Adjusting
Brake Pressure Regulator, AdjustingWork sequence
Car must be empty
Car must be on wheels (Bosch ramp)
Fuel tank full
- remove bleeder screw and connect adaptor to left front wheel brake caliper and right rear wheel brake cylinder
- connect gauge
- bleed both hoses and gauges with bleeder valve on gauges
- have person (approximately 165 lbs) sit on driver's seat
- bounce car several times at rear
- push brake pedal firmly several times
- lift vehicle off ground so load is taken off rear axle
- push brake pressure regulator lever down until stop
- push brake pedal until gauge on front axle reads 50 bar (725 psi)
- gauge for rear axle cylinder must read 35.0-45.0 bar (507.5452.5 psi)
- increase brake pedal pressure until gauge on front axle reads 100 bar (1450 psi)
- gauge for rear axle cylinder must read 57.0-73.0 bar (826.5-1058.5 psi)
- lift vehicle off ground so load is taken off rear axle
- push brake pressure regulator lever down until stop
NOTE: Quattro suspension illustrated.
- loosen nut (1)
- insert 10 mm diameter drill bit between spring (2) and plastic roller
- tighten nut 25.0 Nm (16.0 lb ft)
- repeat pressure test (vehicle on ground)
- push brake pedal until gauge on front axle reads 50 bar (725 psi)
- gauge for rear axle cylinder must read 35.0-45.0 bar (507.5-652.5 psi)
- increase brake pedal pressure until gauge on front axle reads 100 bar (1450 psi)
- gauge for rear axle cylinder must read 57.0-73.0 bar (826.5-1058.5 psi)
If pressure at rear axle too low
- increase brake regulator spring tension
If pressure at rear axle too high
- reduce brake regulator spring tension
If brake pressure readings cannot be obtained
- replace brake pressure regulator