I'm sure you have heard when bleeding brakes... you "start at the wheel furthest away and work closer to the master cylinder." This does not apply to the Mazda 3... it has a diagonally split brake hydraulic system... not a front/rear split like cars of yester-year and most trucks/SUVs.

The left rear and right front calipers are on the same circuit in the MC... and the right rear and left front circuits to share the same port.

The benefit to this is that you will only lose 50% of your braking ability should one circuit start leaking. In a FWD car with a front/rear split, if you lost the front then you would lose about 70+% of your braking ability... not to mention locking up rear brakes would potentially spin you in a hurry, making the situation even worse.


The only reason that the old "start with the wheel furthest from the MC" BS was started was that back in the day cars only had ONE type of brake hydraulic circuit... the fronts were on their own circuit, and the rears were on their own circuit. So of course the rears are the furthest away... so going by that logic you bleed the rear circuit before the fronts... which is exactly how you're supposed to do it on a front/rear split system.


When you bleed the brakes in the "old" and wrong method(on a diagonally split system)... you bleed the right rear just fine... but when you go to the left rear next, you are starting a new circuit entirely... so every time you pump the pedal to bleed the left rear, you are sloshing brake fluid in the RR-LF circuit back and forth, adding a zillion bubbles of air because the new fluid you JUST put in there is getting aerated because it's not going out in one direction. At the very least, you are intermixing old and new fluid... defeating the purpose of bleeding brakes.


Also, I constantly see people struggle with bleeding brakes and nearly EVERYBODY completely screws it up and ends up with only an "acceptable" pedal when done, while thinking it's as good as it gets... but when done properly it is so much better.

The proper way to bleed brakes is to do this(for each wheel... in the correct order... discussed below) if you have a helper available:

1) Have a helper stand on the brake pedal

2) Crack bleeder screw. (Your helper will/should feel the pedal go to the floor... make sure they do not let up until step 4!) Use a clear hose to watch bubbles leave the system and pay attention to the color of the fluid.

3) Close the bleeder screw when the flow stops

4) Have the helper SLOWLY let the pedal up

HERE IS WHERE EVERYBODY COMPLETELY SCREWS IT UP!!! IMPORTANT: DO NOT under ANY circumstances let your helper "pump up the brake pedal." All they are doing is aerating the fluid and introducing more air into the system that you just started bleeding. It is a LOT easier to get out one large air bubble than it is to get 10,000 little micro-bubbles out of the system. The smaller the air bubbles, the more likely they are to stick to the walls of the inside of the tubing... letting fluid go around the air and defeating the purpose of bleeding.

5) Have the helper step on the pedal again... note that it will feel soft and feel like crap, etc etc. Again... do NOT pump the pedal until the VERY VERY end! Fluid WILL come out when the bleeder is cracked! Just the pedal will not feel very responsive until the END.

6) Crack the bleeder screw again and watch the fluid leave the hose again. You can even listen for air bubbles and know if you're in a not-too-loud environment

7) Close bleeder when the flow stops

8) Have the helper slowly let the pedal up again

Then you repeat this until the wheel you're bleeding is good, then go to the next wheel. BE SURE TO CHECK THE MASTER CYLINDER RESERVOIR CONSTANTLY TO ENSURE YOU DO NOT RUN IT DRY! GETTING AIR OUT OF THE SYSTEM WHEN THE M/C INGESTS AIR IS CONSIDERABLY MORE TIME CONSUMING. I generally top off the M/C at the start of each wheel and check/top off about every 4-5 "pumps" with the bleeder open. Start out checking a bit more often to get a grasp on how quickly the fluid is displaced to minimize the risk of putting air into your system!!!

AGAIN... DO NOT "PUMP PUMP PUMP PUMP PUMP" to make the pedal "feel" hard until all 4 wheels are bled and you are done. It doesn't matter what the pedal feels like while bleeding, the idea is to only make the fluid move in ONE direction... that is towards the calipers and out of the bleeder. By pumping it, you slosh it back and forth and intermix good fluid with bad, and more importantly(and stupidly) fluid with air if there is any present.

I guarantee you will not get a better feeling pedal by doing it any other way manually.

I bled the brakes on my 09 Mazda3i last weekend and verified it is indeed diagonally split hydraulically.



(Sorry for the super crappy quality pic... my phone's camera is terrible)

I figured it out by having my friend hold the brake pedal, I cracked the right rear bleeder, and with him still standing on the pedal to hold it at the floor, I walked around to see which rotors I could spin by hand. Surprise-surprise... with the right rear bleeder cracked, the right front and the left rear rotors were clamped solidly... the right rear and left front were free to spin since there is no hydraulic pressure acting on the pistons(since I had the bleeder cracked).

Mystery solved. If you don't believe me then try it for yourself next time you bleed your brakes.

I bled the brakes out with some Prestone DOT 4 in the following order:

(2)LF - RF(4)
...|xxxxxxx|
...|xxxxxxx|
...|xxxxxxx|
...|xxxxxxx|
(3)LR---RR(1)


Or spelled out plainly: Right rear, then left front, then the left rear, then the right front.

The pedal feels amazing now by the way... I really didn't expect to feel a super noticeable difference since it's only an 09 model year with only 36k miles. It's much easier to modulate since it feels more linear.

I will add that in all reality, the order that you bleed the brakes does not really matter... as long as you bleed one circuit entirely before starting on the other. I think the "start at the line furthest away" thing is mainly so you fill the longest line with fresh fluid first.

One more thing to add: If you think you have air bubbles remaining in the system, -a slight- modification to the bleeding procedure above can be done to aid in forcing the air bubbles past high spots.

Tell your helper to let the pedal up, then you open the bleeder... instruct them to STOMP on the pedal as hard/fast as they can, and hold it to the floor(do NOT allow it to come back up)... then you close the bleeder. I tend to do this once or twice after the fluid "appears" good at each wheel to make sure there isn't anything trapped that I don't know about... then finish up with one last "pump" with the typical method above. Neither method will introduce air into the system, it's just what I happen to do.

I posted this in another thread on brake bleeding but thought that it might be beneficial to make its own thread.

I take no responsibility for anything you mess up because you fail to follow my directions or misunderstand something or lack common sense or because of other problems with whatever the hell you're driving.