Brake Master Cylinder Plumbing

[toger13]

Hi I have a saxo vtr well it used to be lol

It is fitted with the standard 4 port MC

When I first used it on track back in 2005 i found it to be locking up all the time at the rear even with the rear bias/load valve fully backed off and servicable

I then fitted some Hispec 300mm 4 pots which made the problem worse presumably due to more weight transfere

I even found it the same on the road and wasnt happy so I removed the standard valve on the rear axle and replaced it with a tilton bias valve

When doing this the bias valve is only single port so i decided to change the diagonal split as standard to a front/rear split obviously as a fail safe if i get a leak

This transformed the handling on the road with no rear locking and loads more confidence especialy in greasy conditions, I only did 1 short track day after this before taking the car off the road for a 16v turbo conversion

Now in 2011 its back on the road and i have done a couple af track days but im not happy with the brakes I seam to have to stand on them as hard as i can and cant brake as late as I think I should im just getting mullered on the brakes by most cars

Now to the point how does the inside of a saxo/106 MC work is it 2 fixed chamberes? As if it is the front brakes will require far more fluid movement than the rears and wonder if im fighting the bias valve?

Sorry for the essay lol

What does every one think?

Si

[Nick3point2]

If the car has been off the road for a while and it has hispec brakes fitted I'd imagine the caliper seals have rotten and are leaking, thats exactly what happened to my hispec brakes.

[toger13]

Na they are in perfect condition free as a bird, first thing i thought but I think they were prob like it all along but was just relived at the time that it didnt try and change ends every time i braked hard lol

Si

[Mr2Mike]

Do you have the ports on the M/C correctly connected? Normally the port(s) nearest the pedal/pushrod/servo end would be connected to whichever circuit has the least volume (normally the rear). If the low volume circuit is connected to the front of a typical master cylinder it can limit the pressure available at the other ports.

[toger13]

Ye the rears are at the back of the mc and the fronts at the front of the mc but in the standard car obviously both circuits will be excactly the same capacity so i wondered if this could be the problem?

Thanks
Si