Brake master cylinder size

[Spider]

In single circuit, nearly all Minis run with a 0.70" Bore. I think it was the early 850's and the Cooper that had a 0.625" but I think they are hard to find. Totally agree with your thinking on the space the servo takes up.

Of course, you don't get something for nothing, here, going to a smaller bore, as you are thinking, will increase the pedal travel, though, you still should have well enough.

Another approach I have done with the Tandem Cylinders as there's no really alternatives here, is to move the Clevis Hole position on the Brake Pedal, moving it closer to the pivot makes it lighter.

However, I'd suggest trying the set up with a stock Master Cylinder and see how you find it. They definitely need more 'push' without a Servo though it's very manageable, I find I get used to them quite quickly.

[Andrew1967]

Pretty sure my 998 Cooper had a standard sized canister .70 bore master and when I fitted S brakes without a servo, the brakes were a massive improvement on the 7" discs and didn't require a huge amount of pressure.

I'd do the same as Chris suggests and try it and see before swapping cylinders.

[Daz1968]

I can only give advice based on 7 inch discs, but on my mk2 Cooper I had a 0.7 cylinder fitted without servo and brakes were not very good, after I swapped to a 0.625 bore they were far better and pedal pressure to stop was much improved, if I had fitted 7.5 discs I would have left the 0.625 cylinder, I think rear cylinder size effects it as well. I have 0.625 rear cylinders.

[MrNoo]

Used to run with a standard S master cylinder on my Mini Se7en race car, as did most of the field, this with 7.5 discs, Performance Friction Carbon metallic pads and was fine. This will be what I will be using on my current restoration. I dont like the pedal when using a servo.

[Polarsilver]

my 997+1071 S also the 1275GT they all have 7.5 inch S Brakes with the single line standard S Mater Cylinder & all cars work without any Servo.. i have standard S Calipers on the 997 the 1071 & GT have either Minisport or Minispares 4 pot calipers fitted .. on all these cars i run with adjustable rear brake bias valve fitted along with Silicone Fluid.. the results are all cars have a deep brake pedal because of using Silicone Fluid.. but the non paintwork damage benefit with using Silicone is an acceptable offset to the deep pedal feel .. whatever car i have the road brakes are fully effective & give good pedal feel using Green Stuff Pads to let me know what the brakes are doing .. even me being an old git i can find enough strength in my Right or Left foot to press a Mini Brake Pedal without any need for a Servo being fitted
But then i would rather my Car to be able to stop than be 100% brake spec correct to the new 997 Cooper build sheet from 1961

[CooperTune]

My US Vintage racer was set up with Tilton brake master standing up with remote. The 700 with 5/8 rear cyl and 7.5 disc produced a high hard pedal requiring some push to work with the hard pads and you had nothing with cold disc. Converting to a .625 master lowered the pedal, reduced push required and gave a better feel under braking. Most of out tracks have 3000 ft straights leading into 90 to 180 turns. Regardless of gear, cam or other changes 116 MPH was all she would do. Living over here I drive in the left seat and have picked up a very late torque tube LHD all in one master/booster kit. In spite of driving my street car 176,000 miles with .700 single line, 7.5 disc and calipers, .625 wheel cyls. When my son came of age to drive I installed a cross over tube master and booster as a safety feature. Five years later he has never ask to or driven our mini. Considering the issues I have had over the years with MK1 boosters I'm thinking about a late kit in my Mk1 project. It will be a driver that is what I do with my minis. Steve (CTR)

[Spider]

If you think you would like to run with a servo, perhaps to keep the engine bay uncluttered, would you consider an alternative location for the Servo ?

eg, some have mounted them under the parcel tray and even under the rear seat.

[abs]

I have a 5/8" bore master cylinder on my 67 cooper with 7.5" discs and it`s so much better with the smaller bore and the extra pedal travel is not noticeable.
Personally with the .70" bore they feel dead and for reference I drive a drum braked mini daily which has plenty of bite and feel it`s just a shame they only work well below 40 mph After 16 years of use I'm going to fit 7.5" disc`s in the summer and I'll be using one of these https://www.ebay.co.uk/itm/Wilwood-Comb ... SwytlZtrWd as i`m not bothered about originality and it`s hardly a big deal to swap it back and I know the 5/8" bore works.
I`m sorry but EBC pads are crap and bog standard AP pads will give more bite and feel and are ample for sensible road use. http://www.minispares.com/product/Class ... o%20search

[MrNoo]

I'll 2nd that about EBC, utter junk in my opinion.