Brake master cyclinder problem

[genkimashi]

recently i swap to a 15/16 brake master cyclinder into my crx... n nowadays when the car stop at a traffic light.. i would just step on the brakes rather than the handbrake... but when i step on the brakes... the brakes pedal will slowly creep to the floor.... does tat mean my BMC r rooted... the piston is gone ??

Any help r appreciate...

Cheers

[CRXer]

does it happen constantly or just on the odd occassion?

[EKVTIR-T]

losing any fluid?

[genkimashi]

constantly been like tis ord... for the past weekk.....n i dun think i'm loosing at fluid....

[bennjamin]

if th pedal sinks down further past and dosent firm up then the cylinder bore is shot or the seals are gone , regardless you need to rebuild it or replace

[CRXer]

did u bleed it fully?

also did u bench bleed the MC before u installed it,or just put it in & bleed the whole system?

[d15z1SUX]

i had the same problem. until i changed my whole master cylinder along with the brakes.

[bennjamin]

did u bleed it fully?

good point
when installing you should "bench bleed" the master cylinder before hooking up the two lines-once with fluid then bleed te entire system as normal
probably a big gulp of air still inside the mastercylinder

[CRXer]

yep,take the MC off again,make sure its level on a bench or in a vice or something & then bleed it before u install it.

[genkimashi]

erm... not too sure whether did it bench bleed... as it was done at a mechanic workshop... i'll double check with him again... 2 confirm stuff...

n wats a bench bleed ? n how u do tat... i know how to bleed the whole brake system... but not sure bout bench bleed... any tips ?

[CRXer]

u bench bleed because the MC sits at an angle when installed in the car,so it makes it difficult to get all the air out.

just take it out & make sure the MC is held close to level,then just push the rod slowly in & out,while making sure the fluid is kept topped up,to get the air bubbles out.Then install it back to the car with fluid topped up,then do a regular bleed on the whole system.

just dont push the rod all the way fully into the cylinder, as it will be going to places it has never been before(except if uve been pushing your foot all the way to the floor already) & u could damage the seals on scores or burrs inside the bore that have always been there previously.

[genkimashi]

thx for the info guys... i'll double check to see wats going on.... much appreciate for the help...!!