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Sandy Munro talks about the teardown of the Model 3

Discussion in 'Model 3' started by Grendal, Jan 3, 2019.

  1. Garlan Garner

    Garlan Garner Well-Known Member

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    I believe "very few" people are going to take their Model 3's to the track. This is why I'm wondering why we are talking about the track for such a long time.

    The Model 3 is not a track car. - Even though it can do well on one.

    I've been to the track with mine - only because I received a free pass. I wouldn't pay track fees - as I would just watch other people on youtube on the track.
     
  2. ricohman

    ricohman Member

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    I thought we had moved on.
    In any case, have you made a pass or two in your car? I am interested in the times.
     
  3. Garlan Garner

    Garlan Garner Well-Known Member

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    exactly 3.1 0-60 twice.
     
  4. ricohman

    ricohman Member

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    1/4 mile?
     
  5. mongo

    mongo Well-Known Member

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    Appreciate the politeness. I was not attempting to contradict any of that with my recent post.
    Weight shifting is real, contact patches are real, tire loading to traction is a less than 1 ratio is real.

    You had mentioned feathering the throttle due to loss of weight shift, am I wrong in thinking that a dual motor EV would not have the same issue due to the front wheels gaining the weight the rears no longer have? Along with the improved traction control.
     
  6. JeffC

    JeffC Member

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    #386 JeffC, Jan 9, 2019
    Last edited: Jan 9, 2019
    I would propose that the car is not overbuilt, and in fact is very well designed. It would be nice if a few kilograms could be saved, but all modern car makers do extensive weight reduction, including Tesla. They reduced weight to the point where it met their design goals.

    One of Tesla's top design goals was safety. Another was efficiency/range. They were and are painfully aware of weight savings and likely spent much effort on it. I would say they met their key goals very well with Model 3.

    None of a car's sheet metal parts would be economically changed since doing so would mean producing new stamping dies and tuning their fit with the other stamped parts together. All modern cars are extensively designed and tested in computers and part of the reason for the excellent crash performance of Model 3 is the excellent software used to design it. The results are then tested and tuned before going into production.

    (In case anyone isn't aware, stamped steel parts in particular spring back when released from the stamping dies. They don't come out an exact match for the dies. And the tuning of the resulting parts is part science and part art. Software has gotten much better at predicting the behavior of the metal that comes out of the stamping dies, but usually some fine tuning is still needed. As with many things, it's actually the quality of the software and physical modelling contained in it, that is a key determinant. Same is true of internal unit body (chassis) panels and exterior panels.)

    Sandy's responses have changed over time. He needs to be slightly political in order to sell his products and keep his customers happy. All of the (recent) praise he has for Tesla is in fairly uncontroversial and obvious areas such as (both electronic and mechanical) module integration, wiring, traction motor, and electronics quality. Any of the car other makers could also see that for themselves very easily.

    (In case anyone is unaware, all car makers benchmark their competitors cars by disassembling and reverse engineering them, as Munro does also as an external third party. All of the car makers also do that internally with any new major competitive car. However their internal reports stay internal since the information obtained is competitive information. A reason to have third parties like Munro is for car makers to get an external "second opinion", or for non-car makers like investment banks to understand the parts costs and profits better. BMW, VW (Audi/Porsche/etc), Mercedes, etc., have already torn apart all Tesla models and come to their own judgements about cost, design quality, build quality, profitability, etc., independent of Munro or anyone else. It's totally normal for a GM, Toyota, Nissan, etc. to tear apart every weld on every competitive car to see how they're build. Same with engines, electronics, etc.)

    While Munro has a lot of experience, the idea that they are smarter than Tesla may be wrong. That does not mean Tesla is perfect or could never improve, but it's pretty clear they've done a very good job designing Model 3.

    I'm not trying to bash Munro or praise Tesla, but I believe Munro's conclusions about the Model 3 unit body are wrong and that Tesla designed it intentionally and purposefully to meet their safety and efficiency goals. It is a matter of fact, not opinion, that the resulting crash performance of Model 3 is the best NHTSA has tested. That happened due to the design of the car.
     
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  7. JeffC

    JeffC Member

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    One way to improve the discussion would be clearer language. As the original poster mentioned weight doesn't shift. Load transfers. Weight does not. (Weight isn't really the right term either; technically it's mass subject to gravity.) Use the team load and not weight when referring to load.

    Regarding the question of load transfer, each wheel will have an amount of force it can generate dependent on load. The greater the load, for a given tire type, contact patch, surface, etc., the more force it can generate. If you could unload the front wheels enough to have very low load, like on a very powerful RWD drag racer, then the front's can't contribute much accelerative force and thrust should be applied at the rear wheels. However a heavy AWD car will have enough load at the front wheels that the front motor can contribute signficantly to forward thrust, up to some limit.

    Some of the load transfer off the front and onto the rear can be mitigated by anti-dive and anti-squat suspension geometries, but they're an aid in the margins and don't overcome ultimate physics of load transfer.
     
  8. apsen

    apsen Member

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    That one I'm aware of. I'm not aware of any video where he says it is not profitable.

    I'll grant you that you were right about him changing the tune because Cleantechnica quotes him so but I have rewatched the video referenced in that article and still can't find him saying that phrase. I guess I could have missed it because it is tedious to watch the same thing again so I may have spaced out during relevant bit plus there are couple of times when I just can't hear what he says but maybe a native speaker would be able to make it out... Or maybe it is in some other video... In any case I would appreciate if anyone could tell me where I could see it.
     
  9. mongo

    mongo Well-Known Member

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    The one time I use weight transfer instead of force to align with the quoted post...
    :)
    An AWD would like to stay 50/50, but can't under all accel/ deccel conditions. If the tires are in the more linear portion of the traction load curve, the load shift would have a smallish impact on overall traction.
     
  10. ricohman

    ricohman Member

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    The Model 3 should require no additional input as it has traction control. Just mash the pedal. The chassis will react in the same way as any other AWD. I doubt the car would have the same trouble as the Nova at higher speeds as it simply doesn't have enough power to break the tires loose even if it didn't have traction control.
    In a full throttle launch on a Model 3 the rears will load and the fronts will lighten. And the traction control should reduce power to the fronts and increase it to the rears as there will be more traction available. As least this is how I assume it will work as the motors are independent of each other. This and the instant torque of EV's is why they are going to become popular. The eCOPO will be here very soon.
    I worry about inner shafts and CV's though. It's only a matter of time and launches until things get very expensive. And the spline count is what it is. But all IFS/IRS cars are the same in that regard.
     
  11. apsen

    apsen Member

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    No that is not what I'm implying. I'm trying to say that using crash tests to dis/prove Munro's statement is silly. It could easily be false or true irrelevant of the crash results. Crash results are exactly that - estimates of the crash worthiness. It could be used to make estimated guesses about certain other areas but is not enough to dis/prove them.


    That is not the only possible trade off. I'll repeat this again: the way that Tesla have built Model 3 may have been a completely conscious decision on their part but other news suggest that there's at least some truths to the Munro's words. And I'm not talking purely about crash tests.

    But if you want to argue about crash tests there's no way to disprove Munro's opinion that you could save weight/cost without compromising crash test results without building a car that would incorporate his suggestions and testing it. Just as there's no way to prove your statement about Model 3 performing above what is currently tested without doing more stringent tests.

    If you are right and the car is indeed has better performance in the crash then I'm glad I have that but I'm not convinced. On the other hand if Munro is right and Tesla changes the design I still cannot benefit from it except potentially in some rather distant future barring sudden big changes in my life.
     
  12. ricohman

    ricohman Member

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    I read years ago that the ideal weight distribution is slightly to the rear. Adds traction for acceleration and balances the car for braking. Road racing designs. I imagine this still mostly holds true as far as purpose built race cars go.
    But lets get back to fit and finish. How is the assembly on the cars that all of you are driving?
    Is it 90's Kia or like a new Honda?
     
  13. paranoidroid

    paranoidroid Member

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    I have two BMWs, not as good as those but not bad at all and very much passes my standards. Closer to new Honda on my example and this includes paint quality as well.

    You def. need to drive a Performance Model 3 with your car experience, you'll love it.
     
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  14. mongo

    mongo Well-Known Member

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    It's literally a 2002 Sierra with rusted out rockers...
    And don't get me started on weight distribution.
     
  15. JeffC

    JeffC Member

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    I will bet you the price of a new Model 3 that there will be no major changes to the Model 3 unit body chassis within the next 5 years.
     
  16. Garlan Garner

    Garlan Garner Well-Known Member

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    no...just 0 - 60 mph. Much shorter than a quarter mile.
     
  17. voip-ninja

    voip-ninja Give me some sugar baby

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    That leaves you lots of wiggle room since the definition of "major" is rather nebulous.

    If they reworked the rear trunk assembly so it wasn't a bunch of welded sub-structures would that classify as major for you? It would for me and we could see that when they start building in China next year.
     
  18. voip-ninja

    voip-ninja Give me some sugar baby

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    It is definitely not as good as a new Honda but not as bad as a 90's KIA. Munro criticism there was too harsh but I also don't know how bad his early production sample was.

    My 1st BMW F30 had a few panel alignment issues, all of them more or less did the 1st year BMW was into production with that model. The paint however was perfect. The car did have a rattle that BMW never sorted out. In that comparison my Tesla is actually better as so far they've been able to fix the things making noise in the car. I haven't asked Tesla to fix the minor alignment problems as I'm more concerned they will do something to make the car worse in the process.

    Weak spots to me;

    • The door seals are really flimsy and don't seem to fit great. I see long term owners having to deal with this at some point.
    • My driver's side door to rear door alignment is off a bit... I've seen multiple copies parked that have the same 'defect'.
    • Hood slightly sunken on one side.
    • Some fabric on the forward dash is bunched up a bit and creased. I was able to smooth it a bit and I'm not obsessing about it.

    And that's about it. I was worried I was going to have tons of issues with fit and finish but really haven't. That said, if you are the type of person who buys and returns five iPhones trying to find a "perfect" one because you obsess over details only seen under magnification then this is not the car for you.
     
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  19. ricohman

    ricohman Member

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    I'm not the iphone guy but I am an automotive enthusiast. Although I am a mechanic I also paint and do bodywork and frame work. As a painter I can be very picky and as a body man I am also picky. I agree with letting some panel issues slide as no doubt they can be made much worse. I saw a video of some guys raising the striker plate on a Model 3 to "fix" a door alignment issue. That is a good example of making something worse.
    Going to order red. I can't figure out how Ford can paint my massive F450 in white platinum tricoat for $550 and Tesla charges $3300 for red?
    I know candy red is expensive as I have used it before but we are getting hosed here.
     
  20. voip-ninja

    voip-ninja Give me some sugar baby

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    Tesla is charging through the roof for options but I wasn't aware they were charging $3300 for red paint. Are you sure that's for just paint and not for paint and a white interior?

    I would anticipate needing to polish the car when you get it, or better yet if you find things at delivery that can be finished by paint correction then twist Tesla's arm and make them eat the cost of paint correction.

    Mine was pretty good when new, they must have some new detail guys at my local SC. I still ended up polishing it and then did a ceramic coat on it.

    Otherwise I think you're really going to like it. Even with the hit to range in the cold weather we get six months out of the year I'm really happy with this car and driving something else now seems mundane.
     

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