B5 Brake Question

[dennisS4]

Sometimes when I come to a stop a notice the brake pedal vibrates lightly. This is my 2nd B5 S4 and both have done the same thing. Can someone tell me why this happens???

[YMJ]

i think its when it overheats... :S im not 100 percent sure..

but whenever i do REALLY hard breaking, i feel it vibrate lightly as well!

someone can give you better info.. thats what i think

[AudiTechS4]

front rotors warped?
lightly pull on e-brake to slow down (please hold the button in so you dont lock your rears up), does it still vibrate? if not its most likely your front rotors

[NOVAS4]

front rotors warped?
lightly pull on e-brake to slow down (please hold the button in so you dont lock your rears up), does it still vibrate? if not its most likely your front rotors

x2 on rotors be warped..

[rick_chicago]

warped rotors

[YMJ]

guys i dont think its a warped rotor..

mine did the same thing.. and it wasnt warped..

i read somewhere that the rotors vibrate when you do hard braking.. i was reading something about breaking new rotors in (BBK)..

mine does that everytime i brake hard! .. it vibrates for a few seconds.. after i stopp..

but im no expert.. and some of you guys might be!

[dc878mmm]

Are you braking really hard beforehand?

[YMJ]

Are you braking really hard beforehand?

me.. yes..

now lets see what the op has to say..

[2000 A6 2.7t 6m]

When braking hard and coming to a complete stop, the pad will leave deposits on the rotor. I felt vibrations from this several times, and a hard braking without coming to a complete stop would clean the rotors off and get rid of the vibration for a while.

[dennisS4]

yeah its not warped rotors because it happens as soon as i lift my foot off the brake. I'm bringing it in for service ill ask them at audi too. It happens sometimes even when not stopping that hard...

[dennisS4]

The only really bad shaking I have ever experienced was in my last B5 which had 86,000 miles, alot more than 26,000 my current S4, and the steering wheel shook after a couple hundred mile drive out to PA, I believe that was the power steering overheating because I was driving hard through those curvy Pennsylvania roads. After I stopped and let it cool off there was no problem.

[rskelme]

I have the same issue. It is a buzz in the pedal after you have come to a complete stop. I researched this before and it looked like it might be a bad relay bouncing causing rapid cycles in the brake system that you can feel in the pedal. The brakes aren't actually engaging (rolls free in neutral) but I think the ABS is spazzing a bit. I notice it more when I have stopped hard or runover a bump before stopping. I think the jostling of the vehicle under those scenarios trips the faulty relay. Having noticed it for almost 2 years now I have seen no negative impact from this behavior aside from the annoyance.

If you track this down let me know.

-Roman

[rick_chicago]

Is it like a vibrator? (no I am not kidding) And do you notice it more when it's warm? (I didn't think Jersey was that warm yet)

I thought I remembered some warm climate guys having ABS pump issues when it gets warm (I wouldn't know, being in Chi-town - I have to switch back snows again soon;) )

The other thought is: slotted rotors? Go find a safe area and re-bed the pads and see if it helps. Or you don't have slotted rotors and I should shut up.

[qwks4]

I have the same issue. It is a buzz in the pedal after you have come to a complete stop. I researched this before and it looked like it might be a bad relay bouncing causing rapid cycles in the brake system that you can feel in the pedal. The brakes aren't actually engaging (rolls free in neutral) but I think the ABS is spazzing a bit. I notice it more when I have stopped hard or runover a bump before stopping. I think the jostling of the vehicle under those scenarios trips the faulty relay. Having noticed it for almost 2 years now I have seen no negative impact from this behavior aside from the annoyance.

If you track this down let me know.

-Roman

I think this is the most realistic answer. My car does this. I looked through the past service records of the 1st owner and he took it to the dealership with this complaint and it said something about the ABS system....

Annoying, but doesn't affect anything and I don't want to pay a dealership to chase ghosts around my car!

[rskelme]

Annoying, but doesn't affect anything and I don't want to pay a dealership to chase ghosts around my car!

No kidding, more likely they'll find a laundry list of things to "fix". Sometimes ignorance is bliss.

[dennisS4]

Its kinda like a vibrator, its more of a buzz feeling though. Yes it has been warmer in NJ recently despite the rain but it was happening in the winter time earlier this year too. I believe it is a faulty relay as rskelme said above, because i notice it when slowing to almost a stop and i hit a small bump it will start to buzz for 1-2 seconds.