Proportioning Valve: Inspection

WARNING: This page is about a different car, the 2007 Kia Optima, 2007 Kia Magentis, 2006 Kia Optima, and 2006 Kia Magentis. However, it is still accessible from the selected car via links, so may be relevant.

Remove the front brake tube (B) and rear brake tube (C) from the master cylinder (A).
Connect two pressure gauges (D); one to the output valve of the front (B) and rear (C) brake.

Fig 1: Checking Master Cylinder Pressure
Courtesy of KIA MOTORS AMERICA, INC.

NOTE: Be sure to bleed the system after connecting the pressure gauges.
With the brake applied, measure the front pressure and the rear pressure. If the measured pressures are within the specified range as illustrated, the proportioning valve is good

Reconnect the brake lines in their original positions and bleed the brake system.

NOTE: This table shows characteristics of the proportioning valve as the pressure increases.

VALVE OUTPUT CHART

Front (Output of master cylinder)	Rear (Output of proportioning valve)
A: 35 kg/cm² (3.43 MPa, 498 psi)	A': 35 kg/cm² (3.43 MPa, 498 psi)
B: 80 kg/cm² (7.85 MPa, 1138 psi)	B': 49.4 ± 3.0 kg/cm² (4.84 ± 0.3 MPa, 703 ± 42.7 psi)

Fig 2: Input/Output Pressure Graph

Courtesy of KIA MOTORS AMERICA, INC.