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EPB Caliper Question

In this thread yrwei52 commented on Aug 25 that it is not normal to have a brake pedal that goes all the way to its mechanical stop when fully depressed with the engine running (car parked). I had asked about this since my pedal does that. Since then I've checked several late model cars whenever relatives or friends visit and so far every one I've tried allows the pedal to go to the stop when the engine is running. All of these cars seem to have normal brake performance when driving. Would anyone like to try this and comment?
 
oops, just noticed that anchorman wrote a great response to my earlier question. Not sure how I missed seeing it. Thank You! BTW, my situation is all good. Replaced calipers work great. E-brake works great. Just still a little disappointed that Mazda didn't do a recall.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
In this thread yrwei52 commented on Aug 25 that it is not normal to have a brake pedal that goes all the way to its mechanical stop when fully depressed with the engine running (car parked). I had asked about this since my pedal does that. Since then I've checked several late model cars whenever relatives or friends visit and so far every one I've tried allows the pedal to go to the stop when the engine is running. All of these cars seem to have normal brake performance when driving. Would anyone like to try this and comment?
When you said “allows the pedal to go to the stop” on every car you’ve tried, did you mean the brake pedal went all the way to the floor with the engine running?

Honestly, I have never had such experience before. But may be I didn’t try “harder” pressing the brake pedal with the engine running. That’s why I said that’s not normal in post #14 originally. @Anchorman did great explanation on this and said it’s possible to press the brake pedal to the floor with the engine running in post #38.

Thanks for the update on this “surprising behavior” (to me, at least).

 
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2022 2.5GT
The tip on air in the vehicle brake system was a handy one as after I got it bled/flushed by myself, I found, what I thought to be, some spongyness in the pedal. Trying it with the motor off, there is definitely excess play in it and I will have to bleed again with a partner (or I could gravity bleed or I have a vaccum pump that I have never used) when I change over to winters. I did use the procedure described in post #10, other than doing it solo.
To test, make sure you pump it several times with the engine off to full exhaust that vacuum in the servo 😉
 
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'16 Mazda CX-5 GT
To test, make sure you pump it several times with the engine off to full exhaust that vacuum in the servo 😉
So, if I am reading this correctly, there should be almost zero play in the pedal once you have pumped it up, but that there would be some initially? That seems to be what I am finding now as some initial play with the car off, that firms up after a few pumps.
 
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2022 2.5GT
So, if I am reading this correctly, there should be almost zero play in the pedal once you have pumped it up, but that there would be some initially? That seems to be what I am finding now as some initial play with the car off, that firms up after a few pumps.
Err, let me put it a different way. If your car has front and rear disc brakes (rear drum brakes are slightly different) now imagine there is no vacuum servo to help you press the pedal. You can’t ordinarily compress a fluid so the only play should be the small amount at the top of the pedal which is actually in the linkage between the clevis pin and the push rod. Apart from that (about half inch), the pedal will feel virtually solid and not travel. If you sit for a minute it should feel the same. If it travels further than it did before but comes back to the top after pumping I would suggest there is air in it and you could improve that by bleeding. Now remember that disc brakes are self adjusting and they sit with the pads in very close proximity to the disc. When you press the pedal, they hardly move before grabbing the disc (I think you call them rotors) and when you release them they don’t actually return to a stop like a drum brake, there is a little straightening up of the piston seal and the rotating discs clear a path. It’s a bit like tensing a muscle rather than physically moving the pads. With that in mind, you will feel that tiny amount of give in the four brakes under your foot when you press and if you take a wheel off you might see the flex pipes tense up so if you feel that slight give right at the top before coming solid then fine. If you’ve got strong legs, you’ll bend the pedal and the bracket slightly too. As long as it doesn’t travel further. To be honest, if it gets to that stage, don’t beat yourself up because it won’t make any difference. Try any new car in a showroom because they’re new and perfectly bled and they don’t get started so there is no chance of any vacuum assistance kidding you.
 
:
'16 Mazda CX-5 GT
Err, let me put it a different way. If your car has front and rear disc brakes (rear drum brakes are slightly different) now imagine there is no vacuum servo to help you press the pedal. You can’t ordinarily compress a fluid so the only play should be the small amount at the top of the pedal which is actually in the linkage between the clevis pin and the push rod. Apart from that (about half inch), the pedal will feel virtually solid and not travel. If you sit for a minute it should feel the same. If it travels further than it did before but comes back to the top after pumping I would suggest there is air in it and you could improve that by bleeding. Now remember that disc brakes are self adjusting and they sit with the pads in very close proximity to the disc. When you press the pedal, they hardly move before grabbing the disc (I think you call them rotors) and when you release them they don’t actually return to a stop like a drum brake, there is a little straightening up of the piston seal and the rotating discs clear a path. It’s a bit like tensing a muscle rather than physically moving the pads. With that in mind, you will feel that tiny amount of give in the four brakes under your foot when you press and if you take a wheel off you might see the flex pipes tense up so if you feel that slight give right at the top before coming solid then fine. If you’ve got strong legs, you’ll bend the pedal and the bracket slightly too. As long as it doesn’t travel further. To be honest, if it gets to that stage, don’t beat yourself up because it won’t make any difference. Try any new car in a showroom because they’re new and perfectly bled and they don’t get started so there is no chance of any vacuum assistance kidding you.
Thanks for the explanation and I will leave off further bleeding as I think I am chasing a non-problem at this point. Brakes work well and are quiet, so will leave well enough alone and monitor them going forward for any excessive dragging.