Hi Thefultonhow,The following is an FAQ about why your Stinger is experiencing vibration under braking. I’ve seen a lot of talk on the Facebook groups about this issue, and a lot of misinformation, and I’ve gotten tired of typing the same thing over and over again, so here’s a comprehensive FAQ that I can link to in the future.
Q. I already know why it’s happening! The problem is due to warped rotors, because Kia cheaped out on the rotors!
A. First of all, that wasn’t a question, and second of all, you’re wrong. The rotors on the Stinger GT are built to Brembo spec. They are annealed at temperatures higher than your brakes will ever see, even on the track, and are 13.9” vented rotors, which results in great heat dissipation.
Q. But they’re not built to Brembo spec! They’re not drilled or slotted!
A. Still not a question, and still wrong. There are plenty of Brembo rotors that are solid (as opposed to cross-drilled or slotted). My Chevrolet SS (RIP) had solid (but vented) rotors of around the same size as the Stinger’s. Also, I never had any problems with them “warping.”
Q. Well, if warped rotors aren’t the problem, why is everyone getting the problem fixed by getting their rotors turned or replaced?
A. Because that actually does fix the problem, at least temporarily. And dealers don’t care because Kia pays them for the work, and Kia wants to make the owners of their first big-selling premium car happy. But that’s like declaring your car a total loss because you got a scrape on the bumper. Replacing the bumper is a much easier, cheaper, and simpler option. And likewise, there is an easier fix for the brake vibration too.
Q. Okay, so if the problem isn’t warped rotors, what is it?
A. Pad deposits.
Q. Wait, what are pad deposits?
A. When you brake hard repeatedly due to spirited driving, or apply the brakes for a sustained period of time as you might if you’re coming down a really big hill, your brakes heat up. Not just the rotors -- also the fluid, which can cause total brake failure in some cases, but more importantly, the pads. As the pads heat up, they soften. Once they are hot enough, large amounts of semi-liquid pad material start coming off and sticking to the rotors. This material stays on the rotors even after the brakes cool.
Q. So why does this cause brake vibration?
A. Because brake vibration is caused by rotor runout (different thicknesses of the rotors at different points around their circumference). This can be due to warping (which we’ve already established is unlikely to happen), due to rust on the rotors that accumulates while the car is sitting and that is scraped off unevenly once the car is driven again, or due to pad material being deposited unevenly around the circumference (thicker in some places, thinner in others).
Q. Why is it unevenly deposited, though?
A. The most common cause is that you heat the pads up, and then come to a stop at a light and keep the brake pedal depressed. It can also be caused by dragging your brakes at low speeds (e.g. inching forward at a light or in traffic). Please note that this scenario (heating up the brakes and then applying them at low speeds and/or keeping them applied) is the most likely reason this problem occurs.
Q. I still don’t believe that this is due to pad deposits and not warped rotors. Where’s your proof?
Take a look at this article by Carroll Smith, who was one of the lead engineers on the original Ford GT40 program for Le Mans and also worked with the Ferrari F1 team and teams in Formula 5000 and the Australian Touring Car Championship:
Here’s the money quote:
(Side note: that article corroborates a lot of the stuff I’m saying here, and goes into more technical detail, with more specific recommendations on how to prevent the problem. Good read!)
Q. Okay, okay, you’ve convinced me. You said there was another way to fix this. How is that?
A. You need to do a “re-bed” of the brakes. This removes the uneven pad deposits, and applies a new, even layer of pad material to allow the pads to properly grab the discs.
Q. Okay, how do you do that? I hope I’m not going to be under the car for 2 hours doing this.
A. Nah, you won’t be under the car at all.
- You need to get in your car and drive to some place where you can get up to 60-80 mph. (With as much power as the Stinger GT has, this shouldn’t be hard, unless you live at the top of a mountain.)
- You then need to brake, as hard as you can (that’s important!), from 60-80 mph to 5 mph, then immediately let off the brake without dragging, accelerate, and repeat.
- Do this 4-5 times.
- After you finish, DO NOT TOUCH THE BRAKES UNLESS YOU HAVE NO CHOICE. You can either drive around for 10-20 minutes without touching the brakes to give them time to cool, or immediately park the car, turn it off, and leave it alone for an hour or two. Either way, the goal is to leave the even layer of pad material intact, and not add any more, until the pads cool enough to prevent further transfer.
Q. Uh oh! I did this and then got to a stoplight that turned red! What do I dooooooooo
A. It’s okay. Not ideal, but okay. Gently brake to around 5 mph (use the paddles to shift to lower gears, so that the engine braking does most of the work), then apply the electronic parking brake (EPB (Electronic Parking Brake)). The car won’t like this (it will ding at you), but it will do as it’s told, as long as you’re slow enough. The parking brake uses shoes inside the rear disc, and these are made of steel and are not affected by the heat in the same way that the semi-metallic pads are. Once the light turns, apply the throttle and the EPB (Electronic Parking Brake) will turn off automatically.
Q. Wait, I read the manual and it talked about a “brake bedding” or “brake burnishing” process, and this sounds much more aggressive? Why? I’m not going to destroy the brakes, am I?
A. Keep in mind that you need to not just put the new even material layer down (which is what the initial bedding process does), but you also have to remove as much of the old uneven material as you can. This process does that too, hence why it’s so aggressive. You definitely will shorten the life of your pads by doing it, but that just means you can replace them with something less crappy sooner (more on that later).
Q. I did this and I’m still having problems. You’re wrong!
A. Again with the non-questions!
Do it again.
No, seriously. Either you did it wrong, or the deposits are so substantial that you need to do it again to fully remove them. We’ll be charitable and say it’s the latter reason. It’s theoretically possible that you’re one of the 1% of people who have this problem not due to pad deposits, but, well, read the article I linked to above to see why that’s probably not the case.
Q. I did this and it worked for a couple thousand miles, but now the vibration is back. I thought this was a permanent fix?
A. Unfortunately, no, it’s not a permanent fix, because Kia used a crappy pad compound that can’t stand up to aggressive braking. In fact, they only used this dumbed-down compound in the U.S. -- in Europe, they get stuff that’s more aggressive and doesn’t do this as easily.
Q. Ugh, Kia is the WORST! Why would they do that?
A. Actually, I don’t blame them. The problem with the more aggressive compound that they use elsewhere, and that many other manufacturers use on their cars equipped with Brembos, is it’s noisy and it’s dusty.
Q. Well why can’t they make a high performance compound that doesn’t have noise and dust?
A. Because it’s a tradeoff. If you want a compound that has better heat resistance and initial bite, it needs to be harder. If it’s harder, you get noise (because it doesn’t conform as well to the rotor, causing harmonic vibrations similar to the ones you cause when you wet your finger and run it around the rim of a wine glass) and dust (because instead of melting off, the material that comes off the pad when you brake hard just kind of flakes off or gets shaved off in very small pieces). If you use the softer compound, it’s going to melt much sooner. Kind of like butter! Brake pads made of butter really suck, BTW.
Q. Well, I’d be okay with more noise and dust. Why wouldn’t everyone?
A. Good question! I love noise and dust. On my old WRX, I had aftermarket pads that squealed at 100 dB every time I touched the brakes, and my wheels literally had rust on them from the pads wearing away at the rotors. But those brakes grabbed like a psycho ex-girlfriend. For most people, though, they don’t want to put up with that.
When I had my Chevy SS (once again, RIP), noise/squeal and dust were the number one complaint on the forums. And that was on a car that’s literally a 4-door Corvette. People buying a Kia with a really nice interior aren’t going to be even that receptive to noise and dust.
Q. Okay, but I said I’m okay with noise and dust. Can I get summa dat?
A. Actually, yes. According to Car and Driver, Kia will be selling the Euro-spec pads through their dealer parts departments. I’m not sure if they’re for sale yet, but when they are, that’s the permanent fix.
Q. What if I'm not okay with noise and dust?
A. Remember that the problem of uneven deposits is caused by either dragging the brakes at low speeds, or keeping the brakes applied at a stop, while they are heated up. The trick I described above, where you are careful after driving hard to apply the electronic parking brake at a stoplight instead of using the brake pedal, can at the very least reduce the risk of the issue happening.
Q. Kia keeps on replacing rotors under warranty on these cars. Can I get them to give me the pads under warranty instead?
A. Good question! I’m currently trying this tack. I’ve had vibration under braking three times in 8600 miles, and have fixed it through a re-bed each time, but I’d like a better solution. I’ll keep you posted on whether I have success.
Any other questions?
Your last Q & A regarding rotor warranty. I spoke to a service tech yesterday 12/19/2021 and they said that rotors and brakes aren't under warranty. How do I get my dealership to cover it under warranty? I only have 6500 miles, bought in March 2020.
Kia says in the owner's manual (words to this effect, manual is out in the hatch), High performance Brembo brakes may give a "rrrr" or "scritching" sound when braking, which is normal operation.
