Brakes not working properly when wet

[Mazdarese]

Hello

I noticed the other day whilst driving (Mazda 6 MPS) at 70mph onto a slip-road, in the heavy rain, that my brakes really don't work in the wet. This surprised me somewhat.

In the dry they are fine, but as soon as it rains heavily and I need to brake I really need to stamp the pedal down a couple of times to get anything like 100% braking power.

Any ideas what might be up?

I will probably take it into the local dealership but could do with being 'forearmed'.

Cheers

[fatboy b]

Water on the discs. My Audi does an occasional dry of the discs if the wipers are turned on by lightly putting the brakes on for me. Cars without this have what seems like seconds between applying them and for them to start working.

[EDLT]

fatboy b said:

Water on the discs. My Audi does an occasional dry of the discs if the wipers are turned on by lightly putting the brakes on for me. Cars without this have what seems like seconds between applying them and for them to start working.

BMWs do the same thing, probably a few others too.

To the OP: What do you think the dealer will do about it?

[anonymous-user]

I'm sure the main dealer is more than capable of bending the laws of physics for you :-D

This is why it's a very, very good idea to lightly use the brakes periodically when it's raining (using your left foot etc) to heat them up and dry them off a bit. Can be a life saver if you need to emergency brake for anything. I thought this was in the highway code or something?

Dave

[Mazdarese]

EDLT said:

fatboy b said:

Water on the discs. My Audi does an occasional dry of the discs if the wipers are turned on by lightly putting the brakes on for me. Cars without this have what seems like seconds between applying them and for them to start working.

BMWs do the same thing, probably a few others too.

To the OP: What do you think the dealer will do about it?

None of my other cars have ever had this problem, so I don't think it's a normal build-up of moisture. I think there's either a serious drainage problem or something else maybe?

I would hope my dealer would diagnose and offer to fix. They've been very good in the past.

[dudleybloke]

a nice thick layer of moly grease will keep the water off!

[Mazdarese]

dme123 said:

I'm sure the main dealer is more than capable of bending the laws of physics for you :-D

Seriously, this is not a normal build-up of water that can be explained away with physics. I've driven in heavier rain in other cars and not had anything like this.

[alfa pint]

I get it in the Alfa occasionally, but it clears after a quick couple of stabs on the pedal to remove the film of water between disk and pad.

[N Dentressangle]

Mazdarese said:

Seriously, this is not a normal build-up of water that can be explained away with physics. I've driven in heavier rain in other cars and not had anything like this.

You need to replace at least the pads, asap.

I bought a Saab 900 a few years ago which did exactly what you describe. It was scary. Otherwise, the brakes worked fine.

I replaced the pads with new genuine items and the problem disappeared. The pads I removed looked worn, but with plenty of 'meat' left.

Never had this problem with a car before or since, but new pads cured it straight away.

HTH

[Mazdarese]

N Dentressangle said:

Mazdarese said:

Seriously, this is not a normal build-up of water that can be explained away with physics. I've driven in heavier rain in other cars and not had anything like this.

You need to replace at least the pads, asap.

I bought a Saab 900 a few years ago which did exactly what you describe. It was scary. Otherwise, the brakes worked fine.

I replaced the pads with new genuine items and the problem disappeared. The pads I removed looked worn, but with plenty of 'meat' left.

Never had this problem with a car before or since, but new pads cured it straight away.

HTH

Ok, thanks. I'll get a price from my local Mazda place and if it's ridiculous I'll do them myself.

If it solves the problem I'll come back and push a custard pie into the faces of people who said I was a mong and that it was physics.

[N Dentressangle]

I'd buy some pies ready, if I were you.

Having thought about it, I'm pretty sure I deglazed the discs with emery cloth at the same time, so you probably ought to give that a go at the same time as the pads to make sure they bed OK.

[nammynake]

I get this with my Clio. Less than 1 year old. I don't think there is a problem with thediscs or pads however. I havent had this problem with any other car, and I can only assume it's just another feature of this car that I need be aware of and adapt my driving to.

[Huntsman]

Dont drive like a tt in the rain?

[Mazdarese]

Huntsman said:

Dont drive like a tt in the rain?

You're right. Next time it rains I will slow down to 40mph. Shall I put on all my fog lights too and stay in whichever lane I was in before the downpour started?

[Roop]

Grooved discs can work here.

[Huntsman]

Mazdarese said:

You're right. Next time it rains I will slow down to 40mph. Shall I put on all my fog lights too and stay in whichever lane I was in before the downpour started?

By your own admission, 70 onto a slip road in heavy rain. Sounds like you need to take account of the prevailing conditions more to me.

Further, if you needed 100% of braking effort, as per your post, you had no extra braking available if you needed it.

No offence intended, maybe I'm just a doddery old fool and keyboard warrior too.

[zcacogp]

fatboy b said:

Water on the discs. My Audi does an occasional dry of the discs if the wipers are turned on by lightly putting the brakes on for me.

Crumbs. I am genuinely amazed that cars do this; having never owned a car made later than about 1990, the notion that a car should be this sophisticated is a revelation to me.

I guess that, if you have the ability for the car to apply the brakes (which it can, as part of the ABS system), and you have the windscreen wiper funtion run from the same computer, then linking the two can't be that difficult, but I am still amazed!

Little things and little minds, eh?


Oli.

[SplatSpeed]

you sure there is any material left??

[fido]

Is that the front or rear brakes?


:audience laughter:

[Mazdarese]

Huntsman said:

Mazdarese said:

You're right. Next time it rains I will slow down to 40mph. Shall I put on all my fog lights too and stay in whichever lane I was in before the downpour started?

By your own admission, 70 onto a slip road in heavy rain. Sounds like you need to take account of the prevailing conditions more to me.

Further, if you needed 100% of braking effort, as per your post, you had no extra braking available if you needed it.

No offence intended, maybe I'm just a doddery old fool and keyboard warrior too.

Nope, you just read too much into my post. I used the 70mph/heavy rain/100% braking terms perhaps to highlight that it was quite a serious issue. In reality, I was probably only doing about 50mph on the occasion I was referring to.

It has happened when I've been pootling down the road at 30mph too.