: Spongey brakes when wet (sometimes)



DPL
10-31-12, 10:01 PM
Hey everyone,

It finally started to rain around here (ya, I know!) and I notice my brakes are spongey at times. It actually freaked me out once when I was rolling to a stop sign at slow speed and went to put the brakes on and had to put way more pressure than usual. It happens every so often, I haven't been able to figure out how to reproduce it.

Anyone?

Trapspeed
10-31-12, 10:52 PM
I live in FL and haven't experienced any issues yet. Even during a downpour.

extrabolts
11-01-12, 08:53 AM
Water on the rotor can cause a slight hydroplaning effect between the pad and rotor, this can happen with any car but only a handful of drivers will ever notice the difference. It is pronounced by differences in brake pads - race compound pads can be worse - and by people who have removed the dust shield that sits on the back of the rotor (which helps to keep water slinging around the wheel well off the rotors). It should stop shortly after you apply the brakes as the surface will be dried off.

If you have to put "way more pressure" then something else is the issue, and I'd suspect air in your lines. The dealer probably will bleed them for you under warranty.

M5eater
11-01-12, 08:58 AM
Extrabolts is dead on.

Pad material is a key factor. In my A6 the issue is more pronouced because it has tiny brakes(that are direct from the A4.. stupid audi) and I'm using autozone pads, and I suspect the master cylinder front seal is bad too(likely the largest cause of the problem).

It really depends on your evaluation of 'way more' and 'spongey' whether or not there's air in the system. I rather doubt there is if your braking power is fine dry.

Newer cars (like the SRX) have a feature that when rain is detected, it will periodicly apply light pressure to the brakes to 'clean' off the water and give you full force when you brake.

The V does not have this feature, and it's a giant rotor. It's going to get wet, and you're going to need to increase braking distances. I would say there is a significant decrease in the A6 when the rotors are wet versus dry and I know for a fact the system is 100% bled and air free. It's just a fact of the pad choise and low braking power to begin with.

baabootoo
11-01-12, 10:53 AM
Any changes to the brakes?

neuronbob
11-01-12, 01:04 PM
I notice that if I haven't braked for a long while (minutes) while on the freeway, in the rain, I have to apply more pressure initially to the brake pedal. Subsequent brake usage in the short time afterward leads to normal brake function.

In the rain, I increase my distance from other cars as a result.

Thanks for the explanation, extrabolts. Very useful.

JFJr
11-01-12, 04:10 PM
Definitely a problem. My brake pedal is never spongey, even in the rain.

Jud

Trapspeed
11-01-12, 10:15 PM
Someone identify this "kimberlywatkins" profile considering its post is mine verbatim.

baabootoo
11-01-12, 10:41 PM
Did you change anything on the brakes? How many miles on the car?

DPL
11-03-12, 10:25 AM
No changes to my brake system. I have recently lowered the car (Eibach) and moved to 20" rims (DPE). Appreciate the comments

thebigjimsho
11-05-12, 07:49 PM
Even with my aggressive DTC-30s, I get immediate bite in the rain and cold.

My stock pads seemed to have glazed over because I noticed a lack of bite when cold...and possibly in rain. Bleeding these brakes is not too hard. I'd go for fresh fluid and pads...

ctsVeteran
11-05-12, 07:57 PM
on a clear sunny day, if the brakes are working normally just take the car through a car wash. Once you get out and the pedal feels spongy you'll have your answer.

I have hawk ceramic pads on my Audi right now adn when i get out of the car wash the car literally has ZERO brakes. I wait for the traffic ahead of me to drive away then i take the car up to 35 ish and give a good brake application.

thebigjimsho
11-05-12, 08:51 PM
Spamdouche surfaces...

JimmyH
11-05-12, 11:10 PM
and just that quickly is eliminated

baabootoo
11-05-12, 11:23 PM
Bedding them is easy also.

ctsVeteran
11-06-12, 04:41 PM
lol who is spamdouche? i think i missed a post during the day?

JimmyH
11-06-12, 06:01 PM
we have been getting hit by spammers alot lately. we ban and remove them as we find them.

Scooter
11-06-12, 07:20 PM
In my '07 the brakes in the rain were brutal, scared the crap out of me a few times when they didn't bite from a high speed. It made me warn the guy who bought my car to watch out for it. My '09 hasn't shown this tendency at all so far.