[ft1330]

I've noticed that in heavy rain and at highway speed, initial braking performance is very poor; I have a floaty feeling for the first couple of seconds, no matter how hard I push the brake. Then after these couple of seconds, the brake is suddenly applied pretty hard, resulting in a bit of a surprise jolt. I know that this is due to a film of water that forms on the brakes and that needs to be expelled before braking becomes effective. Where I'm a little confused is that I believe I saw a BMW video advertising a feature whereby the car detects the rain and keeps the pads very close to the rotors in order to prevent that water build-up. That doesn't seem to be working very well... Is this feature present in the F3X cars?

[BavarianFanatic]

I don't think it helps that much in a heavy downpour. It would really need to be applying a fair amount of pressure to sweep them dry.

[Billfitz]

Originally Posted by ft1330

I believe I saw a BMW video advertising a feature whereby the car detects the rain and keeps the pads very close to the rotors in order to prevent that water build-up.

When they're working correctly the pads are always very close to the rotors. At highway speeds water doesn't build up on the rotors, it's thrown off by centrifugal force. Initial wet braking is more of an issue with a car that's been standing still. I'd have the brakes checked out.

[robbiep]

If the rain is that heavy but you're still driving at normal speeds, then the real problem, as IT people term it, is PICNIC

Problem in chair, not in car

[auf Deutsch]

Originally Posted by robbiep

If the rain is that heavy but you're still driving at normal speeds, then the real problem, as IT people term it, is PICNIC

Problem in chair, not in car

As long as there's good visibility and no ponding on the roads due to heavy rain, I see no problem driving at normal, even above normal speeds.

I swear by Aquapel glass treatment. Driving at highway speeds in the heaviest of rains, the wind pushes the water off of my windshield to such great effect that wipers are not mandatory. It sounds crazy but it's that good.

[DDD31]

According to the manual:

[HighlandPete]

Remember the brake drying feature works in conjunction with driving speed and wiper action, also time/intervals can be dependant on wiper activity.

Intervals are not too frequent, BMW data mentions 90s and above, so plenty of time in heavy downpours for brakes to get very wet again.

HighlandPete

[oceanview]

Change your front rotor with the dimpled and slotted rotor option 34106797602 and the wet braking problem will be solved!

I was not happy with the wet braking behavior on my old E46 and changed to a set of dimpled and slotted rotor. No more "wait a second" with those.
Same now with the dimpled and slotted M Performance Brake rotors on the F31. Better wet braking was one of the reason for me to choose the M Performance Brakes.
However on the standard 335i brake, there is a 340mm dimpled slotted front rotor part option which is a fair option.

[chiefneil]

In heavy rain I allow extra space in front of me and I brake earlier with more gentle pressure initially. That gives your brakes the couple extra seconds to get their usual bite.

Plus you never know how slick the roads are with old oil and dirt getting stirred up from the road surface, so better to take it easy until you see that your tires are sticking. I actually worry more about my tires than my brakes when it rains.

And I worry about the guy behind me even more than I worry about my tires, so slow and easy for me to give the numbnut behind me enough time to wake up and realize my brake lights are on. I see plenty of people sliding around when braking in the rain; enough brakes but not enough traction at the tires.