PoonerElRay

This morning as I was driving out of my garage I noticed a thin layer of ice over the pavement. I was going say 10km/hr and I applied the brakes abruptly and I felt this strange force on my brake pedal while the car was trying to stop. It also sounds different too. It's really hard to explain.

It sounds like a rough, grinding noise when you apply the brakes - like something is going to break. The feeling on the brake pedal is like you're pressing against something hard and rough.

Has anyone experienced something like this?

TimmyC230boy

That the ABS making the noise. Brake assist reads hopw fast you apply force on the pedal and if its over a certain degree it will aply 100% braking power.

darkfact

I experienced the brake assist once.
I was driving at a speed of 20Km/h. at that time one of my neighbors just bought the new SL. So I was looking at it not paying attention to the road. Cuz I thought I was driving slow. I looked in front of me and I realized there is a pothole right in front of my bumper.

I wasn’t driving too fast and all what I needed is to slow a little bet. But my reflexes were a little bit fast…
I pressed the brake with the edge of my fingers yet the car brakes were so strong that the car stopped at the same second and I felt like if I was driving fast and the car stopped all of a sudden. My body was thrown to the front and the seat belt held me back. meaning that the brakes were soooooooooo strong despite the fact that I didn’t press them hard (just fast) and I pressed them only with the tip of my foot!!

That’s really reassuring and gives confidence :p
I guess that’s why I paid 28K for a hatchback.

truelove

yup, that's ABS. it's really surprising if you've never felt it before. then it's cool cause you know the cars working for ya.

bora

Personally I could do without brake-assist, I am trained enough to modulate the brake pedal when necessary and hammer it down in an emergency.

Is there a way to turn this feature off?

darkfact

"...reducing the overall stopping distance by eliminating the delay caused by a common human tendency not to brake hard enough, soon enough."

So, I think no matter how hard u can press it... You'll still want it to be there.

truelove

um, i'm sorry but unless you're some sort of android there is NO way you can pump the brakes fast enough or hard enough to be able to disregard these features. i don't care how trained you are (and you may be VERY trained), you're no computer. i think ABS pumps at something like 20 times a second or something.

MarkL

Ditto that!

bora

I don't recall saying I want to turn off ABS, I said I want to turn off
brake assist. **HUGE** difference.

jswedberg

As far as Brake Assist goes, if you never panic and you are always on top of the situation, you will never feel Brake Assist. It's for those "oh sh..t!" situations.

And for ABS, if you read the car magazines, it is practically impossible for even a professional to stop as fast in a non-ABS car.

The Viper, for instance, has always braked (relatively) poorly, and they invariable cite the lack of ABS. That's why the new one has it.

truelove

you said you were trained enough to modulate the brake pedal which i took to mean ABS. and no human is physically strong enough or fast enough to do the brake's assist's job either. and as for that **HUGE** difference, the difference becomes smaller when you consider both systems are there to save your life in a way that no human can.

sorry, just giving ya a hard time.

bora

If when you floor the brake pedal, the ABS engages, you are strong enough. What brake-assist helps in is when people do not
press the pedal hard enough even in panic stops. I find the MB brake-assist feature obnoxious. It is too sensitive and engages very early. I wish one could tune the sensitivity of this.

As far as ABS itself, if you know how to modulate the pedal so you are doing threshold braking (with no lockup) then you will brake faster than ABS. Most people are not good at threshold braking, and so ABS helps out in this regard. In the wet/snow, I would not dream of not having ABS.

On the track, ABS comes in handy when you go too deep and too fast and end up locking up and it prevents you from flat spotting your tires.

truelove

if you're feeling the brake assist on an everyday basis then you're either driving like a maniac or something is wrong with your car. if you don't need it, the car shouldn't use it.

have you ever tested yourself against a car with ABS (all other things being equal)? or read any articles from people who have? if not, how do you know you or any other person can brake faster (all other things being equal)?

bora

On dry track, I can brake faster than ABS (but not all the time), this is pretty easy to do with my race car (just pull out the ABS relay).

This is a well known fact in open track/racing circles, I am surprised you have not heard this before. The reason is as follows. With ABS, you have a duty cycle of brakes on and off, say with a very good abs unit you are braking about 95% of the time.

With threshold braking at impending lock-up, you are braking 100% of the time.

With threshold braking, one is not pumping the pedal (like ABS does), you are on the pedal all the time, just minutely modulating it so that you do not lock-up. This is easier to do in lighter cars like Formula Ford (think Russell Racing school) and harder to do in heavier sedans. This is one reason why real driving shoes have thin soles, so you can feel the pedal more.

You may want to review some of Carroll Smith's (I hope I got the name right) books on this topic as well, they are available at Amazon.

As I said before, on wet track/snow/ice, all bets are off.

truelove

okay, i see your point here (even though i am an engineer, i can admit when i'm wrong). and you did say that you didn't want to disable ABS which makes sense cause i don't think you wanna mess with your method all the time, like when going to the grocery store (unless it's extremely second nature for you ). and like you said, it's needed for ice and snow.

but do you really feel the brake assist all the time? i don't think i've ever felt it. and i certainly wouldn't want to disable it for those times i choose to blink at the wrong instant.

bora

I am engineer too !

I don't feel brake assist all the time, only when I get on the brakes hard enough to trigger it. I feel that its threshold should be raised a bit.

Matt230K

Big Sheesh, make sure you remember that feel from the ABS and be used to it for when you need it. Many people get in accidents because they feel the pedal pulsating for the first time and lift off the brakes.

bora, I'm assuming you have fast feet as a race car driver. Are you fast enough switching from gas to brake that BAS works, even when it is not in a panic. Not that I try, but I find it hard to make yourself press the pedal as fast as you would in a panic. I used to try locking up when I didn't have ABS, and it's hard sometimes to force yourself to hit the brakes that hard if you don't need to. It's much easier in a panic.

mctwin2kman

I have not had BAS activate on me yet just the ABS when first tapping the brakes in the snow. I have Pirelli P-Zeroes on now so I expect that. But I agree that ABD is not needed on Dry pavement if you know how to brake. You never just slam them down as hard as you can even in an emergency, unless you have ABS because it will actuvate and correct you braking. Without it on a dry road I can stop faster than a car with it probably 7-8 times out of 10. Same with BAS, it may be nice but us younger folk tend to get on the brakes hard in an emergency. Unfortunatelly without ABS we would most likely lock up at first if we just slammed on the brakes, with BAS added it will help the older or just slower in general folk to avoid an accident or two. But if you are that slow that you need BAS you will most likely hit what you are stopping for most of the time. Because if you really do need it you are most likely too darn close to begin with. I like smooth gradual stops, not my chest being held back by a seatbelt.

susemu

Well, if I am driving on ice, snow etc. I sometimes feel the pedal and hear that sound (kinda metal rubbing, creaking sound thingens, really hard to explain) - but that is not the brake assist, in my case it is the ESP breaking the wheels differently.
I once had a real situation where I was da*n glad to have BAS. I was driving down the road at about 40-50 mph when the driver in front of me (about 40 yards away) stepped on his brakes like a maniac. I was at that very moment busy looking into my rear view mirror and when I looked forward I just saw the car in the front getting bigger very fast and I just stepped automatically on the brakes like I'm a maniac myself... :o Well, my car did brake so fast and brutal that everything I had on the back seats came flying to the front, but I stopped in time
BTW - as good as this feature is, you don't want anybody behind you too close....

darkfact

when I first bought my car and when I used to brake some times it feels like if the brake pedal is pushing back. why is that?

It doesn't happen anymore. or maybe I just got used to it and I don't feel it anymore.

bora

Hi Matt

I honestly don't know if I have fast feet, I think my reflex reaction time is pretty fast and when I need to brake, I don't baby the pedal. I guess I just have to squeeze the pedal real gently to avoid engaging BAS even in an emergency stop. And
another comment was right, you do not want a car following you closely when BAS engages.