Who else has had warped rotors?

[Hydrajin]

When you say heat treatment, are you referring to profiling?

Wonderful world of metallurgy. If by profiling, you are referring to DBAs tsp (marketing terminology) than yes. Cast iron as a material just doesn't cut it for applications such as rotors; it must be heat treated to toughen the material, this process is done to many metals that undergo severe conditions or need to be stronger overall for their application. Heat treatment such as quenching, tempering, and other proprietary treatment methods. Most rotors are cast iron but the heat treatment is the vital part of manufacturing that gives it unique (or application specific) properties.

 

[itguy61]

People who have an overwhelming need "to be right", more often than not have fragile egos.

@itguy61, it would be best if you would realize there is more than one correct answer to solving this problem.

Three solutions are proven successful in remediating uneven rotor surfaces: higher quality rotors, different pad compounds, or a combination or both new pads and new rotors.

The pads are Brembo pads. There is no way the quality is sub par. The rotors are not Brembo. Kia cut a corner here. The stock rotors are as cheaply made as possible. Actual dealer cost, not the price they show you as their cost which includes an overhead factor, is less than $50.00 each.

While new pads is your ideal solution, that does not make it the best solution or the only solution: just your preferred solution. Let it go

Wonderful world of metallurgy. If by profiling, you are referring to DBAs tsp (marketing terminology) than yes. Cast iron as a material just doesn't cut it for applications such as rotors; it must be heat treated to toughen the material, this process is done to many metals that undergo severe conditions or need to be stronger overall for their application. Heat treatment such as quenching, tempering, and other proprietary treatment methods. Most rotors are cast iron but the heat treatment is the vital part of manufacturing that gives it unique (or application specific) properties.

So by what your saying there could be hot spots on parts of the rotor if this process is faulty? And maybe some pads that are used as a replacement have a higher tolerance for heat and therefore may not be depositing on the rotor? That makes sense. This is not a simple issue. Kia needs to address this, I am seeing more and more posts on Facebook about this. Gonna give this car a bad rep as there will be frequent comments about the car having bad brakes.

 

[ScottyDangles]

I just recently had all 4 rotors replaced under warranty as a result of warping. I had about 44,000KMs on the car, so kudos to KIA for doing the change. That being said I had been complaining about the breaks for some time. Oddly enough they did not change the pads as I had suggested. I was going to buy aftermarket pads but I figured if they are doing this under warranty let's play this out. So now I'm sitting at just under 48,000KMs and I'm already starting to feel vibrations from braking. Its only going to get worse. So I've made the call to Kia Milton and they are sending to Kia for direction. I'll let you know what I get back.

 

[Helo58]

Wonderful world of metallurgy. If by profiling, you are referring to DBAs tsp (marketing terminology) than yes. Cast iron as a material just doesn't cut it for applications such as rotors; it must be heat treated to toughen the material, this process is done to many metals that undergo severe conditions or need to be stronger overall for their application. Heat treatment such as quenching, tempering, and other proprietary treatment methods. Most rotors are cast iron but the heat treatment is the vital part of manufacturing that gives it unique (or application specific) properties.

I'm very familiar with heat treatments. Just wanted to be sure I was on the same page as you. The cast iron in this case is "gray" cast iron chosen for its thermal conductivity, vibration dampening, and machineability (graphite content)... and cost of course. In that brake rotor gray iron is not alloyed (aside from silicon) and wouldn't require the more complex controls (alloy composition, time, and temp) that a malleable or nodular iron would, most metal producers can reliably make gray iron for brake rotors. Admittedly, it isn't impossible to screw it up though. I think the most recent example would be the debacle with Japanese steel (Kobe) falsifying their metals data that illustrates that it can still happen. Even with that case, no problems were reported by customers regarding the metals they purchased that were falsely certified. I am still inclined to think that the rotors are the simplest part of the brake system to get right, and it is more likely the pads or controls or a combination of the two.

 

[Hydrajin]

So by what your saying there could be hot spots on parts of the rotor if this process is faulty? And maybe some pads that are used as a replacement have a higher tolerance for heat and therefore may not be depositing on the rotor? That makes sense. This is not a simple issue. Kia needs to address this, I am seeing more and more posts on Facebook about this. Gonna give this car a bad rep as there will be frequent comments about the car having bad brakes.

Correct, the pads liquify over the hot spots and cool down becoming embedded. When I tried to clear and reapply an even layer of pad material by bedding the brakes, it only made it worst and the hot spots on the rotor became more visible. I would have just assumed it's bad pad choice like most people but I wouldn't be surprised if others recognize the hot spots on their rotors. Hot spots shouldn't happen if there isn't a flaw because the rotor should heat and cool evenly by nature of it's design, with enough load it could technically fall apart because hot spots are caused by stress in the material (could be poor heat treatment, or impurities) but given that's it's 35mm thick, it would take more load than the Stinger can dish out to break apart due to stress lol. It's completely safe to drive on even with the flawed manufacturing because of the sheer mass but the surface will always be prone to melting pads due to uneven heating and cooling if the problem isn't addressed upstream in manufacturing. Braking vibration does not hinder performance in real world but it does it's fair chunk of wear and tear on suspension and steering parts so they need to acknowledge this and either recall or replace with a new revision of pads or rotors, or both, for occurances.

 

[Hydrajin]

I'm very familiar with heat treatments. Just wanted to be sure I was on the same page as you. The cast iron in this case is "gray" cast iron chosen for its thermal conductivity, vibration dampening, and machineability (graphite content)... and cost of course. In that brake rotor gray iron is not alloyed (aside from silicon) and wouldn't require the more complex controls (alloy composition, time, and temp) that a malleable or nodular iron would, most metal producers can reliably make gray iron for brake rotors. Admittedly, it isn't impossible to screw it up though. I think the most recent example would be the debacle with Japanese steel (Kobe) falsifying their metals data that illustrates that it can still happen. Even with that case, no problems were reported by customers regarding the metals they purchased that were falsely certified. I am still inclined to think that the rotors are the simplest part of the brake system to get right, and it is more likely the pads or controls or a combination of the two.

Agreed, stress indicators on rotors in my case make me lean towards rotor as a cause, not everyone would be able to recognize them so not everyone would be able to report it, mine could very well be a 1 off but at the end of the day there is an issue with the braking system at the friction end and Kia needs to have dealers send rotors and pads back to the lab with every occurance to analyze causes and make corrections. No way for us to know if they are actually doing this or not until we see new part revisions or a recall.

 

[Helo58]

... if others recognize the hot spots on their rotors. Hot spots shouldn't happen if there isn't a flaw because the rotor should heat and cool evenly by nature of it's design, with enough load it could technically fall apart because hot spots are caused by stress in the material (could be poor heat treatment, or impurities) but given that's it's 35mm thick, it would take more load than the Stinger can dish out to break apart due to stress lol. It's completely safe to drive on even with the flawed manufacturing because of the sheer mass but the surface will always be prone to melting pads due to uneven heating and cooling if the problem isn't addressed upstream in manufacturing. ...

The hot spots aren't imperfections in the construction or composition of the rotors as they are delivered. The hot spots occur due to unevenly deposited brake pad material. The mechanism that changes the rotor composition occurs something like this... Pads unevenly deposit on rotor. The unevenly deposited materials are what causes the imbalance in the system and the pulsation in the brake pedal. These uneven deposits are proud of the surface of the rotor (higher), and as such, come into contact with the pads at highway speeds even when the brakes are not applied . More friction is generated as a result, resulting in areas that are locally hotter over these deposits than the rotor as a whole. As these areas remain hot and grow in temperature locally, the composition of the metal ends up containing more cementite due to the rapid heating and cooling (drive cycles). The rapid cooling essentially changes these areas to white iron rather than original gray iron they were delivered as. Over time, this cementite growth process can "grow" deep into the rotor making removal by surface abrasion (abrasive pads or bedding cycles) impossible. Replacement of the rotors (and pads) at this point would be the only solution to the braking and pulsation.

 

[Hydrajin]

The hot spots aren't imperfections in the construction or composition of the rotors as they are delivered. The hot spots occur due to unevenly deposited brake pad material. The mechanism that changes the rotor composition occurs something like this... Pads unevenly deposit on rotor. The unevenly deposited materials are what causes the imbalance in the system and the pulsation in the brake pedal. These uneven deposits are proud of the surface of the rotor (higher), and as such, come into contact with the pads at highway speeds even when the brakes are not applied . More friction is generated as a result, resulting in areas that are locally hotter over these deposits than the rotor as a whole. As these areas remain hot and grow in temperature locally, the composition of the metal ends up containing more cementite due to the rapid heating and cooling (drive cycles). The rapid cooling essentially changes these areas to white iron rather than original gray iron they were delivered as. Over time, this cementite growth process can "grow" deep into the rotor making removal by surface abrasion (abrasive pads or bedding cycles) impossible. Replacement of the rotors (and pads) at this point would be the only solution to the braking and pulsation.

That is a very likely scenario I overlooked, especially if the rotor is not cooling quickly enough for the pad material. There is a design or material choice flaw somewhere they need to investigate. Even if Kia did release a fix, I myself would probably stick to aftermarket regardless and have peace of mind; just like I did with the spark plug upgrade on a stock car after blowing 2 stock plugs.

 

[itguy61]

The hot spots aren't imperfections in the construction or composition of the rotors as they are delivered. The hot spots occur due to unevenly deposited brake pad material. The mechanism that changes the rotor composition occurs something like this... Pads unevenly deposit on rotor. The unevenly deposited materials are what causes the imbalance in the system and the pulsation in the brake pedal. These uneven deposits are proud of the surface of the rotor (higher), and as such, come into contact with the pads at highway speeds even when the brakes are not applied . More friction is generated as a result, resulting in areas that are locally hotter over these deposits than the rotor as a whole. As these areas remain hot and grow in temperature locally, the composition of the metal ends up containing more cementite due to the rapid heating and cooling (drive cycles). The rapid cooling essentially changes these areas to white iron rather than original gray iron they were delivered as. Over time, this cementite growth process can "grow" deep into the rotor making removal by surface abrasion (abrasive pads or bedding cycles) impossible. Replacement of the rotors (and pads) at this point would be the only solution to the braking and pulsation.

I am still befuddled as to what happened to you. Good explanation! So in your opinion would having a pad that does not start melting at the temps and leave deposits resolve the issue? Or maybe a semi-metallic pad with both higher temp capability and more abrasiveness? Kia needs fix this! This is affecting Genesis G70's also, I see posts about it on their forum.

 

[Helo58]

I am still befuddled as to what happened to you. Good explanation! So in your opinion would having a pad that does not start melting at the temps and leave deposits resolve the issue? Or maybe a semi-metallic pad with both higher temp capability and more abrasiveness? Kia needs fix this! This is affecting Genesis G70's also, I see posts about it on their forum.

That is sad that the G70 owners are dealing with it too. Yeah, most evidence points to this being an exceptionally low temp pad from the factory. I'm not sure who they thought their target demographic with the Stinger would be based on their pad choice but it was not hoonigans or enthusiastic drivers they had in mind. A low temp pad explains most of the issues with poor performance on track days, brake fade with extended periods on mountain roads, and average user having the vibration and pad deposits during "normal" use. Any higher temp pad, regardless of composition would be better than the stock pad in my opinion. But what do I know, I still might have the issue. Haha!

 

[MisterMac]

The Brembo pad is the same Brembo pad used on the caddy cts-V, and several other high performance cars. Albeit, they all have better rotors. As in drilled, slotted or both.

 

[Helo58]

The Brembo pad is the same Brembo pad used on the caddy cts-V, and several other high performance cars. Albeit, they all have better rotors. As in drilled, slotted or both.

Read the very first post here...
Brake Pad Recommendation

Found this forum quote to be interesting as well regarding the OEM Caddy pads, "The OEM Pads are Supplied by AC Delco but are made by Ferodo in Italy. They are labeled "Brembo". I bought AC Delco replacements from Rock Auto. The boxes were labeled "AC Delco" and "Brembo by Ferodo".

 

[MisterMac]

Read the very first post here...
Brake Pad Recommendation

Found this forum quote to be interesting as well regarding the OEM Caddy pads, "The OEM Pads are Supplied by AC Delco but are made by Ferodo in Italy. They are labeled "Brembo". I bought AC Delco replacements from Rock Auto. The boxes were labeled "AC Delco" and "Brembo by Ferodo".

Great find! Good stuff to know

 

[Helo58]

Great find! Good stuff to know

Yeah, I am not sure how far it gets us though. I read further down in that forum and there were people that absolutely loved the stock pads and had no problems. I guess in the end, it could have something to do with pads, rotors, systems, and the driver in some odd combination. We may never find the actual circumstances that create this issue with the brake deposits... regretfully.

 

[NS_Stinger]

Accidental post...

 

[Manaz]

The Brembo pad is the same Brembo pad used on the caddy cts-V, and several other high performance cars. Albeit, they all have better rotors. As in drilled, slotted or both.

The caliper is the same as on other cars, yes. The pad shape is probably the same. That doesn't necessarily mean the pads are the same though - the pad compound is potentially quite different.

Drilled and/or slotted rotors doesn't necessarily equal better rotors. Drilled makes basically no positive difference other than aesthetics, and can have negative implications. Slotted helps "sweep" the pad surface, but won't really help prevent pad deposits, and will actually accelerate pad wear.

More needs to change than just adding slots or drilled holes to the rotors to fix this issue. I used to think the rotors weren't part of the problem (I'm still sure that they're not warping), but I am starting to lean towards the issue being an interaction between pad and rotor materials.

 

[Phil11]

I have 1800+ miles and brought my car in today because the rotors were so horribly warped.. dealer said they resurfaced all 4, and if it occurs again everything would be replaced.

Yes me too, complained to my dealer, who said that if the car was under 20,000klm they would replace under warranty, rotors being replaced on Monday

 

[ShannonC]

Yes me too, complained to my dealer, who said that if the car was under 20,000klm they would replace under warranty, rotors being replaced on Monday

Can you ask the Service Manager why this happened? I'm only aware of a small number of issues in AUS. And, are the rotors actually "warped" or only have a build up of pad deposits.

 

[Phil11]

Can you ask the Service Manager why this happened? I'm only aware of a small number of issues in AUS. And, are the rotors actually "warped" or only have a build up of pad deposits.

They measured the rotors and confirmed they were badly warped (they did tell me the measurements but I can't remember) hence the replacement, this is the second Stinger I have owned in the last year and the first one had the same problem however I didn't notice it until about 30,000klm

 

[friss]

With the vibrations is this something you are feeling in the break peddle or steering wheel or seat or some combination? Want to be on the look out as I approach 9k miles.