I've been wondering about this for a while now, if this is a common problem or just my car being a bitch... But, when its raining out my brakes are complete garbage. its an 01 a4 quattro 2.8. When its dry outside, or even just a little wet outside my brakes are fine. great pedal feel, stops well and doesnt pull. but when its raining out, its almost like the pads/rotors are getting super cooled by the water on the road. when im coming to a stop, the first few seconds im on the brakes the car doesnt slow down at all. its like im not even on the brakes at all. but after a moment the brakes come online and the car stops normally. Now, is it just a combination of the rain cooling the brakes, heavy car, and shitty single pot calipers? (mind you im coming from my rx7 with 4 pot calipers so i guess im biased..). I checked the brakes and they arent in need of replacement. the rotors arent heavily grooved, the pads are in good condition. Im used to it now, i just brake early. but it does worry me a bit. is this normal??

also i was thinking of doing the a8/tt upgrade once i get a couple things tidied up. will that possibly help my rain issue? thanks guys

 

its normal for brakes to act like that when its wet. Slotted rotors will improve braking on wet surfaces.

When you first apply on brakes when its wet, the pads are riding on a film of water when its wet. After a few moments the water dissipates and the pads finally make full contact on the rotors. Slotted rotors prevent this by channeling the water away through the grooves.

 

yea i know whats going on with all of that, but ive never had a car that was this bad before. Normally its something that you just get used to but with mine you litterally feel like youre going to rear end the person in front of you every time. its a good 2 to 4 seconds before you feel anything happen in the braking system, even if you get on it pretty hard. maybe bad line pressure?

 

How old are the pads and rotors? The pads could be glazed and are only acting up in the wet conditions. If you haven't done pads in a while, it prolly wouldnt hurt to change the pads anyways especially for only 25 or so dollars (if you DIY)

 

Mine does this too, but I know for a fact that my rotors and possibly pads are bad.

 

Im not sure how old they are. they were on the car when i bought it ~10 months ago. i just checked thickness and did a visual inspection a few weeks back. but they are semi-metallic (which i hate) so im probably going to pick up some ceramics and resurface the rotors. maybe that will help?

Does anyone know if the dual pot s4 brakes are a direct bolt on?

 

The S4 brakes may be a straight bolt on for you being an '01. Most of us have to switch to the Aluminum uprights from the S4 along with some other parts in order to use them.

I'm not sure how much credence I give to the slotted rotors being better in the rain. At the pressures and temperatures involved in braking, water will quickly turn to steam. more likely is cheap pads and old rotors.

 

Are you speaking of the rear brakes? I have always thought of buying a S4 rear brake sets from a part out.




@legend I hear that you'll need to swap out your rotors too if you choose to get ceramic pads, or the ceramic will just eat through your rotors. Someone correct me if im wrong.

 

I've had this issue with stock brakes and with my A8 set (using drilled/slotted Powerstop rotors and Hawk HPS ceramic pads). Seems to be a trait with our cars - these discussions have come up in the past as well.

 

Check out this link: http://www.audiworld.com/tech/wheel31.shtml