If you have had brake issues, then read this.

[itguy61]

I learned something here! Helo maybe you have an issue that is causing the .45mm to not be there.

 

[Manaz]

Does the piston actually retract significantly when you let off the brake? I know when you remove the pads to change them out the piston is right up against the back plate and you have to get a wrench or caliper tool to push the piston in enough to put the newer pads on.

As the pads wear, the piston has to extend further before the pad makes contact with the rotor. This is why initial pedal travel often gets longer as pads wear down.

The hydraulic system is a sealed system (it has to be, it wouldn't work otherwise) as soon as you apply pedal pressure - when you release the pedal, the pistons have to retract to maintain the volume of the system between the booster and the calipers. The distance the pistons move is determined by the volume of the sealed environment.

The pad retaining/aligning spring keeps the pad in position against the piston. The square-cut seal's main role is to ensure the piston remains square in the caliper, as well as keeping crap out of the piston/sleeve (grindy brakes aren't fun, or effective).

It would be interesting to check the profile of the top of the pads to see if there is an issue there preventing them from staying in contact with the pistons, or, as noted, if something is engaging the brakes when the car is stopped (the latter seems relatively unlikely, there's no vacuum assist when the car isn't running, and you'd know it when you got into the car because the brake pedal would feel wrong (as something else would already be holding the brake system under pressure - you'd also feel the hold feature "release" through the pedal as it lets go if you had your foot on it).

But it certainly seems rotors aren't the issue here (*surprise*)!

 

[itguy61]

If you verify that the pad is being held against the rotor while stopped then the next question I would have is why this would cause the pad to deposit the material to the rotor? Almost like it is sticking to the rotor. I would suspect that is the pop you hear, the rotor breaking free from being stuck to the pad. This is very strange. I may go out tomorrow after work and lift one of the front wheels after it has set for a while and see if the wheel spins freely or if the pad is putting pressure on the rotor. I have had the vibration problem too so maybe it is an issue with something in the brake system. I still don't understand why the pad would stick that hard. This is very perplexing.

 

[Manaz]

If you verify that the pad is being held against the rotor while stopped then the next question I would have is why this would cause the pad to deposit the material to the rotor? Almost like it is sticking to the rotor. I would suspect that is the pop you hear, the rotor breaking free from being stuck to the pad. This is very strange. I may go out tomorrow after work and lift one of the front wheels after it has set for a while and see if the wheel spins freely or if the pad is putting pressure on the rotor. I have had the vibration problem too so maybe it is an issue with something in the brake system. I still don't understand why the pad would stick that hard. This is very perplexing.

My suspicion is that the hot pads are releasing a little of their binding compounds, and as they cool, that's causing them to stick.

 

[Helo58]

If you verify that the pad is being held against the rotor while stopped then the next question I would have is why this would cause the pad to deposit the material to the rotor? Almost like it is sticking to the rotor. I would suspect that is the pop you hear, the rotor breaking free from being stuck to the pad. This is very strange. I may go out tomorrow after work and lift one of the front wheels after it has set for a while and see if the wheel spins freely or if the pad is putting pressure on the rotor. I have had the vibration problem too so maybe it is an issue with something in the brake system. I still don't understand why the pad would stick that hard. This is very perplexing.

I agree. The pad definitely stuck to the rotor and "popped" off when the car was moved. There was a very visible patch of pad material before I tried to "scrub" them while driving and braking hard. There was enough to show the service manager when I got to the dealership after a 20 mile drive. It really is unfortunate that it is happening to such a great car. I have never had any brake issues on any of my cars, motorcycles, trucks, equipment, etc. and I am really put out that this is happening a second time with what I thought would be "the fix." I am eager to find a solution so that I can get my car back and fully enjoy it again.

I was reading through the service manual again and I am learning all kinds of things about the brakes and braking systems. Of interest is that the parking brake is tied in with the hydraulic system (at least through the vehicle computers). If the parking brake is pulled when the car is moving, it will progressively engage the hydraulic brakes (not the drums on the inside of the rear disks). The features of auto hold will interact/alternate with the parking brake when the car is turned off/on, door is opened, trunk is opened, etc. Auto hold uses the hydraulic brakes primarily but can use the parking brake depending on things like hood/trunk/door open or closed, vehicle speed sensors, slope sensors, etc. And lastly, the parking brake has two levels of clamping force depending on whether or not you are on an 8% or steeper slope. None of this helps me with my problem, but I found it interesting in any event.

I would love to hear any additional brain storming or thoughts from the forum members regarding what could be going on, so keep those ideas coming!

 

[Tobstertx3]

Very interesting....

I’m returning this week from a 3 week vacation, the longest my Stinger has sat without being driven. I’ll be checking to see if I have any deposits.

 

[itguy61]

I wonder if there is some kind of software issue causing the brakes to apply some kind of hydraulic pressure causing the warm pad to stick when parked and deposit crap on the rotor. If that is true then then you add in various pad compounds, maybe some are more prone to melt at lower temp and end up sticking due to pressure being applied. If that ends up being it Kia needs to fix this. I wonder if some of the rest of us who have different brands of pads will start seeing it too.

Dang, sorry it is happening to you!

 

[itguy61]

Very interesting....

I’m returning this week from a 3 week vacation, the longest my Stinger has sat without being driven. I’ll be checking to see if I have any deposits.

Curious to see what you find.

 

[Tobstertx3]

Curious to see what you find.

I’ll report back this weekend.

 

[Chucky]

Maybe have someone bleed the brake lines? I would think a mechanic who knows brakes could look at it and tell pretty quickly what's going on; maybe leave the car with them for a few days since you don't drive it much. Better solution...: Drive the Stinger more!

I would be surprised if this was a Brembo issue they are the go to supplier for high performance brake calipers for Ferrari, Lamborghini, Porsche, BMW, Mercedes Benz and almost every other European Sports car manufacturer; they just put their own name on the calipers. Brembo also supplies brake calipers for Formula 1 race cars and every race category below it. I know nobody can produce 100% fault free parts but these are the best in the business.

We are lucky to have Brembo's on the Stinger; thank you Albert Biermann!

 

[Metalmania82]

Also, neither the parking brake or brake hold use the calipers or pads; these brake systems use a drum brake inside the rotor so that would not have been a contributing factor.

Brake hold uses the calipers. E-brake/parking brake uses shoes inside the rear rotors/drums.

 

[Helo58]

Very interesting.... I’m returning this week from a 3 week vacation, the longest my Stinger has sat without being driven. I’ll be checking to see if I have any deposits.

I would appreciate your feedback. Have you had any brake issues to date? BTW, 3-week vacay? Nice!

I wonder if there is some kind of software issue causing the brakes to apply some kind of hydraulic pressure causing the warm pad to stick when parked and deposit crap on the rotor. If that is true then then you add in various pad compounds, maybe some are more prone to melt at lower temp and end up sticking due to pressure being applied. If that ends up being it Kia needs to fix this. I wonder if some of the rest of us who have different brands of pads will start seeing it too.
Dang, sorry it is happening to you!

Thanks man. It is frustrating to say the least, but in the big scheme of things it is only one thing on an otherwise fantastic car. It will get sorted I am sure.

Maybe have someone bleed the brake lines? I would think a mechanic who knows brakes could look at it and tell pretty quickly what's going on; maybe leave the car with them for a few days since you don't drive it much. Better solution...: Drive the Stinger more!
I would be surprised if this was a Brembo issue they are the go to supplier for high performance brake calipers for Ferrari, Lamborghini, Porsche, BMW, Mercedes Benz and almost every other European Sports car manufacturer; they just put their own name on the calipers. Brembo also supplies brake calipers for Formula 1 race cars and every race category below it. I know nobody can produce 100% fault free parts but these are the best in the business.
We are lucky to have Brembo's on the Stinger; thank you Albert Biermann!

Normally, I would agree with you on chasing the problem, but the more I find out about this brake system and look at the Kia diagnostics in the manual, there is no methodology to check for this. It will take the "brake whisperer" to find it. All kidding aside, I think it will take a slightly above average person to find this but I hope I am wrong.

I do agree about driving the Stinger more. If I didn't lease it, I would drive it most of the time. I let my truck the day to day beating and then road trip in the Stinger. Knowing what I know now, I would have purchased it rather than lease but with it being the first model year, I played it cautiously.

I also doubt that it is the Brembos. I have had several other cars equipped with Brembos with no issue. I think it is a hardware adjustment or software fix away from being corrected. I have really struggled with understanding why people with the same driving style have had varying experiences with the brake issue. Some are completely unaffected and others have the vibration. Given that, I think it then boils down to differences between cars... namely things that can be adjusted, shimmed, or otherwise vary in tolerance from car to car.

 

[Tobstertx3]

I would appreciate your feedback. Have you had any brake issues to date? BTW, 3-week vacay? Nice!

Will do. I’m at 7000 miles and have no brake issues to date. I am in a similar position to you where I use my truck a couple of days a week for work and my Stinger the rest so there are times when my Stinger may sit for 4-5 days without being driven. So far no issues, but 3 weeks that’s a whole new ball game.

3 weeks in Bonnie Scotland as well. Wish I had my Stinger here, it would be a blast compared to Houston traffic.

 

[oddball]

Er....... Granted, I haven't verified which method the Stinger uses, but here's some useful background.

Most modern brake systems DO NOT retract the pistons. They release the pressure pushing the piston onto the pad, but they usually leave everything more-or-less touching each other. This leaves slight residual drag which is why drag racers have special systems or use drums. In the 80's car manufacturers experimented with "quick take up" systems that did pull back on the pistons a bit. This ended up being too complicated and leaked too easily.

Many of the seals in the brake system work best when sealing against forces from one direction. Piston seals are stopping fluid from pushing out around the pistons - they're terrible at stopping air from coming in past them. Hence a system that pulls back on the piston will fail sooner than a traditional system. Calipers are better than drum brakes at least. Back-in-the-day, the brake system needed a minimum of 10psi at all times or else the seals would literally fall apart.

Re: A sealed system, yes, but the seals that make the master cylinder work are unidirectional lip seals. As the master cylinder piston is pushed, the lip seal is forced against the bore, and pushes fluid towards the calipers. When released, the master cylinder piston retracts. While there is more pressure in the calipers than the master, the fluid will return to the master and keep the lip seal sealed. Once the pressure equalizes, the lip seal essentially folds down and fluid is drawn from the reservoir. If if was 100% sealed then the calipers wouldn't be able to accommodate pad wear by drawing fluid from the reservoir.

Anyway.... When pad deposit problems like this happen it's usually because the rotors are extremely hot when stopped (see: all pad manufacturer's bed-in instructions). In this case, I fully expect it's a manufacturing fault in the pad. They just messed up that set and the binders in the material didn't set correctly. The unfortunate thing is you'll probably need to turn the rotors to get them cleaned up.

Re: different bed-in instructions: They're all actually the same. And they all work. Any consumer pad is "scorched", which causes it to bed itself with just general driving. It takes a while - 200-500 miles, but it'll happen all on its own. The various bed-in procedures are just a method to force a layer of deposit transfer on one go. So bed-in or don't, doesn't usually matter.

Anyway x2, the liklihood that the computer applied the hydraulic brakes while the car was parked is extremely low. Even if it did, that wouldn't cause this problem - if that was enough, then every time you sat at a red light would be a problem. This is a quality problem with that set of pads. (or your rotors were completely cooked for some reason)

 

[robz32]

Another possibility is that the disks are not able to dissipate heat efficiently, therefore overheating the pad and making them stick to the surface.

I recall the same issue was present on the 370Z Nismo (with Akebono brakes) back when it was new, the guys from R&T were testing it at the track and the brakes simply faded and the car hit the wall at a moderate speed. Years later, it was the enthusiast community that figured that, the Akebono calipers had enough clamping force and the pads were appropriate, however the rotors did not have enough surface area or ventilation to properly dissipate the heat accumulated from braking. The solution was either go with a two piece oversized ventilated disk or a stock size drilled or slotted disk.

 

[Helo58]

Er....... Granted, I haven't verified which method the Stinger uses, but here's some useful background.

Most modern brake systems DO NOT retract the pistons. They release the pressure pushing the piston onto the pad, but they usually leave everything more-or-less touching each other. This leaves slight residual drag which is why drag racers have special systems or use drums. In the 80's car manufacturers experimented with "quick take up" systems that did pull back on the pistons a bit. This ended up being too complicated and leaked too easily.

Many of the seals in the brake system work best when sealing against forces from one direction. Piston seals are stopping fluid from pushing out around the pistons - they're terrible at stopping air from coming in past them. Hence a system that pulls back on the piston will fail sooner than a traditional system. Calipers are better than drum brakes at least. Back-in-the-day, the brake system needed a minimum of 10psi at all times or else the seals would literally fall apart.

Re: A sealed system, yes, but the seals that make the master cylinder work are unidirectional lip seals. As the master cylinder piston is pushed, the lip seal is forced against the bore, and pushes fluid towards the calipers. When released, the master cylinder piston retracts. While there is more pressure in the calipers than the master, the fluid will return to the master and keep the lip seal sealed. Once the pressure equalizes, the lip seal essentially folds down and fluid is drawn from the reservoir. If if was 100% sealed then the calipers wouldn't be able to accommodate pad wear by drawing fluid from the reservoir.

Anyway.... When pad deposit problems like this happen it's usually because the rotors are extremely hot when stopped (see: all pad manufacturer's bed-in instructions). In this case, I fully expect it's a manufacturing fault in the pad. They just messed up that set and the binders in the material didn't set correctly. The unfortunate thing is you'll probably need to turn the rotors to get them cleaned up.

Re: different bed-in instructions: They're all actually the same. And they all work. Any consumer pad is "scorched", which causes it to bed itself with just general driving. It takes a while - 200-500 miles, but it'll happen all on its own. The various bed-in procedures are just a method to force a layer of deposit transfer on one go. So bed-in or don't, doesn't usually matter.

Anyway x2, the likelihood that the computer applied the hydraulic brakes while the car was parked is extremely low. Even if it did, that wouldn't cause this problem - if that was enough, then every time you sat at a red light would be a problem. This is a quality problem with that set of pads. (or your rotors were completely cooked for some reason)

I remember from rebuilding/cleaning some brake calipers on a motorcycle that I previously owned (because they were dragging), that the square seal inside of the caliper would actually retract the piston slightly when pressure at the brake handle was released. Squeeze and it pushed on the piston/pad, let off and the piston retracted slightly but enough to clearance the disk. It didn't do this before it was rebuilt due to the corrosion/dust/dirt caked around it. With the run-out of the rotors included, the distance had to be measured with a feeler gauge, but there was still clearance.

I also doubt that the computer applied the brakes while the car was parked, but when considering that the brakes have had the same issue with two sets (stock pads/rotors and new aftermarket pads/new stock rotors), we are definitely in the "low occurrence percentage rate" area of any explanation. I am trying to be open to any possible explanation. As I learn more about the braking system, some ideas rise to the top. However, I am certainly a believer that the simplest explanation is often the correct one, but this one has me entertaining ideas outside of that line of thinking.

I hate to think this, but I have to entertain all solutions at this point. With respect to a bad Stoptech pad, in my mind, there is a higher probability of the shop reusing stock pads (resulting in pad transfer) than there being a bad Stoptech set of pads. I hate to think they didn't use them, but I have had a different shop not use the oil I left with them (on a previous car). I found this out when I did a routine oil analysis. Thankfully, pads will be easier to check than oil. I will ask the service manager to personally verify that it is the Stoptech pads that are installed. On a side note, unless they are using a Blanchard grinding process to resurface the rotors (which they aren't), I won't have the rotors resurfaced. I had a road racing friend convince me of the "evils" spiral machining a brake rotor.

Lastly, when the unaffected cars (cars with no pad deposits) are parked, are the rotor and pad in contact with each other enough to melt pad onto the rotor of average "hotness?" There was no aggressive driving prior to me parking the car. If anything, it was just the opposite. I can think of anything I could have done to avoid this happening again and I certainly don't drive the Stinger any differently than my past cars. I am truly at a loss to understand why this is happening.

 

[Helo58]

Another possibility is that the disks are not able to dissipate heat efficiently, therefore overheating the pad and making them stick to the surface.

I recall the same issue was present on the 370Z Nismo (with Akebono brakes) back when it was new, the guys from R&T were testing it at the track and the brakes simply faded and the car hit the wall at a moderate speed. Years later, it was the enthusiast community that figured that, the Akebono calipers had enough clamping force and the pads were appropriate, however the rotors did not have enough surface area or ventilation to properly dissipate the heat accumulated from braking. The solution was either go with a two piece oversized ventilated disk or a stock size drilled or slotted disk.

I remember reading about this a few years ago and couldn't believe that a factory "Nismo" car hit the wall. The magazine did a big write-up on it explaining what happened. This is the first thing I thought of when "Car and Driver" magazine was testing the Stinger and a similar thing happened. Quoted, "After a few warm-up laps, we went for it, fully opening the throttle through Hog Pen and hitting more than 130 mph on the front straight. But when we stomped the brake pedal, very little happened. Well, that’s not exactly true. A big something happened. Without sufficient stopping power, the Stinger sailed into the grass outside Horse Shoe at 58 mph. We got the hint: This wasn’t the setup for track work. So we stopped lapping and started calling and emailing Kia. On the final day, its PR team delivered a Stinger GT fitted with European-spec pads, which, according to the company, you’ll be able to get at dealerships for about $700. They worked, hauling the Stinger down from 133.8 mph on the front straight."

 

[MerlintheMad]

Isn't it interesting that Randy Pobst had nothing but good things to say about the Stinger on the track; not a word about brakes going soft.

I remember reading about this a few years ago and couldn't believe that a factory "Nismo" car hit the wall. The magazine did a big write-up on it explaining what happened. This is the first thing I thought of when "Car and Driver" magazine was testing the Stinger and a similar thing happened. Quoted, "After a few warm-up laps, we went for it, fully opening the throttle through Hog Pen and hitting more than 130 mph on the front straight. But when we stomped the brake pedal, very little happened. Well, that’s not exactly true. A big something happened. Without sufficient stopping power, the Stinger sailed into the grass outside Horse Shoe at 58 mph. We got the hint: This wasn’t the setup for track work. So we stopped lapping and started calling and emailing Kia. On the final day, its PR team delivered a Stinger GT fitted with European-spec pads, which, according to the company, you’ll be able to get at dealerships for about $700. They worked, hauling the Stinger down from 133.8 mph on the front straight."

 

[robz32]

Different track, different environment. It was good but not enough to discard the issues.

 

[Helo58]

Isn't it interesting that Randy Pobst had nothing but good things to say about the Stinger on the track; not a word about brakes going soft.

Yes, 100% agree. That is the part I wrestle with is that people can have polar opposite experiences with the stock brakes. However, in that particular case, I would be inclined to think that any cars loaned to publications for long-term testing may have had their brakes changed after the "Lightning Lap" fiasco. I'm throwing my hands up at this point.