[andrew0871]

Hi all,

I drive a E92 320d M Sport (new on 1st March this year) 160 miles a day between Mid Devon and the centre of Bristol. When it rains on the motorway and I brake the car wiggles around and the brakes are mushy and ineffective for the first second or so of braking.

Obviously water on the discs as it’s fine for a few miles and then the same happens again once the water has built up on the discs.

I need to know if it’s just me! I thought BMW’s had a system where the brakes kept the discs dry in the wet? (Braking in the dry or on damp roads is spot on, no problems at all)

I can speak from so experience of wet discs; my MK IV Golf had the same issue, VW eventually replaced the car admitting it wasn’t safe. Interestingly VW had changed the wheel style between models and the problem never occurred on the replacement MK IV. I did read somewhere that certain wheel styles create more of a vortex drawing water onto the discs, never was sure if this was the problem/cure.

I then had the same problem on a 225 TT, after reading the forums at the time I went for a set of drilled Brembo’s which solved the problem straight away. The idea being that the holes in the disc allows the steam gasses generated by the pad heating up the wet surface of the disc to escape quickly. Whatever it was it definitely worked.

My MK V Golf GTI never had a problem with stock discs and pads but now I have the problem back in a £37k BMW! I’m thinking of getting the BMW Performance brakes fitted with the drilled discs, but I don’t see why I should fork out another £1k on a car that should be able to cope with a bit of rain.

Perhaps it’s just a fault with my car, which is why I would like to hear from anyone else with this problem before I go back to the dealer.

And before anyone suggests leaving a bigger gap between me and the car in front to allow for longer braking distances - has anyone actually tried to do this on a British motorway? I leave a gap, it gets filled by another car if I tried this all the way home I would end up going backwards! Joking aside the car should be capable of stopping safely without weaving in the wet, even a gentle push on the brakes and the car pulls one way or another - but only when wet!

[Hairyarse]

Hi Andrew

BMW do fit a brake drying feature (auto operation of the brakes in the wet) but I believe it's only on the 6-cylinder models. I don't have this issue - only had the car 3 weeks but drove in torrential rain the other day but then mine is 6-cyls

What wheels do you have - std or options? Maybe someone with the same could comment

personally aside from an initial lack of stopping power like you'd get with any car in the wet I wouldn't expect it to be noticeably bad

Re your comment about hanging back - very true! Hang back and some one will fill the gap

Hope you get it sorted

Cheers
Andy

[NFS]

If you have the brake drying function you will feel a slight pulsing vibration through the brake pedal. This is timed to coincide with windscreen wiper operation.

I can't remember which cars get this as standard, but my 330i and 335i had / have it.

[andrew0871]

Looks like you're right about the lack of brake drying on the 4 cylinder models, just checked specs from the BMW site and this is listed for 6 cylinders only:

Dynamic Stability Control Plus (DSC+) comprising: Brake Drying, Brake fade compensation, Brake pre-tensioning, Hill-start assistant

I guess I need some drilled discs - cheaper than buying a new car and probably cheaper than having a crash!

[Dr Dave]

You need the BMW Performance brake setup!

[briers]

I always wondered why the brake pedal pulsed when the wipers were going.

[Dr Dave]

Originally Posted by briers

I always wondered why the brake pedal pulsed when the wipers were going.

Can't say I've ever noticed any pulsing!

[chris330D]

I've often thought it would be a difficult function to know if it is working or not. Mine has it and whereas the brakes work straight away in the wet, better than my previous 4 cylinder car, haven't noticed the pedal pulsing. If the brakes are wet though, surely the car should still stop in a straight line albeit take longer? Teh weaving the OP describes sounds wrong

[F30 Steve]

Ahhhhh!I thought there was something wrong with my wipers because i can some times feel a slight pulse on brake when they are on!! Phew!

[Jules6]

The pulsing that you can feel through the brake is because the wipers are mounted on the same bulkhead and is nothing to do with the brake drying function.

[F104]

Originally Posted by andrew0871

When it rains on the motorway and I brake the car wiggles around and the brakes are mushy and ineffective for the first second or so of braking.

I have exactly the same after driving 50miles or so in the rain and not having touched the brakes. Think it is not just water but a film of oil and other stuff, as it does take a noticeable time / distance before the brakes bite. I now lightly brake once in a while under those conditions.

[Jon D]

Originally Posted by Dr Dave

Can't say I've ever noticed any pulsing!

Same here and I have 6 cyl.
Fortunately I've never had to brake hard in the rain, but I do notice a slightly disconcerting difference to pedal response in the wet. It's as if there's just a very brief moment before the brakes bite as you'd expect in the dry.
It's hard to define and I'm sure they'd respond normally were the need to arise - I'm not worried enough to test it in anger!

[NFS]

Originally Posted by Jules6

The pulsing that you can feel through the brake is because the wipers are mounted on the same bulkhead and is nothing to do with the brake drying function.

I read that it was the brake drying years ago when I first got the 330i and accepted it as gospel.

Just done a search and it seems that there is quite a big difference of opinion on the cause of the pulsing.

Don't know who is right.

[briers]

The pulsing I feel is very faint when the wipers are on and only when stationary.

[Jules6]

Originally Posted by NFS

I read that it was the brake drying years ago when I first got the 330i and accepted it as gospel.

Just done a search and it seems that there is quite a big difference of opinion on the cause of the pulsing.

Don't know who is right.

Whilst the car is stationary depress the clutch pedal to the floor and use your wipers and you will feel the slight pulse through the pedal. ie nothing to do with brake drying but just that the wipers are attached to the same bulkhead. It's even more noticeable if the windscreen is relatively dry as there is more kick at the end of each stroke.

[nottsE90]

Originally Posted by andrew0871

Hi all,

I drive a E92 320d M Sport (new on 1st March this year) 160 miles a day between Mid Devon and the centre of Bristol. When it rains on the motorway and I brake the car wiggles around and the brakes are mushy and ineffective for the first second or so of braking.

Obviously water on the discs as it’s fine for a few miles and then the same happens again once the water has built up on the discs.

I need to know if it’s just me! I thought BMW’s had a system where the brakes kept the discs dry in the wet? (Braking in the dry or on damp roads is spot on, no problems at all)

I can speak from so experience of wet discs; my MK IV Golf had the same issue, VW eventually replaced the car admitting it wasn’t safe. Interestingly VW had changed the wheel style between models and the problem never occurred on the replacement MK IV. I did read somewhere that certain wheel styles create more of a vortex drawing water onto the discs, never was sure if this was the problem/cure.

I then had the same problem on a 225 TT, after reading the forums at the time I went for a set of drilled Brembo’s which solved the problem straight away. The idea being that the holes in the disc allows the steam gasses generated by the pad heating up the wet surface of the disc to escape quickly. Whatever it was it definitely worked.

My MK V Golf GTI never had a problem with stock discs and pads but now I have the problem back in a £37k BMW! I’m thinking of getting the BMW Performance brakes fitted with the drilled discs, but I don’t see why I should fork out another £1k on a car that should be able to cope with a bit of rain.

Perhaps it’s just a fault with my car, which is why I would like to hear from anyone else with this problem before I go back to the dealer.

And before anyone suggests leaving a bigger gap between me and the car in front to allow for longer braking distances - has anyone actually tried to do this on a British motorway? I leave a gap, it gets filled by another car if I tried this all the way home I would end up going backwards! Joking aside the car should be capable of stopping safely without weaving in the wet, even a gentle push on the brakes and the car pulls one way or another - but only when wet!

i have the exact same problem in my 320d, where when it rains on the motorway and I brake the car wiggles around and the brakes are mushy and ineffective for the first second or so of braking.

i'd be interested to know what the cause of this problem is?

[creepy coupe]

I think the wheel design plays a very important part in this, a few years ago we had a 318is as a company car. It came delivered with some 15" something or other OEM wheels.

The car was fine in all weather condition, it felt very planted compared to my Vauxhall Cavalier I owned at the time. After a few weeks of running the car, the company decided to fit some 17" Zenders, which put the fear of Christ into me one day while

I also think it’s the reason some cars have bigger problems with brake dust than others, the wheel design act like giant fans, sucking road dust into them.

[wright761359]

Hi,
I have the same lack of stopping power on wet days,i have 320d M-Sport edition and have had the car 2 years(65,000 miles).
I have asked for the bads and discs to be checked many times and the dealer(Sytner Leicester) has driven the car in the wet on the M1 and agrees that the stopping power is poor when the discs are wet,they suggested dabbing the brakes to dry the discs,prior to actually braking hard!
I did point out that to drive along dabbing the brakes,may cause a pile up!!
Other than upgrading the pads and discs,nothing can be done..
Nice attitude........Audi........here we come

[m1bjr]

Originally Posted by wright761359

Nice attitude........Audi........here we come

GLWT.

From experience, you'll need it

[Jules6]

Originally Posted by wright761359

Nice attitude........Audi........here we come

My experience with my old A4 was horrific with wet brakes! Grass is greener etc