Brake bias valves and 4port MC's - Saxperience

saxostuart · 18th April 2011, 23:01

am currently throwing a oilite disk axle from im axles onto the mighty 1.0

wanting to do away with the standard brake bias valve and put an internal adjustable bias valve.

currently have a 4 port master cylinder so do I;

1. t piece the 2 rear lines into 1, run inside to bias valve, then "T" back out to callipers

or.

2. block one port from the master cylinder run one line to bias valve then t off to callipers.

option 1 seems too many connections (thus less braking efficiency), option 2....will i still get good braking power from one port? or will blocking one port make up for this?, and can you get blanking unions? ie what do I use for blocking a port?

Any help/ advise is greatly appreciated

Stuart

saxostuart · 18th April 2011, 23:38

bump no track fanatics on tonight?

AndySAXO^p · 19th April 2011, 08:57

Run one line into the bais valve, thrn one out and t off for the rear capliers,

rorz_vts · 19th April 2011, 09:03

yea i'd also go with option 2 mate hell of alot easier and cheaper, as for blocking it off i cant see why you couldnt use a small bolt with a washer on

Gareth_R · 19th April 2011, 10:16

option 1 is more appropriate, otherwise you'll have 2 outlets going to the fronts and one to the rears, which messes up the balance

run the two pipe from the mc to a T - only needs to be short, just after the master cylinder - then a single line through the car to the bias valve, then single line to the rear and T out to the back brakes

assuming you are running rear calipers as per VTR/S, none of this is necessary for drums

saxostuart · 19th April 2011, 12:01

thanks for the advise, yes its for vtr/s calipers. will it matter if i only have one outlet? as the other one is blocked off will i not get the same fluid flowing through the single port?

swampy · 19th April 2011, 12:13

Its better to run the two lines from the mc in to a t piece and then through the car.
As you use one front and one rear port on the mc it builds a safty margin in to the system.

saxostuart · 19th April 2011, 12:15

swampy, how much for rear setup lol?

kristel10589 · 21st April 2011, 00:27

Quote:

Originally Posted by swampy

Its better to run the two lines from the mc in to a t piece and then through the car.
As you use one front and one rear port on the mc it builds a safty margin in to the system.

Not really.........

wicked-vtr · 21st April 2011, 00:36

Sorry for the hijack but what is the point of these adjustable valves? Iirc the standard unit can mess up if the beam is lowered alot, is this a way around it?

swampy · 21st April 2011, 12:47

Quote:

Originally Posted by kristel10589

Not really.........

erm yes.
That is why a standerd non abs system runs a front port and a rear port for each axle.
So if one circuit fails you still get diagonl braking on one front and rear brake working

kristel10589 · 21st April 2011, 20:20

Quote:

Originally Posted by swampy

erm yes.
That is why a standerd non abs system runs a front port and a rear port for each axle.
So if one circuit fails you still get diagonl braking on one front and rear brake working

sorry re read what you said. I assumed you meant using say, the two rear ports for the rear brakes and the two front for the front etc, which obv isn't failsafe.

Furioman · 21st April 2011, 23:56

Swampy but you are connecting the circuits together, if a pipe bursts on either, both circuits are effected so it wont be any safer than option 2

kristel10589 · 22nd April 2011, 00:03

Quote:

Originally Posted by Furioman

Swampy but you are connecting the circuits together, if a pipe bursts on either, both circuits are effected so it wont be any safer than option 2

This is what I thought when i first read his post.

If you use one port of the MC say front one, that is connected to the front right, then the other front port will be connected to the back left.

Then the back ports on the mc connect to the other brakes. This is how all modern brakes are piped, so if you have a brake failure on one system, you lose braking in one front and one rear brake, leaving you two working brakes, to allow the driver to stay in control, well thats the theory.

On a 4 pot mc the front ports are seperated to the rear.

kristel10589 · 13th May 2011, 17:30

Quote:

Originally Posted by Furioman

Swampy but you are connecting the circuits together, if a pipe bursts on either, both circuits are effected so it wont be any safer than option 2

actually looking back on this, swampy is wrong, the whole system will fail still.

swampy · 13th May 2011, 18:10

Quote:

Originally Posted by kristel10589

actually looking back on this, swampy is wrong, the whole system will fail still.

so every major car company is wrong?
One front port and one rear port is used to provide a diagonal split
so if one hose fails you have one front brake and one rear brake still working.
For safety purposes.

DanGT · 15th May 2011, 08:39

I think people are getting confused. Swampy is correct that the cross diagonal systems manufacturers use are safer as one front and one rear work on the same circuit, however if you convert to 2 ports (blocking off 2) using the one front and one rear then if a pipe bursts you will lose all your brakes, as they are both on one circuit. If you use 2 lines (one from the front right brake and one from the left) you are eppectively using 2 circuits. One for front one for rear, therefore if a line bursts, you will lose either front or rear brakes.

I think, lol.

kristel10589 · 22nd May 2011, 22:45

But your connecting to seperate systems together when they meet at the t piece for the brake bias.

The standard bias keeps the two systems seperate. I.E you have a 4 port M/C. This has two sepratly filled and sealed systems. The back system that feeds the back two ports and the front system that feeds the front two ports.

On standard oem system, one back port would feed one front wheel and the other port will feed the back opposite wheel eg, left hand port of the back group will feed the front right brake, and the right hand port will feed the back left brake. that systems runs fully independant to the front port systems.

Where swampy fails in his statement is that, he is saying use one port of one system to feed the in car brake bias valve and the other port of same system to feed a front left brake.

On the front system one port feeds the front right brake and the other port is linked to the brake bias valve.

That means if one line breaks you will lose all brakes.

If you have the back system only providing the back of the car and the front system providing the front then if one system faisl, you will still have one axle braked.

swampy your system using an adjustable in car brake bias will cause all brakes to fail even if one pipe is leaking.

On the front system one port is feeding the front

kristel10589 · 22nd May 2011, 22:46

Quote:

Originally Posted by DanGT

I think people are getting confused. Swampy is correct that the cross diagonal systems manufacturers use are safer as one front and one rear work on the same circuit, however if you convert to 2 ports (blocking off 2) using the one front and one rear then if a pipe bursts you will lose all your brakes, as they are both on one circuit. If you use 2 lines (one from the front right brake and one from the left) you are eppectively using 2 circuits. One for front one for rear, therefore if a line bursts, you will lose either front or rear brakes.

I think, lol.

you sound confused.