Thanks for the info guys. I have two to play with. The original one from my Mk 2 'S' and a Deluxe one.
Thanks for the drawing. I didn't realise the 'S' was different, just different size rear wheel cylinders.

Do you remember when that was? I'll have a look for the technical bulletin.

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

From memory around 66 or 67. But it could be any time between 62 and 69!
I had a bit of a scout through my stuff but it didn't turn up.

From memory they changed from copper washers to save money, and they changed back for the same reason!

Thanks for the discussion and the drawing. You learn something new everyday. Mine has the alloy washer under the nut. That's why it was deceiving that it looked like it was part of the valve. I also have a deluxe one to play around with.
I didn't realise they were different operating pressures, just that the wheel cylinders were different diameters.
What a great forum!

I'm impressed, Morris. You're not just a pretty face.

It was Feb 1967, although I came across another TB in 1966 documenting the reduction in pressure for the Cooper S valve. I saw this change in the parts book when looking earlier but didn't mention it in my rant above as I thought it might confuse things. The 1966 one also has some info on displacers.

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

Hi,
Another question. The bore where the piston runs is fairly pitted. Is it possible to have the valve body re-sleeved?

Thanks for the feedback I thought somebody would have came across the same problem

Sorry, I thought this one was answered.

I have generally found it easier to find another as they are a common part to all minis, with the exception of the spring. It may be a lot cheaper than sleeving, although undoubtedly you could have this done.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I have now disassembelled three units that I have. two have a coppery coloured spring, one has a black spring. Two with copper washers, one Aluminium (with no sign of corrosion on it).

Does anyone know which spring colour I should use?

It is going on a sedan with 7.5 discs on the front and the small bore rear brake cylinders, new lines, hoses and DOT5 brake fluid.

thanks,
Frank

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Roundy Sedan project with/for daughter

I don't think it really matters. People (me included) routinely have fitted S/GT or 1275LS front discs and 5/8" rear wheel cylinders to all sorts of Minis, as long as the rears don't lock up in the wet it's fine, IMO.

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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.

That is lbins which is a torque unit. psi is a pressure unit. Should not be confused.

And 500/600 lbins is not as high as you think - your normal unit that you think in in imperial torque terms is lbft which is 12 times smaller

So that is 41-50 lbft in fact (truncating to integers).

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

If you really want to know the difference you would be better off measuring the load rate of each spring than relying on a colour.

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

So I measured the load rate (bathroom scales, drill press (to apply force) and vernier calipers) with the following result



Don't take these figures as truth, accuracy is very questionable, but was good enough to note a large difference. With the gold coloured spring being the strongest by a large margin.


So I then assembled a valve unit using a black spring (with the best bits of the four units I have), dropping some brake fluid down the body to lube it. As I tightened the large nut the unit exploded, blowing the end of the casting.





Obviously too much fluid in the body, and the seal was good. So good that it cut the lip off the best piston I had with the pressure the wrong way.

Not Happy, my second best piston is not all that good, with the other two being (in my opinion) not useable at all.

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Roundy Sedan project with/for daughter

It must have made a big noise Frank!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I know we have a long way to go...but that's shaping up as the quote of the year

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"Show me the Mini!"