I have a 67 mk1 Cooper S and these are the master cylinders I'm pretty sure the tin brake master is correct but not sure about the plastic tank cluch master
Can someone enlighten me
Thanks
Glenn

Plastic master cylinder is incorrect. They came in around 1970/1971

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For a 67 model it would have had tin brake and clutch master cylinders originally

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1965 Morris 850
1966 Morris Mini Minor
1967 Morris Cooper 'S'
1977 Leyland LS

Here is the engine bay for a 1967 S. If your car is pre YKG2S2 3792 it would have also been fitted with the plastic extensions. The brake master should be Lockheed .7" and have a tall reservoir. The clutch master should be a Lockheed .75" and have a shorter reservoir.

I had the same question today !
My 67 deluxe came with the same setup as yours , so obviously its been changed out along the way too.
My plastic tank is PBR and must be for the clutch ....cant remember which side I pulled it off !
This is what happens to the tin after 50 years



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Simonw
Brisbane QLD
1st car - 1964 Mini Panelvan 850
Previous - 1978 Leyland LS 1275 Gold
- 1969 Mini K

Mine is 3688 I have never seen the plastic extensions befiore, never seen them is any of the mini sellers catalogues.
Where would I be able to get them

Here is one example https://minikingdomonline.com.au/produc ... with-seal/

I bought a new one recently, and found it was a slightly different shape to the older style ones. The old ones were parallel the whole way up, and the new one I bought was thinner above the thread. E.g.

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That is about right.
John Sneddon's book lists the change from tin tanks to plastic as August 1969, in early Mk2 production. That suggests that 300+ Mk2s had tin tanks.

My Mk2, 1969 car 940, had the tall plastic clutch master cylinder & the original Mk1 type tin brake master cylinder, which I believe was correct for the era?

See this Service Liaison Letter.

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

This may help date the clutch master cylinder change. Car 839 was fitted with tin master cylinders.

Many thanks for the Service Liasion Letter
It makes reference to "... and spacers are used to obtain pedal height" Can anyone tell me where these spaces are located and what thickness they are.

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Mk1 Cooper S
Mini K Rally car

This suggests that my plastic reservoir replacement is inappropriate as my threads on the pedal box will be too short ... let me go measure them. Didn’t know there were 2 types of pedal boxes


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Simonw
Brisbane QLD
1st car - 1964 Mini Panelvan 850
Previous - 1978 Leyland LS 1275 Gold
- 1969 Mini K

These 2 spacers came with a car I'm rebuilding. They are 1/16" or 1.6mm thick. Both master cylinders are the plastic reservoir type and spacers are placed between cylinder body and the pedal box mounting point. Have no idea if they are original. I'm sure an expert will set this straight.
I also have a car with a metal brake master and a plastic reservoir clutch master which has metal spacer.

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Clive G
1969 Mk II Cooper S
1970 MK II Cooper S
1963 Triumph Spitfire
1982 RX-7 Series 2