Performance Model 3: Excited or Disappointed?

[Brando]

@kbM3

INTERNET SEARCHING TIP - do your own research - data may set you free (as in free to think for yourself)

example:
Dodge Viper site:consumerreports.org

Using site:website instructs google to only search your website of choice

 

[Knightshade]

A 5th generation Dodge Viper stops in ~90 feet. The Model 3 is 10% heavier but takes ~40 feet more. It's all brakes and tires. Wimpy tires will give you a reduced contact patch. And wimpy rotors / calipers will increase the time-to-lock-up and ABS to engage translating to longer braking distances. It's simple physics.

So yes, put in any of the following options and you will get a shorter stopping distance.
- Wider summer tires
- Bigger rotors
- Bigger pistons or calipers.

That's simply, factually, wrong.

Bigger rotors, pistons, or calipers do literally nothing to reduce stopping distance.

It is simple physics. Here's the formula-

Braking Distance

d = V2/(2g(f + G))

Where:
d = Braking Distance (ft)
g = Acceleration due to gravity (32.2 ft/sec2)
G = Roadway grade as a percentage; for 2% use 0.02
V = Initial vehicle speed (ft/sec)
f = Coefficient of friction between the tires and the roadway

That's the formula for the stopping distance of a car.

Notice how it does care about the friction between tires and road- and does not care how large your brake rotors are?

That's because as long as the brakes can lock the wheels/engage ABS, bigger brakes don't help

How could they? More force, in excess of what the tires can use, is completely wasted force.

 

[Knightshade]

Again, that's not true.

Of course it is.

As supported by multiple sources I have continued to provide.

Where are your sources again?

I encourage you to read up on the fundamentals of ABS. Short story is that ABS works by precisely controlling wheel speed relative to vehicle speed, which--most importantly--controls tire slip. It is explicitly not a binary thing--It is in the grey area between slip and no-slip that a tire enables the greatest braking force.

I suggest you take your own advice.

Here's Road and Track explaining it-

When ABS is activated, this tells the onboard systems that your wheel has stopped rotating, meaning that you’ve exceeded the maximum stopping force of the tire. In other words, your stopping distance is limited by the tire. Your brake was likely perfectly capable of applying more pressure, however the tire lost grip, so more pressure serves no purpose

The one thing that doesn't help in the slightest in what you describe is more force than the tires can use

Which is all bigger rotors or calipers or pistons get you.

Similar to how adding a bigger steering wheel on a vehicle, a longer lever arm on a torque wrench, or any other similar situation where a bigger thing adds more precise control, larger brakes [in an all else equal system] will allow the ABS to more precisely control that tire slip and thus better maximize traction. Which of course reduces braking distance.

No, it really does not.

Factually.

Because more force doesn't help. At all.

As explained repeatedly by myself, R&T, the SAE Master Engineer who wrote Pulp Friction, etc...

Still think they're all wrong?

here's Stoptech and Brembo on the topic-

Where can I find test data on stopping distances? | Race Technologies | Brembo Official Partner

At the speeds that stopping distance is generally measured from (60 to 70mph), the test is primarily testing the tire's grip on the pavement. As delivered from the manufacturer, nearly all vehicles are able to engage the ABS or lock the wheels at these speeds. Therefore, an increase in braking power will do nothing to stop the vehicle in a shorter distance. For this reason, we do not record stopping distances at this time. The Brembo systems will show their greatest advantages when braking from higher speeds, or when tasked with repeated heavy braking.

Brake System and Upgrade Selection

The brakes don't stop the vehicle - the tires do. The brakes slow the rotation of the wheels and tires. This means that braking distance measured on a single stop from a highway legal speed or higher is almost totally dependent upon the stopping ability of the tires in use

If big brakes improved normal stopping distances don't you think the folks who make those kits would be screaming it from the mountains?

Instead they're honest and tell you the same thing I am.

Those parts can be useful for track situations to make brakes more resistant to fade when stopping repeatedly from 100+ MPH.... but in normal real-world use will do nothing at all to stop the car shorter.

Because they can't.

Its physics, as it were.

yes, it is.

See my post above where I give you the actual physics formula for stopping distance.

it doesn't ask about your rotors- because it doesn't care.

 

[Daniel in SD]

A 5th generation Dodge Viper stops in ~90 feet. The Model 3 is 10% heavier but takes ~40 feet more. It's all brakes and tires. Wimpy tires will give you a reduced contact patch. And wimpy rotors / calipers will increase the time-to-lock-up and ABS to engage translating to longer braking distances. It's simple physics.

So yes, put in any of the following options and you will get a shorter stopping distance.
- Wider summer tires
- Bigger rotors
- Bigger pistons or calipers.

Haha. The Dodge Viper has 295 width front and 355 width rear tires that are "Streetable Track & Competition" tires. They have the bare minimum amount of tread to be DOT legal.

I don't think the response time of the brakes has anything to do with it.

 

[FlyNavy01]

Haha. The Dodge Viper has 295 width front and 355 width rear tires that are "Streetable Track & Competition" tires. They have the bare minimum amount of tread to be DOT legal.
View attachment 305342
I don't think the response time of the brakes has anything to do with it.

I think you missed the part where he mentioned wider/sticky tires as one of the things that decrease stopping distance. And brake response times are still relevant. Any delay in the pads getting full grab on the rotors is still a delay regardless of rubber compound.

I think we can all agree in a one-time, emergency braking event, larger rotors/pads may not make much measurable difference for most daily driving uses. However, larger and/or high performance brake systems absolutely make a significant difference on the track or under any sort of performance driving. Decreased brake fade, increased surface area to volume ratio for better heat dissipation, potentially less unsprung mass, etc., all play a role.

A performance car without equally performing brakes is nothing but a poser-mobile in my opinion. Why spend 80k on a performance car that can't do anything but drive around in city traffic? If it's being advertised (via Elon's twitter as of late) as a trackable car, then it will absolutely require larger brakes than the base model.

 

[Daniel in SD]

I think you missed the part where he mentioned wider/sticky tires as one of the things that decrease stopping distance. And brake response times are still relevant. Any delay in the pads getting full grab on the rotors is still a delay regardless of rubber compound.

I think we can all agree in a one-time, emergency braking event, larger rotors/pads may not make much measurable difference for most daily driving uses. However, larger and/or high performance brake systems absolutely make a significant difference on the track or under any sort of performance driving. Decreased brake fade, increased surface area to volume ratio for better heat dissipation, potentially less unsprung mass, etc., all play a role.

A performance car without equally performing brakes is nothing but a poser-mobile in my opinion. Why spend 80k on a performance car that can't do anything but drive around in city traffic? If it's being advertised (via Elon's twitter as of late) as a trackable car, then it will absolutely require larger brakes than the base model.

I agree.
I get the feeling that they're still designing the car. I'm convinced that they were not originally planning to have bigger brakes on the P. Maybe all our armchair racing on the internet is paying off! haha

 

[McRat]

You have plenty of brakes up until you don't.
At that point, you'd rather have more.

Most serious cars in 2018 will stop in under 100 feet from 60 mph, but that is nothing. Zero stress, low heat.
The problem is going from 100-160 mph, then braking down to 45mph as aggressively as possible.

Every time. Because you have plenty of brakes until you don't.

It's not necessary to believe it. Just do about three, 0-100-0-100-0-100-0. Don't wimp it. Use 100, and try to bend the brake pedal.
You can probably do a dozen 0-60-0's without even stinking up the car. Big difference after the triple digits though. And cars go over 100mph now.

BTW, there are cars that stop in under 100 feet on runflats. Not the greatest track tires, but they work.

 

[Brando]

Just a quick thank you to all those willing to pay for performance options.
These options help Tesla income and therefore P&L - and helps to starve the gas guzzler production/sales.
And eventually improvements trickle down to the rest of us.

My '89 turbo Saab 165hp; 22-24 m/gal. city; 34-36 m/gal. highway; (used to be quick) 0-60 about 8.5 seconds - snail pace today
Seems near the pinnacle for ICE machines. read below
Consumer Reports finds small turbo engines don't deliver on fuel economy claims

 

[Knightshade]

brake response times are still relevant. Any delay in the pads getting full grab on the rotors is still a delay regardless of rubber compound.

Can you explain, specifically, how "bigger rotors" make any difference in delay time of the brakes in any way that impacts stopping distance?

I ask, because a guy who literally writes books on brake system design, teaches SAE master classes on the topic, and designed braking systems for everyone from Ford to Stoptech explicitly says they don't.

And Brembo, Stoptech, Road and Track, and others, all seem to say the same thing.

As does the actual physics formula to determine stopping distance.

I think we can all agree in a one-time, emergency braking event, larger rotors/pads may not make much measurable difference for most daily driving uses.

I'd hope we'd all agree it makes none since that's the actual fact- unless you're discussing some car designed in the 70s with brakes that can't handle the traction of a modern tire.

By all means if one is still rocking a '73 Nova with drum brakes, but modern performance tires, they'd very likely see a significant improvement with swapping in a modern braking system.

But anything made in the last decade or two? Not so much.

However, larger and/or high performance brake systems absolutely make a significant difference on the track or under any sort of performance driving. Decreased brake fade, increased surface area to volume ratio for better heat dissipation, potentially less unsprung mass, etc., all play a role.

Absolutely.

Big brakes make zero difference stopping once in a panic stop from highway speed.

They can make a tremendous difference when stopping the 10th time in a row from 150 mph though.

But it's worth noting even then- the difference they make is that they keep your stopping distance nearer what it was the first time since they're a lot harder to overheat.

They still don't ever make it shorter than the first time.

They can't.

(barring some magical non-street-legal track tires so good they can out-friction the stock brakes on a Yaris or something I suppose).

A performance car without equally performing brakes is nothing but a poser-mobile in my opinion. Why spend 80k on a performance car that can't do anything but drive around in city traffic?

Given 99% of folks don't track their cars, including most performance cars, it's pretty obvious a lot of people think it's worth spending that much (and more in the case of imports or some vettes/vipers) doing nothing but driving on public roads.... and of the maybe 1% who do track, many of those do so just at drag strips- where again a brake upgrade is pointless (unless you're at a really really really badly designed drag strip )

Not saying it's a great use of money- but clearly the market for that use is way bigger than the market for people who buy them to drive around tracks with turns.

If it's being advertised (via Elon's twitter as of late) as a trackable car, then it will absolutely require larger brakes than the base model.

And his twitter already said it would have them.

Just pointing out for the vast majority of owners who don't take it to a (non drag) track, that upgrade doesn't actually do anything for them.

And just watch and see if Tesla makes the "sport brake" option available on the non-P models later and people who also never track their cars waste $ on it thinking it'll help in normal use... (I know tons of folks who do exactly that with ICE cars that offer brake upgrades they'll never benefit from).

 

[Garlan Garner]

Everyday recently there is something that shocks me about Tesla.

Elon tweets that if they were able to produce 10K model 3's per week...….the price could definitely come down to $28k.

Teslas inability to produce cars in numbers costs the customer?

Tesla Model 3 teardown points to only $28,000 in potential material and production cost

 

[FlyNavy01]

Can you explain, specifically, how "bigger rotors" make any difference in delay time of the brakes in any way that impacts stopping distance?

Never said that.

Absolutely.

Big brakes make zero difference stopping once in a panic stop from highway speed.

They can make a tremendous difference when stopping the 10th time in a row from 150 mph though.

Agreed.

But it's worth noting even then- the difference they make is that they keep your stopping distance nearer what it was the first time since they're a lot harder to overheat.

They still don't ever make it shorter than the first time.

Never said that either.

Given 99% of folks don't track their cars

That's a statistic you frequently use but don't provide any data or source to back it up. I'm pretty confident a lot more than 1% of people who buy performance cars drive them in a manner in which would require a better-than-base-model braking system. And I would bet a lot more than 1% track their cars too at the BMW M3/Alfa Quadrifoglio level, if they're true enthusiasts.

Just pointing out for the vast majority of owners who don't take it to a (non drag) track, that upgrade doesn't actually do anything for them.

And just watch and see if Tesla makes the "sport brake" option available on the non-P models later and people who also never track their cars waste $ on it thinking it'll help in normal use... (I know tons of folks who do exactly that with ICE cars that offer brake upgrades they'll never benefit from).

That sounds like it's their problem, and is why I was saying why (in my opinion) it's really dumb. But I also can't really complain-- if they're paying Tesla just as much money as me, they're equally contributing to Tesla's mission of bringing more sustainable transport to the masses, as well as supporting high-quality American jobs, which are both good things (again in my opinion).

Finally, to get back on topic to the thread: I am very excited for my performance model. I was also excited to hear Elon tweet that it would be getting a brake upgrade.

 

[FlyNavy01]

Everyday recently there is something that shocks me about Tesla.

Elon tweets that if they were able to produce 10K model 3's per week...….the price could definitely come down to $28k.

Teslas inability to produce cars in numbers costs the customer?

Tesla Model 3 teardown points to only $28,000 in potential material and production cost

Careful... That's cost to produce, not cost to buy.

 

[Garlan Garner]

Careful... That's cost to produce, not cost to buy.

I don't agree.

They are talking about total costs.

 

[FlyNavy01]

I don't agree.

They are talking about total costs.

Elon is agreeing that at that 10k/week rate, Tesla's profit on the $35k car will theoretically be ~$7k. It doesn't mean they will be reducing the price of the car down to $28k for consumers.

 

[Brando]

Everyday recently there is something that shocks me about Tesla.

Elon tweets that if they were able to produce 10K model 3's per week...….the price could definitely come down to $28k.

Teslas inability to produce cars in numbers costs the customer?

Tesla Model 3 teardown points to only $28,000 in potential material and production cost

That is a particularly good article - IMHO. thank you Garlan.

Note: $35,000 x 0.75 = $26,250 - isn't that a 25% margin ? How about
$35,000 x 0.80 = $28,000 what is the margin at this price? that isn't a trick question is it? for some perhaps.
AND yes volumes do matter, a great deal. Isn't that also obvious?
AND yes, the customer always pays. Just where do you think the money comes from? cost the customers, duhh.
(Military Industrial Complex is of course an exception as all the money comes from wage earners as most all others find loop holes to avoid taxes, even payroll taxes, right? Did I lose anyone?)

I don't see any surprises here. Now goals don't equal performance and running a business, especially auto manufacturing is very very complex - which may partially explain why GM claims to lose money on the Bolt as do most all other of the Major Auto Companies claim to lose money on BEVs (except Renault/Nissan?)

Perhaps the Chinese also make money per car? Lack of transparency leads some to claim China a "faith based economy". But considering US Banksters and the Federal Reserve banking cartel I'd say the same for US economy - isn't Fiat money and Wall St. very faith based?

NOTE: All Tesla margin information can clearly be read in quarterly and annual SEC filed documents. You should all try to read. With a little practise and some word look ups you can easily learn for yourself and not be manipulated/conned by our main stream media such as it is often called. It may how ever shake your faith just a little.

 

[McRat]

You cannot make a Model 3SR as promoted by Tesla for $35k. Something has to be surrendered. It was a price pulled out of the air to claim superiority over competitors. It had no bearing on costs. Or they are making 50% on every Model S/X and are hiding the cash in Krugerrands in a Boring Company tunnel, or it's orbiting in a SpaceX orbital vault.

 

[Garlan Garner]

You cannot make a Model 3SR as promoted by Tesla for $35k. Something has to be surrendered. It was a price pulled out of the air to claim superiority over competitors. It had no bearing on costs. Or they are making 50% on every Model S/X and are hiding the cash in Krugerrands in a Boring Company tunnel, or it's orbiting in a SpaceX orbital vault.

Pulled out of the air? Really?

They pulled a price out of the air - and told it as fact to shareholders and investors...….? Elon Musk....a Capex expert just pulled the price out of the air?

Elon was on stage and without the Tesla board knowing or anything.....just spewed forth " $35k.....yeah.....that sounds good".

 

[McRat]

Pulled out of the air? Really?

They pulled a price out of the air - and told it as fact to shareholders and investors...….?

Elon was on stage and without the Tesla board knowing or anything.....just spewed forth " $35k.....yeah.....that sounds good".

They had no idea what the nVidia Drive PX system would cost. Hint, it's more than the $8k charged for AP 2.5 + FSD.
They had no idea what batteries would cost in 2019. The price did not fall as much as hoped for.

The first clue was Elon claiming a mass-produced 60kWh car must cost $46,500. "The Bolt loses $9000 per car" were his words. If anybody knows what a 60kWh car would cost it would be Elon.

 

[kbM3]

Just a quick thank you to all those willing to pay for performance options.
These options help Tesla income and therefore P&L - and helps to starve the gas guzzler production/sales.
And eventually improvements trickle down to the rest of us.

My '89 turbo Saab 165hp; 22-24 m/gal. city; 34-36 m/gal. highway; (used to be quick) 0-60 about 8.5 seconds - snail pace today
Seems near the pinnacle for ICE machines. read below
Consumer Reports finds small turbo engines don't deliver on fuel economy claims

Porsche moved the Boxster from a naturally aspirated six to a turbo four for improved fuel economy, and the epa fuel economy declined.

They had no idea what the nVidia Drive PX system would cost. Hint, it's more than the $8k charged for AP 2.5 + FSD.
They had no idea what batteries would cost in 2019. The price did not fall as much as hoped for.

The first clue was Elon claiming a mass-produced 60kWh car must cost $46,500. "The Bolt loses $9000 per car" were his words. If anybody knows what a 60kWh car would cost it would be Elon.

That German article, based on the LR premium model, proves just how wrong you are.

 

[McRat]

That German article, based on the LR premium model, proves just how wrong you are.

How many Model 3's a week is the German factory making, and who is the comptroller?