Installed drilled/slotted rotors with Hawk HPS Street Compound on my C5Z. the problem I'm having is when braking the rear pads make a series of clicking sounds. I was told it might be the Calipers shims, as I re-used
the old ones. So I replaced them with new shims and the problem is still there. Any help would be appreciated!

 

It is not uncommon to hear a card in the bicycle spokes kind of noise with slotted rotors.

Not all cars will do it but some do.

I had an S550 Mustang that did it badly with slotted rotors on it.

Some will do it only with hard braking but under normal braking not do it.


Without being there these are things that can be hard to troubleshoot over the internet.

 

^This. Slots and especially holes produce quite a bit of cards in the spokes sound. I feel the holes make much more sound than slots, at least in my case. I have DBA slotted rotors on the C5 and drilled rotors on my Jeep, the drilled rotors produce much more of the cards sound when braking vs the slotted only rotors on the C5. Take a ride on a motorcycle with drilled rotors, they make a lot of card in spokes noise when applied which is easily heard.

 

I had drilled and slotted stoptech rotors, 3 of them cracked at an HPDE, was using Hawk HP+ pads. Switched to AC Delco Gold, slotted only, 2 cracked at an HPDE. I’m never using drilled and slotted again. I now have KNS brakes plain rotor made by DBA, 320 dollars shipped to my house, have Hawk HP+ pads, which have the best stopping power I’ve ever had in a brake pad, and for some reason with the KNS brake rotors, the pads don’t squeal that much. It was really bad with the drilled and slotted. HP+ pads produce some dust, but you’re definitely going to sacrifice stopping power with a ceramic. Ceramic will have little to no dust. Even for spirited driving canyon runs which is hence illegal, I would use a plain rotor and get some good brake fluid, I use hawk HP600 which is a dot4. My combo can be daily driven as well, it just produces dust, wipe it off, it’s no big deal.

 

The best rotor you can use is a solid rotor. The Rotor is a heat sink and needs to draw the heat from the pads to the rotor and radiate it out. The holes only remove metal that could be absorbing the heat. The also become weak spots to where they will fail.

Note the reason for the holes were with organic pads that used to out gas but we no longer have that issues. Also they were drilled to reduce unspung weight in cars that were very light and not pushing 2 tons. They never saw the heat and often were replaced every race.

Just get solid rotors and good pads from GM, Hawk or EBC. Judge the pads you need based on your driving. If you do track time you may want to change pads as track pads on the street are not great. Often the also will eat up rotors in daily use.

Why do they make drilled rotors. Because they make money. A number of companies will lie about them but the truth is they are very profitable. Slotted will help clean a rotor if off roading or if you have rubber from track time accumulate. Most race rotors just have dimples that serve the same job. Most real race rotors will do dimple or like a squiggly line cut in them or nothing at all.

We deal with all the major brake and rotor companies and not all are honest. I had the head of EBC in a meeting and he said he would never sell a drilled rotor. But they sell dimpled rotors. He said they will not crack and why because they make money.

If you want better brakes go to larger rotors that can absorb more heat. Unless you track you will not likely over use them on the streets legally.

To many brakes are just a vanity item. and that is fine if you just want the looks. If you want better brakes leave them alone.