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Discussion Starter #1
Hi all

I was in a situation earlier today where I had to break suddenly. The breaks felt really hard rather than the usual soft touch.

The circumstances meant that it was safer to overtake so I didn't get to see if the break efficiency was normal. Does anyone know if this is an issue or some sort of feature?!

It's a brand new car and I have had 0 issues with it so far.

Thanks in advance

MrG
 

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Hi all

I was in a situation earlier today where I had to break suddenly. The breaks felt really hard rather than the usual soft touch.

The circumstances meant that it was safer to overtake so I didn't get to see if the break efficiency was normal. Does anyone know if this is an issue or some sort of feature?!

It's a brand new car and I have had 0 issues with it so far.

Thanks in advance

MrG
In an emergency situation your perception of things can change but you could have experienced the car sensing an accident was going to happen and pre-tensioned / assisted your braking.

It may not be exactly the same thing, but I remember in my 1 Series that I felt a similar sensation and the car would stop in a much shorter distance - I tried to invoke this on an empty road but it just didn’t seem to happen so I concluded that the car sensed a real emergency situation probably by sudden deceleration caused by a panic stomping of the brakes!

I assume you didn’t come close to an accident, but did it feel like the car was stopping well or did it feel like you weren’t going to stop?

The other thing to remember is that these hybrids carry at least an extra 200kg over the equivalent non-hybrid model and that weight transfers forward and can feel quite alarming when experienced for the first time. I drive a MINI Countryman PHEV and I definitely had that sensation when I swapped from my 1 Series.
 

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CTiD
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410 Posts
Hi all

I was in a situation earlier today where I had to break suddenly. The breaks felt really hard rather than the usual soft touch.

The circumstances meant that it was safer to overtake so I didn't get to see if the break efficiency was normal. Does anyone know if this is an issue or some sort of feature?!

It's a brand new car and I have had 0 issues with it so far.

Thanks in advance

MrG
I read that and thought you had a sudden urge to pee or grab a Flat White...
 

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Discussion Starter #5
It was late when i wrote that!! I went into bmw today and said that that BRAKES lose the vacuum when slammed on which causes the hard feeling I experienced. Everything is ok! Thanks for your replies
 

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It was late when i wrote that!! I went into bmw today and said that that BRAKES lose the vacuum when slammed on which causes the hard feeling I experienced. Everything is ok! Thanks for your replies
Unless this is something to do with the emergency brake assist mentioned then I would question the feedback you were given... the Servo should only drop the vacuum after a number of pedal presses and when the engine is running that vacuum should be maintained... strange feedback unless the whole principle of servo assistance has changed since I did my training and trained others...
 

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Yes the BMW advice seems strange.

I know the leaf is a completely different beast, but when you brake hard in it, the braking force is the sum of the regen plus friction brakes. If during this hard deceleration you trigger ABS for example by having one wheel slide on a manhole cover, the computer seemingly can't cope and regen instantly goes out of the window leaving you with only the friction brake component, the effect being you actually lose instantly a good proportion of the braking force you had been applying. Has happened to me a few times, and in one particular roundabout approach in the wet it is a given, and it can feel like the brakes have failed, and you do have to slam on to compensate. Could it be something like this?
 

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its probably been either emergency brake assist (though that would have meant you were VERY close/about to crash), or more likely the ABS/ESP system taking over. When ABS/ESP cuts in it does all manner of weirdness with the brake pedal, as it needs to take the driver out of the loop. The pedal usually feels "locked out" in that situation. Older ABS cars you'd feel the pedal bouncing as the ABS did its thing, but newer systems have their own pumps to generate pressure, and the pedal just goes hard instead.
It only takes a bit of gravel, a white painted line, or a wet manhole cover to allow a wheel to lock if you hit the pedal hard and then the ABS/ESP system steps in.
 

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Discussion Starter #9
The collision alert didn't beep so it wasn't that. At the time I thought a bottle had rolled under the pedal as it seemed to brake but only moved an inch, the issue was that it was a risky situation so i wasn't prepared to assume all was ok. Ive decided to get a second opinion just to be safe. Ive been out quite a bit this week and have had no issue. Thank you all for your replies!
 
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