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Brake Master Cylinder Union Size...


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#1 screech

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Posted 20 March 2012 - 07:29 PM

Iv got non-servo type mast cylinder, twin line set-up....

Iv purchased a new pipe set, and one of the unions is the wrong size.

The top union is the same as all the others, but the bottom one is bigger. It doesn't look like its been re-tapped, as the body itself around it is bigger.


Any ideas what size this is??


Cheers

#2 tiger99

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Posted 20 March 2012 - 08:55 PM

On a master cylinder with different unions they are usually 10mm and 12mm.

Take care, because all other brake fittings are likely 3/8" UNF, which is dangerously close to 10mm, but when mated the combination is dangerous. make sure they all screw together fully with fingers before using a spanner, and you will not go wrong.

#3 screech

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Posted 21 March 2012 - 11:14 AM

Thanks for that.
So on a mini that everything is imperial, these are metric??

I have already tried the top one with the 3/8 union by hand, and it seemed alright, I'm guessing it will strip as soon as a spanner sees it..?


Cheers.

#4 Dan

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Posted 21 March 2012 - 11:21 AM

Who said everything is imperial? Mini was in production for a very long time, standards changed during that time. It's covered in all sorts of fixings, whatever standard was in place when a part was developed was used.

#5 Ethel

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Posted 21 March 2012 - 11:52 AM

GMC227, "yellow band" master cylinder:

Top union M10x1 - connect to front brakes
Bottom union M12x1 - connect to the rear (Note that there are several other M12 threads)

3/8" is just over 9.5mm, the 1 is the pitch (1 turn per mm): 3/8unf has 24 turns per inch, slightly bigger

#6 screech

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Posted 21 March 2012 - 01:43 PM

I think what I meant was, that I'm pretty sure every nut and bolt on my mini when iv taken it off and put back on has been imperial, except these 2.

Thanks everyone, I shall get an M10x1 and an M12x1 union.

Cheers

#7 Ethel

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Posted 21 March 2012 - 03:28 PM

M12x1 can be a pig to track down. It was used on Metro clutches and could well be found on MGF's - they use the same pattern cylinders.

#8 screech

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Posted 21 March 2012 - 08:56 PM

Really? That's a bit stupid then, if they make and sell brand new parts that require that size surely they would also make the union!

Cheers




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