the rear brakes to match the braking force of the front brakes. Whatever percentage change is made to the front brakes must also be made to the rear brakes (and vice versa) to maintain balance. If the braking force is doubled on the front, it must also be doubled on the back.


    Making significant increases in the braking force is going to require a combination of increasing caliper piston area, increasing rotor diameter, and increasing pad friction coefficient, and matching the braking force on the front and the rear of the vehicle.

    Find a caliper with a pad of equal or larger size to the OEM equipment, which also provides an available range of piston areas.

    Considering the size of the caliper and the clearance requirements inside the wheel, find the largest diameter rotor that will fit within the available space.

    Calculate out the braking force across a range of available caliper piston sizes (piston area) and available brake pad coefficients. Keep in mind the physical limitations of the brake master cylinder and if the vehicle is going to be street driven, the practical limitations of a pad that is usable for street use (noise, heat range, dust).

    Adjust the sizes and specifications within the range of available component specs so that the front braking force and rear braking force are matched with relation to the stock or desired brake bias ratio. With a nose heavy FWD car, the required rear brake force is much lower than the required front brake force. Don’t be surprised if the rear brakes look anemic compared to what has to be jammed into the inside of the front wheels.

    Keep in mind that any braking system will need to be fine tuned in order to maximized performance for different tires, pavement conditions, weather, and intended use of the vehicle. An assortment of brake pads for the front and back of the vehicle, and a proportioning valve (or two proportioning valves for a four channel system) can be used to fine tune the braking action at the track.


    Comparing Braking Force of Vehicles
      Remember the braking force calculated for the Geo Storm on the TCE Performance Brake Calculator:
        Baseline Numbers, Impulse XS / Stylus XS
          Front: 2530 In.Lb.
          Rear: 1065 In.Lb.


      The following is a sample of the braking force of several vehicles as calculated on the TCE Performance Brake Calculator (assuming .30 coefficient pads).

      High Performance Vehicles
        2003-2014 Mitsubishi Lancer Evo with Factory Option Brembo Brakes
          Front: 6806 In.Lb.
          Rear: 1900 In.Lb.
        2004-2014 Subaru Impreza STi with Factory Option Brembo Brakes
          Front: 6239 In.Lb.
          Rear: 1815 In.Lb.
        2003-2009 Nissan 350Z with Factory Option Brembo Brakes
          Front: 6079 In.Lb.
          Rear: 2134 In.Lb.
        2010-2014 Hyundai Genesis Coupe R-Spec with Factory Option Brembo Brakes
          Front: 4783 In.Lb.
          Rear: 1370 In.Lb.

      More Current Small Cars
        2007-2014 Mini Cooper with Factory Brakes
          Front: 3109 In.Lb.
          Rear: 1393 In.Lb.
        2007-2014 Mini Cooper S with Factory Brakes
          Front: 3323 In.Lb.
          Rear: 1393 In.Lb.
        2007-2014 Mini Cooper John Cooper Works with Factory Brakes (four piston front calipers)
          Front: 3585 In.Lb.
          Rear: 1520 In.Lb.
        2012-2014 Fiat 500 Abarth Turbo (Single Piston Front Calipers)
          Front: 3262 In.Lb.
          Rear: 1080 In.Lb.
        2009-2013 Honda Fit with Factory Brakes
          Front: 2942 In.Lb.
          Rear: (Drum Brakes)

      Historic Market Segment Rivals and Related Vehicles
        1994-2001 Acura Integra Type R with Factory Brakes
          Front: 2511 In.Lb.
          Rear: 683 In.Lb.
        1994-2001 Acura Integra Type R with Spoon Big Brake Kit (4 piston caliper and 300mm rotor)
          Front: 2674 In.Lb.
        1991-1994 Nissan Sentra SE-R with Factory Brakes
          Front: 2982 In.Lb.
          Rear: 870 In.Lb.
        1989-1994 Lotus Elan M100
          Front: 2635 In.Lb.
          Rear: 1213 In.Lb.


    Conclusion
      Today’s crop of performance oriented cars are providing in the range of double the braking force as the Geo Storm, Isuzu Impulse XS and Stylus, while today’s comparable compact cars are providing 20% additional braking or more.

      Bringing the Storm and its Isuzu sister cars up to today’s standards, and a level that will really allow the car to shine on the track, is going to require some pretty serious changes to the three variables that increase braking force:
      • Increase brake caliper piston area.
      • Increase rotor diameter.
      • Increase break pad friction coefficient
        • .
      And to of utmost importance, the balance between the front and rear brakes must be considered and addressed, and the magnitude of increase in rear braking force matched to the magnitude of increase in front braking force.




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