kap1

I have 02 4.2, replaced rear pads 2K ago; front pads replaced 15K ago, a lot of visible front pad remaining. No front pad warning light.

Last few weeks, I've noticed pretty strong grinding noise when first moving out of parking. No grinding in normal operation or high speed, but when first braking at very slow speed (leaving parking spot), sounds almost like metal on metal. If rear pads new and front at least half pad remaining, what can cause that ? summer heat (I'm in MD) ? thanks much.

carbonLORD

Does that on all the loaner A4's Ive ever had.

Edd W

This often seems to happen on the inner centre of the friction surface and builds up into a type 'crust' on the friction face.

It will probably mean new disks.

Truewit

I'd suggest checking the rotors before you start in the morning (or whenever you start). I've had a similar experience with rust on the rotors -- i.e. grinding sensation -- that disappears after a few brake applications. It could be other factors as Edd W and carbonLORD suggest, but rust seems like a possibility. Good luck.

kap1

If it's rust, do I need to replace rotors soon ? I estimate at least 5-10K left on front pads, rather not replace now if I can wait. Thanks again.

Edd W

from the inboard side and only then we help further.

Generally, it is unlikely to severly reduce braking perfomance unless it has spread more than about 1/2" into the swept area.

Remember, brake are one area where it is not a good idea to economise with suspect parts, especially when you are getting warning signs something is wrong. I would fix it now rather than wait for the sake of a few $.

Truewit

Not necessarily -- you need to check how close to the tolerance limit they are. If they're within it, you can continue with them until you've reached it. I'm sure someone has posted what the limit is in this forum. In my experience rust can occur after driving in the wet without warming the rotors up by some braking action prior to putting the car away, and especially if it's not driven for a day or so; but rust can form overnight, though perhaps not as deep a crust.