cobradav

This is a quote from the UK BMW web site in March of 04 specifically in reference to the E60.

"Brake Force Display.
How does it work?
Brake Force Display is based on a variable brake light, which warns following drivers if the car in front is slowing down dramatically. Braking deceleration on the wheels is measured via the ABS sensors, and if deceleration of more than 5m/sec2 is detected, then an additional section of the brake lights is illuminated (or depending on the model, additional LEDs are activated within the brake lights). The third centre brake light is not affected."

Now from this I gather that it is more than simply of ABS is active. It uses the sensors of ABS to measure the deceleration and it has to meet the figures above, and yes it it probaly means that in 99.9 % of these cases you would be into the ABS, but not just because you have ABS active.

Once I get past my break in period I plan on trying in an out of the way parking lot some night with one of my eager sons to monitor the effect.

Iceman

Actually dont ALL BMWS have LEDs now besides the E60?
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X5, Z4, X3, and 1 Series dont have

So for the current production BMW's only the 7 and 6 have
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ALL BMW's have it in the one or the other way.
The E60 has LED's in the third brake light.



That's correct. That's why I said "to a complete stop". At the end the BFD is activated. It's not just the fact your ABS is active, but it wont happen when ABS is not active.

EBMCS03

Cool have your sons record it on film too...

E60Speed

Actually dont ALL BMWS have LEDs now besides the E60?
[/quote]

X5, Z4, X3, and 1 Series dont have

So for the current production BMW's only the 7 and 6 have
[/quote]

The 3 has it too. 3 has it but 5 doesn't??????
[/quote]


There are no 3 Series in customer production at the moment, and it has not been confirmed if the new 3 has LED or LED look brake lights

The old 3 series coupe only had it as indicators

And as Iceman said they all have them in the 3rd brakelight.

Anywhay whats so great about having them as the normal brake lights ?

Rudy

Iceman, I'm confused. I always thought that the principle behind BFD was to differentiate between normal, gradual stops and panic or emergency stops. The thought being that if I am stopping suddenly, the driver behind me needs to know about it before the deceleration is so sudden that a rear-end collision happens. In many dry-weather conditions, you can panic stop (and BMW's Brake Assist or whatever it's called will maximize brake pressure) without ABS intervening (even though ABS is always "active" and monitoring the current wheelspin to detect impending lockup.) If BFD only illuminates the extra bulbs "when ABS kicks in" and when you come "to a complete stop," it pretty much defeats the purpose of the system, doesn't it?

cobradav's post makes way more sense. The ABS sensors (which are always active) calculate a deceleration rate that is known to be sudden (based on the formula he posted) and immediately activate the extra BFD bulbs to warn other drivers that the car is slowing more suddenly than normal. The bulbs may stay illuminated up to the complete stop -- that's sensible.

What am I missing?

wrlominick

I remember reading something somewhere about how it also assited braking. If you take your foot of the gas "suddenly" then it will move the brake pads even closer to the brake disc in anticipation of you hitting the brake, then if you slam the brake really hard it applies full brake force even if you back off on the pressure a little. This latter is due to the fact that people tend to not press hard enough on the brake in an emergency, they hit it initially but then don't get full stopping power because they don't press all the way, way way, down. Do we have this feature on the e60?

E60Speed

Thats what the DSC+ asof March production does amongs other new features

We are still waiting to hear if it will be available as a software upgrade for earlier cars

Rudy

You're describing two technologies. I don't know much about the one that moves the pads closer to the rotors but I remember reading something about it recently and I think E60Speed may be right that it's part of the newer version of DSC. (I know M-B's brake by wire system dries the rotors by dragging the pads slightly.)

The other thing you mentioned is what I referred to in my earlier post as "Brake Assist." I don't know if that's the right name for it but that feature is on the E60 right now. It detects panic stops and applies maximum brake pressure because studies have shown people don't press the pedal enough for fear of locking up or something.

Guest

Iceman, I'm confused. I always thought that the principle behind BFD was to differentiate between normal, gradual stops and panic or emergency stops. The thought being that if I am stopping suddenly, the driver behind me needs to know about it before the deceleration is so sudden that a rear-end collision happens. In many dry-weather conditions, you can panic stop (and BMW's Brake Assist or whatever it's called will maximize brake pressure) without ABS intervening (even though ABS is always "active" and monitoring the current wheelspin to detect impending lockup.) If BFD only illuminates the extra bulbs "when ABS kicks in" and when you come "to a complete stop," it pretty much defeats the purpose of the system, doesn't it?

cobradav's post makes way more sense. The ABS sensors (which are always active) calculate a deceleration rate that is known to be sudden (based on the formula he posted) and immediately activate the extra BFD bulbs to warn other drivers that the car is slowing more suddenly than normal. The bulbs may stay illuminated up to the complete stop -- that's sensible.

What am I missing?
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I can assure you that cobradav's post is correct. I was driving and needed to brake very hard. I decellerated from 200 kph to approx. 90. Now a friend of mine was driving behind me and saw all of a sudden that the lighted area changed. My wife who was sitting in front of me swears that she saw the emergency button light up. So I'm convinced that it works when you need to deccelerate a lot.

Best regards

Rudy

I just looked in the manual. BMW calls it DBC for Dynamic Brake Control. (I think M-B calls it Brake Assist.)

I can't say that anything's tied to the Emergency button light. I'm a bit doubtful that they'd tie it to that light...