2 replies to this topic

[dave houston]

I have 1974 innocenti cooper s,when i start the engine the front brakes lock up. When i disconnect the vacuum pipe with engine still running the brakes free off. Any idea where the issue is. The servo is a Benditalia unit cant get spares for the Benditalia servo.

[panky]

As mentioned yesterday it's the air valve, or air valve diaphragm. When operated this valve allows air onto one side of the main diaphragm, on the other side of that diaphragm is a partial vacuum from the inlet manifold. Push the brake pedal and the internal piston pushes the air valve open allowing atmospheric pressure to act on the main diaphragm and gives the brake assist. If the air valve is passing then there is constant pressure on the main diaphragm when the engine is running - remove the vac line and the pressure is equalised so the brake assist is removed.

Hopefully this will explain your problem, wont help with parts availability though

 

Edited by panky, 02 January 2017 - 08:38 PM.

[carbon]

If you've got a strong right leg you can run a Mini on 7.5 inch discs using road pads and still lock up the front brakes in the dry.