Model S Plaid Brakes Are Terrible!

[Trompazo]

They just 5-10 times more expensive for 2-3 times longer life. So if you go on track a lot - it's not good from budget perspective.

Also, they have lower convection performance (since they are lower density and it's actually hard to form venting channels in CCB rotors) to cool down between applications. That basically means that average rotor temperature would be higher.

Also they have lower heat capacity (weight is lower) that you need to have a heat energy buffer during single application.

Hotter rotors end up heating pads more although convection from rotor to pad is slower on ccb, but infrared radiation starts to be an issue with very high rotor temperature.

Positives are - less dust, lower unsprung and rotational mass, no rust. So CCB is better for street if money is not an issue. Relatively modern CCB don't have cold temperature problem. High temp pads, whether for iron or for CCB, have lower friction when cold (unless it's some high cost sintered metal pads), but still higher friction than what Tesla uses.

Since Plaid is heavy - it uses more energy to go through the same lap with the same speed. But it also can go much faster on that lap since it's capable of much higher average power than normal cars - hence even more energy.

Most of that energy needs to be radiated and convected by brakes to the air (smaller portion by tires to the pavement and air + by general air resistance + regen recuperation).

It would have to be much larger CCB rotors vs steel and you don't want to go with large wheels on the track - you need a sidewall.

So all in all - CCB is not a better choice than iron for the track.

Now if money is not a problem and you can have proper forced air rotors cooling, CCB might become good enough. And you get an advantage of lower dust, no rust and better suspension performance.

Yes, there is a reason that the Porsche and Mclaren owners who track a lot, put the Carbon rotors on a shelf and replace them with Iron discs. They essentially dont wear at all at temps seen on the street, but for track days the temps get so much higher that they may last only 6 to 8 days.

I have a Mclaren 720s, and I am getting Girodisc Iron rotors for it. You add about 10 pounds per corner, but a set if OEM rotors and pads cost about $36,000. So the price gets insane per track day.

Carbon rotors also need to be bigger than irons for the same heat dissipation. There is a reason that Porsche that have the Carbon option have discs that are 30mm bigger than the same car with irons.

In a Tesla, the MPP 400mm rotors would need a Carbon rotor of around 420-430mm to dissipate the same amount if heat. Which means you likely would need 21” wheels, which limits your track tire options.

 

[Nathan 4]

I have been following this thread, great info coming in.
Question on the stock 4 Piston Calipers. Is there enough clamping power in them for this 4800lb vehicle?

I want to up-grade my Plaid, But question the front calipers.
Would 2 piece steel rotors and up-graded pads with the stock front Calipers be a safe/dependable combo for street/occasional track days?

Thanks in advace, Nathan.......

 

[MountainPass]

Hi Nathan,

Contrary to popular belief, the number of pistons does not affect the stopping power. The OEM calipers have no problem locking the tires and creating the required pressure on the pads to create plenty of friction

The more difficult challenge is the heat, which more pistons do not solve!

An upgraded caliper has the advantages of being lighter, having more pad selection options, and possibly being stiffer (although that is unlikely to be the case with cheaper race calipers as these OE calipers are fairly stiff). Racing calipers may also have some drawbacks - often not having any dust seals or making noise if they do not have anti-rattle springs.

It will all come down to pad selection which is an individual choice based on how hard you drive on the track, how many laps you do, and what kind of compromises you're willing to make on the road (dust, noise, etc).

As Mash said, even the most aggressive race pads still work fine at cold temperatures, I've used very low friction endurance racing pads for many years in my racing career (with manual unassisted brakes) and it has never been an issue. I've never run over any spectators while leaving the garage going onto the track! With boosted brakes and regen it's not even something that should be discussed as it is a non-issue!

 

[Nathan 4]

Hi Nathan,

Contrary to popular belief, the number of pistons does not affect the stopping power. The OEM calipers have no problem locking the tires and creating the required pressure on the pads to create plenty of friction

The more difficult challenge is the heat, which more pistons do not solve!

An upgraded caliper has the advantages of being lighter, having more pad selection options, and possibly being stiffer (although that is unlikely to be the case with cheaper race calipers as these OE calipers are fairly stiff). Racing calipers may also have some drawbacks - often not having any dust seals or making noise if they do not have anti-rattle springs.

It will all come down to pad selection which is an individual choice based on how hard you drive on the track, how many laps you do, and what kind of compromises you're willing to make on the road (dust, noise, etc).

As Mash said, even the most aggressive race pads still work fine at cold temperatures, I've used very low friction endurance racing pads for many years in my racing career (with manual unassisted brakes) and it has never been an issue. I've never run over any spectators while leaving the garage going onto the track! With boosted brakes and regen it's not even something that should be discussed as it is a non-issue!

Thanks for the quick repsonse, Glad no spectators were harmed during this coversation.......lol...

So I believe for me and my Plaid:
Up-grade Fluid
Steel Braid Lines
2-piece Steel Rotors/directional vented
Perfered- Track compound, Brake Pad

 

[impastu]

Thanks for the quick repsonse, Glad no spectators were harmed during this coversation.......lol...

So I believe for me and my Plaid:
Up-grade Fluid
Steel Braid Lines
2-piece Steel Rotors/directional vented
Perfered- Track compound, Brake Pad

I read about a brace also? I think it was MPP mentioning that they would try to post a video showing the firewall flex but I’m unsure the impact on braking performance.

 

[MountainPass]

I read about a brace also? I think it was MPP mentioning that they would try to post a video showing the firewall flex but I’m unsure the impact on braking performance.

Yes, that's right! We'll do that test very soon and show the results. There isn't any difference in braking performance from a stopping distance or deceleration perspective. There is an improvement in terms of pedal travel vs braking force - which is what we perceive as "quality brakes".

Thanks for the quick repsonse, Glad no spectators were harmed during this coversation.......lol...

So I believe for me and my Plaid:
Up-grade Fluid
Steel Braid Lines
2-piece Steel Rotors/directional vented
Perfered- Track compound, Brake Pad

I'm glad too lol. The closest I got to harming spectators was driving a GT3 Cup car that has no radiator fans... Coming off of a hot track with one of those things and you'll soon consider running someone over to protect that expensive engine!

Your plan sounds solid and is the same upgrade so many of our Model 3 customers do and love!

 

[oktane]

Pedal feel is certainly an issue. It feels like running out of brake is possible with spirited driving, or that more pedal travel and pressure is required than expected compared to most modern cars.

This is not to say stopping distance is unacceptable. I’ve never measured.

 

[Nathan 4]

Thanks for all info:
Would the Racing Brakes 410/390 Kit work with the Plaid Factory 19" Wheels?
410mm- Front Rotors
390mm Rears
I see that they have relocation brackets for the Stock OEM Calipers.

I see in the discription they say fits 19's/ Just want to be sure.

Thanks in advance, Nathan.........

 

[Mash]

Comparing rotors it's important to take a width into account. More width allows to use more cooling surfaces for vanes, thicker iron for faster spread of heat, more weight for increased heat capacity. Tall and narrow rotor is not optimal.

And for wider rotors you have to change calipers...

Piston quantity doesn't really mean anything. But with larger diameter rotors you can use taller pads. And to keep reasonable pad ratio you make it wider as well. Wider pad might require to use more pistons with the same pistons area. But clamping force is defined by brake fluid pressure and total pistons area. Whether its 1 or 6 pistons - doesn't matter.

Larger pad is better buffer of heat in front of the piston. And piston is in direct contact with brake fluid which you don't want to overheat at all. But a lot depends on a design, because larger pad is also larger heat source for caliper.

At the end of the day there are way too many interconnected things, so it's a matter of trust to the company that does the product. And I can only applaud to those who do actual instrumental tests and post results. Pictures of weight on scales is not instrumental test of brakes.

 

[lbowroom]

What a nice Christmas gift, arrived yesterday. Love the simplicity. Since the calipers are radial mount, all you need is a spacer and longer bolts, genius.

 

[impastu]

View attachment 748376View attachment 748377View attachment 748378
What a nice Christmas gift, arrived yesterday. Love the simplicity. Since the calipers are radial mount, all you need is a spacer and longer bolts, genius.

can't wait for the on road reviews!

 

[xEvoLveDx]

Did this concept ever go anywhere outside of posrche? I don't think I've seen anything aftermarket. How Porsche Is Changing the Brake Game With Tungsten Carbide

 

[FlatSix911]

Did this concept ever go anywhere outside of posrche? I don't think I've seen anything aftermarket.
How Porsche Is Changing the Brake Game With Tungsten Carbide

Porsche has been using Porsche Surface Coated Brakes (PSCB) for years as a step between Iron and full Carbon Ceramic rotors.
They last longer than traditional Iron rotors and perform better when repeated braking is required at the track Win/Win!

"The PSCBs are meant to fall in between Porsche's basic cast-iron systems and its full-blown carbon-ceramic systems in terms of price and performance. Fenske managed to get some pricing quotes for the Cayenne Coupe he had on loan for this video, and found the replacement cost for the tungsten carbide-equipped system was about a third of the price of the carbon ceramics."

 

[Mash]

Tungsten is really useful mostly to have less dust on iron rotors. The rest is insignificant.

 

[Trompazo]

Multiple options keep coming. I am aware that Essex racing is working on an AP set up, but they have not listed it their website yet, but in email they said it would be soon and on the website you can select 2021 and Tesla model S becomes an option but the page is blank.

The unplugged Large sweep package is very interesting. They are 34 mm wide as opposed to 32mm. They do keep the 380mm outer diameter, but the large sweep results in a significant difference as shown below where I have calculated the rotor surface area of all options:

	Total diam in mm	total area (mm2)	hub (mm2)	rotor surface area
OEM/RacingBrake	380​	453645.596​	202682.8204​	250963​	mm2
Racingbrake	390​	477835.839​	202682.8204​	275153​	mm2
MPP	400​	502654.4​	202682.8204​	299972​	mm2
Racingbrake	410​	528101.279​	202682.8204​	325418​	mm2
Racingbrake w calipers	432​	586296.0922​	202682.8204​	383613​	mm2
Unplugged	380​	503546.6116​	182597.1355​	320949​	mm2
Essex AP racing	?	?	?	?

The unplugged 380mm large sweep rotor is the equivalent of a 408.25mm rotor and has the larger area for the pad to rotor ratio, but allows 19" wheels if needed.

With regards to the above options, PFC and AP racing are by far the largest names in motor sport. These were used by professional race teams across all areas of racing.

Based on this, and definitely leaning to the Unplugged PFC large sweep package, but will wait until the Essex AP options are announced. I assume that they will be offering their Radi-CAL calipers as they offer on the Tesla model 3 package. These are essentially the best in the business and used by all levels of motorsport, but are expensive. I suspect they will be above $6000 for the fronts,

I did more calculations and calculated the rotor surface area across multiple vehicles and compared surface area vs weight of vehicle.

The 5 comparisons are 2 Sports cars with the closest acceleration (Mclaren 720S and Porsche 992 Turbo with iron brakes). The other 2 are relatively heavy track prepped cars (Camaro ZL1 and Mustang GT500). The final one is the Lamborghini Urus, which weighs 4850 lbs and has the largest rotors of any vehicle made (440mm).

My estimates may be off as I dont have the exact rotor hat dimensions, but interestingly, those 5 vehicles have fairly close front rotor area to weight ratios.

The car that has the highest rotor to weight ratio is the 992 Turbo. And compared to it the others are:

992 Turbo 100% (reference)
Lambo Urus 96.6%
Mustang GT500 96.2%
McLaren 720S 93.5%
Camaro ZL1 84.6%
Tesla Plaid 60.1%

The Plaid is not even close. To match the Porsche 911 Turbo, it would need 440mm Front rotors.

The RB 6 pot calipers at 432mm come close at 91.9%.

The RB 410mm (78.0%), the UP 390 wide annulus (71.2) and the MPP 400mm (71.0%) are still way back of even the Camaro.

The available Carbon options are even worse as you need larger Carbon rotors to match the heat dissipation of iron.

Synopsis, Plaid has extremely small rotors compared to other similar fast and heavy cars.

 

[juanmedina]

I did more calculations and calculated the rotor surface area across multiple vehicles and compared surface area vs weight of vehicle.

The 5 comparisons are 2 Sports cars with the closest acceleration (Mclaren 720S and Porsche 992 Turbo with iron brakes). The other 2 are relatively heavy track prepped cars (Camaro ZL1 and Mustang GT500). The final one is the Lamborghini Urus, which weighs 4850 lbs and has the largest rotors of any vehicle made (440mm).

My estimates may be off as I dont have the exact rotor hat dimensions, but interestingly, those 5 vehicles have fairly close front rotor area to weight ratios.

The car that has the highest rotor to weight ratio is the 992 Turbo. And compared to it the others are:

992 Turbo 100% (reference)
Lambo Urus 96.6%
Mustang GT500 96.2%
McLaren 720S 93.5%
Camaro ZL1 84.6%
Tesla Plaid 60.1%

The Plaid is not even close. To match the Porsche 911 Turbo, it would need 440mm Front rotors.

The RB 6 pot calipers at 432mm come close at 91.9%.

The RB 410mm (78.0%), the UP 390 wide annulus (71.2) and the MPP 400mm (71.0%) are still way back of even the Camaro.

The available Carbon options are even worse as you need larger Carbon rotors to match the heat dissipation of iron.

Synopsis, Plaid has extremely small rotors compared to other similar fast and heavy cars.

Maybe compare them to other electric cars, other cars that have a regenerative braking. The Nevera, Lucid Air, the Taycan and the Audi GT.

 

[Trompazo]

Maybe compare them to other electric cars, other cars that have a regenerative braking. The Nevera, Lucid Air, the Taycan and the Audi GT.

Taycan turbo is 87.7%, which is way more than any of the Plaid aftermarket options except for the RB 432mm 6 pot caliper kit.

 

[FlatSix911]

Maybe compare them to other electric cars, other cars that have a regenerative braking. The Nevera, Lucid Air, the Taycan and the Audi GT.

I agree. Given the smaller Plaid OEM rotors, it would be interesting to understand the impact of regen braking (if any significance).

 

[Gninoked]

I agree. Given the smaller Plaid OEM rotors, it would be interesting to understand the impact of regen braking (if any significance).

If we are 'lucky' we might get something like 200kW regen, here's my math:

The 3 in Track Mode V2 maxed out right about 120kW: See the dash at this point in our Eagles Canyon video from this year's one lap:

Which you can think of as ~1.6C charging.

Compared to the 2018 3, the plaid has newer chemistry, new design, and a larger pack - so perhaps we get 25% more than that or 2C, 200kW. Now, 2C would be a stretch considering that the pack maxes out at 2.5C on a supercharger at low state of charge, but it could be possible. For comparison If the car is at the same 1.6C then that is 160kW.

Decelerating the car at 1.2g needs about 1300 kW of braking (used this calculator: Car Acceleration) so this could offer something like 15% of the total braking power needed. However that's not the whole story, using regen in the places where you don't need threshold braking allows the brakes to cool for a greater portion of the lap, reducing the max heat capacity needed and ideally keeping the pads in the temp range that works best.

On the other side there's also the electronics to think about - the limit in the old pack is actually not the cells or inverters etc, but some of the control electronics, so using 160/200kW might cause additional heat that you would rather use to accelerate the car (the electronics heat up regardless of which way the current is flowing.)

From a driver's perspective getting used to regen takes a bit of effort - the car slows significantly even when you are not on the brake pedal, it's like engine braking, but more aggressive. But like everything else you can adapt to it and personally I like it - when going at the limit it does still require a little trail brake in the 3 to get the car turned in, but you can get back to the accel pedal more quickly than a high powered RWD car because of the regen and use that to modulate the trail and then transition to accel.

Realistically the only way to know what is enough for a given situation is to do the math, make some prototypes, instrument the car and go run it! That's what we are hoping to do with MPP here in the next month or two.

 

[Gninoked]

Taycan turbo is 87.7%, which is way more than any of the Plaid aftermarket options except for the RB 432mm 6 pot caliper kit.

Do we know if the design of any of those is the air pump style, and do any of them have dedicated ducts for fresh air? Both of those make a massive difference to overall system performance but usually are not on OEM cars of any kind (unless they are track only cars) for cost and complexity reasons.