Fiat Uno Manual
Pressure regulating valveBraking system / Pressure regulating valve
1 The pressure regulating valve is a load proportioning valve which restricts the hydraulic pressure to the rear brakes according to car weight during heavy applications of the brake pedal. This prevents the rear wheels locking.
2 A faulty or non-operational valve should be renewed complete, no repair being possible.
3 To remove the valve, unscrew the pipe unions and disconnect the hydraulic pipes from the valve. Cap the ends of the pipes to prevent loss of fluid.
4 Unbolt the valve mounting bracket, withdraw it and disconnect the tension spring (photo).
10.4 Pressure regulating valve bracket and tension spring
5 Refit the new valve and then adjust it in the following way.
6 Have the car standing on a level floor.
7 The car should be normally loaded (kerb
weight) with fuel, oil, spare wheel etc. Load
the luggage compartment immediately behind
the seat back with:
65 kg (143 lbs) on three-door models or 55 kg (121 lbs) on five-door models 8 Refer to Fig. 8.10 and slacken the valve bracket securing bolt (1).
9 Attach a 6.0 kg (13.2 lb) weight to the bracket eye (2) as shown and then tighten the bracket securing bolt.
10 Bleed the braking system if a new valve has been fitted. Bleeding will not of course be required if only adjustment has been carried out to an existing valve.
Fig. 8.8 Pressure regulating valve (Sec 10)
Fig. 8.9 Components of the pressure regulating valve (Sec 10)
Fig. 8.10 Weight attachment point for pressure regulating valve adjustment (Sec 10)
1 Fixing bolt
2 Bracket eye