Threshold Braking vs ABS

[HiTempguy1]

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threshold braking in urban environments is inferior to the letting the ABS handle things if you need to step in an emergency.

The trouble with threshold braking in these situations is that a typical urban street has too much variability in traction levels across small distances. You might have a few feet of ice, a few feet of snow, then a few feet of pavement, etc. You can't adjust your threshold quickly enough to adapt to taking advantage of a foot of clear pavement or tacky snow. Modern computers have that advantage because they will brake harder when they can detect an increase in traction.

Just... just so wrong.

[Darell_n]

Threshold braking is just taking a modern 3 or 4 channel braking system and downgrading it to 1. Works fine if all four tires have similar traction, won’t do squat on bad winter roads. How does one apply the brakes without ABS interference when 1 tire is one glare ice? The stopping distance would be 3000ft.

[Mitsu3000gt]

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Threshold braking is just taking a modern 3 or 4 channel braking system and downgrading it to 1. Works fine if all four tires have similar traction, won’t do squat on bad winter roads. How does one apply the brakes without ABS interference when 1 tire is one glare ice? The stopping distance would be 3000ft.

What I notice is that at very low speeds or with extremely light breaking application, I can prevent the ABS from kicking in no matter what the conditions (even pure ice). In every car I've driven it seems the system needs a certain amount of pressure on the pedal for ABS to engage. Especially at low speeds, the car stops harder when I can prevent ABS from engaging, regardless of the road conditions. If it's sheer polished ice though, you're probably SOL no matter what method you prefer haha.

[Buster]

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Just... just so wrong.

nope.

[tonytiger55]

My understanding of ABS (feel free to correct me if I am wrong) is your meant to press the brake as as hard as you can and let the computer work it out. It can calculate a lot better and faster and some can do that with all four wheels independently.. something my big hairy foot can't.

The issue I have with the video posted regarding' threshold breaking vs ABS' is a typical road is not like that. Also Is the driver in the video typical driver? No offence Ie is he/she Asian/Indian/white soccer mom..?

When you suddenly have to react to another driver/road condtions suddenly, its instinctive to press the brakes without calculating what to do after. The only people I can think of who can brake and calculate super fast consistently are race car drivers.

Buster and Darell are pretty much spot on. How does the average driver calculate and react to changing road conditions several times a second? Especially when each of your wheels may be hitting a different patch of snow, ice, black ice etc You can't..

[Buster]

^ some guys think they are Schumi

[Sugarphreak]

...

[RealJimmyJames]

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Threshold braking is just taking a modern 3 or 4 channel braking system and downgrading it to 1. Works fine if all four tires have similar traction, won’t do squat on bad winter roads. How does one apply the brakes without ABS interference when 1 tire is one glare ice? The stopping distance would be 3000ft.

this is exactly how I picture it. Can anyone explain whats incorrect about this?

[r3ccOs]

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My understanding of ABS (feel free to correct me if I am wrong) is your meant to press the brake as as hard as you can and let the computer work it out. It can calculate a lot better and faster and some can do that with all four wheels independently.. something my big hairy foot can't.

The issue I have with the video posted regarding' threshold breaking vs ABS' is a typical road is not like that. Also Is the driver in the video typical driver? No offence Ie is he/she Asian/Indian/white soccer mom..?

When you suddenly have to react to another driver/road condtions suddenly, its instinctive to press the brakes without calculating what to do after. The only people I can think of who can brake and calculate super fast consistently are race car drivers.

Buster and Darell are pretty much spot on. How does the average driver calculate and react to changing road conditions several times a second? Especially when each of your wheels may be hitting a different patch of snow, ice, black ice etc You can't..

I'm pretty sure that today EBD/DSTC just like ABS/TC is all based on those sensors, and ABS being the most simple of them all just detects when a wheel locks and inparts a control to modulate the locking under those braking conditions.

The reason why ABS will kick in, even with light braking pressure is because one of your wheels have "locked"... which is not uncommon under any close to 0 traction conditions.

I think the only thing that I'm aware of that provides any level of "intelligence" outside of pedestrian detection, is an active braking system when you suddenly apply brakes outside of a normal driving condition, say evasive driving, it will providing maximum braking while also downshifting the transmission... but I don't believe this changes any parameters of when to use ABS

I really don't think those BOSCH abs systems change the parameter of ABS engagement... you lock a wheel, the control executes.

[rage2]

Pretty sure all vehicles today are 4 channel, so yes, it's ABS'ing each wheel independently of each other. If you're threshold braking, to get optimal stopping distances, you would need to threshold brake to the point where only 3 wheels have ABS engaged and at the threshold of adhesion on the single wheel with the most grip. That's impossible for a driver to know especially in varying conditions. In similar conditions such as say a snow track on Ghost Dam, you can probably figure out the pressure where ABS is triggering and find the sweet spot.

Google says trucks have 3 channel (2 for each front wheel, 1 for both rear wheels) but those are all articles and forum posts from over 10 years ago, so I'm assuming even trucks have moved to 4 channel ABS.

When I'm in emergency braking situations, I threshold brake by habit, hammer on brakes and ease back till ABS pulsates less. I dunno if that's actually better or not because there certainly are small gaps during the entire braking event where ABS isn't kicking in for any wheel because of varying traction limits, but it's impossible to change habit. I certainly can't adjust braking pressure 30 times a second, especially at my age.

[Seth1968]

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Weird. I always assumed that's how everyone did it too. I didn't even know it had a name until I looked it up just now.

I assumed the same, and also had to google threshold breaking.

Like momma said, assume nothing.

[r3ccOs]

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Pretty sure all vehicles today are 4 channel, so yes, it's ABS'ing each wheel independently of each other. If you're threshold braking, to get optimal stopping distances, you would need to threshold brake to the point where only 3 wheels have ABS engaged and at the threshold of adhesion on the single wheel with the most grip. That's impossible for a driver to know especially in varying conditions. In similar conditions such as say a snow track on Ghost Dam, you can probably figure out the pressure where ABS is triggering and find the sweet spot.

Google says trucks have 3 channel (2 for each front wheel, 1 for both rear wheels) but those are all articles and forum posts from over 10 years ago, so I'm assuming even trucks have moved to 4 channel ABS.

When I'm in emergency braking situations, I threshold brake by habit, hammer on brakes and ease back till ABS pulsates less. I dunno if that's actually better or not because there certainly are small gaps during the entire braking event where ABS isn't kicking in for any wheel because of varying traction limits, but it's impossible to change habit. I certainly can't adjust braking pressure 30 times a second, especially at my age.

with electronic brake force distribution, this would have to be the case no? I thought it was years ago where they went away from wheel speed sensors for the 3rd channel.

Also, if ABS wasn't beneficial... why would it have been so controversial in F1 all these years?

[rage2]

With EBD, if you crank on the brakes, it's still going to ABS pulsate every wheel, at least that's my understanding. With threshold braking, it would do the job. That's why I have no idea if I'm braking any better using threshold vs ABS. Worth a test one day.

As for F1, ABS was banned with traction control more because F1 engineers could most likely hide traction control type behaviors using ABS, not because ABS was so effective. Although I'm sure F1 guys can engineer a perfect ABS system that maximizes traction for each corner.

[tonytiger55]

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With EBD, if you crank on the brakes, it's still going to ABS pulsate every wheel, at least that's my understanding.

As for F1, ABS was banned with traction control more because F1 engineers could most likely hide traction control type behaviors using ABS, not because ABS was so effective. Although I'm sure F1 guys can engineer a perfect ABS system that maximizes traction for each corner.

Didn't Mclaren have a system that was banned? It allowed the outside wheels to spin faster during turning/braking back in the 90's?

[rage2]

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Didn't Mclaren have a system that was banned? It allowed the outside wheels to spin faster during turning/braking back in the 90's?

Yea, the 3rd pedal.

[JustinL]

A big advantage on track is not wrecking tires.

[lint]

Just saw that this was posted already in post #7. Not sure why this debate is going on 3 pages, but carry on beyond.

https://jalopnik.com/how-to-stop-on-...kes-1790269905

[ercchry]

BRAKING

...fuck

Now I feel better

[J-hop]

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BRAKING

...fuck

Now I feel better

I seen them breaking and figured there gunna crash. Irregardless of if they use abs or threshold breaking

[RealJimmyJames]

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Just saw that this was posted already in post #7. Not sure why this debate is going on 3 pages, but carry on beyond.

This video is a good example of road conditions that would be extremely rare inside the city limits. Could achieve the same results in dry pavement too. Doesn't really matter.
Put that same rally instructor on variable sloppy partially icy roads and let's see him threshold brake shorter.