Adjustable Brake Bias Proportioning Valve Kit for Mazda MX-5 NA NB

1 Review

£51.91 ex VAT

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The Adjustable Brake Proportioning Bias Valve Kit allows you to adjust the brake bias on your Mazda MX-5 NA or NB. The non-ABS MX-5 proportioning valves are heavily biased towards the front brakes, meaning they lock up prematurely whilst the rears are doing little work. The stock bias valves were adjusted for the later models. However, on track, it is still easy to lock up the front wheels under heavy braking. So over-worked are the front brakes that in race series where bias valves are not permitted, racers will opt to use a more aggressive compound on the rear brakes than on the front.

We have had brake line adapters made especially for us. These allow any adjustable brake bias proportioning valve with 1/8NPT ports to be fitting to your Mazda MX-5. With a brake bias valve fitted, the brake balance can be adjusted so that the rear brakes are worked as hard as the front. Brake balance can be finely tuned for different tyre compounds and weather conditions, ensuring braking performance is always maximised.

Does not fit cars with ABS


  • Motamec brake bias valve with 1/8NPT ports
  • 1 x M10x1 inverted flare female to M10x1 inverted flare female brass union
  • 2 x M10x1 inverted flare female to 1/8NPT male brass adapter

1 review for Adjustable Brake Bias Proportioning Valve Kit for Mazda MX-5 NA NB

  1. ilnaconaco (verified owner)

    I bought this proportioning valve when I updated the brakes.
    It’s been a few months and I’m very happy with how it works.
    Hassle-free assembly with this kit.

    Be careful not to risk it when it rains, because if you have adjusted for when it is dry, it could become tricky.

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Make Model Year
Mazda MX-5 1989 - 2005