Hi I'm having some serious issues with brakes. Originally they did the same in my old car with rear discs too and now I've put engine brakes servo master cylinder etc in another car. The master cylinder was knackered on old car so I replaced on new car. It's had 4 new brake likes from front to back and used a master cylinder with 4 outlets. Using Mondeo calipers and 300mm discs with the RS turbo drums on back. No compensators in line at back.
Anyways I'll be driving along say around our town and the brakes will start getting harder and harder until I get to a point where it's undriveable, the pedal will lock solid and even with engine off its still solid. Give it 3-4 mins and take pipe from servo off to relieve pressure and it frees brakes. Then it starts doing it again? I went classic ford and it was fine on way there but as soon as I start using the brakes more once off motorway it starts locking tight again. It's all brakes too not just one. I've run out of ideas now and even adjusted the servo pin but still does it. Anyone have an ideas cheeRS

 

Is their any chance that the rod in the mastercylinder isn't returning properly?

 

Brake bar jammed, servo rod bent, or new MC has a knackered return spring?

 

The rod in servo is loose? Master cylinders brand new. Only done about 200 miles and was still doing it in the first mile. Never thought of bar jamming. I've bought a mk5 escort xr3i servo and master so might just put that on? Got another servo I could try first though?

 

Brake Booster rod over-extended therefore not allowing fluid to return fully. As everything heats up, the pads etc expand to the point of locking the brakes.

Take the MC off and adjust the booster rod in slightly (8mm socket (iirc) clockwise, use grips on the main rod to hold steady). Do half a turn see if it improves, then adjust from there onwards.

 

I've wound that nut tight mate and won't go in any more 😐

 

I would be trying another servo if the adjustment is wound in.

 

Thinking about it before I bolt the master back into the servo there is about a 5mm gap which obviously closes once nuts are tightened. Is this right or should it be flush before nuts tightened?

 

I would expect it requires a small amount of clearance at all times, that said its been many years since I've had one in bits.

What you could do is, when the brakes start binding slacken the master cylinder a little and if they then release you either know the servo is faulty or the rod is over adjusted?

 

Yer, there should be a minute gap at all times. Unsure what the setting is tho on Fords. Does sound like an incorrect MC if its wound right in tho and still binding up