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Old 03-22-2014, 03:42 PM
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Brake pedal hard on second press?

Just noticed this today.. I pressed the pedal, stopped (on an uphill).. let my foot off and pressed again (not sure why i did) but it became like a rock to press??

once I moved abit forward.. it was fine.. but I can reproduce this.
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Old 03-23-2014, 11:34 AM
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Mine does the same, very reproducible. Perhaps someone with more automotive knowledge can chime in on this and tell us if this is normal.
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Old 03-23-2014, 05:52 PM
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Normal. The first press preloaded the brakes. On the second press they barely need to travel to make contact, hence the harder feel.
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Old 03-23-2014, 06:03 PM
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Old 03-23-2014, 06:50 PM
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I also just noticed the "uphill" reference as well. That could also be hill start assist -- it will also pressurize and preload the brakes to hold you on an incline before you accelerate. Either way it's normal behavior.
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Old 03-23-2014, 08:30 PM
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Re: Brake pedal hard on second press?

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Originally Posted by Peter_K View Post
Normal. The first press preloaded the brakes. On the second press they barely need to travel to make contact, hence the harder feel.
So why doesn't it do it downhill?
And if you just touch the gas why are the breaks suddenly no longer preloaded.

The breaks actually preload when you take your foot off the gas.

I believe it's some sort of anti rollback feature.

My wifes VW has an "Auto Hold" feature on her manual transmission. But the Automatic Transmission version also has the same "Auto Hold" feature (dual clutch transmission). I think it's some variation of that. It would allow engine to run at lower RPM at idle with less friction in the torque converter. Cars generally are not supposed to roll back with automatics (with in reason) even with foot off the brake.

It disengages as soon you touch the gas.

Yet another reason why alarms go off if you drive two footed.
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Old 03-23-2014, 09:15 PM
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Quote:
Originally Posted by mswlogo View Post
So why doesn't it do it downhill? And if you just touch the gas why are the breaks suddenly no longer preloaded. The breaks actually preload when you take your foot off the gas. I believe it's some sort of anti rollback feature. My wifes VW has an "Auto Hold" feature on her manual transmission. But the Automatic Transmission version also has the same "Auto Hold" feature (dual clutch transmission). I think it's some variation of that. It would allow engine to run at lower RPM at idle with less friction in the torque converter. Cars generally are not supposed to roll back with automatics (with in reason) even with foot off the brake. It disengages as soon you touch the gas. Yet another reason why alarms go off if you drive two footed.
Read my second post
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Old 03-23-2014, 09:20 PM
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Re: Brake pedal hard on second press?

Quote:
Originally Posted by Peter_K View Post
I also just noticed the "uphill" reference as well. That could also be hill start assist -- it will also pressurize and preload the brakes to hold you on an incline before you accelerate. Either way it's normal behavior.
Correct, you are stacking pressure ahead of the ABS module, already charged for the hill keep assist.
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Old 03-24-2014, 08:45 AM
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Re: Brake pedal hard on second press?

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Originally Posted by Willx View Post
Correct, you are stacking pressure ahead of the ABS module, already charged for the hill keep assist.
Actually you are probably pushing against a closed valve. And not applying any pressure to the actual brakes. Hence the "rock hard feel".
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Old 03-24-2014, 09:22 AM
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Re: Brake pedal hard on second press?

lol ok.. i thought maybe it was something to do with the hill assist.. It was odd I had never noticed this before! Panicked a little (Bad memory of my old 68 camaro Master cylider lock up! lol)
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