Brake Master Cylinder

[KnezicDex]

So today i put in the 2010 mazda 6 brakes and the brake pedal has much free play (i need to push it more than half before it engages). I think that the stock brake master cylinder isn't cut out for the job. Is there some easy upgrade or mod to improve the master cylinder? What do you recommend?

[MonoxideChild]

Sounds like you need to bleed the brake's some more.

[Black Widow]

When I did my Mazda 6 brakes, I flushed out all the old fluid...and I had much better pedal feel...almost too touchy, 'till I got used to it.....MUCH better braking power now

I think you still have air in the system causing a soft pedal feel.

[stoker100]

ive have the same issue (pre mazda 6 brakes) ive been thinking its the booster too as ive bled my brakes 3 times (used about 2l of brake fluid) and its still not any better, ive even engaged the ABS diagnostics to hopefully pass any old air/fluid out and then manually engaged them by locking the wheels up on gravel. nothing seems to work IMO.

[KnezicDex]

Ok. I'll try bleeding the brakes once more. Should i replace the brake oil with new? I replaced it last year. Any tips on bleeding the brakes? And most important, whats the capacity of brake oil(how much is in the car? eg. engine oil is 4.6l according to pp.com)?

[MonoxideChild]

If the system was totally dry, It might have 1L in it. Being that its not, you wont even go through half of that.

[notso swift]

Any tips on bleeding the brakes?

Buy one of those tubes with a one way valve
Saves so much time and cost bugger all from a parts store
Doesn't need to be the fancy "gun style" pumps, just a simple clear tube, 8" long with the valve, then another 8" to a bottle

[MonoxideChild]

I have a chunk of 1/4 inch clear tube thats like a foot and a half long. Then a Mountain dew bottle with a hole drilled in the cap that the hose goes through.

I just put the hose over the brake bleeder. and the other end of the hose stays under the fluid level in the bottle. Total cost, Not a cent.

Ive been using the same exact bottle and hose for over a decade. Many members cars on this very forum have had there brakes bled through that very bottle.

[KnezicDex]

How to know if my brake master cylinder is dying?
I tested my brakes and my rear brakes hardly brake and you need to floor the brake pedal.

[RWT]

When you say that you installed the Mazda 6 brakes, does that include the calipers?

If so, are the pistons in the Mazda 6 calipers the same size as the Probe's?

If not, you'll need to change the size of your master cylinder.

[KnezicDex]

I spoke too soon. The more i drive the better the brake feel is. Very happy with the new brake kit from the 6.
I'm worried about my rear brakes, they are very very weak. Pads are almost new, disc sucks but i cant believe the braking is so weak because of the discs... Maybe the mc cant pump enough oil to the back or the lines are bad.

[1989probe]

For better feel try using a master cylinder from a 1993 Mazda 929, it has a larger bore and looks like it will fit like stock but you will need to change one line to a flare fitting. I am going to try this on mine and I know the rx7 guys have been doing it and they have the same size of master cylinder as ours.

[KnezicDex]

When you do it, let me know if it fits. Would gladly upgrade the mc!