Do upgraded rotors provide any performance advantage?

[ElChanclo]

I'm seeing a lot of owners here replacing and upgrading their rotors, along with the pads, lines and brake fluid. I just replaced my pads with powerstop Z26 and fluid with motul RBF 600.

Would I see any braking/cooling improvement on the track with upgraded rotors? Also is there any point in getting the expensive 2pc ones?

 

[Snicklefritz]

No. the oem rotors are good ones. replacing the lines and fluid to race spec is of course overkill for the street but will likely confer a warm feeling of satisfaction, knowing that you are 'loaded for bear' should the day ever come, requiring massive amounts of brakes performance. it is not an 'upgrade' either, to put on drilled or slotted rotors. a high quality smooth faced disc is best, the rest just looks cool.

 

[LordKOTL]

What I learned (and I could be wrong) is that slotted is supposed to shave a bit of the pad away to prevent pad glazing. The negative is that they wear through pads faster. Drilled or dimpled are supposed to help with cooling and outgassing, but they have less rotor surface area for friction.

Honestly, unless you are racing often, the stock rotors should be fine.

 

[Volfy]

The advantage of the 2pc rotors is mainly weight savings. Most of them still have the same cast iron wearing outer sections and just have a lighter weight inner section, so the weight savings isn't all that much. Since the hub section is near the center of rotation, there isn't a whole lot of reduction in rotational inertia.

As for the all-too-common drilled and slotted rotors, they are mainly for looks. Back in the days when brake pad compounds used to off-gas, the holes and slots allowed the gases more ways to vent off the mating surface. These days, brake pads compounds don't need that any more. If any thing, these "discontinuities" over the rotor wearing surface introduces stress risers, especially when the rotor go through repeated heat and cooling cycles. This can lead to thermal cracking.

Also, to do it properly, the drilling pattern needs to be stochastic both radially and circumferentially, in order to avoid uneven wearing patterns across the rotor surface. One common problem you'll see quite often is the holes lining up circumferentially, such that the rotor quickly develop "rings" across the wearing surface, alternating between where the holes line up, and where they don't. The resultant uneven wear not only compromises braking effectiveness, they further exacerbate the thermal stress.

Slotting might possibly still have some uses, but it is still a compromise any way you slice it... literally.

Truthfully speaking though, unless you run your car hard for extended track sessions, where the brakes are pushed to their thermal capacities, none of this really matter much in everyday driving, so if the racy looks are your thing... knock yourself out.

And if you do run on the track and push limits, switching to the appropriate track/racing pad compounds is the proper way to deal with the elevated heat range. Bear in mind that the stock Brembos are really not as large as they should be to handle the weight of the car at track paces. Stinger is an excellent Gran Turismo car that you can have a little fun occasionally at the track. Dedicated track machine it is not. To get to the level of cars like the M2/M3 Competition, Blackwings, etc., a lot of work needs to be done... more than just changing rotors. Just compare the size of their rotors and brake calipers... and the extent to which their engineering went through to deal with cooling and heat dissipation.

 

[ElChanclo]

That confirms my suspicions. I've seen some rotors that advertise fancy vent patterns but not sure those are worth it either.

 

[D.J.]

That confirms my suspicions. I've seen some rotors that advertise fancy vent patterns but not sure those are worth it either.

Our stingers already come with similar tech.

Brembo PVT technology

There's a thread on it here.

Stinger Brembo Rotors Tech Tidbit

I was doing a little research and found a little info on the Brembo rotors that Kia is using on the front and rear of the Stinger GT models. These rotors incorporate Brembos “PVT Vented Disc” design. Basically, the cooling vanes molded into the rotors have a special unique design that...

stingerforum.org

 

[Volfy]

Directional vented rotors would amplify that cooling effect even more, since the vanes can be constructed like turbine blades in a centrifugal pump and draw air from the center. When it comes time to change out the front rotors, that's what I'm going with. That said, they would work so much better if there weren't the dust shields there. In fact, some of the track-focused hiperf cars delete the dust shield for this very reason. I thought about doing that when I did the Brembo conversion, but decided to keep the dust shields. Stinger is a street car first and foremost. Not worth sacrificing all weather protection for the extra cooling capacity.

Realistically, switching to thin-spoke aftermarket wheels (like the Enkei TFR I went with) enhances brake cooling dramatically. Might even help more than what the directional rotors would. For me, that is almost a "free" upgrades, since I was going to get aftermarket wheels anyway... so might as well pick one that is as open as possible. Makes cleaning the wheels (and the Brembo calipers) easier.

 

[DavidinGA]

Splitting hairs at best, unless you seriously track your car, and if you seriously track your car you probably don't own a stinger...

 

[Ohiocruiser]

I'm running front and rear two piece girodisc rotors. Did it only for weight saving and "cool look" purposes. It shed around 15-20lbs of unsprung weight. Didn't really notice any performance differences. But I don't race or track my car.

 

[ElChanclo]

That said, they would work so much better if there weren't the dust shields there. In fact, some of the track-focused hiperf cars delete the dust shield for this very reason.

Are the shields easy to remove, like while you're changing over to track tires? Might be a worthwhile temporary mod for track days.

 

[Ohiocruiser]

Are the shields easy to remove, like while you're changing over to track tires? Might be a worthwhile temporary mod for track days.

After removing caliper and rotor, it's 4 10mm bolts.

 

[Volfy]

Are the shields easy to remove, like while you're changing over to track tires? Might be a worthwhile temporary mod for track days.

On a RWD, the front axle isn't too bad. However, if there is a drive shaft there, it is a royal PITN. Since I did the Brembo conversion, I had to change out the rear dust shields because they were smaller than the Brembo rear rotors. The rear is worse, since I had to disassemble the drum brakes to get at the rotors. No something I'd want to do again, unless I absolutely have to.

 

[NYBIOMED]

On a RWD, the front axle isn't too bad. However, if there is a drive shaft there, it is a royal PITN. Since I did the Brembo conversion, I had to change out the rear dust shields because they were smaller than the Brembo rear rotors. The rear is worse, since I had to disassemble the drum brakes to get at the rotors. No something I'd want to do again, unless I absolutely have to.
View attachment 81147

Dust shields on the 22' are fine with the Brembo calipers/rotors now. I did the conversion, no modifications necessary anymore, might've happened in 2020 MY, when the 2.0T calipers/rotors were increased in size?

 

[Volfy]

Dust shields on the 22' are fine with the Brembo calipers/rotors now. I did the conversion, no modifications necessary anymore, might've happened in 2020 MY, when the 2.0T calipers/rotors were increased in size?

Probably when they upgraded to 2.5T... always need more WHOA with more GO. I helped a guy on G70 forum with Brembo retrofit on his '22(?) G70 3.3T, and he said not only were the dust shield the same, the rotors were already the same size as Brembos too.

Honestly, that's what Kia/Genesis should've done from the getgo. The rotor sizes were not that much different. Would've been a lot easier - and probably cheaper for mfg logistics - to have the same set of rotors for all trims of Stinger/G70s.

 

[7Andrei7]

I have the upgraded OEM brakes on my GT Line. It came from factory with 19" wheels and 345mm rotors on the front and 330mm vented rotors on the rear.
Do you guys think I could do a direct swap to the Brembo rotors&callipers?

@NYBIOMED do you know what size rotors you had on your '22? Or maybe part numbers? Did you need to change anything else? Brake lines etc?

I have the possibility to get a set of Brembos (full set) with minimal wear at only 300 EUR.

 

[NS_Stinger]

I'm running front and rear two piece girodisc rotors. Did it only for weight saving and "cool look" purposes. It shed around 15-20lbs of unsprung weight. Didn't really notice any performance differences. But I don't race or track my car.

2pc rotors also make a significant difference in brake cooling versus standard 1pc rotors. It would help with brake fade but only during track duty.

 

[GT Elite]

One advantage of two piece rotors is that with the aluminum top hats there is less heat transfer into the wheel bearings. However, this only applies to track use and it is not a concern for street use.

 

[Volfy]

The OEM rotors are made by Brembo and good quality. The next step would be directional rotors with internal vent channels that are optimized for moving air in one direction. Most have curved ribs that mimic the impeller blades of a centrifugal pump or turbo charger. The OEM rotors have straight radial channels.

Two-piece rotor construction is more for weight savings, as the heavy cast iron is only used for the wear ring that the pads clamp against. The hat can be made from lighter material, most often aluminum alloy.

Crossing drilling and slotting are really a cosmetic thing. Decades ago, early disc brake pad compounds would off-gas, so the cross drilling allowed an escape path. Slotting used to help clean pad contact surface to prevent glazing. These days, quality performance road (and even track) pad compounds don't typically suffer from any of those ills. For some full on race compounds, maybe still applicable.

Anytime you cut up the rotor contact surface, you introduce non-linearities and stress risers, which create temperature gradients that will compromise the rotor's structure integrity. Race cars don't care cus they get tossed after every race. I myself cannot afford to do that, so I run solid vented rotors, for road and track. That said, if you run street only, your drilled&slotted rotors likely won't get hot enough often enough for heat checking to happen. So if you like the racy looks, go for it.

 

[7Andrei7]

I helped a guy on G70 forum with Brembo retrofit on his '22(?) G70 3.3T, and he said not only were the dust shield the same, the rotors were already the same size as Brembos too.

Don't all 3.3T G70s/Stingers come with the Brembo set?

Also, when you did your upgrade to the Brembo set, why did you need to take apart the parking brake drums in the rear? Was it so you can take out the dust shield? Besides that, did you need to change anything else to fit the new callipers/rotors?

I suspect I might already have the larger dust shield since my rear rotors are 330mm and vented, rather than 315mm solid as it was standard on the GT Line. The Brembo rear rotors are supposed to be 340mm.

This is how my front and rear rotors look like (this is when the car was new ).
The front Brembo should be 5mm (0.2 inches) larger in diameter and the rear should be 10mm (0.4 inches) larger.

What do you guys think? Would they fit?

 

[Volfy]

Oh, forgot to mention... one thing that helps brake performance actually isn't part of the braking system - the wheels.

When I shop for aftermarket wheels, I always look for ones that have more open spokes

Don't all 3.3T G70s/Stingers come with the Brembo set?

The 2019-21 G70s with 3.3T all had Brembos, IIRC. The with the facelifted 2022+, Genesis cheaped out and fitted Brembos only with the Sport Prestige package.

Also, when you did your upgrade to the Brembo set, why did you need to take apart the parking brake drums in the rear? Was it so you can take out the dust shield? Besides that, did you need to change anything else to fit the new callipers/rotors?

When I first retrofitted the Brembos on the 2.0T, I just bent the rear dust shields and drove it like that for several months. I knew I was going to swap out the open diff for an LSD later, so I waited till then to replace the rear dust shields with the larger ones that fitted the larger rear rotors. To do that required disassembly of the rear drum brakes, which was a PITN.

The front dust shields are flat so the rotor diameter doesn't matter. I don't even know if the Brembo brakes came with larger front dust shields or not. If they did, I really don't care. If anything, smaller front dust shields would mean slightly better cooling, though I doubt by much.

The only other parts I changed out were the crush washers. Brake lines were the same.

I suspect I might already have the larger dust shield since my rear rotors are 330mm and vented, rather than 315mm solid as it was standard on the GT Line. The Brembo rear rotors are supposed to be 340mm.

This is how my front and rear rotors look like (this is when the car was new ).
The front Brembo should be 5mm (0.2 inches) larger in diameter and the rear should be 10mm (0.4 inches) larger.

What do you guys think? Would they fit?

The only way to be sure is to try it out.