Braking problem.
Posted: Mon Feb 08, 2016 6:32 pm
Opinions welcomed on this issue....
When braking firmly and releasing rapidly - no problems. When braking gently - releasing slowly the brakes sometimes hang on, a tap on the pedal is required to release them.
Master cylinder, front calipers, pipes and hoses are all new. Rear calipers professionally reconditioned. Girling servo overhauled by me; it was well gummed up but cleaned up ok and new seals and diaphragm fitted.
My first thought was a sticking control piston or it's return spring was weak and that may still be the case. I stripped the servo again and double checked all was correctly assembled. It was hard to judge whether or not the control piston returned smoothly as there's some natural resistance from the seal. The bore looks ok, but that's not very scientific.
My next thought was an air valve not seating properly and allowing uncalled for atmospheric pressure to the diaphragm but all looks ok there and it does pass the test of operation after 2 minutes of engine off.
I don't know if a fault with the new master cylinder would have these symptoms?
I could send the servo for reconditioning, but it's expensive if the fault lies elewhere. Likewise a Lockheed replacement.
I still suspect the servo, but any ideas?
Dougal.
When braking firmly and releasing rapidly - no problems. When braking gently - releasing slowly the brakes sometimes hang on, a tap on the pedal is required to release them.
Master cylinder, front calipers, pipes and hoses are all new. Rear calipers professionally reconditioned. Girling servo overhauled by me; it was well gummed up but cleaned up ok and new seals and diaphragm fitted.
My first thought was a sticking control piston or it's return spring was weak and that may still be the case. I stripped the servo again and double checked all was correctly assembled. It was hard to judge whether or not the control piston returned smoothly as there's some natural resistance from the seal. The bore looks ok, but that's not very scientific.
My next thought was an air valve not seating properly and allowing uncalled for atmospheric pressure to the diaphragm but all looks ok there and it does pass the test of operation after 2 minutes of engine off.
I don't know if a fault with the new master cylinder would have these symptoms?
I could send the servo for reconditioning, but it's expensive if the fault lies elewhere. Likewise a Lockheed replacement.
I still suspect the servo, but any ideas?
Dougal.