warriorp

I just installed a set of AC Delco drilled and slotted rotors with a set of Hawk ceramic street pads. I just went on my first test drive and followed Hawk's bedding procedure. I'm getting a slight or faint grinding noise under braking. I double checked my install, everything looks good. The car has good stopping power and feels normal. I've done several brake jobs in the past but no drilled and slotted rotors. Is this normal? If so will it fade with driving?

Thanks,
Chuck

StKnoWhere

Hard to know without hearing it but grinding noise does not seem normal. Especially with ceramic pads.

jackhall99

I would triple check the work, or have another pair of eyes do a check.

cclive

If you check both sides of the rotors and they look fine, then it's normal. Be sure to look at both inside and outsides of the rotors though, not just the outsides.

cthusker

There should not any grinding.. period! Maybe you have a retainer clip that got turned or miplaced while putting the pads in! Are you sure you have the clips facing the correct way? Jack the car up and check each wheel individually for any stranges sounds while turning the wheel by hand... Gotta be something wrong somewhere to have a grinding sound with new brakes imo...

warriorp

Just put about 20 miles on it. Im getting a normal wear pattern being established on all but the LR. It has some streaking that is aligned with the drilled spots. I took the wheel off triple checked everything. The retaining clips are in place and have no rub marks and pads look good. The only thing I've seen different is that the drilled holes do not have as much champer on the LR than the rest. But it is smooth to the touch. The noise has lessened but can be faintly heard with radio, AC, and windows down at a slow roll into the driveway. It sounds more like a dragging noise now. Thanks for the input.

Chuck

warriorp

LR Rotor

This is a minor issue and probably over analizing but we leave in a couple of weeks to ride the tale of the dragon and I want to make sure its perfect before we drive 900 miles away from home to push it in the mountains.

AORoads

hmm, altho that's a very close up pic, I've a question. when you say it feels smooth, are you running the back of your nail over it (like strumming a guitar), or feeling with your fingertips? sometimes, it's more obvious to the edges of your nail. I know that's one way to at least test the surface of a rotor surface.

cthusker

.... the new rotors should be totally smooth if the pads are new! I really do not think you should be seeing those type marks on a new rotors... I can say mine didn't look like that when I installed new rotors and pads... The only thing I can think of is perhaps the outside pad is not releasing all the way..... Did you jack up the car and turn the wheel by hand? If there is much drag you'll here it but you need a lot of pressure to put those type marks on the rotor..... If you do not see the same marks on the other rotors then something is different to say the least...

mvcrash

Agree, that is not normal wear for new pads and rotors. I would remove the caliper and look at those pads.

toomuchcar

warriorp

Everything is smooth as glass. I jacked it up and rolled them over and everything feels good and free. I can how ever hear a slight drag. The best explaination I have is there may be a slight riser at the edges of the drill holes. You can see a slight shine around a few of them.
Thanks
Chuck

rmedina

Put your old rotor on and take it for a spin. If the noise is gone, it's your rotor..

warriorp

And yes the pads are new Hawks and look flawless.

rmedina

I installed some new z51 rotors about 8 months ago and had to return 2 of them because they were defected. Good luck.

StKnoWhere

"I have is there may be a slight riser at the edges of the drill holes. "

Looks to me like maybe some the holes drilled in the rotor are not fully deburred? The streaks are mostly aligned with the holes.

What's the other side look like?

A properly bedded rotor will have a consistent color around the diameter if the pad material has transferred properly.

The rotor probably needs to be exchanged for a good one.

warriorp

Back is the same as the front.

toomuchcar

Did you do the rears? If so, check the ebrake drum. There is a casted part in there that is broken away from adjacent casting during mfr and can have a burr at that point that touches the rotor drum. I had to file the burr on mine.

Dennis08

I installed new (slotted&drilled) rotors and ceramic pads on mine a few weeks ago. I don't have a grinding noise but do have a deep growling noise when coming to a stop. Its not real loud or distracting but you can hear it. I checked everything and all appears fine and everything is wearing evenly???????????

cthusker

Ask yourself a simple question.... Did you hear deep growling noises BEFORE you installed new rotors and pads? If not then you SHOULD NOT be hearing them now! I suspect many do not know how to properly bed the pads so that might be part of the problem?

If everything is installed properly, the parts are within specs, the pads are properly bedded then you should not be hearing strange or new noises emanating from your brakes when stopping.... I'd keep looking or have someone that knows braking system look at the car. Just because the car stops doesn't mean there isn't a problem...