Knightshade
Well-Known Member
You're right, it is pretty basic physics. Its easier to explain to the lay person that way. We'll get to that later in my response. You're also right, shortest possible stopping distance is limited by your tires. But that isn't what I commented. It was your assertion that only the tires matter.
Because that remains a fact.
You can't stop shorter than the tires are capable of no matter how much you upgrade the brakes
There are a whole host of reasons why that's not true.
It's weird you admit you are limited by the tires and then deny you're limited by the tires...
Wrong again: Stopping Distance Retest After an ABS Firmware Update - 2017 Tesla Model 3 Long-Term Road Test
"Our initial 2017 Tesla Model 3 full-ABS panic-stop measurement of 133 feet was indeed below average.
you realize you just confirmed I was right and you lied right?
They're saying it was below average for "comparable cars" (which is a stupid comparison anyway- since they didn't have the same tires)
In fact, they POINT THAT OUT IN THE NEXT SENTENCE YOU QUOTE-
But it didn't seem outrageous, especially given the characteristics of the standard 18-inch tires. They're hard (with a treadwear rating of 500), they run at an abnormally high tire pressure (45 psi), and their 235 mm tread width isn't generous considering the car's 3,884 pounds of weight. It all seemed to fit
Huh- look- they TOO note the tires are the relevant thing.
, but that was before Consumer Reports reported a 60-0 mph stopping distance of 152 feet, nearly 20 feet longer than ours...
Except, of course, CR reported 133 feet. Same as they got. On the first stop
It was LATER stops (showing the ABS glitch) that got them to 152.
We caught you lying about this- remember?
YOU claimed ALL of CRs stops were excessively long. That's a lie.
it's factually untrue.
I directly quoted CR in my last post showing you lied about it.
here we go again-
moridin2002 said:and it wasn't just that their tested stopping distances got longer and longer. It was poor calibration of the ABS system that caused both an initial longer stopping distance.
What CR ACTUALLY SAID said:In our testing of the Model 3, the first stop we recorded was significantly shorter (around 130 feet, similar to Tesla’s findings)
Further- when they got the gltich fixed and retested- guess what they got as results?
Tesla Model 3 Gets CR Recommendation After Braking Update
CR said:In retesting after the software update was downloaded, the sedan stopped in 133 feet from 60 mph
133 feet.
exactly the same distance as the first stop with the bad software.
So- once again- the actual facts exactly confirm what I told you, and caught you lying about
Don't imagine we should wait around for an apology though huh?
Interesting that you claim I have difficulty reading, but it appears you forget about the information in your (recently) Googled links
...and caught lying again
You can find posts from me citing that specific "how ABS works" paper going back years including on this very forum.
: "a quick calculation, the ABS determines that in order to have slowed 1 MPH in a 50ms period the wheels must be decelerating at a rate of 0.91g's. Because you are driving a sports car, the engineer who calibrated the system 'taught' the ABS that your car is capable of decelerating at this rate, so the ABS continues to hang back and watch the event from the spectator's booth. No problem so far."
Weren't you saying something earlier about when Edmunds swapped on the 19" wheel and tire combo, and the car stopped shorter? Which value (rather, envelope) does the engineer calibrate to then? The stickier 19" tire or the 18"? Optimizing for one results in sub-optimal effects for the other, because as you've stated, the vehicle doesn't know what tire is on the car.
But, I thought it was all about the tires?
Your minimum stopping distance is.
That's not at all what the bit you quote is discussing though.
Why wouldn't they come up?
I mean- I literally tell you that in the paragraph you're quoting.
There's that not actually reading what you're replying to thing again!
Both matter?! But, I thought it was only the tires as you've so fervently and verbosely explained
I mean- if you're gonna keep both not reading most of what's actually posted, then lie about what you imagine it said- I guess it's your time to waste
With the exception that rotors can't make the tires stickier (just like tires can't make the rotors bigger), 100% incorrect.
Rotors make your tires stickier?
Are you high?
They won't change the tire, but they will change how you use that tire under braking. Why, because tire friction isn't static? This is the part that you seem to have trouble understanding and way out of your element on. Something that a few Internet articles can't explain. Your formula that you like to use, uses an average tire u under the deceleration event for the entire vehicle - kinematic equations from high school physics. When you direct your attention to the tire itself, the resultant force that the tire produces back on the suspension assembly (as a result of the brakes operating) is the combination of the normal force on that tire (which changes from static with weight transfer and road irregularities) and the available u (which also changes with normal force and the slip ratio of that tire). Do you know what slip ratio is? You seem to know it all, so please educate us on how maximize longitudinal tire friction using slip ratio data and load sensitivity of the tire.
If this was all figured out, then why would researchers continue to work on ABS control dynamics to improve control and potentially stopping distances? Like these:
Anti-Lock Braking System Using Predictive Control and On-Line Tire/Road Characteristics Estimation - ScienceDirect
So from that link-
Your source said:the longitudinal deceleration is considered to be directly and exclusively linked with the tire/road friction force. Furthermore, the brake level is often supposed to be equally distributed on the wheels. For other applications, as aircraft braking, these hypotheses are not appropriate
In other words they're saying the existing system is fine for cars- but they think there's a better brake-control methods for aircraft (for reasons gone into in further detail in the rest of the paper- eventually ending with landing simulations done on a Airbus A340.
Academically interesting- but not super relevant.
Title is certainly interesting- though full doc hidden behind a paywall.
I did find one graph apparently from that study (though again full thing requires login)- it shows no divergence in stopping distance for the first 1/3rd of the braking event, and by the end of it a difference of a few tenths of a meter
Well stop the presses on that one!
More relevantly though- maybe you forgot... the thread is about the P3D+ vs P3D-?
Where the different in braking systems is things like the rotors and pads and calipers.
And it says nothing whatsoever in that source about changing rotors or pads or calipers to reduce braking distance.
It doesn't suggest, at all that changing to bigger/better brake parts can reduce stopping distance.
it seems to suggest that more optimized ABS control can get better use of the tires max available friction against the road.
Because, after all, that's what stops the car
Same deal
YOUR source said:the actual friction force between tyre and road will oscillate around a ”maximum” point
They are trying to improve the ABS system to again keep things as near that maximum point as much as possible.
NOTHING in there suggests bigger rotors, or different pads, or bigger calipers, or stainless lines, or anything of the sort, will help you stop any shorter.
It is, again, all about the tire and road interface
You know- the thing that stops the car
...did you not read your own source again?
Because guess what that ones actually about?
YOUR source said:The key idea of the system proposed in this paper is that a significant improving in service life can be achieved, especially during transient operations, by a small reduction in the dynamic performance of the system
He's suggesting he found a way to make ABS performance WORSE- but the parts will last a lot longer!
So also incredibly not relevant- but kinda funny!
So... 4 sources.
0 of which support the idea that the P3D+ brakes would stop you any shorter than the P3D- brakes on the same tires and same external conditions (road surface in particular).
Several of which reinforce it's the tire/road interface that actually matters and actually stops the car though... like you keep being told and keep getting confused about.
You're 0 for HOW MANY now?
DING DING DING! By golly, I think we're starting to understand.
Are we? Because that's literally what I've been explaining to you since the very beginning- and you keep trying to disagree with.
I mean- if you're finally admitting I was right in the first place, kudos... but I rate that as unlikely
Sure, to the untrained person, they're likely to not gain anything from brake upgrades for cold stopping distances
Also to trained ones.
Since you've been quoted by major brake OEMs, professional braking system designers, and folks like Car and Driver all confirming the same thing.
The car won't stop any shorter in a normal panic stop by upgrading any of those things on a properly working factory system.
But, to someone who knows what they're doing, they could probably find some items in the braking system (and suspension) to better optimize the tires that came on the vehicle for even cold max decel events.
And yet you continue to present 0 evidence or sources for this claim- a claim directly contradicted by a slew of sources given to you.
And the sources you DID provide all ignore the idea of upgrading any of those parts and instead focus on tuning ABS to better maximize the TIRE TO ROAD FRICTION.
Ya know- the thing that actually stops the car
. But, more time on here = less time in other threads )
I admire the consistency with which you manage to be wrong about everything