Richard, it sounds like the master cylinder is hokding sone residual pressure when everything is hot This is because there is NOT enough freeplay in the system You need to adjust the pushrod where it fits to the clevis You should aim for around 1/2 free play at the pedal pad (where you press with your foot) when everything is hot
Regards Simon Mulberry Fabrications
Simon (or anyone) - in practice what does this mean? Should the clevis be free to move between the two nuts on the push rod (the previous one was held fast between the two bolts)?
Or should the pedal be clear of the floor bolt when cold so that it when the system "expands" there is room for it to come back....
Did you compare the pushrod length? If the new one is slightly longer, that could be it. Grind a bit off the end if so. (Or use the old one). You should be able to feel a bit of slack in the pedal and pushrod. if it feels tight,as I suspect it will, the pushrod may be a tad too long. When I said does it come off OK, I meant does it release OK.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4
I have just been in the garage, I removed the clevis pin and loosened the nut behind the clevis pin quite a way back. I then reconnected the clevis pin (with ease - was much harder last time). I then finger tighten the nut up behind the clevis pin until it was just touching.
I tried the brakes, the travel in the pedal was much more (previously could be measured in millimetres). I pumped the brakes many times and it did not harden (like before). I may have cracked it.
As a brief test I asked my wife to press the pedal and I could not move the car (OK not great but the brakes are engaging and releasing).
I will take it for a drive later in the week and see how it goes.
Probably should check the brakes now to see if the shoes/pads are OK. Any guidance?
Thanks for all the input and help - a nice easy fix and an important lesson learnt!
Jacked up - if the handbrake works as it should on each side, I wouldn't worry until the next inspection is due. Keep an eye on the fluid level.
A mate of mine drove his Midget with the handbrake seized on one side, not very far, but the heat was so great that it melted the rubber covers on the wheel cylinder, and melted the piston seals, so all the fluid ran out and his brakes failed. No damage other than ego, but I've never seen such a mess before or since. The rubber had turned to charcoal.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4
I had the same problem once (upon the time...). The workshop people told me that without the push rod 'play' the fluid can't return to the reservoir. Every time the pedal is pushed the system will fill up until the pads/shoes stays solid aginst the disc/drum. Exactly what happend to me. Goog luck with yours
Here is a diagram showing the bypass port. If the piston cannot fully retract do to linkage problems, pressure cannot escape back into the reservoir through this hole and the brake will remain applied. Another problem that can occur on older or high mileage cars is swelling of the rubber in the flexible brake lines that restricts the passage and acts somewhat like a check-valve-common on cars that have been in storage.