Wilwood 340-12509 Reverse Swinging Dual Brake Master Cylinder Pedal Assembly For Two Master Cylinder

The 340-13837 and the 340-12509 are basically the same pedal assembly. The only difference is that the 340-13837 has a slightly shorter arm than the 340-12509.

• 340-13837 is 10-1/2" from mounting surface to bottom of pedal and a 5.11:1 ratio
• 340-12509 is 12-1/4" from mounting surface to bottom of pedal and a 6.15:1 ratio

This pedal assembly was designed for 4 wheel brakes. One master cylinder will feed your front brakes and one master cylinder will feed your rear brakes. Inside the pedal arm there is an adjustable uniball. For a tandem brake master cylinder pedal assembly, offroad trucks and buggies will have more bias to the rear brakes. 60% rear and 40% front is a common starting point, with a lot of offroad racing vehicles ending up at 30% front and 70% rear. Opposite of a street vehicle.

The bias bar inside the pedal arm is 3/8". It can be upgraded to 7/16" if you purchase Jamar or Tilton's brake bias balance bar if you're concerned about bending Wilwood's 3/8" bar.


When selecting master cylinders, you'll notice with a smaller bore, you get more pressure but less volume. With a larger bore you get less pressure but more volume. You need to make sure that you have enough volume to supply your brake calipers, but at the same time, enough pressure.

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