Originally Posted by: holden05 
My thoughts are to screw a longer bolt in the front of the master cyl and lock it with a nut
Then tap the head of the bolt with a chisel towards the front of the car. Only thing I’m concerned is that it might stuff the thread in the front of the master???
I'd be worried about stripping the thread too. If the MC is corroded on that tightly it may be tighter than the thread is strong.
Try using a clamp as a spreader between the mudguard and the MC. Put a fair bit of pressure on it but don't try to loosen the MC with it, then reapply penetrating fluid. The idea is to flex the join just enough so the fluid can get in there through tiny gaps. Check the next day for any looseness in the clamp and spread it a little more if there has been movement. Or add more penetrating fluid for a couple of days.
Or once the MC is under a bit of pressure from the spreader clamp (you could use a small screw jack instead if that works better for you) you could give it a few more taps with a hammer. I wouldn't hit the MC directly with the hammer. Use a short length of broom handle/bit of wood and place that against the MC and hit the other end of the wood.
Couple of options:
Tap the end of the MC. This gives you better leverage against the sticky part. If unsuccessful, soak, spread and tap again the next day.
Or hit the base of the MC near the booster. You can hit fairly hard here because everything is fairly solid.
Either way have the retaining nuts on loosely or the MC may go flying!
Personally, I would hit hard downwards right by the booster. Use a piece of 2mm thick ally or similar. Put this on the base of the MC and rest a steel rod, a bit of reo rod would do but flatten the end of it, against it. This will stop the steel marking the MC. Hit the other end with the biggest hammer you have. You are not trying to remove the whole MC, just knock it down 1 or 2 mm to loosen it, so give it a hard tap without any follow-through rather than hit it at full stretch.
Ain't working on old cars fun!!
