Braking in the wet!

[dloureiro]

Hello everyone!

I have a Leon 20VT Topsport. I have had the car now for 2 months and I am extremly happy with it. Goes like a dream. One question that I have is regarding the brakes. For the last 2 months, the weather has been unusual for Holland in that it hasn't been raining. The brakes in the dry are fantastic. They kill speed increadibly well. The problem occurred yesterday when it was raining and I was travelling down the motorway with loads of spray. Had to brake and to my surprise there was no reaction for a bit. Only after a couple of metres did the brakes start bitting. Never had this before in any other car. I have read a couple of comments on this board about this but nothing conclusive. Therefore I have a couple of questions. Is this normal? Do others share this experience? Is it because the brakes are still new or maybe have muck? Do I need to continuously tap the brakes to make sure they are dry? How the heck do I handle emergency braking (apart from leaving 30 car lengths!)?

Thanks in advance. BTW. great forum!

Cheers,
David

[mik]

This was a subject of discussion some time ago (stemming from a similar issue with S3 brakes).

Need to do a search to find the thread.........

I've not had any "bite" issues whilst on the move, but have nearly ran into things after washing the car and finding I had no brakes on initial pedal press. Scary

[prc]

There have been quite a few threads regarding this over on the vortex site as well.
If I remember correctly it's got alot to do with water buildup between the pads and the disc (going away after the water burns off).

Most resolved the problem by using slotted pads and/or discs.

[arfur]

There was an issue I remember from a few years ago when I had an A4. Certain designs of wheel allowed road spray to hit the discs which cause the braking problems. The fix was a guard of some type that Audi could fit which would stop the water getting on the discs. The downside was that the guard would also interrupt airflow and cause your brakes to run hotter that desirable(not a problem in the UK). It might be that a similar problem exists with your Leon.

[dloureiro]

Thanks for your replies guys.

My car is a standard Dutch Topsport model with the same alloys as in these pictures:

http://elmundomotor.elmundo.es/elmun...leon_sport_fr/

Can it be because the disks are really exposed? Anyone got these alloys and doesn't have a problem then?


David

[prc]

Well I only have the problem when driving for a while on the highway without braking. When I hit the brakes it takes a while to the brakes to initially bite.

[Alice_Cupra]

I seem to remember reading a while ago about some top-spec Mercedes which, when the rain-sensitive wipers told the ECU it was raining, VERY lightly applied the brakes to skim the water off the discs from time-to-time, just in case you needed to use them in a hurry.

Or was I just dreaming? :dunno:

[Syphon]

Brake fade in the wet.

Especially when driving for some distance on the motorway in the wet. Water builds up between the pad and the disc. The first time you apply the brake the water gets trapped between the pad and the brake, this reduces your ability to brake as well. If you release the brake briefly and then re apply it the water will have cleared and you will get the full effect.

Hence signs that say "Now try your brakes".

Someone told me once that drilled discs do not suffer from this as the water can escape.



Scott

[prc]

Originally posted by Syphon
Brake fade in the wet.

Especially when driving for some distance on the motorway in the wet. Water builds up between the pad and the disc. The first time you apply the brake the water gets trapped between the pad and the brake, this reduces your ability to brake as well. If you release the brake briefly and then re apply it the water will have cleared and you will get the full effect.

Hence signs that say "Now try your brakes".

Someone told me once that drilled discs do not suffer from this as the water can escape.



Scott

Yep! most of what I've read mentions that the slotted and/or drilled discs don't have this problem.

[mark sheerin]

When I first got my Leon there was talk at the time about this problem and a couple of times I had that horrible feeling where you apply the brakes and nothing seems to be happening..but then it never did it again and hasn't done it in the last 40k miles...the only problem I have with them is if I have a fast blast round the hilly yorkshire Dales where I live and then they start to overheat and fade...
I notice that on the left the front brake cooler opening has been nicked by the intercooler and on the right its just a dummy opening....If I drove that fast that often I would modify them with some vacuum hose and cable ties and have some brake cooling arranged.

[prc]

Originally posted by mark sheerin
When I first got my Leon there was talk at the time about this problem and a couple of times I had that horrible feeling where you apply the brakes and nothing seems to be happening..but then it never did it again and hasn't done it in the last 40k miles...the only problem I have with them is if I have a fast blast round the hilly yorkshire Dales where I live and then they start to overheat and fade...
I notice that on the left the front brake cooler opening has been nicked by the intercooler and on the right its just a dummy opening....If I drove that fast that often I would modify them with some vacuum hose and cable ties and have some brake cooling arranged.

Mark,
Brake fade can be solved most times by just going with a sport compound brake pad like the pagid FR or Hawks.
Sort of an off-topic but:
Some new sport discs like the ones from ECS come with directional vanes instead of the radial outward vanes (as OE disc). They're supposed to pump much more air through the disc than the OE ones.

[RobG]

I had my first experience of this this morning. 80 on the m23 and no brakes. really scary!

Sounds like grooved discs will be the solution.

What dya reckon the chances are of getting them fitted as a warranty repair? A mate of mine with a cupra got the dealer to fit grooved to prevent heat fading and they did it under warranty.

rob

[jezyg]

This brake fade problem...Never had it on any car that I have owned so far, why is a problem on the Leon and not on the Golf?. They share the same disks, pads and servo ect (correct me if I am wrong)

If you get fade just from one long brake this surley must be a design fault, in that the brakes are not getting enough ventilation.

What is Seat's line on this problem?

[edc]

You're unlikely to get brake fade from 80 in the wet. Probably just wet brakes. Much more likely to get fade from very high speed eg 100mph plus and braking very hard to a standstill. Brakes work by generating heat (and a little noise). Do this repeatedly and whilst the brakes are still roasting then you may well notice fade. IMO you won't notice any fade from one huge stomp on the brakes unless your brakes are already in bad condition.

[RobG]

definitely not fade, i get that in the dry occasionally.

this was wet slippy discs. no question. never had it in any other car before.

rob

[Surfer_D]

It's the same with beeza 20VT...

[mark sheerin]

Originally posted by edc
You're unlikely to get brake fade from 80 in the wet. Probably just wet brakes. Much more likely to get fade from very high speed eg 100mph plus and braking very hard to a standstill. Brakes work by generating heat (and a little noise). Do this repeatedly and whilst the brakes are still roasting then you may well notice fade. IMO you won't notice any fade from one huge stomp on the brakes unless your brakes are already in bad condition.

tis true . but I am a little dissapointed in the std leon brakes because if you drive fast somwhere hiily like the yorkshire dales it doesn't take more than about four hard slows before you have to start making allowances for the spongy pedal feel and lack of power

[prc]

Originally posted by mark sheerin
tis true . but I am a little dissapointed in the std leon brakes because if you drive fast somwhere hiily like the yorkshire dales it doesn't take more than about four hard slows before you have to start making allowances for the spongy pedal feel and lack of power

The best way to solve this problem is by upgrading the pads & the brake fluid.

jezyg:
I has happened on some of the Audis as well. It tends to happen more often with wheels that have larger front openings, allowing more road spray to hit the disc. I didn't have this problem before going with the cupra4 wheels.