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Model 3 Track Day: Laguna Seca

Discussion in 'Model 3' started by mattcrowley, Mar 3, 2018.

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Will the Model 3 battery limit power on the track?

Poll closed Mar 5, 2018.
  1. Yes

    76.9%
  2. No

    23.1%
  1. mattcrowley

    mattcrowley Member

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    The tire pressure warning was on at the start, since I lowered the tire pressure to ~33 front / ~35 rear psi from 45 psi. Yes, I have TPMS on all wheels. The tire pressure monitor warning seems to come on if the tire pressure is lower than 40 psi. For track days you need to lower the tire pressure to provide an optimal contact patch. The ambient temperature, internal tire temperature, track temperature...can all change the characteristics of grip on the track. So a stock 45 psi setting on a Model 3 is way too high and makes the tires feel like rolling stones and provides no satisfaction.

    Yes, the Model 3 software provided a general check brake light at the top left of the display. Autopilot and Automatic Emergency Braking were also disabled...since there were no brakes. That is all good and normal.
    IMG_20180306_195936 (1).jpg
     
    • Informative x 8
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  2. Doug_G

    Doug_G Lead Moderator

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    I think there's some sarcasm there. Brake ducts will help with cooling. But the real problem is that the pads are not designed to work at those high temperatures. You need a different compound.

    Holes are supposedly added for cooling... but their biggest impact in my experience is they're where the rotor cracks start.
     
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  3. LCR1

    LCR1 Member

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    Dude, you're completely ignoring the fact that the car did exactly what it was designed to do. It made multiple aggressive stops multiple times in succession over 10 minutes. You will never encounter that in the environment it was designed and advertised to be.

    Nothing failed, there aren't any pad sensors because it's a needless maintenance item. I know you replace them with the pads, I've replaced them. But they aren't needed so why spend the money on them? So 1 guy out of ~10,000 can take his on the track? If you do inspections on your car regularly then you'll see when they need to be replaced.

    You're simply trolling for amusement, nothing failed within its design parameter, it failed on a race track, when a set of pads "fails" in ten minutes on a public road then get your pitchforks.
     
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  4. mattcrowley

    mattcrowley Member

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    I still have my second reservation after waiting in line at Palo Alto (video) on day 0. I was holding it for possibly an AWD, Performance (+Ludicrous), sunroof...toy.

    What would you guys do if you had this option? :)
     
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  5. jerjozwik

    jerjozwik Active Member

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    given how well the 3LR drive, got to admit i am a little jelly of those holding out for the 3P. its is going to be an impressive machine.
     
  6. MP3Mike

    MP3Mike Well-Known Member

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    Interesting, in watching the video I couldn't see the check brakes indicator on the screen at all. All the way up to where you pulled in to the garage. Did it come on after that or did the camera just not catch it?
     
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  7. mattack4000

    mattack4000 Member

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    This is what you are suppose to use on track.

    Good fluid prevents overheating fluids, you can have pads and a soft pedal because of boiled brake fluid

    Oem pads are fine for a lap or two, but you really need dedicated racing compound if you want to do a full session at high speeds.

    Brake duct doesn’t hurt, but I think it gave me an extra half a lap before my pedal went soft
     

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  8. Carnook

    Carnook Member

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    I've always been told and had success with increasing tire pressure to increase precision with a stiffer tire/sidewall. Of course I also have Z rated tires so maybe its different for street tires.
     
  9. mattcrowley

    mattcrowley Member

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    I didn't notice. I could feel the brakes failing long before any light was needed. I don't think the brake warning came up during the track event.

    That alert you see during driving and parked in the garage is the low tire pressure icon. Below is zoomed in on the last few frames parking in the garage.
    tire-pressure.jpg

    On my drive from the paddock to the Supercharger, the brake indicator light came on. This light came on ~1-2 minutes into 'normal' driving.
     
    • Informative x 2
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  10. Xminus6

    Xminus6 Member

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    Video brings back great memories of my Keith Code track camp there.
     
  11. arnis

    arnis Member

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    Laguna is not Dakar. It appears Model 3's harsh suspension (even with DIY softening)
    tips people to soften the suspension up with incorrect tire pressures for driving on asphalt.

    Tires are not designed to be dampers. Their pressure is set according to dimensions and weight applied.
    Pressures change somewhat when tires heat up but not that much.
    Preference of softening up tires is the result of inappropriate suspension on the vehicle. It might theoretically
    even help. Which is a sign of bad suspension.
    [​IMG]

    Brake warning light therefore is flawed if it requires significant time to activate.
    Luckily, brake failure was smooth and did not result in a crash.


    Tell that to BMW M-division engineers. Those crazies use same brake fluid on their M3, M5 cars as on any other BMW. For many decades. They must be really bad engineers and people here must be really smart ones:oops:
     
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  12. diamond.g

    diamond.g Active Member

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    So with the brakes being an issue. Would you guys rather the regen be moved to the brakes to prolong pad life in a track event?
     
  13. mongo

    mongo Well-Known Member

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    Or brake reservoir meets the requirement of holding at least the volume needed to go from full pad to no pad, and the level switch is set below that value (it only reports if the system has leaked).

    Fluid level as a pad wear indicator seems a flawed design concept.

    4-6 psi with normal driving, more with track use. BWM specifies higher pressure for >100 MPH operation (sample point of one model's owner's manual)

    @mattcrowley I see what you did there, hence the funny, like the post overall.
     
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  14. McRat

    McRat Well-Known Member

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    #174 McRat, Mar 7, 2018
    Last edited: Mar 7, 2018
    Tire pressure depends on camber, track temp, speeds, banking, downforce, compound, heat distribution, aspect ratio, driver, etc.
    Big wide low profile tires in light cars don't take much, 32 often work great. Narrow tall tires on banked ovals at high speeds takes a ton of pressure, 55psi might be over MFR limit, but will be safer than 41 psi.

    AFAIK, serious cars sold with serious brakes don't have brake pad babysittters. The brake need to be bedded then checked after each session or if you experience sponginess (vapor pressure) or fade (overtemp). I doubt if the next ZR1 or 1LE will have brake idiot lights for wear because the last batch didn't. It's about as necessary as a "tire wear warning lamp".

    Serious = always stops in under 30m from 100kph even in light rain. 1.5g roughly.

    Trivia, the brakes and tires were so aggressive on the Z/28, they needed special rims to keep the tires from rotating on rims during braking.
     
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  15. Doug_G

    Doug_G Lead Moderator

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    Regen isn't helpful to balancing the car. You'll have to left-foot brake to turn in properly.

    Like almost all street cars, it isn't designed for the race track. Most street cars, even the base model Corvette Stingray, can't handle a race track session without overheating something. As a minimum you will need to upgrade brake pads, and switch to DOT4 brake fluid (and they're not all equal, get a good one).

    My old C6 Corvette needed the following upgrades to reliably run 30 minutes on a race track: Hawk DTC60 or DTC70 brake pads, larger diameter disc brakes, ATE DOT4 brake fluid, brake ducts, aftermarket differential cooler, aftermarket transmission cooler, aftermarket oil cooler... and it was borderline on overheating the power steering. And I had to periodically replace the brake pads (because even track pads wear quickly on a track), brake discs (because they would crack), and brake fluid. I got very good at servicing my own brakes - way cheaper to do it yourself.

    I also got wider rims and better tires (which had to be replaced regularly), and upgraded the suspension with stiffer bushings (huge difference!), coilovers, and sway bars.

    And that's a Corvette - a car that ostensibly is designed for this kind of thing. Right now if you want a good deal in a reliable streetworthy track car, which you can drive off the lot and onto a race track (well okay, the manual says you should change the oil and brake fluid), you're going to have to get the C7 Grand Sport. That's probably the least expensive car on the market that can do that.
     
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  16. McRat

    McRat Well-Known Member

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    Actually Corvettes are designed for middle aged divorced women. Look at how many are sold with automatics and convertibles :D

    My C6 (2010) vette said Super DOT 4 only IIRC. And you replace it every track day. Same stuff goes in the clutch and gets replaced every time, just like any track car.

    Note that a C6 is a 13 year old car. It was sold in grocery getter variants, fun day variants, hotshoe variants, and death wish variants.

    Rotors on my C5 Z06 were under $200 a set. Seriously. You throw them away when swapping out tires. They are disposable and meant to be.
     
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  17. moridin2002

    moridin2002 Member

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    #177 moridin2002, Mar 7, 2018
    Last edited: Mar 7, 2018
    None of them are pure switched reluctance (including the Model 3), but they do take advantage of switched reluctance effects:
    BMW’s hybrid motor design seeks to deliver high efficiency and power density with lower rare earth use
    http://www.motortrend.com/cars/chevrolet/volt/2016/2017-chevrolet-bolt-ev-drivetrain-first-look-review/

    There are some deeper dive presentations that GM has given at SAE conferences on the Bolt EV's motor with more information. But you'll have to dig around for those.

    BTW, no pure switched reluctance motor has permanent magnets from what I understand. What we see in the vehicles are PM motors taking advantage of switched reluctance effects to increase torque density and efficiency.
     
  18. moridin2002

    moridin2002 Member

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    #178 moridin2002, Mar 7, 2018
    Last edited: Mar 7, 2018
    Get yourself out to some track days. You're embarrassing yourself. I see lots of Googling and not much understanding of how things work. Nor a good understanding of what track days can do to a vehicle, particularly in the hands of a driver that knows what they are doing. BTW, tires are a somewhat self-damped part of the suspension. A somewhat self-damped spring that changes spring rate according to pressure. And pressure changes with heat. And tires get hot when run hard. Like at a track.

    There's also a reason why people spend good money on brake fluid. The factory BMW fluid has a dry boiling point of 446 F, and a wet boiling point of 311F. A decent fluid by most standards (which is the DOT4 rating). If wet and dry boiling points don't matter, why not run water? It has excellent hydraulic properties under compression. There is a reason people run $65/L Castrol SRF brake fluid.

    If you want to spend some time learning, here's a Stoptech whitepaper on brake fluid: Brake Fluid

    And one on the physics of braking systems: http://www.stoptech.com/docs/media-center-documents/the-physics-of-braking-systems

    And one with a couple of formulas for vehicle dynamics in regards to braking: http://www.stoptech.com/docs/media-center-documents/formulas-for-vehicle-braking-dynamics?sfvrsn=10
     
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  19. Doug_G

    Doug_G Lead Moderator

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    LOL! That said, the automatic versions are actually better if you want to drag race them. If you want to track them, definitely go with the manual.

    Mine was half that age when I started taking it to the track. Yeah out of the box, the Z06 version was definitely configured better from the track. Even so, if you wanted to run it for 30 minute stints you needed to add aftermarket tranny and diff coolers. Otherwise you'd be popping seals.

    Yeah I switched my C6 to those same rotors. And the cheap Chinese-made ones I used were only $40 each. They were way cheaper than the brake pads; in fact I considered it a benefit that the aggressive pads were a little hard on the rotors - cheaper than the other way around. I'd keep a spare set of discs handy, just in case one cracked unexpectedly. Those damned holes...
     
  20. mattack4000

    mattack4000 Member

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    What are you talking about? All Tesla suggest high tire pressure to get better mpg. Track driving is different as you want to get a bigger contact patch without overheating it.

    I don’t have to tell the engineers, plenty of bmw owners have experienced track fade themselves. I know you don’t understand since you have never been on one, but do people a favor and stop talking about it. I guess at this point you are just trolling.

    Regardless street cars are not race cars, you can have a nice fun weekend with your daily driver, but you should have some backup safety plans. The faster the car is, the more you are going to wear out. I have tracked my other car since the car had 800 miles. I think I have gone through one set of pads every 3 track days....

    Op, please get the brakes ready and do the refuel event. I am shocked that you didn’t have power cut after al those laps, let’s get a good lap at the refuel event. Remember you only need one

     
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