buddies 99 firehawk...
stock brakes except for ceramic pads that were put on 3-4 weeks ago

brakes were working properly for weeks after we changed his pads (to reduce brake dust)

last friday it rained during the day and we all know how when rotors get wet, they rust slightly, instantly (just the surface stuff that wipes off if you just rub your finger on the rotor)

well he drove 45 miles that night, and made 4 passes at the track with hard braking..

and that little bit of "rain rust" was still coating the inside half of both of his front rotors...

they are not warped at all (no fludder to speak of) no cracks, no uneven or unusual wear on the rotors... and his old pads didn't show uneven wear of that type (a little that showed one of the pistons was working harder than the other, side to side not up and down, but not even enough to bother worrying about)

but they are flat out not making contact with the inside half of the rotor, on both fronts... rears are normal and we changed them at the same time.


anyone have any ideas???

 

Did you turn the rotors?

 

no... because they aren't warped

 

I noticed this same problem on my GF's mom's LH car (94 Concorde). The rear discs on that car are doign the same thing, but only on one side.

Is this problem on one or both sides? Seems like it could be a slide pin or pad issue, in terms of how the pads mount in the caliper. So basically an R&R and a thorough regreasing of the slide pins is what I'd try next.

 

its on both the driver and passenger side of the car... as far as if its not touching the inside of the rotors too.. i don't know... i've only looked as far as i can see thru the wheel.


but you lost me on the slide pins?

what/where are they and what do they do?

 

They don't have to be warped to require turning. I know lots of people (including myself) don't have the rotors turned every time pads are swapped (if the rotors look good). However, most shops would never do a brake job without turning the rotors. They would not be able to guarantee their work.

The new pads should eventually wear to the worn surface of the rotors, but to do it "right", always turn the rotors when doing pads.

 

can we have the rotors turned now? and just put the broke-in pads back on? or would we have to sand the glaze off the pads now to reuse them?

 

Ideally, you would want both the rotor and the pads surfaced so that they mate properly. You might get by with just the turn of the rotors.

Other suggestions like the caliper guide pins could also play a role in the irregular meeting of the pad to rotor, but since both sides are doing it, that may not be as likely.

 

so how would we check these pins? to make sure all is kosher? where/what are they exactly?

shoebox to the rescue again

 

You can see the pins in this view of the rear calipers. They just need to be straight and lubricated so the caliper bracket slides easily. Normally, they are not a problem.

 

That sort of problem can come from spread calipers.

 

and what are spread calipers?

 

Caliper spread can happen over time and with stress. The top remains stationary but the bottoms spread ******d. Thsi is known too happen with cars that open track race, or even cars that are used only for lapping. A lot of these guys will not buy a reman. caliper for fear that they will get one that has been spread.

 

Can you post a picture of the problem?

 

no i can't


but its fairly simple


the rotor is a circle...

the inside half (closer half to the center) of the circle where the pad touches the rotor isn't getting contact... and is evident by the accumulation of rust on on the rotor surface, after a rain and 50 miles worth of dry-driving