What Engineers Found When They Tore Apart Tesla Model 3

[EEVblog]

[langwadt]

doesn't seem so surprising that where Tesla is lacking is the area that all the other car manufacturers have been perfecting  for many many decades

[Mr. Scram]

The body is too stiff? I know that flex is part of the design, but in general cars are made as stiff as possible to improve the drive-ability.

[tooki]

Indeed.

I think it's the "weak" part only with respect to manufacturing efficiency, since Teslas' frames are what give them their >5 star crash ratings and excellent handling.

[langwadt]

The body is too stiff? I know that flex is part of the design, but in general cars are made as stiff as possible to improve the drive-ability.

once it is stiff enough for the job, any more is just added weight and cost

[Zad]

Not only that, but making a body too stiff compromises crashworthiness - not in that car, but in other vehicles in the collision, or with any humans it collides with. Normally vehicle bodies are designed to deform in a controlled way to dissipate the kinetic energy in a collision. Sure you can make it stiffer, and more protective of the occupants, but it also makes it more likely you will kill the other person, and you may well induce higher energy secondary collisions within the body of the occupants. This is where the  internal organs suffer very high G and jerk loadings because the outer body slows down too quickly. e.g. the heart and lungs collide with the inside of the rib cage.

Not convinced that anyone who says Neodydium knows what he is talking about. I'm sure his engineers do, but that's a different matter. Neodiddlium on the other hand, that's a different matter, I'd buy that gennlemans a pint and discuss Chinesium tools with him.

[tooki]

Neodiddlyium magnets are the best! 

Well, as I understand it, since Teslas have no engine up front, they were able to make the passenger cabin spectacularly stiff, while having a much more crumply crumple zone, essentially combining all the benefits of both very rigid and very soft bodies.

[Mr. Scram]

once it is stiff enough for the job, any more is just added weight and cost

There's no "stiff enough for the job". There's a reason sports car manufacturers flaunt their rigidity numbers like they do their horsepower. It's like complaining they didn't build the car shoddily enough. It's an odd complaint.

Stiffness isn't directly related to occupant or pedestrian safety. One can't extrapolate conclusions from having a stiff car chassis. You need impact tests for that and the results of those appear to be excellent.

While I understand the potential issue with building a too complicated car, it really is the results that matter. I think Tesla does pretty well in that area. It turns out they may even have room to build a cheaper car that's equally as good. That should be good news for everyone, except the people who went short on Tesla stock.

[Zad]

As the saying goes, "the Devil's in the detail". We'd need to know what exactly they meant by "too <X>". I'm surprised they can make them so cheaply though, especially given their lack of optimisation.

[Jr460]

The body is too stiff? I know that flex is part of the design, but in general cars are made as stiff as possible to improve the drive-ability.

once it is stiff enough for the job, any more is just added weight and cost

Having worked close by engineers in the auto industry.....

You had "smart guys" that would come in and say design this way or that way, and then the old guys in the in drafting department would know what size of fillet you need to put at what place in a brake caliper to prevent cracks and failures.   They didn't need to run complicated FEA models for a couple of days on the fastest CPUs of the day to know what would work and wasn't too much in terms of weight.  On the other hand a new idea could be tested faster by FEA rather than a bunch of one off builds and tons of road testing.  Remember these guys in GM, Ford, etc have been doing this for a very long time.   

On top of that, you can't come up with something new that they don't see rather quickly.  If you have ever been to one of the major test centers, they stick things on the cars so that the guys in tress with long lenses can't figure out that they are looking at the 2021 model of a car. 

I was offered to go out to lunch in a Bentley.   They had one in a garage just so it could be torn down to see how it ticked.   The car company never directly bought those cars, but trust me they have one of everything.  A brother-in-law of an employee buys one, and then sells it after a month for no loss to the car company is mainly how it was done.   They all did it, and all knew it happen.   However they were shocked in the 70s when at car show in Detroit, people from asian car companies when would take detailed picture of cars and measure dimensions out in the open.

Bottom line, the old car makers have a lot of hard learned knowledge and steal from others.  I think Tesla has a lot of great ideas, but they might not have the cut throat attitude it takes in that industry.

[IanB]

Definitely an interesting video. I'm curious why Tesla wouldn't have hired engineers from the traditional automotive industry to help them with efficient engineering and production of their products? At the end of the day, the majority of their car is a rolling chassis with four wheels and a suspension, just like every other car. "Reinventing wheels" in this area is not sensible.

As far as "too stiff" is concerned, I interpret that to mean that there is unnecessary weight and cost involved that leads to no discernible benefit.

[langwadt]

once it is stiff enough for the job, any more is just added weight and cost

There's no "stiff enough for the job". There's a reason sports car manufacturers flaunt their rigidity numbers like they do their horsepower. It's like complaining they didn't build the car shoddily enough. It's an odd complaint.

Stiffness isn't directly related to occupant or pedestrian safety. One can't extrapolate conclusions from having a stiff car chassis. You need impact tests for that and the results of those appear to be excellent.

While I understand the potential issue with building a too complicated car, it really is the results that matter. I think Tesla does pretty well in that area. It turns out they may even have room to build a cheaper car that's equally as good. That should be good news for everyone, except the people who went short on Tesla stock.

what sports car manufacturer do is whole different matter, that is mostly marketing wank for their specific audience who for the most part won't be able to tell the difference anyway.

it is easy to over build things, building things strong and stiff enough with the least amount of time and materials needed is what engineering about

[EEVblog]

doesn't seem so surprising that where Tesla is lacking is the area that all the other car manufacturers have been perfecting  for many many decades

Yeah, but surely they hired some top people from the other to players? The knowledge would have walked with them.

[langwadt]

The body is too stiff? I know that flex is part of the design, but in general cars are made as stiff as possible to improve the drive-ability.

once it is stiff enough for the job, any more is just added weight and cost

Having worked close by engineers in the auto industry.....

You had "smart guys" that would come in and say design this way or that way, and then the old guys in the in drafting department would know what size of fillet you need to put at what place in a brake caliper to prevent cracks and failures.   They didn't need to run complicated FEA models for a couple of days on the fastest CPUs of the day to know what would work and wasn't too much in terms of weight.  On the other hand a new idea could be tested faster by FEA rather than a bunch of one off builds and tons of road testing.  Remember these guys in GM, Ford, etc have been doing this for a very long time.   

On top of that, you can't come up with something new that they don't see rather quickly.  If you have ever been to one of the major test centers, they stick things on the cars so that the guys in tress with long lenses can't figure out that they are looking at the 2021 model of a car. 

I was offered to go out to lunch in a Bentley.   They had one in a garage just so it could be torn down to see how it ticked.   The car company never directly bought those cars, but trust me they have one of everything.  A brother-in-law of an employee buys one, and then sells it after a month for no loss to the car company is mainly how it was done.   They all did it, and all knew it happen.   However they were shocked in the 70s when at car show in Detroit, people from asian car companies when would take detailed picture of cars and measure dimensions out in the open.

Bottom line, the old car makers have a lot of hard learned knowledge and steal from others.  I think Tesla has a lot of great ideas, but they might not have the cut throat attitude it takes in that industry.

They have whole teams doing nothing but cutting up competitor cars to figure out how they build them, how many robots, how many welds, where they use glue etc.

https://www.wired.com/2006/02/teardown/ 

[tpowell1830]

Seems like an overall good report card. Other than the fact that the Model 3 is overpriced, seems like there was no big safety issues. 

It is odd that Bloomberg has the power to ban the viewing of this other than on YT. Screenshot:

[Mr. Scram]

They have whole teams doing nothing but cutting up competitor cars to figure out how they build them, how many robots, how many welds, where they use glue etc.

https://www.wired.com/2006/02/teardown/

It'd honestly surprise me if they wouldn't do that.

[T3sl4co1l]

Seems like an overall good report card. Other than the fact that the Model 3 is overpriced, seems like there was no big safety issues. 

It is odd that Bloomberg has the power to ban the viewing of this other than on YT. Screenshot:

Not odd, they just turned off embeds.

The body is too stiff? I know that flex is part of the design, but in general cars are made as stiff as possible to improve the drive-ability.

"As [extreme in magnitude] as possible" is a thing that a lot of so-called experts get very, very wrong.

"As stiff as possible" would be making it of solid diamond.  At least among currently known materials.

That would blow the budget by an astronomical margin, obviously, and also not be very strong (diamond may be hard, but single crystal material cleaves easily), and be extremely brittle (undergoes very little flex before failing catastrophically).  And that, even including the assumption that a solid-diamond design would be made with heavy use of flextures to try to lend what compliance can be had!

"Possible"?  Absolutely, that can be done with today's materials.  But making such a gross statement completely misses the holistic, multidisciplinary truth of the matter, a truth that is real, practical, production engineering.

A much simpler version of this, and perhaps more accessible, is that of "minimize inductance" in switching power supplies.  It's actually quite a bad idea indeed to attempt it, with modern materials and components.  It's advice that came from the bad old days, when devices were slow enough, and boards were only 1 or 2 layers, that you were unlikely to run afoul of it.

So, really, what we are after in this case, is most likely:

once it is stiff enough for the job, any more is just added weight and cost

This is supported by his note that the body is made of far too many pieces, joints and fasteners.  It may be very safe, but if none of the other players are going for a crash rating that high, there is probably a reason for it: it's not worth it.

Keep in mind, the calculus extends all the way to the life cycle of the product, and of the customer.  Remember back when Fiestas were blowing up in crashes?  Management made the decision that so-and-so risk factor was an acceptable cost.  Lives are worth money, both in and of themselves (a typical person in a developed country is worth something like $5M in productive economic output over their lives -- a statistic you won't see thrown about very often, nor be all too willing to give out in polite company!), and in direct impact to the company (the more important consequence: how much will they sue us for).  If the risk is very well known, and small, it is perfectly rational (even if questionably ethical) to make the decision to go ahead with that risk.  (In that particular example, of course, it wasn't as well known as they thought, and they screwed up badly as a result.)

As engineers and ethical actors, it is our personal duty to make a moral decision on things like this; but remember also, as a company, they are only bound by morals to the extent that it affects their bottom line.  Business in general -- law in general -- is amoral, and it is usually but a happy coincidence when the two line up, not a necessity.

Back to the Tesla: probably, they wanted it at least stronger and stiffer than usual, to account for the mass and hazard of the battery.  They wanted to make especially sure to avoid a Fiesta made of rocket fuel*.  That would of course be pretty damning, not just to themselves, but to EVs as a whole, and to lithium battery technologies (as if swelling phones and incendiary laptops weren't bad enough already).

*Rocket fuel is the combination of fuel and oxidizer, so that combustion proceeds in the absence of any particular kind of atmosphere.   Batteries meet the same description, it's just that high temperature combustion isn't their intended mode of operation.

But this assurance came at a cost, and probably due to a number of other forces (like poor management and cost optimization), they never bothered to simplify it to the point of being as cheap as possible while still being just questionably safe enough that no one worries about it.

Tim

[CatalinaWOW]

Hiring veterans of the business can bring in lots of hard won knowledge.  It can also lock in what may or may not be the optimal way of doing things. 

Detroit had many decades to optimize the car building and selling process.  Each year was slightly better (in some sense - cost, power, ...) than the previous.  And then they got their clocks cleaned by people who started with a cleaner sheet of paper and found a better operating point.   

Musk may have intentionally tried to set different initial conditions to find an optimum point.  Not an intrinsically stupid approach, but not guaranteed to work.  The mark of a high risk gambler, which does seem to fit his style.  If Toyota et al have already found the global (in the math sense, not the geopolitical sense) optimum then Musk will have blown this gamble.  The best he can do is catch up, and he will have chosen less than the best way to do so.

[james_s]

it is easy to over build things, building things strong and stiff enough with the least amount of time and materials needed is what engineering about

Unfortunately it usually comes down to building things strong and stiff enough that the car lasts through the warranty period before it starts to fall apart. As someone who keeps cars far longer than average, I'm a big fan of over-engineering and things being stronger and stiffer than they need to be. I still have a Volvo 240 which while light by modern standards was a tank in its day. They could take a lot of abuse and keep on rolling, part of the reason that at 35 years old, having been rear ended at least 4 times while I've owned it, it's still on the road.

[IanB]

Detroit had many decades to optimize the car building and selling process.  Each year was slightly better (in some sense - cost, power, ...) than the previous.  And then they got their clocks cleaned by people who started with a cleaner sheet of paper and found a better operating point.

The problem there was that Detroit was complacent and didn't learn, or didn't try to learn. Hubris can lead to downfall. The same might be the case here with Tesla.

[Mr. Scram]

Not odd, they just turned off embeds.

"As [extreme in magnitude] as possible" is a thing that a lot of so-called experts get very, very wrong.

"As stiff as possible" would be making it of solid diamond.  At least among currently known materials.

That would blow the budget by an astronomical margin, obviously, and also not be very strong (diamond may be hard, but single crystal material cleaves easily), and be extremely brittle (undergoes very little flex before failing catastrophically).  And that, even including the assumption that a solid-diamond design would be made with heavy use of flextures to try to lend what compliance can be had!

"Possible"?  Absolutely, that can be done with today's materials.  But making such a gross statement completely misses the holistic, multidisciplinary truth of the matter, a truth that is real, practical, production engineering.

A much simpler version of this, and perhaps more accessible, is that of "minimize inductance" in switching power supplies.  It's actually quite a bad idea indeed to attempt it, with modern materials and components.  It's advice that came from the bad old days, when devices were slow enough, and boards were only 1 or 2 layers, that you were unlikely to run afoul of it.

So, really, what we are after in this case, is most likely:

This is supported by his note that the body is made of far too many pieces, joints and fasteners.  It may be very safe, but if none of the other players are going for a crash rating that high, there is probably a reason for it: it's not worth it.

Keep in mind, the calculus extends all the way to the life cycle of the product, and of the customer.  Remember back when Fiestas were blowing up in crashes?  Management made the decision that so-and-so risk factor was an acceptable cost.  Lives are worth money, both in and of themselves (a typical person in a developed country is worth something like $5M in productive economic output over their lives -- a statistic you won't see thrown about very often, nor be all too willing to give out in polite company!), and in direct impact to the company (the more important consequence: how much will they sue us for).  If the risk is very well known, and small, it is perfectly rational (even if questionably ethical) to make the decision to go ahead with that risk.  (In that particular example, of course, it wasn't as well known as they thought, and they screwed up badly as a result.)

As engineers and ethical actors, it is our personal duty to make a moral decision on things like this; but remember also, as a company, they are only bound by morals to the extent that it affects their bottom line.  Business in general -- law in general -- is amoral, and it is usually but a happy coincidence when the two line up, not a necessity.

Back to the Tesla: probably, they wanted it at least stronger and stiffer than usual, to account for the mass and hazard of the battery.  They wanted to make especially sure to avoid a Fiesta made of rocket fuel*.  That would of course be pretty damning, not just to themselves, but to EVs as a whole, and to lithium battery technologies (as if swelling phones and incendiary laptops weren't bad enough already).

*Rocket fuel is the combination of fuel and oxidizer, so that combustion proceeds in the absence of any particular kind of atmosphere.   Batteries meet the same description, it's just that high temperature combustion isn't their intended mode of operation.

But this assurance came at a cost, and probably due to a number of other forces (like poor management and cost optimization), they never bothered to simplify it to the point of being as cheap as possible while still being just questionably safe enough that no one worries about it.

Tim

I'm not sure why you insist on being facetious. I acknowledged that flex is part of a car's design, so even if you completely ignored any context it would be fairly obvious that diamond is not an option being discussed. Taking an argument to an extreme is generally considered a fallacy and bad form. Meanwhile, it's rather clear that "as stiff as possible" refers to a conventional car body made with somewhat conventional techniques, which means steel, aluminium and possibly composites. I may have missed some options. There really isn't something like "stiff enough" the context discussed in this thread, as it's mostly a case of a car handling worse or better. It's a gradient without well defined borders.

[maginnovision]

So they still haven't found the billion+ dollars they lose ever year? That's a shame. Keep taking them apart.

[CatalinaWOW]

Detroit had many decades to optimize the car building and selling process.  Each year was slightly better (in some sense - cost, power, ...) than the previous.  And then they got their clocks cleaned by people who started with a cleaner sheet of paper and found a better operating point.

The problem there was that Detroit was complacent and didn't learn, or didn't try to learn. Hubris can lead to downfall. The same might be the case here with Tesla.

I actually think we are saying the same thing, in different ways.  Detroit work on making their cars better, and making them cheaper to produce.  But they weren't willing to rip up the whole industry and start over.  For many reasons, some good, some not so good.  So they perfected large family sedans that are replaced every two years.  They didn't much care about reliability since their customers were going to get a shiny new one before they old one wore out.  They cared a little about fuel economy, more about power, a little about cornering, a lot about ride comfort and so on.   But they did make improvements each year making those large family sedans a little better, a little nicer.  Power brakes.  Automatic transmissions.  Air conditioning.  Turn signals.  Power windows.  Nicer radios.  But once they got the local slope to zero they didn't explore the world to see if there were other good operating points. 

[MT]

Bloomberg and many others, insist on adding stupid music to a reportage as to pretend to be ballsier then they really are!

The Detroit dude try to makes a number of the Neodiddlium Hallbach effect so could every other motor manufacturer do
when needed , surely they can make that cheaper then Tesla.

Former Tesla super fan now fed up with Tesla! Almost impossible to find third party mech's they say, sounds like Apple manouvers!

[AntiProtonBoy]

If money didn't matter to me, I'd still get one.