[55]

Hello all.
I drive e91 x-drive. Yesterday drove for a few hours on a highway.
Strong rain.
Speed about 120 km/h.
When I touched a brake pedal, the car pulls to the right. It feels scary. Released the brake. Second time pulls to the right less. Third time seems OK.
After driving for a while and braking again-same story.
Obviously it is related to wet discs. But why it pulls to one side.
The question is-should i call to dealer? I thought BMW should go straight under braking? My other much less sofisticated cars didn't do it to me.
Any opinions?
thanks

[R608]

I thought these cars had a system that automatically touched the pads to the rotors periodically in the wet to help keep the brakes dry. I'm guessing here, but if the braking does straighten out after a couple of uses, could that not be working on the left side, or left-front wheel specifically?

[bsamoul]

Originally Posted by R608

I thought these cars had a system that automatically touched the pads to the rotors periodically in the wet to help keep the brakes dry. I'm guessing here, but if the braking does straighten out after a couple of uses, could that not be working on the left side, or left-front wheel specifically?

They do when the windshield wipers are on.

[JayKay335i]

Water tends to accumulate on the shoulder of the right lane.

[cb1111]

Originally Posted by JayKay335i

Water tends to accumulate on the shoulder of the right lane.

Bingo

To the OP - welcome to hydroplaning.

[55]

Originally Posted by cb1111

Bingo

To the OP - welcome to hydroplaning.

Thank you. It is not a hydroplaning. I know how that feels. Traction was never lost.

[55]

Originally Posted by JayKay335i

Water tends to accumulate on the shoulder of the right lane.

Actually i was in the left lane and if there is more water on the left shoulder than there is more water on the left discs. Than it makes some sense why it was pulling to the right.
Still, I've never experienced that before and I've been through a lot of driving in all kind of weather. The car is new for me (first winter), and I am disapponted with such behavier.

[R608]

Originally Posted by 55

Actually i was in the left lane and if there is more water on the left shoulder than there is more water on the left discs. Than it makes some sense why it was pulling to the right.
Still, I've never experienced that before and I've been through a lot of driving in all kind of weather. The car is new for me (first winter), and I am disapponted with such behavier.

FWIW, I've never once observed my car pulling either direction like that, or even just exhibiting any kind of noticeable loss of performance due to being wet. Is this something you're seeing with some consistency or just a once-time thing?

[55]

Happened few times during that trip(total 5 hours of driving). Have never noticed that before. May be never drove throught that much rain, i don't remember. I have the car only since April

[wsybert]

Does this only happen in the rain? If so , I would tend to lean toward losing traction on one side or the other. If not, take it in.

[55]

I'll try some hard breaking tomorrow on a dry pavement.
Thank you for opinions guys.

[55]

On the dry it is OK. BTW had a chance to try it through blizzard, snow, ice. The car behaved perfectly. (i have winter tires as well).

[55]

Some development: Another long run in the rain, same problem, but this time i was in the right lane and the car pulled to the left. It is pretty much clear that there is more water on the shoulder and more water getting inside the wheels on that side.
Wild guess: with cruse control engaged, brake drying function doesn't work. Is it possible?
I had cruse on in both cases.

[Nick.CBR]

There are a lot of other factors - tire width, tread depth, speed, suspension setup, it's really hard to compare cars like this unless they are side by side. I mean is it really that bad? Not trying to flame or anything but it just sounds like it's an annoyance about the car on these roads in the wet - not something wrong with it. My car wanders all over the place on the concrete that has been grated or the road is worn down on either side of the center of the lane - just the car being the car (wider tires, stagered, etc.).

I've never understood the brake drying thing - does it work when the wipers are on, only when they are on auto, does it cancel with cruise, etc. I suppose it's all in the manual I've never totally read.

I personally think that your car is fine and that's just one of it's characteristics although if you do start to hydroplane, sometimes it can throw the TC light since the wheel speeds change at different rates.

Nick

[ElRedOne]

Originally Posted by 55

Some development: Another long run in the rain, same problem, but this time i was in the right lane and the car pulled to the left. It is pretty much clear that there is more water on the shoulder and more water getting inside the wheels on that side.
Wild guess: with cruse control engaged, brake drying function doesn't work. Is it possible?
I had cruse on in both cases.

Cruise control should not be used in rainy conditions. Maybe the car is trying to tell you something.

[55]

Originally Posted by ElRedOne

Cruise control should not be used in rainy conditions. Maybe the car is trying to tell you something.

Why not? If traffic allows, sure it can be used. If she is trying to tell me something it is stupid and dangerous way to do it. And i repeat the car was perfect on the snow and bllizzard.

[55]

Originally Posted by Nick.CBR

There are a lot of other factors - tire width, tread depth, speed, suspension setup, it's really hard to compare cars like this unless they are side by side. I mean is it really that bad? Not trying to flame or anything but it just sounds like it's an annoyance about the car on these roads in the wet - not something wrong with it. My car wanders all over the place on the concrete that has been grated or the road is worn down on either side of the center of the lane - just the car being the car (wider tires, stagered, etc.).

I've never understood the brake drying thing - does it work when the wipers are on, only when they are on auto, does it cancel with cruise, etc. I suppose it's all in the manual I've never totally read.

I personally think that your car is fine and that's just one of it's characteristics although if you do start to hydroplane, sometimes it can throw the TC light since the wheel speeds change at different rates.

Nick

NO hydroplanning. And yes it is pretty bad. It pulls sideways strong, and i don'really brake hard, because i always keep proper distance.
But it is amazing how good the car was on ice and snow.

[ElRedOne]

Originally Posted by 55

Why not? If traffic allows, sure it can be used. If she is trying to tell me something it is stupid and dangerous way to do it. And i repeat the car was perfect on the snow and bllizzard.

I was being facetious, however I do believe the manual, in concert with those of other manufacturers, recommends against the use of cruise in wet conditions. Too easy to hydroplane and lose control of the vehicle.

[lcs]

I thought i read somewhere that DSC is not active during cruise control, which is why it should not be used in raining conditions. Correct me if im wrong

[FrankFi]

Wow - had this exact same problem today driving down the Sea-to-Sky Highway from Whistler to Vancouver. The car pulled hard to the right - towards the cliff, in other words! - when braking during a hard rain. This was quite scary. Later on, on the dry Rt 1/I-5 from Vancouver to Seattle, there was no problem whatsoever.

I have a one year old 335ix. Never had this problem before, and driving in Seattle I do have a lot of experience with wet conditions. The car wasn't hydroplaning. I did hit a pretty good pothole on the way up to Whistler... I wonder if the alignment got out of whack... but why would that only show when braking in wet conditions?

Puzzled in Seattle,
Frank

[Alpina_B3_Lux]

Originally Posted by FrankFi

Wow - had this exact same problem today driving down the Sea-to-Sky Highway from Whistler to Vancouver. The car pulled hard to the right - towards the cliff, in other words! - when braking during a hard rain. This was quite scary. Later on, on the dry Rt 1/I-5 from Vancouver to Seattle, there was no problem whatsoever.

I have a one year old 335ix. Never had this problem before, and driving in Seattle I do have a lot of experience with wet conditions. The car wasn't hydroplaning. I did hit a pretty good pothole on the way up to Whistler... I wonder if the alignment got out of whack... but why would that only show when braking in wet conditions?

Puzzled in Seattle,
Frank

I also had such an experience this summer during strong rain.

I very much assume it is the same problem that already occurred with the E46 and that I also experienced with my previous car, an Alpina B3 (E46) where I saw no reaction to the brake pedal for almost one second under strong rain and then a pull of the car to one direction. At the time (and still today) there are lots of threads discussing this phenomenon on the German BMW forums, as it is a common defect to the big 6 cylinder models (330i / 328i). Apparently the brake discs which are particularly large for the 6 cylinder models (348mm for the 335i if I'm not mistaken) get covered with a water film and prevent the brake pads from generating sufficient friction with the discs, until the water film is removed. This is also why BMW installed the dry brake function on the E9x, but which apparently does not always work properly.

Now, how to avoid the problem? One can always try to complain to BMW, have them replace discs or pads but IMO (and as proven by numerous similar cases I'm aware of) this does not solve the problem itself which is IMO related to the design of the brake discs. With my E46 I solved that problem by installing aftermarket slotted brake discs where the water was evacuated more efficiently and where the reaction to braking under wet conditions was significantly improved. I tend to believe that this would also be a solution for the E9x - and that is the reason why some months ago I had slotted and dimpled aftermarket brake discs installed (EBC Turbo Groove) on mine. I haven't had any problem since.

Just my 2c.

Alpina_B3_Lux

[cotmfk]

Originally Posted by 55

I had cruse on in both cases.

How are you braking with cruise on? I thought when you touch the brake, the cruise turns off. Active cruise option?

Anyways, if it is a potential safety issue to you, I would take it in. Better safe than sorry.