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jag 420 brake issue


Freshman Member
Hi when I start the engine the brake pedal pushes back, is it possible tnat the remote servo hoses are reversed?

thanks inadvance for any ideas


Darth Vader
Country flag
Have they been moved before this happened?


Freshman Member
Have they been moved before this happened?

Hi LarryK, This has always happened since i bought the car. I have refurbished the Servo and the Master Cylinder. Replaced the fixed pipe work and the flexible connections both at the Master Clinder and the Servo end. Fitted a Vacuum reservoir which had been removed by previous owner (The pipe was sealed off with a jubilee clip and coach bolt.) I have found so many bodges during my rebuild I do not trust the previous owner. It is possible that he connected incorrectly. Its difficult to physically check connections as the fixed pipework goes beneath the radiator.

I guess I can diisconnect at the manifold and the servo and blow through the pipe and see which pipe is which at the servo, if they are connected the correct way I guess it will be replacement Servo. As its a pain doing the test I thought I'd ask first.

Best regards



Darth Vader
Country flag
There are two hard lines and 4 hoses. Booster top port on vertival front goes to Master cyl. front. Booster back goes to back of M/C. There is a T on one of the hard lines. The check valve from reservoir long stem goes to manifold, short stem goes to T. Hope this helps, taken from diagrahm in old Haynes manual.
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