While Ive got my rear sub-frame apart for rebuild I'm looking at my brakes.

Its an 850 so it has the standard rear drums, I understand the later minis i.e. clubmans had twin leading shoes.
Since I have everything apart would it be worth my trouble upgrading to twin leading shoes?

As I understand all I need are the backing plates and new shoes? Are the slave cylinder any different?
What would a second hand set of backing plates be? are they common?

Rear drums on all mini's were single leading shoe. Only the front drums were upgraded from single to twin leading shoe.

The rear slave cylinders should be 3/4" for 4 wheel drums and 5/8" if you have disc's on the front.

You can still buy new backing plates.

I just want to make sure - you are talking about the rear brakes?

It is worthwhile upgrading to twin leading shoe brakes these days, you will need new shoes (twin leading ones are 1/4" wider) and new slave cylinders (as there is two and not 1)

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

Yeah, as 1018 says, all mini rear brakes on minis are single leading shoe, however IF you have single leading shoe front brakes the wheel cylinder size could be either 3/4"or 5/8" - they should match the same size as the fronts, that is if you have 5/8" wheel cylinders in the fronts, then you should have 5/8"in the rears.

Early cars had 3/4"and later ones 5/8".

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upgrade to disks if you can. however the difference between single and twin leading shoes is pretty big in its own right and well worth the upgrade on the front brakes. (i've driven all 3 went from single leading shoe to disks on the 850)

as for the rears nothing wrong with singles. you could also go a brake booster but thats another thing entirely.

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1962 850,Frog

I will be going discs in the front, but im starting at the rear of the car.
Would it be possible to fit the backing plates from front twin leading shoe setup to the rear brakes, thus getting twin leading shoes, would it be worth it. Since I have it all pulled apart it doesn't sound like a lot of effort.

Are there any differences with the cooper spaced drums, other than the "spacer"?

Are the brake slave cylinders just left and right or are they different for each corner?

While I'm asking questions:

Ill be going with front disks, 7.5" as I cant fit anything larger under my wheels. What would I be needing in terms of brake boosters / tandem master cylinders etc?

The standard rear brakes are more than up to the task, in fact the brake pressure limiting valve (little T piece fitted to the brake line bolted to your rear subframe) is there to stop the rear brakes from locking up.

Just make sure everything is in good working order, and fit new 5/8" cylinders to go with your impending front discs. The S drums are the same bar the spacer.

Have a search as it has been discussed many times, but like most mini people I would recommend you stick with a standard master cylinder and no booster (but opinions are divided on the booster).

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Too many cars, and too little time.

The twin leading shoe front brakes do not have a handbrake. So you can't fit them to the rear.
The difference between stock rear brakes and Cooper S rear brakes is the size of the wheel cylinders and the width of the spacer on the drum.

Just remember you need the rear brake trailing shoes to give some braking in reverse. When reversing the rear trailing shoe becomes a leading shoe.

RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

Ill be putting on 7.5" disk at the front, Since they whre cooper originally do they have as much offset as the rear spaced drums, If they do it may look a bit odd with sticking out front wheels and standard at the back?

If you fit the 7.5" discs you will need spacers (preferably Cooper S spacered drums) to have matching track front & rear.

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Too many cars, and too little time.