Rotors

[vmi9d3]

Hey all,
2018 G80 here, 98k miles on it. Bought used in 2019 with 28k miles.
I replaced front brake pads and the rotors were resurfaced in Jan 2023 and now, approx. 8k miles later, I am getting a shudder while braking. Seems like a rotor issue. The repair facility that did last job claims they will fix under warranty if the rotors are truly the issue. The reason for the resurface vice replace back in Jan is that they couldn't find replacement rotors. I am not sure what/where they were looking but a quick search found AutoZone has replacement rotors. There is an Autozone in the same parking lot too.
Google also showed me that it is possible the control arm or tie rods could be bad. I am not sure what other symptoms I would have for those issues. Does 100k seem like a reasonable time frame for that repair? Probably need to do both sides for those repairs, right?
Thanks.

 

[joegr]

There is something you can try to help diagnose this, if you have somewhere where it is safe to do this, with no traffic.
Get as fast as you are willing to safely do. Do very hard steady braking down to 15/20 MPH, then release the brake and drive a little ways to cool the brakes off. Now try a normal stop. Is the shudder much less now? If so, then it is material transfer to the rotors.

 

[bubbaG80Sport]

Warped rotors are a myth. Most of the time brake shudder is caused by uneven brake pad material transfer to rotors as @joegr indicates above. Try re-bedding the brakes. THE REAL TRUTH ABOUT WARPED BRAKE ROTORS. In my own experience re-bedding resolves brake shudder.

Scored rotors can also cause shudder. Run your finger nail across rotor surface. If there are noticeable bumps then replace rotors. I'm surprised you were able to get rotors turned. It's becoming a dying service as rotors are being manufactured thinner to save cost/weight. Most shops save time and make a little more money just replacing the rotors.

Suspension issues (i.e. control arm) usually do not only exhibit issues under braking.