Replacing brake master cylinder

[NoviceM]

I intend to fir a Ford disc conversion to front brakes. While I am comfortable doing the work on the wheel end of the job, I don't fancy replacing the master cylinder....probably a bit to difficult without a car lift.
Question.....if I get a professional garage to fit the new master cylinder, (including bleading brakes) can i then safely drive the car away back home where I complete the job, fitting the disc kit etc. (And obviously reblead the brakes when done).
I am concerned the lack of the (removed) small valve in the master cylinder might mean I would have no working brakes.
Any advice greatfully received.

[King Kenny]

It seems an unnecessary complication to split the job in two. I believe that if you are confident enough to fit the disks and bleed the system yourself you should be able to take out and replace the master cylinder. There is a method of easing the torsion bar down enough without dismantling the suspension. Last time I used a piece of wood and a prise bar. I first did mine in the eighties having little experience with no problem. Do a lot of homework and I think you too will be able to complete the job in one go.

[les]

Maybe I’m missing something here, but assuming you do drive back after the work, and intend removing the said piece from the master cylinder, you would be, in fact, doing the thing you say you’re not comfortable with in the first place, ie removing the master cylinder.
So why not get the garage to modify the master cylinder before they fit it ? Assuming they know what they’re doing, of course !
As mentioned I may be misreading your post

[simmitc]

I second King Kenny. You will need ramps or axle stands to have the front of the car raised sufficiently to crawl underneath in order to reach the union and retaining bolts and nuts, but this is easy enough. Remember normal safety precautions such as chocking the rear wheels and ensuring that everything is stable. The cylinder is removed via the opening in the driver's footwell after removing the cover for the master cylinder.

I have always found that the worst part of the job is getting the union for the rear pipe threaded correctly - small fingers are helpful. It is useful to have spare brake pipe and unions plus flaring tool to hand as you can never be 100% certain which pipes will unscrew properly and which, after many years being stationary, will fracture. You will be able to buy such things for far less money than a garage will charge for doing the job.

Do not be put off by the manual that states that you have to remove the front suspension. You do not. As above, there are ways of safely moving the torsion bar to allow the cylinder retaining bolts to be withdrawn and refitted.

[King Kenny]

One trick I have employed is once the long bolts are out is to file the flats off one side of the bolts so that the torsion bar does not need to be moves so much next time.

[NoviceM]

Thanks for all the helpfull replies. However, given my age, I would still prefer not to start crawling under cars. At 40 or so years old, I did this regularly no problem, but in my 70s I would prefer not to, hence the question....is it possible/safe to drive car after master cylinder has been modified ready for disc brakes.

[philthehill]

The rubber 'top hat' seal is there to keep a small amount of pressure in the brake lines.
That pressure keeps the lip of the wheel cylinders hard against the cylinder wall so alleviating wheel cylinder seal failure.
Whilst wheel cylinder failure is uncommon due to lack of line pressure it would be unwise of anyone to say that removing the seal and line pressure is safe.
I would recommend that that you get the workshop to complete the whole job instead of doing part of the job.
Phil

[NoviceM]

Bit confused, when 100% converted to front fiscs, back brakes will still be drum, and their slave cylinders presumably suffer same 'lip' failure as a result of the modification of the master cylinder? I may have misunderstood.....happens a lot these days!

[philthehill]

You are absolutely right and not confused.
When you convert the front brakes to discs and you remove the line pressure you do indeed remove the light pressure on the lip seal of the Morris Minor 7" rear brakes but that is your choice and you take responsibility for that action.
I have Marina disc brakes on the front of my Minor but have Wolseley 1500 rear 8" brakes which have a different type of seal and do not require the line pressure to be maintained.
I am not aware of any Morris Minor brake wheel cylinders failing due to a lack of line pressure but it would be foolish of me to say that it safe because knowing my luck the seal(s) would fail.