Midland Brake booster

[Thor Nogson]

Hi guys , I'm John from Uk , the chap who is rebuilding the French W300M Crew Cab . It's just about ready to go on road tests but I have a problem with the brakes. They are all new , adjusted and with good pedal , the problem is that once vacuum has built up , the brakes lock on without the pedal being touched. I've disconnected the vacuum line and this doesn't happen. The booster was rebuilt with the overhaul kit from VPW.
Anyone dealt with this problem before ? Any ideas would be appreciated

[Frank Irons]

Make sure the pushrod in the master cylinder has a little play, if not the piston may not be fully retracted. In other words the pedal should have a little play before it engages.

Frank