R32 Brake System Problems

[blackrb20silvia]

hey all i hope you can help

im having problems with my brake system

i have equipped

R32 M spec 4 piston callipers

ABS system bendix ultimate pads

castroll super dot 4 fluid

stock rear callipers and pads

nissan patroll ABS master cylinder

i am having problems when i blead the brake system the brakes are fantastic for like 3 months then they go really soft over like 2 week period

i dont know what the problem is as there are no leaks in the system anywhere and the master cylinder never needs topping up

i cant work it out

is the master cylinder not suited (patrol cylinder is a long story basically the brake shop lost it and replaced it with this supposed to be the same throw and bore size

what can it be is the fluid not suited should i be using a better brand fluid and if so what brand as i want better fluid anyway as i will be doing club level racing next year

should i change the master cylinder to something else (the car is a s13silvia with RB20 allready eqiupped with standard ABS in the silvia)

and if so what?

if any one has expieriance with any of these problems please let me know its starting to get annoying bleeding the brakes every couple of months

should i get the lines remade?

can i use thread tape on the lines for "just in case"?

thanks guys heaps

cheers

Matt

[blackrb20silvia]

also if i can ask sydney kid and any other expeirienced or knowledgable people a question

i bleed the brakes this arvo all was well and good flushed 3 bottles of motul 5.1 (i used this because on motuls web site they said specially designed for ABS units so wont ruin seals in the ABS)

any way as i bleed the ABS unit the front the ABS again the front again

then moved round the back did the passanger side all good so far but when i got to the drivers side i found a problem

when i bleed the brake calliper after the fluid ran out the line (you can see it) no matter how long i bleed them for it looks like its sucking air in some where in the system and ill be stuffed if i know where from and it only happens on this calliper

if it only happens on this side what can it be

and is this causing my previuos problem

[blackrb20silvia]

problem found worn wheel bearing pushing calliper pistons apart have to presss once to clamp then second to grab