I just noticed that when I apply my brakes there is a circular pulsing/ vibration. Anyone else seeing this?

It is more noticeable the faster you are traveling or harder you apply the brakes.

 

It sounds like in might be uneven pad deposit on the rotors. Do a brake pad bedding procedure and see if it goes away. Below is an example but there are others that are similar:
https://www.powerstop.com/brake-pad-break-in-procedure/

 

Anti lock brakes do pulse when applied hard. If it isn't the normal pulsing you likely have a warped raptor.

 

Yep possible it's uneven pad build-up on the rotors BUT that usually leads to squealing on low speed light brake application.

Pulsing sounds like it could be a rotor runout etc issue. That would increase with speed (i.e. faster rotor movement with pulsation usually once per revolution.)

Bedding worth a try. For OEM pads I would suggest using what GM calls "burnishing" for tracking in the Owner's Manual. However don't need the 25 times they recommend, 5 or 6 cycles should do it. For my 2014 Z51 had a squeal at ~1000 miles and 5 GM recommend burnishing cycles eliminated it for me. Have also read with performance pads you must occasionally use your brakes aggressively to maintain that small amount of pad material evenly on the rotor. (Don't know why GM uses burnishing when the rest of the world calls in "bedding.") And a dealer can NOT burnish (bed) for you- in addition to GM not paying him it's a bit dangerous as have to find an area where you can aggressively apply brakes from speed several cycles in a row.

BTW it is not visible but there. In fact I recall seeing it on my 2014 Z51 NOT by looking but on the surface of the sanding pad I used to remove it when I switched to Carbotech 1521 pads. I foolishly waited 6 months and was having to clean the brake dust every ~200 miles as it not only looked bad was pitting my Black wheels. Switched to Carbotech street pads and 80% less dust AND most important what dust was there did not pit my wheels.

Got smart with my 2017 Grand Sport and installed Carbotech 1521 low dust pads as I did on my C8 as soon as I got it home. NO NEED to clean OEM pad material from the rotors!

Frankly since CJ8 has a good relationship with his dealer service folks I'd have them check all rotors for runout with a dial gauge. GM will pay them to do that!

 

Many times brake pulsation is blamed on warped rotors when it is really due to uneven pad deposit buildup on the rotors. A way to tell is use a dial indicator on the rotor to see if the runout is within service limits.

 

I live in a hilly area and have have fought this battle on many vehicles. Quite often the vehicle will have brake pulsations but the rotor runout is within service limits.

 

I'm at the dealership to get my replacement wheel for pitting. I'll have him check it out.

 

He'll probably just want to turn the rotors without checking the runout. This would fix the problem whether it is excessive runout or uneven pad buildup. See if he will check the runout first to see if the rotors are within limits. This information would be useful if the problem recurs.

 

Correct! The first thing people assume is warped rotors when there’s pulsing, however re-bedding the brakes is often all that’s needed.

 

Apparently GM is aware of the issue. My technician just talked to GM. It has to do with wet brakes sitting parked. One MUST only park the Car with dry brakes - typically after washing your C8. Do not put it away wet - make sure that the brake pads and rotors are dry. I thought mine were as I blow everything dry and then go for a 2-5 mile drive before putting it away after a wash.

Btw this is a new development. It didn't do it until recently. The only thing that is different is I started using my car cover in the garage apx 6-8 weeks ago. I'll leave it off for a while to see if it makes any difference.

Solution is to turn front rotors and replace rear rotors. Rears can not be turned or the coating on the outside diameter will be removed leading to corrosion!

I'm going to live with it for now. I can always have it "fixed " under warranty later.

 

Great input. I have always driven my cars and use the brakes aggressively a number of time after washing. In fact my MO is before using tire dressing I drive the car down the block applying the brakes aggressively to get the rotors hot. Then pull back in and pick-up water drops from the mirrors, spoiler, wheels etc. Then apply tire dressing.. Been using just 303 aerospace.

Yep, if you don't they quickly get a light brown iron oxide. Then when you drive it come off on the wheels!

 

I may just have to drive my C8 more often and harder. I don't see a problem with that.

 

This was an issue on my friends cars too. The wife religiously washes both cars EVERY week. She's obsessed with everything she/her husband owns looks sparkling clean. So eventually the brakes would pulse. So I explained the iron oxidization on wet brakes and bedding. Now she leaf blows the wheels dry when done 😆

 

^^^^^^^^^^
This. They use stock Z51 brakes at Ron Fellows and I have never leaned on brakes like I did out there and they were extremely smooth and fade free with zero pulse. On the street you couldn't use Z51 brakes hard enough to hurt them. (at least not before you are arrested)

 

I didn't realize the rear Z51 rotors were FNC coated. I had thought all Z51 rotors were uncoated and all base rotors were FNC coated. I'm surprised the FNC coated rotors were affected by residual water.

 

pebble in the brake pad?

 

He'd hear a loud squeal straight up if it was a stuck pebble.

 

There is an apx 1/4-1/3" Ring on the outermost portion of ONLY the Rear Rotors. If it is milled off, there will be corrosion fairly quickly. There is no such ring on the front rotors - so they can ne turned/milled without any problems.

I am not aggressive on braking. I am also not a putz riding the brakes forever to a stop. Just right as Goldilocks said. On my return ride home on local roads. I applied the brakes fairly hard when possible and there may be a slight improvement, but I'll have to keep driving to tell for sure - my problem. LOL

 

Answer from GM in Post #10.
Don't let wet brakes/rotors sit parked for long.
I guess that makes the case for Garage Queens that never drive in the rain or at least don't park for a long time (days) before driving after the rain.

 

^^^
This has been a common issue for years, re rust not pulsing. It doesn't take much to heat the rotors so driving in the rain is often not an issue. Stopping a 3500 car requires a lot of energy. So if you have been driving just braking for your driveway and garage gets them hot. It's when washing where the car is usually cold as are brake rotors where the problem occurs.

Recall a poster complaining of rusty rotors on his new and first Vette. I asked before the Vette was he bringing his cars to a car wash? He indicated yes. They use a lot of water and the car may be cold if in line a while. BUT as soon as you leave, driving and stopping will mean little time for them to rust!