Hiss/scoring after brake upgrade
 

I upgraded the brakes recently with drilled rotors, lines and pads, I've done brake jobs a million times but have never run into an issue like this.

After changing the rear brakes I am getting a loud annoying hiss under braking and an audible hiss/grinding or metal on metal sound at speed... Usually above 25mph. There is a clean band scored around the outer most edge of the drivers side rear, but upon disassembly and inspection I saw couldn't really see anything that might be touching the rotor other than the pad. I cleaned off the pads and rotor, loosened and realigned everything and it's still doing it. The car stops great, way better than it ever did before, it's just irritating and I don't want to damage anything. I put that paste shit on the backs of the pads and replaced the shim. But the only thing I can think might stop the grind sound is swapping the pads or getting more shims? It only does it on the one side I think. The other side looks normal as well.

Thanks for any advice.

Greased the slide pins? Its probably just the brakes seating themself in.

this is with the brake applied or not applied?

If applied: I'd assume the drilled rotors aren't properly chamfered

if not applied: I'd look at the dust shields.

I changed the rears weeks ago still doing it. Off the brakes the hiss is light, but there is a sound of something touching lightly like metal. On the brakes it sounds like there is I light sand paper stopping pressing against the rotor like the pads are rough.

Some rotors come coated with some light film of silvery zinc. It may sound like crap till this wears off.

If thats not the case, I think some slotted/drilled rotors do make a zzzzzzzzzzz noise due to the slots and holes.

I thought that might be the case as well but there is a line about .125" scored into the outer edge of the rotor. It's only on the visible side. Also I have drilled all around and the fronts have been fine. The oem pads had the 2 sets of shims but the new ones only have 1. Could the compound of the pad be a problem and could adding a shim or 2 help with the noise &/or scoring? I can't imagine anything else touching the rotor.

You fail to mention what pad your running. This might help diagnose. Use the shims that came with the pad. Retaining OEM with the new pads is not advisable as clearance will not be per the new pads clearance design. Check to see thath the pad slides freely in the upper and lower u grooves in the calipers. I have seen many sets, mostly EBC, that had to be lightly filed. If the pad is hanging on one pin it can leave a witness mark on the disk. Also it sound from you post you may have drilled them yourself(?). Bad practice as the rotors are heat treated and drilling after is a really bad idea. Warping, cracking, and short ter rotor fatigue can occur.

Utah

The rear pads are oem replacements from Kragen... The fronts came with the rotors and I know better than to drill my own rotors. Everything was purchased and appropriately manufactured for its job. I did not reuse shims just wondering if I should have. I don't really want to but I think I will have to try another set of pads... I can't imagine it would be anything else. They were 2 weeks old when I did the swap and they were quiet on my oem rotors.

Possibly a sticking caliper? I had an issue very similar to what you are describing on my old S13 and it ended up being the caliper sticking and not retracting fully.

Make sure the dust shield isn't hitting anywhere. Remove rotor and check for rub marks to be sure.