Brake master cylinder boot

[Andyhereford]

Slowly working my way around the brakes renewing parts as I go. I think that I have done the four wheels...replaced cylinders as needed....but am still finding it hard to bleed the brakes satisfactorily. No obvious leaking from the master cylinder to be seen under the car but I have removed the covering plate to get a closer look. The cylinder itself looks dirty but fairly dry but the front boot which surrounds the brake pedal rod where it enters the master cylinder is completely perished. The function of this boot is presumably to keep dirt out of the cylinder. I have no idea how long this boot has been in this condition. Should I try to replace this boot or is it simply a sign that the brake master cylinder is in need of replacing. I have read the cautionary tales about the difficulty / problems in replacing the master cylinder but I am quite happy to have a go if this is what is needed. I obviously don’t want to take on the work / cost of replacing the master cylinder if simply replacing the boot , if this is possible, is sufficient.

[King Kenny]

Tricky one. You could (might) get away with just changing the boot, but the master cylinder will have to come out to change it I think. As you have done the wheel cylinders and the master is an unknown quality I would err on the side of caution and renew that as well. Taking it out is quite a struggle but not difficult. I use a crowbar and a length of wood, to spread the load, to bent the torsion bar in order to remove the long bolts. Whilst they were out I filed one of the flats down to the shank to make things easier next the time I have to take them out.

[Trickydicky]

One of the main things to consider when overhauling brakes is that if the M/C is old the cylinder bore may be pitted. When you start bleeding the brakes and pumping the cylinder to it’s full stroke it will wreck the seals.
As a belt and braces approach I would consider replacing the cylinder.

[Murrayminor]

When it comes to the brakes leave nothing to chance, For the cost of a new master cylinder you will have peace of mind.

[ManyMinors]

I agree. I wouldn't try to save money where the brakes are concerned. Fit a new one and be done with it. And don't buy a cheap "pattern" one either - make sure you purchase an original type Lockheed one.
Once the cylinder is out, it is also a good opportunity to clean all the muck out of the chassis rail and spray some rust preventative into the box section and also ensure that the pedals are working and lubricated properly.

[Andyhereford]

Thanks for all your advice. A new master cylinder it will be then. Might come back for some help / suggestions if I get stuck.

[Andyhereford]

Sorry to keep asking questions. About to take the old MC out. There is no brake pedal return spring or obvious place where the brake pedal return spring is attached inside the chassis leg. This is presumably needed for the MC to work effectively.
I am anticipating, therefore, therefore that I will have to improvise some form of attachment inside the chassis leg. This would presumably be a sufficient distance from

[Andyhereford]

Sorry..continuation from previous message....distance from the pedal to ensure that the brake and clutch pedal are in line.
Any advice gratefully received.