the mk4 rst master cylinder has only 2 ports, one has a larger nut than the other but does anyone know how these actually work?
is the section with the larger hole completely seperate from the smaller one and is it for the fronts or rears?
my master is linked together into one pipe then i have it splitting into 3 pipes with a bias valve on one of them but im not convinced this is the right way to pipe up the system.
if i split the system again will the pedal not go hard if i fit bias valve on just one of the master cylinder ports?
i really dont know how these work so any help would be great

 

Might be easier if you can post some pics of what you have as it doesnt sound right but it very hard to explain without knowing what yours looks like at present - if you can post some pics i am sure i could see whats wrong and put you right.

 

its a bit of a mess but you may be able to see how its all one system.
2 into 1
then into 2
1 splits of for the fronts and 1 into bias valve and then splits off into the 2 rears again.
it works but locks even with bias valve at 60%
http://s19.photobucket.com/albums/b1...=biasvalve.jpg

 

You were right it is indeed a mess - what a nightmare.

Personnally i would strip it out and start again.

The basic principal of the brake system is they run as follows:-

Line 1 (top pipe nearest front of car) from master cylinder to t piece - t piece splits to front o/s and rear n/s.
Line 2 (bottom pipe nearest the servo) from master cylinder to t piece - t piece splits to front n/s and rear o/s.

The line should never supply the same side and they never supply either both front or both rears - hence why i think you have problems.

Some pics of the lines i created on mine (ABS removed)

 

As standard the car is (as you say) diagonally split.

I've re done mine and now run a front/rear split... not as safe (if one braking circuit goes down) but it means I can run a brake bias valve and set the rears up to my liking.

Makes a BIG difference with sticky tyres, the rears can get away with doing so much more than standard.

PS, why didn't you get your brake pipes powdercoated , good job though.

Rob,

 

and this pic shows where the bias valve is mounted



How much are you upgrading? if you are doing a rear disk conversion I would highly recommend a bias adjuster of some sort.

Rob,

 

"Diagonally split" - thats what i was trying to say but in my very own longwinded way

Didnt see the point of powdercoating or even painting them the original ford green as over time i can only see the paint or powdercoat chipping so just left them in copper.

I know the copper will discolour over time but at least it should be a consistant discoluration as opposed to chips in paint/powdercoat here and there.

 

Not a bad point I tried painting them but as you say it chipped too easily. Next time round I will see how they survive powder coated...

 

Didn't think you could powder coat copper ?

 

Suppose you could I've zinc coated them first

 

They powder coat up fine mate, thats what the powder coater I use told me any way. Just got to make sure they mask up the unions properly.

Rob,

 

Good to know. Dunno were I got that from then, just always assumed you couldn't.

I've got a 4 port rs2000 mc to plumb up in my fiesta turbo at some point. Been putting it off for ages.

 

I tend to find powdercoat as likely to chip as much as paint to be honest - can be quite brittle.

 

To be honest the only real way of doing it is using the proper Ford "green" pipe but it is expensive at £90+ for 10 metre reel and to do the whole car you are looking at £180 + compared to about £35 using copper pipe.

http://www.carpartsexpress.co.uk/RS-...5-249-763-561/

 

Anyway cheers for comments. i cant keep it diagnal and fit a bias valve so it will have to be one system as i already have or a front back split. if i do front back split im worried that restricting one part of the master with a bias valve will make pedal hard and not allow the fronts to work enough???!!!?