First time driving on snow; hideous noise from applyling brakes

[autoque]

First time driving on snow, when I apply brakes even lightly, there's a really loud griding noise from front brakes, especially from front driver brake. It sounds as if lots of stone chips are between the pad and rotors. It's also alarmingly loud. What could be the problem?

[blktoptrvl]

Normal. At least for mine it was.

[spacegraye70]

its ABS

[Fastbuck]

Originally Posted by spacegraye70

its ABS

I agree. 100% normal and as designed.

[brian5]

Originally Posted by Fastbuck

I agree. 100% normal and as designed.

I agree too. The first time I felt ABS kick in (in my old 3-series), I thought I'd hit the truck that had swerved in front of me! I could not believe that there was not a scratch. That was in dry conditions.

[jaaX3]

Could be ice build-up, as well.

[II Kings 9:20]

Agreed, ABS, interesting that the OP apparently has never experienced this in other cars.

ABS has been around for a long time.

First on the 1966 Jensen FF AWD with Lockheed ABS, the '69 Thunderbird (rear only) and the '73 Chrysler Imperial and popularized on the mid '70s S Class with modern electronics.

Edit: I would add that light application of brakes on snow usually does not activate ABS (it depends), it will most certainly activate with very light application on ice.

[ard]

+3 Normal... ABS.

Have you never felt ABS actuation?

Do a search on google- I bet there is a youtube on it...

The abs actuator is applyign and releasing the brake calipers very rapidly- 10+ times per second. Feels/sounds like a griding noise.

No worries. Try it with one tire on gravel/mud/grass at 20-30 mph in a straight line....same thing

[autoque]

I had felt ABS kick in when I was applying full brake in a rainy day in my old vehicle (non-bmw), so I thought the ABS only kicks in when braking fully and hard. But I'm finding out that it's very easy to get the ABS working on a snowy and slippery road in a BMW. I drove someone's Lexus ES350 back-to-back in the same snowy condition right after driving the X5, and from what I can tell, the Lexus needed harder braking to activate the ABS and the grinding noise was more muted than the BMW. So I found the X5 to be a little more sensitive in its ABS activation, which I think is nice. I felt more sure-footed. Was just a tad bit concerned about the louder ABS noise.

[Price]

Lexus is 1000+ pounds lighter than X5. BMW may be better in muffling the energy required to stop almost 5,000 lb beast, but they can't bend the laws of physics.