I have recently purchased a reco master cylinder. I have heard that I need to take it apart and remove the top inner valve so it can be used with disc brakes. Is this correct? What does this valve look like?
thanks

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

They're not getting it mixed up with a Clutch Master Cylinder are they ?

I would make sure its actually in there
Not take it out

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Removing it for disc brakes is correct. Its a line pressure retention valve for front drum brake cars.
Disc brake calipers dont have any mechanism to release the pads from the disc other than disc runout and flex in the piston seals so pressure retention wont help this.
Looks like a little rubber top hat pushed into the spring end at the outlet end.

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....you just lost him his insurance bonus!

997

thank you.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

minis still have drum rear brakes,,, if you run without that "Slow Return Valve" then as the rear shoes wear, the distance the shoes have to travel is quite far & your brake peddle will travel to the floor before it gets any pressure,,, release the peddle & the rear shoes return with the springs pulling them back home & upon the 2nd application of the brakes you will still find a very low brake peddle

that valve is meant to be in there whether you have disc front or drums because you still have drum rears... without it you will not be able to pump up a peddle

it is (However) detrimental to fit that valve into a clutch master cyl, because you really don`t want the clutch to be able to "Pump-up",,, if it does then you can easily break the lugs off the alloy clutch wok at the base of the clutch arm,,, or even worse (if you don`t have the "Anti-over-throw-nuts" fitted & adjusted correctly,,, you can break the bolts off the center main cap inside your engine

make sure the valve "IS" in the brake master cyl !!!!!!!!
make sure it`s "NOT" in the clutch master cyl !!!!!!!!!!

simple as that

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

What's happened to your usual "easy peasy" signoff?

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

sorry, i was "In the moment" trying to get the point across that the "slow return valve" is still needed

all the brake master cyls in minis should still have the "Slow Return Valve"

definately not in a clutch master cyl tho,,, certainly not

but definately yes in a brake master cyl

easy-peasy

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

http://minisport.com.au/reconditioned-b ... 50-plastic

I'll leave it in.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

Question
is not .75in bore for clutch and .70in bore for brake ?

Usually is yes.
But 850 had 3/4" brake master, late 997 Cooper & 998 Cooper had 5/8" brake master.

re clutches, 1970? on Minis with the Lockheed/PBR clutch MC (plastic reservoir) mostly had a .70" bore MC. Hardly moved enough oilz to work the clutch properly.
Other Minis clutch MCs were .75".

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yes. The smaller diameter piston will give you more psi (best for brakes) and the larger piston will move more fluid (best for clutch)