Sandy Munro talks about the teardown of the Model 3

[ricohman]

You still aren't listening.

If you make all of those modifications you mentioned....then the car would be more expensive.

What modifications can you make that won't change the price?

I haven't built any cars myself, however I do cost analysis EVERY DAY on production and manufacturing.

For goodness sake..you could probably replace a lot of things on the Model 3 with carbon fiber....but can you do it with no up-charge.

Keep in mind that Tesla's don't have one purpose and the least likely purpose is being a track car.

Tesla Model 3's are safe / fast / quick / safe / family sedan / tech savy / safe / attractive / self driving / affordable ( for some ) / etc.... What modification can you make to improve the Model 3 and NOT change any of the factors that I listed?

I see. This explains everything.

 

[ricohman]

That's definitely not a convincing arguement and it's not clear what you are saying I'm wrong about (because you quoted my entire post).

So, no, you didn't change my mind about anything because you didn't say anything.

That's definitely not a convincing arguement and it's not clear what you are saying I'm wrong about (because you quoted my entire post).

So, no, you didn't change my mind about anything because you didn't say anything.

You said....
Both the RWD LR Model 3 and the P3D with the OEM 18" Michelin MXM4 Primacy tires are on the ragged edge of being traction limited on most common types of blacktop, especially if the battery is warm and 90% charged and the pavement/air temperature is cool. This means that to get signifiicantly quicker 0-60 times from removing weight, you might need stickier tires. Yes, making a car lighter generally does make it faster but, when traction limited, there are other factors at play and the experiences you've had with ICE vehicles over the decades might not transfer directly to a car with the torque and heavy battery of the Model 3.

You do not understand that when there is less weight to accelerate the demands on the tire are also less.
The laws of acceleration and deceleration apply to all vehicles. No matter what they are powered by.

 

[TT97]

The square root of 2 is about 1.41, so it's about 41% faster, presumably than if the permanent magnets were not used in a more conventional reluctance motor design.

I took math in elementary school, I know 2^(1/2) is roughly 1.41, but if it was just a matter of being 41% faster, he would have said that. Munro using the reference "root of two" faster must have a connotation.

 

[mongo]

You said....
Both the RWD LR Model 3 and the P3D with the OEM 18" Michelin MXM4 Primacy tires are on the ragged edge of being traction limited on most common types of blacktop, especially if the battery is warm and 90% charged and the pavement/air temperature is cool. This means that to get signifiicantly quicker 0-60 times from removing weight, you might need stickier tires. Yes, making a car lighter generally does make it faster but, when traction limited, there are other factors at play and the experiences you've had with ICE vehicles over the decades might not transfer directly to a car with the torque and heavy battery of the Model 3.

You do not understand that when there is less weight to accelerate the demands on the tire are also less.
The laws of acceleration and deceleration apply to all vehicles. No matter what they are powered by.

Maximum available motive force is proportional to friction and down force (mass if ignoring aero), acceleration is proportional to force and mass.
Ignoring the non linearity of tire coefficient of friction to load, the mass terms cancel out. So if you are friction (traction) limited, changing mass does not change acceleration.
(with u as coefficient of friction, g as gravity, a as acceleration, f as force, m as mass)
f=m*g*u,
f=m*a, or a=f/m
a= m*g*u/m
a = g*u

 

[apsen]

I already told you why, I simply don't want to spend the time to re-listen to them to index them to what your requesting.

Here's a proposal: Since you are such a fan of Munro's opinions, just keep watching them until you find what you're looking for. In one of them he is standing by the trunk of a Model 3 and explaining how Tesla could save money and weight by simply stamping the trunk out of sheet steel like most car makers do instead of constructing it from multiple stampings welded together.

I didn't ask you to index them but to provide links to them.

If you are paying as much attention to what Munro says than your opinion is irrelevant...

 

[ricohman]

Maximum available motive force is proportional to friction and down force (mass if ignoring aero), acceleration is proportional to force and mass.
Ignoring the non linearity of tire coefficient of friction to load, the mass terms cancel out. So if you are friction (traction) limited, changing mass does not change acceleration.
(with u as coefficient of friction, g as gravity, a as acceleration, f as force, m as mass)
f=m*g*u,
f=m*a, or a=f/m
a= m*g*u/m
a = g*u

Seriously? I spent a pile of my time in the mid 80's racing early superbikes on skinny 130's. The only way we could get those bikes into the 10's was by reducing weight. And oh yeah, they were traction limited with those skinny rock hard tires which you could smoke at will. And this applies directly to 4 wheels. And yes, I have done this as well.
So yes, reducing mass changes acceleration. In racing this a proven fact.
How many race cars have you built? Or perhaps bikes?

 

[mongo]

Seriously? I spent a pile of my time in the mid 80's racing early superbikes on skinny 130's. The only way we could get those bikes into the 10's was by reducing weight. And oh yeah, they were traction limited with those skinny rock hard tires which you could smoke at will. And this applies directly to 4 wheels. And yes, I have done this as well.
So yes, reducing mass changes acceleration. In racing this a proven fact.
How many race cars have you built? Or perhaps bikes?

I'm not discounting your experience.
For a two wheel bike with a rear drive wheel, there is also the factor of whether weight (mass) adds to traction or inertia. Only a fraction of the mass adds to the drive wheel traction. The mass on the front wheel must be accelerated, but does not increase friction. Once in a wheelie, all mass is on the rear wheel. This force transfer to the rear wheel only comes into play once the object starts accelerating (or the tire torque reacts the front wheel on its own).

For a 4 wheel drive car (esp a Tesla with dual motors), the transfer and initial distribution is a non-factor. All mass provides friction to drive wheels

Ye cannae change the laws of physics
-Scotty

 

[ricohman]

I'm not discounting your experience.
For a two wheel bike with a rear drive wheel, there is also the factor of whether weight (mass) adds to traction or inertia. Only a fraction of the mass adds to the drive wheel traction. The mass on the front wheel must be accelerated, but does not increase friction. Once in a wheelie, all mass is on the rear wheel. This force transfer to the rear wheel only comes into play once the object starts accelerating (or the tire torque reacts the front wheel on its own).

For a 4 wheel drive car (esp a Tesla with dual motors), the transfer and initial distribution is a non-factor. All mass provides friction to drive wheels

Ye cannae change the laws of physics
-Scotty

After reading this I realize you have zero experience racing anything.
BTW, if you are doing it right every single run is traction limited. When you have the power to smoke the tires at 100 mph you bet less weight is a good thing. The skinny pedal is a rheostat, not a switch.
Unless you are racing 40 hp cars of some sort.

 

[mongo]

After reading this I realize you have zero experience racing anything.
BTW, if you are doing it right every single run is traction limited. When you have the power to smoke the tires at 100 mph you bet less weight is a good thing. The skinny pedal is a rheostat, not a switch.
Unless you are racing 40 hp cars of some sort.

Nope don't race, but that doesn't stop me from knowing that if you put 10kg over a non-drive wheel, you will accelerate slower (same f, higher m, less a), if you put it over the drive wheel, you will accelerate roughly the same (higher available f, higher m, ~same a).

(bikes have throttle pedals? )

 

[ricohman]

Nope don't race, but that doesn't stop me from knowing that if you put 10kg over a non-drive wheel, you will accelerate slower (same f, higher m, less a), if you put it over the drive wheel, you will accelerate roughly the same (higher available f, higher m, ~same a).

(bikes have throttle pedals? )

Good grief.
Proper race cars drive both wheels. You have a specific non drive wheel? Interesting. In an open diff the wheel with the least traction always spins. I take it you are not a mechanic either.
No kidding you don’t race.

 

[StealthP3D]

You said....
Both the RWD LR Model 3 and the P3D with the OEM 18" Michelin MXM4 Primacy tires are on the ragged edge of being traction limited on most common types of blacktop, especially if the battery is warm and 90% charged and the pavement/air temperature is cool. This means that to get signifiicantly quicker 0-60 times from removing weight, you might need stickier tires. Yes, making a car lighter generally does make it faster but, when traction limited, there are other factors at play and the experiences you've had with ICE vehicles over the decades might not transfer directly to a car with the torque and heavy battery of the Model 3.

You do not understand that when there is less weight to accelerate the demands on the tire are also less.
The laws of acceleration and deceleration apply to all vehicles. No matter what they are powered by.

Please look up "coefficient of friction" and how it varies with weight before you look silly. I'm NOT saying removing weight will make the car slower, but, when traction limited, it might not make you significantly faster.

 

[mongo]

Good grief.
Proper race cars drive both wheels. You have a specific non drive wheel? Interesting. In an open diff the wheel with the least traction always spins. I take it you are not a mechanic either.
No kidding you don’t race.

Ok, you mentioned:

I spent a pile of my time in the mid 80's racing early superbikes on skinny 130's. The only way we could get those bikes into the 10's was by reducing weight.

Most bikes I am aware of only have a rear drive wheel. Unless you are talking electric, which was not big thing in the 80s.

Now you are back to taking about cars.
Unless the car is four wheel drive, the front wheels are undriven, so the same effect holds.
(of course I'm not talking about one half of a differential, open, Detroit locker, limiter slip or otherwise)

 

[ricohman]

Ok, you mentioned:

Most bikes I am aware of only have a rear drive wheel. Unless you are talking electric, which was not big thing in the 80s.

Now you are back to taking about cars.
Unless the car is four wheel drive, the front wheels are undriven, so the same effect holds.
(of course I'm not talking about one half of a differential, open, Detroit locker, limiter slip or otherwise)

I can talk of both because I haves raced both.
Unlike yourself.
You should head immediately to the local track and tell everybody that they are doing it wrong.
Hahahaha!

 

[ricohman]

Please look up "coefficient of friction" and how it varies with weight before you look silly. I'm NOT saying removing weight will make the car slower, but, when traction limited, it might not make you significantly faster.

You should also head to the local track and tell everyone they are doing it wrong. Go with mongo!

 

[StealthP3D]

Seriously? I spent a pile of my time in the mid 80's racing early superbikes on skinny 130's. The only way we could get those bikes into the 10's was by reducing weight. And oh yeah, they were traction limited with those skinny rock hard tires which you could smoke at will. And this applies directly to 4 wheels. And yes, I have done this as well.
So yes, reducing mass changes acceleration. In racing this a proven fact.
How many race cars have you built? Or perhaps bikes?

I'm sorry but you are ignoring that racing superbikes of the 1980's were not traction limited past 60 mph. So your example doesn't prove your point, the formulas provided by Mongo show the reality of the situation. Also, the superbike analogy is not directly applicable to 4 wheels because superbikes are acceleration limited by the rotational force that wants to "loop" the bike under strong acceleration. Reducing weight above the center of gravity allows the bike to accelerate more quickly without looping. This does not apply directly to 4 wheels.

 

[mongo]

I can talk of both because I haves raced both.
Unlike yourself.
You should head immediately to the local track and tell everybody that they are doing it wrong.
Hahahaha!

If you can talk about both, then use some common sense to realize which is being discussed.

 

[ricohman]

I'm sorry but you are ignoring that racing superbikes of the 1980's were not traction limited past 60 mph. So your example doesn't prove your point, the formulas provided by Mongo show the reality of the situation. Also, the superbike analogy is directly applicable to 4 wheels because superbikes are acceleration limited by the rotational force that wants to "loop" the bike under strong acceleration. Reducing weight above the center of gravity allows the bike to accelerate more quickly without looping. This does not apply directly to 4 wheels.

I race cars also. For decades.
And there is so much wrong with your statement I'm not even going to bother to comment.
The eCOPO is coming and it’s a game changer.

 

[voip-ninja]

Basically this entire 12 page thread boils down to this argument;

Is the Model 3 body "overbuilt" or not?

What defines overbuilt?

If the body could provide the same handling (stiffness), protection to occupants, battery, etc., with less material/welds/cost then the body is indisputably overbuilt.

Munro insists, emphatically that the Model 3 unibody is overbuilt. According to Munro, Elon Musk seems to acknowledge this with the admonishment that the guy who did the body design was fired.

If Munro is correct in the insistence that the Model 3 body is overbuilt then Tesla is wasting materials/welds/cost with the current design.

And we have a lot of people here, arguing very strenuously, with little to no evidence, that the body is not overbuilt. Arguments in this camp boil down to;

• Body needs this level of build to protect passengers
• Body needs this level of build to protect battery (treated as passenger)
• Body needs this level of build to handle torque of electric propulsion system
• Body needs this level of build to provide handling characteristics.
• Munro is an idiot who doesn't understand EVs even though he took apart both the BMW i3 and GM Bolt in addition to the Model 3.

I personally haven't found any of those arguments very persuasive.

I present one fact that I don't think has entered the discussion yet;

300 spot welds removed from Model 3 design to meet production target

Tesla removed 300 spot welds from the Model 3 design after the car was well into production. If Tesla did a full analysis on the design before they began building the cars what possible explanation could there be for reducing the number of welds? After all, shorts argued loudly that this was an indicator that Tesla doesn't know what they are doing. Why would Tesla do it?

I think it's telling. Telling that Tesla revisited the design, and made the changes they could that would not require them to resubmit the car for crash testing. Their reason for removing unnecessary welds is to reduce cost, there isn't any other reason that passes the smell test.

 

[diamond.g]

Really? I bet an identical Model 3 stripped of its interior, A/C, door panels and the glass replaced with polycarbonate would be faster.
Actually, I know it will be faster. I've done it already with many other vehicles over decades.
You speak like you've never built a race car. How many cars have you built?

Do Tesla's have more than 1 A/C system (compressors, tubing)? Seems like removing the system that keeps the batteries and motor(s) cool would hamper performance (see Model S track performance) than help it.

 

[omgwtfbyobbq]

Basically this entire 12 page thread boils down to this argument;

Is the Model 3 body "overbuilt" or not?

What defines overbuilt?

If the body could provide the same handling (stiffness), protection to occupants, battery, etc., with less material/welds/cost then the body is indisputably overbuilt.

Munro insists, emphatically that the Model 3 unibody is overbuilt. According to Munro, Elon Musk seems to acknowledge this with the admonishment that the guy who did the body design was fired.

If Munro is correct in the insistence that the Model 3 body is overbuilt then Tesla is wasting materials/welds/cost with the current design.

And we have a lot of people here, arguing very strenuously, with little to no evidence, that the body is not overbuilt. Arguments in this camp boil down to;

• Body needs this level of build to protect passengers
• Body needs this level of build to protect battery (treated as passenger)
• Body needs this level of build to handle torque of electric propulsion system
• Body needs this level of build to provide handling characteristics.
• Munro is an idiot who doesn't understand EVs even though he took apart both the BMW i3 and GM Bolt in addition to the Model 3.

I personally haven't found any of those arguments very persuasive.

I present one fact that I don't think has entered the discussion yet;

300 spot welds removed from Model 3 design to meet production target

Tesla removed 300 spot welds from the Model 3 design after the car was well into production. If Tesla did a full analysis on the design before they began building the cars what possible explanation could there be for reducing the number of welds? After all, shorts argued loudly that this was an indicator that Tesla doesn't know what they are doing. Why would Tesla do it?

I think it's telling. Telling that Tesla revisited the design, and made the changes they could that would not require them to resubmit the car for crash testing. Their reason for removing unnecessary welds is to reduce cost, there isn't any other reason that passes the smell test.

Based on everything I've seen and read, I think it's a little bit of both. Like you pointed out, Tesla was able to remove a bunch of welds with no appreciable impact on production that anyone is aware of, and like Sandy pointed out, certain parts of the car like the trunk have been a little bit of a mess in terms of design/assembly.

With that said, Sandy may be correct to point out that the frame alone is enough for current crash testing requirements/ratings, and that Tesla could save $600/car by optimizing their design, but may still be missing how much Tesla wants to protect the battery pack because of consumer sentiment. Because of the amount of FUD out there, it may be financially worthwhile for Tesla to spend an extra $600 and build a body that is an order of magnitude better at protecting the pack even if the difference is practically speaking very small.