Ive only had this car about a month now and only drive it on the weekends but Ive noticed that when Im at a stop light with my foot on the brake i can feel a knocking coming through the brake pedal. I seems to do it worse with the AC on and seems to go away if i put it in neutral. It also seems to do it worse when the car is hot after driving around town. Any ideas what this could be? The only mods I have is a lid and flowmaster muffler BTW, its an A4

 

Exhaust hitting the floor? Things are tight underneath and a lot of people don't get the pipes in perfect and they hit....

 

I really dont think its the exhaust. I only had the muffler put in so the rest of the system hasnt moved. Also it did this before i had the muffler installed. This is not an audible thing. Its just someting you feel in the floor. My buddy felt it in the passenger side too. Any more ideas?

 

There are common problems with the Idler pulley which runs the accessory belts making a lot of noise and causing unnnecessary vibrations. I'd let the delaer have a look at it. I'm guessing it's one of the small pulleys.

 

Very true. I replaced mine at 35,000 miles. I need to figure out if you can just replace the bearing instead of the whole assembly so at 70,000 I can do it cheaper (I think it was $60)...

 

thanks Ill check out the pullys this weekend