Rotational Scratching Noise
 

Hi C5 Track Drivers:

I have a problems with my brakes and was wondering if you could give me any advice and recommendations.

Problem
After installing racing brake pads (both Hawk DTC-30s & Hawk HP+s at different times) and a hard day at the track with aggressive braking the front wheels now make a loud scratching sound as each wheel rotates. This happens while accelerating or coasting, but not braking. The noise is annoying like the sound of scratching nails on a chalkboard.

Details
I was told by a local Brake Shop that my pads (Hawk DTC-30s) were too agressive and as a result the rotors were showing signs of glazing. This glazing was potentially causing the scratching noise.

They removed these brake pads, turned the rotors and installed new, less aggressive race pads (Hawk HP+s). I then went on a second track day, again, with hard braking. Likewise, my front rotors are showing signs of glazing and the brakes are again making that rotational scratching sound even louder than before.

Recommendations
Thus far I have received three suggestions to fix this problem from a couple of shops.

Option 1 - both sources suggested deal with scratching sound. I can’t deal with it. It’s embarrassingly annoying.

Option 2 - one shop suggested dedicating a set of rotors and brakes for track days and dedicate another set of rotors and brakes for street driving.

Option 3 - the other shop suggested that my pads are not aggressive enough. Since I've turned the stock rotors twice already, buying another set of stock rotors and replacing the pads with Hawk DTC-60s in the front and Hawk DTC-30s in the rear.

Questions
What other options do I have? What other options do you recommend?

I just bought cooling ducts thinking that perhaps the brakes got too hot and this may alleviate future problems.

Thanks,
CRT

Have any pics of your rotors prior to turning them? All pads above will make noise, nature of the beast. So depending on how frequently you track the 2 sets would likely be a good idea. I melted the DTC-30's in ZL1 sizes as well so I would agree on a pad upgrade although I would go with Cobalt Frictions. Ducts can only help so much in our big heavy pig of a car.

First, thank you for your reply. Second, I'll photo the rotors for you. Third, I'm OK with the screeching sound of hitting the brakes, but that's not my problem. My problems is the "scratch, scratch, scratch" sound the brakes make each time wheel rotates WITHOUT braking.

Yup, mine will too now and then. Cooking off the brake lube will cause it too.

Make sure your brake dust shields are not hitting your rotors....

Interesting. I forgot to mention that one of the shops I talked to suggested brake shield rebuild. How do I check if they are hitting the rotors?

Are your rotors stock? If not, are they slotted? Maybe you have some build-up in one of the slots. (I have slotted rotors and they do make a small amount of rotational noise).

Since they do this all the time, is it all wheels or just one?

If you can isolate it to a specific wheel then jack the car up and manually spin the wheel to figure out where in the rotation the scratching begins/ends as it comes into contact with the pads. Inspect that region of the rotor (both sides) to see what is different. You also might want to pull the offending caliper to see if one of the pistons is stuck in the out position.

I've changed my rotors and calipers. It strikes me that changing rotors for track days would be a real pain. I think you have to pull the caliper (or at the very least the pads) to get the rotor off. If you have to pull the caliper then you'd have to get a supply of caliper bolts as they are not to be reused.

Stock rotors. Both front wheels. When I turn the wheel slightly to the right the front left wheel scratching noise goes away.

Well you can just crawl under the car a see the cap between your brake dust shield and rotor.

Take a look at the spring clip on top of the pads. The triangular shaped metal pieces that go down and contact the top of the pads appear to me to be designed to push the pads away from the rotor when no brake pressure is applied and also tension the pad against the caliper pistons and on the retaining pins so they don't rattle. Take a close look at these. I forsee one of two issues here.
The non-stock pads are not held off the rotor surface by the spring clip and you are hearing minor rubbing between the pad face and the rotor surface with no brake pressure applied. This would go away with pressure applied.
The non-stock pads are not held in tension against the pistons and on the retaining pins by the spring clip and you are hearing the pads rattling on the pins or against the spring clip or pistons. This would also go away when you apply brake pressure.
The change when you turn could be attributed to some flex when the wheels are turned.
Did the pins and spring clip get replaced when you changed the pads?
I would inspect the pad retaining pins and the spring clip for wear and proper tension and replace them if there is an suggestion of this being part of the problem. They are not expensive. I can get you the ACDelco part number. I have a set at home. PM me if you want the number.
I would also check the front wheel bearings. The lateral loading on the bearing will change with and without brake pressure applied and while turning.

The 1LE comes with a very small front "dust shield" on the lower portion of the spindle. It is more of a heat shield to protect the outer tie rod end and the lower control arm joint and front radius arm bushing. There is very little chance unless it has been hit by something that it would contact the rotor and then I think it would be in continuous contact not just when the brakes are not applied.

Thanks, everyone. I'll look into this over the weekend and report back.

CRT, did you find anything abnormal?