What does this brake rotor tell you?

[Ucsdryder]

This is a new to me Chevy suburban. 2018 with right around 100,000 miles. Brakes look new, both pads and rotors. Was getting a shimmy while breaking. Assumed that the rotors were warped. Left side looked brand new. This is what I saw on the right side. Is this just a warped rotor? I just replaced it with a new rotor. As you can see in the pictures only about 50% of the rotor was getting contact with the pad.

 

[2muchhp]

Rotors not flat/square with the face
On my phone, pics not great for me...

 

[JDPAPA]

I would bet the rotors may have been installed without cleaning the hub faces properly. Most home mechanics NEVER know to do this.

 

[Ucsdryder]

I’m confident they were replaced at a shop based off of the Carfax. That being said there was a lot of rust on the hub on the rotor that was messed up. I cleaned it up with a wire brush. The other side had almost no rust and the wear looked much better.

 

[Laelkhunter]

Maybe someone did a brake job, and turned the rotor, but it wasn't turned to the same depth across the face of the rotor. The portion closest to the hub is deeper, so the brake pad is not making contact there. Just a wild a** guess, I am not a mechanic.

 

[fngTony]

Bad piston in n the caliper maybe?

 

[JDPAPA]

Another thing that I have found very often was the caliper hardware was not lubricated.
There are some other things that can’’t be assumed with the pictures. Caliper looks new, so it should be okay, but would need to confirm that it is able to move freely.

 

[Ucsdryder]

Dammit… I didn’t check the calipers/pistons before I put it back together. They did look like they were in really good shape.

 

[Truck24hr]

Bad piston in n the caliper maybe?

Another thing that I have found very often was the caliper hardware was not lubricated.
There are some other things that can’’t be assumed with the pictures. Caliper looks new, so it should be okay, but would need to confirm that it is able to move freely.

I'd bet on one of these, and lean towards the caliper hanging on unlubricated pins

 

[JDPAPA]

I have worked on hundreds of cars over the years and have come across a lot of stuff, from broken off wear indicators to bad brake hoses etc. Even work that has been done at dealers I have seen with ZERO lubricant on the caliper hardware and rusty rotors.
Take it apart check the caliper operation and if you see one of the pads is worn more than the other and there is lubricant, you can make a good guess the caliper isn’t working properly or a brake hoses has failed. If and when you pull the hubs, take a good wire brush on a drill and clean up BOTH faces where the hub and rotor meet.

 

[Wrench]

How's the wheel bearing?

 

[tt_johnsclist]

Another vote for caliper hanging up or binding

 

[sz28]

Rotors rarely ever actually warp. The "warping" is usually due to pad material build up. But yours probably isn't build up.

THE REAL TRUTH ABOUT WARPED BRAKE ROTORS

The REAL truth about warped brake rotors... The typical situation: New pads are fitted to a new pair of brake discs. A week later there’s a vibration or “judder” when the brakes are applied. A call to a mechanically inclined friend and an online search offers the diagnosis—the brake rotors are...

alconkits.com

 

[bmart2622]

Did you put new pads on with the rotor?

 

[Ucsdryder]

Did you put new pads on with the rotor?

I didn’t. Usually I do but I could tell they were brand new. Didn’t think it was an issue until I pulled that tire and saw that rotor. I’m hoping the pads wear to the new rotor?????

 

[Ucsdryder]

How's the wheel bearing?

Hell if I know.

 

[TaperPin]

Many new pads leave an uneven smear of material on the surface - it may not matter if you replace the rotors, some pads just cause that vibration. I’ve used different pads, sanded the old pad material off the surface of the rotor and it was good as new. I’ve also had the shimmy show up right after some expensive Napa pads were installed, so I replaced them with cheap Napa pads, did a few hard stops and problem solved. Your rotors still have machining marks so they haven’t been used much - the pads will eventually wear down to make full contact. Loose front ends can make a vibration much worse - might be worth checking for a shot tie rod end, ball joints or arm pivots.

 

[bmart2622]

I didn’t. Usually I do but I could tell they were brand new. Didn’t think it was an issue until I pulled that tire and saw that rotor. I’m hoping the pads wear to the new rotor?????

They might but thats probably why you are getting uneven contact, the old pads wore to the old rotor and now the new rotor is flat and the pads arent

 

[Kroezer54]

I used to be a mechanic. I would remove and reinstall the calipers to ensure they're aligned properly and have the rotors turned (or replaced if they cannot be turned any more)

 

[SDHNTR]

Either you have a stuck piston in the caliper (usually pretty easy to diagnose), or a sticking rail on a pad foot (also easy). Take the caliper off and have someone pump the brakes while you inspect. And fwiw, pads and rotors should always be replaced (resurfaced) together.