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Mx5 master cylinder & prop valve plumbing
sdh2903 - 3/10/15 at 03:40 PM

Ive been a numpty when removing the master cylinder and proportioning valve and not labelled them up as to where each port feeds. Can anyone shed any light?

The prop valve has 4 ports, 2 come from the master cyl marked 1 & 2), where do the other 2 go?

Master cylinder1
Master cylinder1


The master cyl has 3 outlets, 2 to the prop valve and 1 on its own

Master cylinder2
Master cylinder2


Typical the first lines im running are the only ones ive not labelled


sdh2903 - 3/10/15 at 04:08 PM

after much googling I think i have my answer, front 2 ports are front brakes, left front goes through the prop valve as a ref pressure, right front straight to caliper, rear port on master cyl goes through prop valve and to rear brakes.

prop valve
prop valve


Now this leads me on to another question, to minimise pipework is it ok to blank one of the front ports so i can run a single line to the front and tee it off to each caliper?


hizzi - 3/10/15 at 10:27 PM

i am in the same boat as you, my donor was a 1.8 s reg master cyl has two outlets to two outlets on the proportioning valve that then went to the abs pump, how it splits from there i am stuck too


thepest - 4/10/15 at 09:18 AM

Photo as sdh2903 posted is correct. I used one of the ports on the master for the brake pressure switch, so yes blanking one off would work all the same.


sdh2903 - 4/10/15 at 09:33 AM

Cheers thepest

Which port did you blank? Did you run the front through the prop valve?

Clever idea to use the port for the switch


thepest - 5/10/15 at 09:49 AM

Here you go


sdh2903 - 5/10/15 at 09:57 AM

Thank you sir!

Have you recently started building? as I sat in a chassis at MNR that was destined for Malta when I went and placed my order


thepest - 5/10/15 at 10:36 AM

You're welcome, yes I think this is it. The only MNR on the island I believe.
Stated building in July, should be running by end this month if all goes well with the engine.