AO Platinum Member
Join Date: Feb 2002
Location: The land that Time forgot
Re: Front Brake Noises
The pins get worn, as effectively the braking forces goes thru them. If you imagine the caliper gripping the disc, the tendency is for it to be twisted in the direction of the brake rotation, against it's carrier bracket.
Of course, the pins is what holds the caliper in it's fixed position on the disc, and the pins are trying to squeeze the caliper piston at the same time as being forced against the side of the pin hole.
The other thing is the carrier bracket holes the pins go through also feel this force, so you get the carrier pin hole being turned "oval" over time.
The symptoms there is a slight "knock" when you dab the brakes on, as the caliper pins take up the slack they're able to move about in.
My P4 would be quite happy at most speeds but if you stuck the brakes on suddenly and hard you would get a sort of "Zzhhhhhoooooh" noise from the front. It was pretty loud, and as you say it either does it or not at all.
I did have a thought ages ago but never followed it up. Do your discs have the optional (Euro) ABS notches in them? I had one disc changed after a shunt and it was ABS spec whereas the original disc wasn't. The noise seemed worse from that side and I wondered if the notches acted as some sort of amplifier. Just a thought...
No bullets for Chaingun..