# Model 3 on-track at Laguna Seca: 20 minutes, NO throttling



## KarenRei (Jul 27, 2017)

https://jalopnik.com/watch-a-tesla-model-3-go-flat-out-on-laguna-seca-racewa-1823532600

Includes a video. Nearly 20 minutes spent racing. 2/3rds of a charge burned through. No power throttling whatsoever. Now, I've expected this, and mentioned it many times here, but it's nice to see it confirmed! The only problem he had was that he completely burned his (friction) brakes out during the run. So if you want to spend time with your Model 3 on the track, put some more durable brakes on it!


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## macrow69 (Nov 21, 2017)

Here is the original thread at Tesla Motors Club.
https://teslamotorsclub.com/tmc/threads/model-3-track-day-laguna-seca.109818/


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## Michael Russo (Oct 15, 2016)

KarenRei said:


> https://jalopnik.com/watch-a-tesla-model-3-go-flat-out-on-laguna-seca-racewa-1823532600
> 
> Includes a video. Nearly 20 minutes spent racing. 2/3rds of a charge burned through. No power throttling whatsoever. (...)


Karen, thanks for sharing. Watched about half of it, up to the point brakes started to be 'scary'... (watching track is like watching tennis... after a while, you kinda would like to be at the wheel... )

Couldn't help but noticing that he seemed to have a particular challenge with the one (right turning) curve before the blue Cooper Tires overpass...

With regards to brakes, trust it is related to weight and inadequacy of stock brake pads for this purpose... Also wonder if you could get a bit of extra longer brake performance by optimal use of regen...

Not that I'm an expert...


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## garsh (Apr 4, 2016)

Michael Russo said:


> Also wonder if you could get a bit of extra longer brake performance by optimal use of regen...


If the 3 offered an option to turn on a much stronger regen setting, it would help. The motor should be capable of regenning past the point of locking up the rear wheels, but that would be bad, so you'd have to dial it back a bit. It would be dangerous for everyday use, but would take a lot of the burden off the brakes for racing, and keep the battery charged better.

The other issue is, would the inverter & batteries be able to handle that much power? The batteries were designed to allow supercharging, so that shouldn't be too much of an issue. But a regenning motor generates alternating current (AC), so the car's onboard charger would need to transform this to direct current (DC) to charge the batteries. Remember, supercharging is DC, so it doesn't involve the onboard charger. The onboard charger is designed to handle at most 48amps, so if tire adhesion isn't the limiting factor, that will be.


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## garsh (Apr 4, 2016)

I'm going through the TMC thread. Some highlights:

He installed the tow hook. I think you have to have one installed in order to race there. Anyhow, he broke the tow hook cover. So, be careful if you ever decide to remove the cover - it is fragile.
He had regen set to low. That's a shame. Setting it to standard would have helped a great deal to keep the brakes from cooking.
I have no idea what it means to "blow sound", or why that gets you kicked off the track.


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## KarenRei (Jul 27, 2017)

garsh said:


> If the 3 offered an option to turn on a much stronger regen setting, it would help. The motor should be capable of regenning past the point of locking up the rear wheels, but that would be bad, so you'd have to dial it back a bit. It would be dangerous for everyday use, but would take a lot of the burden off the brakes for racing, and keep the battery charged better.


Hardware-limited max charge amps 192A, max charge power 46,9kW. Versus a max output of 1200A and 370kW, respectively.


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## garsh (Apr 4, 2016)

KarenRei said:


> Hardware-limited max charge amps 192A


Woah! AC charging? Citation?


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## garsh (Apr 4, 2016)

Michael Russo said:


> Couldn't help but noticing that he seemed to have a particular challenge with the one (right turning) curve before the blue Cooper Tires overpass...


That's the location of the "river" of water crossing the track. It had rained the previous day, and not everything had dried out.


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## garsh (Apr 4, 2016)

From 4:00-5:00, watch him reel in that race-prepped BMW. 
And from 6:10-7:05, he catches up to and passes a Porsche! 

Wow. Not once did anybody pass him up through 8:30, which is when the brakes began to fail.


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## Michael Russo (Oct 15, 2016)

garsh said:


> (...) Wow. Not once did anybody pass him up through 8:30, which is when the brakes began to fail.


Still wasn't impressed by his driving skills, IMHO.


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## KarenRei (Jul 27, 2017)

garsh said:


> Woah! AC charging? Citation?


Well, technically regen power starts out as AC before being converted to DC, yes. But why the surprise that Model 3 has regen? The topic of discussion is regen charging of the pack, not wall charging of the pack. 

The limits are from "Factory Mode", as hacked into by Ingineerix.


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## garsh (Apr 4, 2016)

KarenRei said:


> But why the surprise that Model 3 has regen?


I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?


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## KarenRei (Jul 27, 2017)

garsh said:


> I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?


I have no clue how the charger, pack, and inverters are structured internally  Sorry!


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## m3_4_wifey (Jul 26, 2016)

I'm sure he was trying to do low regen so that his acceleration would not be limited, but given that his brakes got cooked, maybe it would have been better to see if the BMS could have handled the heat with hard accelerations and standard regen. How long driving that way before your acceleration is limited? Maybe his acceleration was limited towards the end. I know the Model 3 doesn't have the second binnacle, but it still would be nice to see when the BMS is limiting the acceleration or regen.


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## garsh (Apr 4, 2016)

m3_4_wifey said:


> I'm sure he was trying to do low regen so that his acceleration would not be limited,


You mean "due to the motors getting too hot", because that's what happens when you try to hot-lap a Model S. Yes, that does make sense. It'll be interesting to see if a Model 3 is better able to handle keeping the motors cool.


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## KarenRei (Jul 27, 2017)

m3_4_wifey said:


> I'm sure he was trying to do low regen so that his acceleration would not be limited, but given that his brakes got cooked, maybe it would have been better to see if the BMS could have handled the heat with hard accelerations and standard regen. How long driving that way before your acceleration is limited? Maybe his acceleration was limited towards the end. I know the Model 3 doesn't have the second binnacle, but it still would be nice to see when the BMS is limiting the acceleration or regen.


If designed right, acceleration should never be limited on a Model 3. Ever. No induction = no induction currents = no rotor heating (for the most part). Stator heating is trivial to lose because you build as extensive of a heat exchanger on it as you want. Rotor heat loss is limited by shape constraints near the windings, viscous drag elsewhere, and the flow rate between them.


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## Dangermouse (Apr 27, 2016)

garsh said:


> I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?


My car charges much faster while braking than it does from being plugged in. Since braking events are usually small chunks of time, the higher limit while braking is likely not damaging to the cells.


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## m3_4_wifey (Jul 26, 2016)

garsh said:


> You mean "due to the motors getting too hot", because that's what happens when you try to hot-lap a Model S. Yes, that does make sense. It'll be interesting to see if a Model 3 is better able to handle keeping the motors cool.


 Yes, motor and battery, but based on watching other videos pushing the Model S/X, it was specifically the stator that got hot.


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## garsh (Apr 4, 2016)

m3_4_wifey said:


> Yes, motor and battery, but based on watching other videos pushing the Model S/X, it was specifically the stator that got hot.


I thought I remembered reading that it was the stator. But I wanted to look up the source for that information before I dare disagree with @KarenRei publically.


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## Petra (Sep 12, 2017)

garsh said:


> He had regen set to low. That's a shame. Setting it to standard would have helped a great deal to keep the brakes from cooking.


Standard regen may have helped a little, but Laguna Seca will trash most OE pads super quick. Remember, the usage pattern when you're on a track is basically: accelerator to the floor, quick switch to very hard braking, a bit of accelerator feather in cornering, and then to the floor again. There isn't much in the way of 'coast time' for regen to do its thing--you're either on the brakes hard or you're on the accelerator. Repeat 11 times every 2.238 miles, or about 2 minutes.

Willow Springs is probably a better track to run if you're gonna roll with OE pads... it'll just eat your tires instead. 


garsh said:


> I have no idea what it means to "blow sound", or why that gets you kicked off the track.


Laguna Seca has strict noise rules in place thanks to people who decided to build very expensive houses nearby. You get kicked off the track if you're too loud.


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## alpinebum1 (Sep 7, 2017)

garsh said:


> I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?


The inverter used for propulsion (and presumably regen) is part of the motor assembly. The AC charging inverter is separate and part of the battery pack.

https://electrek.co/2017/08/24/tesla-model-3-exclusive-battery-pack-architecture/


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## Kbm3 (May 24, 2017)

As I understand it, regen would be active during braking also, thus unloading the brakes.


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## macrow69 (Nov 21, 2017)

Michael Russo said:


> Still wasn't impressed by his driving skills, IMHO.


How about now...? ;-) 





This was more about "Hey my Porsche GT4 isn't fixed in time for my track day, can't cancel, so...why not see what happens with the Model 3...?" There were three track cars that were destroyed on Sunday, since the track was wet/muddy and they went into the wall. Not ideal track conditions to push anything.


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## Petra (Sep 12, 2017)

Kbm3 said:


> As I understand it, regen would be active during braking also, thus unloading the brakes.


Considering that you can experience brake fade in the performance versions of the Model S even on a brief spirited canyon run with regen set to standard, I think you're significantly overestimating the contribution of Tesla's regen relative to the braking forces being applied in this use case.


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## KarenRei (Jul 27, 2017)

m3_4_wifey said:


> Yes, motor and battery, but based on watching other videos pushing the Model S/X, it was specifically the stator that got hot.


Ref?

Model S running cool:









Model S running hot:









No difference to stator temperature. Aka, not cooling limited; it stays at design temperature whether pushed hard or light. The only difference is the temperature of the outgoing coolant.

Here's a MS rotor, only 20k miles on it:









Now, anyone who's worked with metal knows that that discoloration isn't anything terrible - it's just a thin oxide layer. But it does mean that this piece of metal has been very hot. This is the sort of oxidation you get on metal around welds or when you put it under a blowtorch.

It's fine to get the metal hot... so long as you don't get it hot enough that it becomes too ductile and warps under torque! So there have to be limits.


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## Sandy (Jun 3, 2017)

Michael Russo said:


> Still wasn't impressed by his driving skills, IMHO.


Curiously Mike how come? Genuinely interested. I personally thought he did really well especially considering the track was green after rain, it was his first time on track with the car and it was a 40 deg F morning on summer performance tires. It would take 2 to 3 laps minimum in those temps for the tires to start to work. He wasn't pushing and was hitting his marks including the late apex corners as he was feeling out the car. I could tell he's very familiar with the track.


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## Maevra (Oct 24, 2017)

Two minutes into the video and it's still freaky that there's no noise! I'm used to driving the car on a daily commute, but watching it on the track, my subconscious still feels like there needs to be sound.


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## m3_4_wifey (Jul 26, 2016)

KarenRei said:


> If designed right, acceleration should never be limited on a Model 3. Ever. No induction = no induction currents = no rotor heating (for the most part). Stator heating is trivial to lose because you build as extensive of a heat exchanger on it as you want. Rotor heat loss is limited by shape constraints near the windings, viscous drag elsewhere, and the flow rate between them.


I guess the jury is still out on whether the motor cooling system is adequate with standard regen at the track, but there still have to heat being built up. What is the rotor made of? Will the permanent magnets start losing magnetism as they approach the curie temperature?
The track result does make me wonder how the dual motor or dual motor w/ performance do. There you can spread the heat from acceleration and breaking to both motors. How about a Model S go against and Model 3 with comparable acceleration performance. The lighter Model 3 could last longer.


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## Michael Russo (Oct 15, 2016)

Sandy said:


> Curiously Mike how come? Genuinely interested. (...)I could tell he's very familiar with the track.


As I said, I'm no expert race driver - hence the IMHO qualifier - yet I did watch a lot of F1 races back in the Schumacher glory days... granted an F1 is a different beast...

Basically I did not get the feeling he was as comfortable with the track; lots of his steering wheel movement lacked smoothness, probably because, again, IMHO, he did not always take the optimal trajectory in certain curves.

Now, I did not necessarily catch there had just been rain and certainly empathize with the fact he did not want to crash the car!!


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## KarenRei (Jul 27, 2017)

m3_4_wifey said:


> I guess the jury is still out on whether the motor cooling system is adequate with standard regen at the track, but there still have to heat being built up. What is the rotor made of?


Generally reluctance rotors are an iron alloy, although many combinations of iron, cobalt, and nickel will do. All very high temperature materials. Without anything meaningful to heat it (I'd expect more radiative heat from the stator than anything else).



> Will the permanent magnets start losing magnetism as they approach the curie temperature?


IIF the motor is what's been suggested, the PMs are in the _stator_, not the rotor. 



> The track result does make me wonder how the dual motor or dual motor w/ performance do


That's going to be a sight to see


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## DR61 (Apr 10, 2016)

Michael Russo said:


> lots of his steering wheel movement lacked smoothness,


Michael, I think what the video shows is rather normal considering the conditions and type of tires he was using (not designed for racing). If the car had been on optimal 'R' tires and warmer surface it would have looked smoother. His line was nice. I am far from a pro driver, but I did hold a club racing class lap record at Laguna Seca 24 years ago in a street-legal vehicle class. Formula race cars with downforce are very different beasts.


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## Michael Russo (Oct 15, 2016)

DR61 said:


> Michael, I think what the video shows is rather normal considering the conditions and type of tires he was using (not designed for racing). If the car had been on optimal 'R' tires and warmer surface it would have looked smoother. His line was nice. I am far from a pro driver, but I did hold a club racing class lap record at Laguna Seca 24 years ago in a street-legal vehicle class. Formula race cars with downforce are very different beasts.


Thank you, and good to know. I stand corrected.


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## John (Apr 16, 2016)

Michael Russo said:


> Still wasn't impressed by his driving skills, IMHO.


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## Kbm3 (May 24, 2017)

Petra said:


> Considering that you can experience brake fade in the performance versions of the Model S even on a brief spirited canyon run with regen set to standard, I think you're significantly overestimating the contribution of Tesla's regen relative to the braking forces being applied in this use case.


How did you get that from what I said? The commenter I was replying to was under the assumption that regen only applied when one was coasting and I explained that it also applies during braking.

Edit: in my initial comment I meant offloading the brakes but I said unloading. I didn't mean to imply to what degree.


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## Mad Hungarian (May 20, 2016)

Man, was I excited to discover this on The Drive today, now realizing I'm late to the party here.
I was dying to know if it would suffer the same toasty fate as the S after a few laps.
I hope that the Dual Motor and Plus models will cope just as well. Don't much care if Standard Regen winds up overburdening the cooling system, good track pads (hopefully coming soon to a Store Near You) and leaving it in Low should solve the problem.


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## JWardell (May 9, 2016)

garsh said:


> The other issue is, would the inverter & batteries be able to handle that much power? The batteries were designed to allow supercharging, so that shouldn't be too much of an issue. But a regenning motor generates alternating current (AC), so the car's onboard charger would need to transform this to direct current (DC) to charge the batteries. Remember, supercharging is DC, so it doesn't involve the onboard charger. The onboard charger is designed to handle at most 48amps, so if tire adhesion isn't the limiting factor, that will be.


Nooo.. The drive inverter can also work backwards to convert the AC generated by the motor during regen into DC if programmed correctly. There's no reason despite some efficiency loss that the regen can't be as powerful as the motor can make during acceleration. The battery charger is not used. I'm literally using this function at work.


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## macrow69 (Nov 21, 2017)

Here are the brakes after the track day:





Going in for appointment tomorrow. Tesla is fully aware.


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## Mad Hungarian (May 20, 2016)

macrow69 said:


> Here are the brakes after the track day:
> 
> 
> 
> ...


 Wow, toast doesn't even begin to describe those fronts. I'll be interested to see how they handle this.
Thanks so much for filming and sharing!


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## KarenRei (Jul 27, 2017)

Mad Hungarian said:


> Wow, toast doesn't even begin to describe those fronts. I'll be interested to see how they handle this.
> Thanks so much for filming and sharing!


? They'll just replace them.


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## garsh (Apr 4, 2016)

KarenRei said:


> ? They'll just replace them.


Yeah. It's not unreasonable to provide brake pads that are not designed to handle continuous hard braking like that. They need to stop the car during a panick stop periodically, but otherwise the car's regen makes sure they don't get much of a workout in normal circumstances.

I wouldn't expect this use to be covered under warranty.


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## Mad Hungarian (May 20, 2016)

garsh said:


> Yeah. It's not unreasonable to provide brake pads that are not designed to handle continuous hard braking like that. They need to stop the car during a panick stop periodically, but otherwise the car's regen makes sure they don't get much of a workout in normal circumstances.
> 
> I wouldn't expect this use to be covered under warranty.


I agree. It's a very fluid area and depends greatly upon what the manufacturer's policy is. And those vary considerably.
Here's a good article from Autoblog on the matter.
When cars like the Nissan GT-R, or _Porsche's entire line_, are NOT covered, I have a hard time believing a much more broad-market vehicle like the 3 would be.

Here's currently the only thing that Tesla says on the matter. See the last line.










It's now completely up to Tesla as to whether they consider lapping on a racetrack normal use. If they do, they open themselves up to a LOT of free replacement brake pads and rotors, because unless they decide to dramatically change the pad compound to one that is track-biased (highly unlikely) this is going to happen to every (at least non-Plus) 3 that hits the track on the weekend.

Now, my personal hope is that they'll do a complete change N/C for @macrow69 under Goodwill, as their warranty is admittedly vague and he's the first (as far as we know) to track a 3 and discover this issue. Once that's done though, I wouldn't be the least bit surprised to see them issue a TSB saying that this isn't covered. And hopefully an amendment to the warranty policy clarifying this.

If I could wave my magic wand I'd also really hope they start offering a Performance Brake package for regular 3's, like BMW does with M-Performace packs for regular 3 series cars.
Could simply be the Plus brakes with a more aggressive pad.
But I don't think it's huge priority for them at the moment. Maybe once Production Hell is finally over?


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## Mad Hungarian (May 20, 2016)

So I reached out to Hawk Performance this morning to see if they had anything in development yet for Model 3 and they did not, thinking as many of us did that the 3 might have the same issues as S and X when it came to the track. Clearly we know that's no longer the case.

Here's the schematic they sent for what looks like the closest pad in their inventory, based on a screen cap of the front that I sent from the post-mortem video:










It would be very interesting to know if that's a match.

@macrow69 , would you be willing to pull one of the old (or new, once it comes back) front pads off your car and measure the backing plates? Even better if we could get for front and rear.
I, Hawk and the Model 3 community would be greatly indebted .


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## JWardell (May 9, 2016)

garsh said:


> I wouldn't expect this use to be covered under warranty.


I don't think anything was defective here, brakes are typically a wear item and not covered under any warrenty, unless there was a clear manufacturing issue.
I did have my BMW's brakes replaced for free once only because after less than 10k mi they were pulsing quite a bit despite light use, and maybe because the dealership liked me. I think docs said defective rotors. Problem never appeared again. 
What's great to see is the very clear video on just how easy it is to replace the brake pads yourself. I hope we get some aftermarket options soon. No doubt at the moment this person had no other choice but to have Tesla replace them until others make them.


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## macrow69 (Nov 21, 2017)

KarenRei said:


> ? They'll just replace them.


With a little cash from me.


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## macrow69 (Nov 21, 2017)

Mad Hungarian said:


> Now, my personal hope is that they'll do a complete change N/C for @macrow69 under Goodwill, as their warranty is admittedly vague and he's the first (as far as we know) to track a 3 and discover this issue.


Thanks for the hope.  I never went into this thinking Tesla was going to cover the cost here. I don't consider track days 'normal' use. I will be covering the cost here.

I plan to send out a summary of the service and cost when completed (expected by end of week).


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## macrow69 (Nov 21, 2017)

Mad Hungarian said:


> @macrow69 , would you be willing to pull one of the old (or new, once it comes back) front pads off your car and measure the backing plates? Even better if we could get for front and rear. I, Hawk and the Model 3 community would be greatly indebted .


You bet. I requested from Tesla Service that I would like to obtain all the original parts replaced.


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## Mad Hungarian (May 20, 2016)

macrow69 said:


> You bet. I requested from Tesla Service that I would like to obtain all the original parts replaced.


Fantastic, many thanks!


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## macrow69 (Nov 21, 2017)

Update on Tesla service replacing brakes, here.


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## KarenRei (Jul 27, 2017)

As crazy as that price is, note this comment:



> Model S rotors are $330 each. Not $90. Similar repair would be ~$8500.
> 
> The "other" M3, at the time I owned it, had rotors that are priced at $650 EACH.


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## garsh (Apr 4, 2016)

macrow69 said:


> Update on Tesla service replacing brakes, here.


I hope you don't mind a C&P of the contents:

Sorry it took so long to respond. I have been busy at work and life.  Watching my kid's high school robots Team 971 "Spartan Robotics" compete in the San Fransisco FIRST regional (videos) competition. Kinda proud. ;-)

Ok...here is what I just posted on a YouTube comment in the brake video:
_"The Tesla Model 3 brakes are obviously not designed for this [track day]. No surprise. What is promising is that the Model 3 lasted the session without thermal limiting. EVs lasting this long on a track is still a new thing. We are not there yet, but this year is promising for what could happen with performance EV modifications and potential tracking._

_I (and many others in the industry) are still looking for performance 3rd party brake pads...they don't exist, YET... There are some options to make custom performance brake pads that we are looking into, but those will be expensive. Unplugged Performance is offer front carbon ceramics, but they are very expensive (~$9K)._

_There is also an option to use Model S pads and cut them down to fit. This might be a short term option, since the Model S pad compound is better than the stock Model 3._

_Tesla currently doesn't offer Model 3 pads for sale by themselves. Not an option at all...YET. Apparently, Brembo doesn't YET sell Tesla Model 3 brake pads separately from the brake system (rotors/pads/calipers), so complete set needs to be replaced...at this point in time. Yes...that is rough, but that is what is happening right now._

_Leave you all with a positive note here...the market is listening and there will be solutions coming. Just not right now. EV performance modifications is coming."_

Here is the final cost brake down *(Total was: $3,101.75)*:


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## PNWmisty (Aug 19, 2017)

Petra said:


> Standard regen may have helped a little, but Laguna Seca will trash most OE pads super quick. Remember, the usage pattern when you're on a track is basically: accelerator to the floor, quick switch to very hard braking, a bit of accelerator feather in cornering, and then to the floor again. There isn't much in the way of 'coast time' for regen to do its thing--you're either on the brakes hard or you're on the accelerator. Repeat 11 times every 2.238 miles, or about 2 minutes.


Don't underestimate the power of regen to greatly reduce brake temperatures. Even though the braking is intermittent, the heat soaking that discs go through is cumulative (minus however much heat they can dissipate to the wheels and surrounding air). If the brakes are generating more heat than they can dissipate, the brake temperatures will continue to climb.

It looks like no one has a definitive answer regarding how much current the regen braking can generate but, based on how strong regen feels, I would guess it's more than the 48 amp max wall current limit. And whatever the max regen current is, that can be directly converted to heat energy that is NOT being added to the brake discs for the duration of every braking event. In addition to that, any inefficiencies in the regen/charging circuit also represent heat that doesn't make it to the brakes.


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## KarenRei (Jul 27, 2017)

PNWmisty said:


> Don't underestimate the power of regen to greatly reduce brake temperatures. Even though the braking is intermittent, the heat soaking that discs go through is cumulative (minus however much heat they can dissipate to the wheels and surrounding air). If the brakes are generating more heat than they can dissipate, the brake temperatures will continue to climb.
> 
> It looks like no one has a definitive answer regarding how much current the regen braking can generate but, based on how strong regen feels, I would guess it's more than the 48 amp max wall current limit. And whatever the max regen current is, that can be directly converted to heat energy that is NOT being added to the brake discs for the duration of every braking event. In addition to that, any inefficiencies in the regen/charging circuit also represent heat that doesn't make it to the brakes.


Also, note that AWD and P have two motors for regen, not just 1. According to Elon, the max regen force on non-P AWD is enough to overpower the traction force on all but the sticky 20" tires. I sure hope so, that would be awesome


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