Hi all,

Recently changed my master cylinder from the clubby tandem to a yellow tag rover cylinder. The supplier said that that brake lines need to be changed, so I bought the conversion kit too.

Now, the conversion kit didn't fit - the lines were about 3" too short to get to the bias valve. I was going to just get the lines lengthened, but then I found an adapter so I could use my existing lines.

Now the brakes are absolute rubbish - the back brakes lock up well before the front. I read a little more, and I found that the new MC has a split bore, to increase the bias to the front. The conversion kit swapped the lines so the right sized bore went to the proper side of the car, but with the adapter (which was sold specifically for this reason), they didn't. So the front/back bias has been messed up.

I'm not keen on defaming the supplier of the adapter, but I thought I'd put it out here to make sure I'm right before I contacted them about it. I'm concerned that someone will change the MC without realising this problem. Is there any setup that this adapter will work for? The adapter is to drop the thread size down from 12mm to 10mm.

BTW, has anyone else changed to this master cylinder? How did you do it?

Hi

I am investigating doing the same with my current project and I have found some good info on the minispares UK web site.
I assume you have fitted the yellow tag master cylinder GMC227 ?

They talk about ditching the front limiter valve and replace it with a later version. But all the info is on their web site.

http://www.minispares.com/Articles.aspx?ty=ad&aid=129
Some other good info here as well

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Yep, it's the GMC 227.

Interesting article that one, and it does make sense too. But a little expensive, because even after buying this valve you'll still need to get some custom lines made.

I was just surprised that the conversion kit didn't fit! This is the kit:
http://www.minispares.com/Product.aspx? ... 911&title=

This is supposed to swap the lines, and most suppliers provide this - for some reason they just don't fit! They're too short, and probably a bit too high as well. But I'm more concerned about the adapter bit - it's only provided by one supplier, and it makes the brakes dangerous.

I've also heard that the bias valve from some models of toyota corollas work well in minis - I was at the local mini specialists and they had one with a corolla valve. But at the moment, I still want to see if I can get what I've got working.

There is no reason at all why the 'standard' rear pressure shut off valve from the early minis won't work with a tandem set up. I haven't actually done this, but the UK Minis from about 1976 to 82 and the late Mokes had the next generation of this valve (interal valve) fitted with tandem brakes and has a similar effect.

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