Grinding/rubbing/squealing from rear FNSL and BP30's
 

I have 4-piston FNSL and Spec 37's on the rear of my Firebird track/street car. I had BP10's in all calipers (fronts are Aerolite 6's) for my first track day in May. The brakes performed ok, but I wanted more response for the street and track. I went to a DSE booster and Master cylinder (was a manual Wilwood) and BP30's. I scuffed the rotors with 80 grit before changing pads and bedded them in before my last track day in August. I now love the feel of the brakes, but I'm getting an annoying grinding/rubbing/squeal from the rears. I hear it when I am pulling up to a stop and probably slow to between 5-7 miles an hour. It isn't heard when I am on the brakes....only when coasting. If it starts, I can make it leave by applying the brakes. My rotors had a weird look to them after my last track day and didn't have a uniform burnished look to them. I scuffed the rotors again, but the sound is still there.The sound has been there since I changed pads no matter what I have done. Could it be the pad-rotor interface, of maybe I need to lube some contact points? Thoughts?

I assume your not using a C clip rear and fixed calipers? If so, have you measured rotor runout? Sounds like maybe a warped rotor. If that's good, have you verified the rotor is centered in the caliper? Could be a pad dragging slightly due to the caliper being off center.

Are you running a hat with integrated E-brake?

Strange-built non-floating 9" with S-track diff. I am using the integrated E-brake. I already had a problem with that....one of the retractor springs broke. I suspect it was from rubbing/vibrating on the heads of my ARP screw-in studs (also causing a high-pitched squealing). I replaced the spring (Ford Explorer kit) and clearanced the heads of the studs. Something is still causing a faint squeal at low speed, but the current noise when coming to a stop is much louder and noticable. I aren't checked rotor run out and I don't remember doing much to center my rotors other than eye-balling it. I plan on digging into it tonight. No problems coming from the front. Thanks!

Pulled the passenger side wheel last night and started looking around. There is nearly no gap between the pads nad the rotor on either side. However, I noticed a witness mark on my frame rail and started to look around. I have a crushed section of copper line that is basically at the fitting where the hard line meets the SS flex line. It looks like the tab I welded on to the axle tube as well as the copper line itself have contacted the frame when the rear suspension on that side bottomed out. I suspect it is at a section of the track (Autobahn) that is called "The Jump". Luckily no leak and the drivers side is ok, but probably contributing to my problem!