Quote from axus :

Note that that curve ends at 0.8, where as mine does so at 1.0. If you continue the curve supplied by Todd you will see that the car will loose 20-25% of its braking ability with fully locked wheels which is close enough to what I said.

im not a fan of this "if im off by 33% im still close enough" but anyway the point is tyres dont lose half as much grip if they slip than what popular belief tells you

These things probably have improved over the years. I'm probably quoting stats quoted by a person quoted by another person quoting some textbook from 15 years ago... I'm pretty sure there was a time when those values were correct - they may even be true for some tyres today. Any idea from what tyres Todd's data comes from?

sry no idea ... youll have to ask him

Quote from http://www.lfsforum.net/showthread.php?p=165048#post165048 :

"On loose gravel, all nine vehicles stopped in shortest distance with a disabled-ABS panic brake application, regardless of loading condition. Stops made on gravel were lenghtened considerably when ABS was utilized."

Now, let's talk about ABS and LFS

Quote from Shotglass :

if the snow turns to ice it should have some sand on it (otherwise your road seaty department is well ... crap) for which the same rules as loose snow and gravel apply

The main routes are allways clean, "salted" and dry. And you must have winter tires in winter months. The roads I had in mind are smaller and have way more lower speedlimits and therefore lower priority, and those roads are under maintainence of the town/city/whatever and how quickly the roads are sanded is about the money. But you really need to be a pro to drive out of the road in 40km/h, but it happens. We have sand on the roads, but it doesn't mean it would make the tires grip like hell if you put it on clear and smooth ice, nothing helps there if you go too fast :P And oh boy its fun when there is ice under loose fresh snow

Quote from Becky Rose :

Oh believe it we do, just thankfully it's quite rare so only on a few days of the year.

Except for the Scottish who get loads of it, but then the rain next day just washes it away ...

Where do you live, I've never seen proper snow in the UK, what we call 'blizzards' are a joke really and as Blackout said most roads are gritted.

We do a good line in black ice. Here around oxford we get some of the coldest temps in the country but it's also one of the dryest areas (If you can believe that at the moment) So during the winter we can get snap freezes that put a lovely sheen of ice over the roads. Great thing black ice, you don't know your on it untill you try and turn a corner or stop. When you don't do either you know your on Black ice.

On topic with a point made earlier about stopping on gravel, would it be the same as stopping on snow?

I.e.the gravel builds up a wall in front of the tyre if you lock up, so the tyres dig in, whilst abs would allow you to ride over the top of the gravel? Just a thought.

Still not convinced that locking up your wheels on a race track is in any way beneficial.

The coefficient of static friction is greater than the coefficient of kinetic friction, which is why locked tyres will take longer to stop than tyres _just_ on the verge of locking. For a simple diagram, see here: http://230nsc1.phy-astr.gsu.edu/hbase/imgmec/fsta.gif

ABS was invented to stop wheels from locking by sensing when a wheel slows past a PRE-SET point, this point may or may not be the perfect point to get the best braking power. But that's not the reasoning behind ABS; ABS was invented so drivers could steer while braking. Imagine Rappa Z runs out in front of your car, if you slam on the brakes in a non-ABS car you will lock the wheels, which will stop you from being able to steer, you will kill Rappa Z. In an ABS car the wheels will not lock, and you will still have the ability to steer the car around Rappa Z. I'd hazard a guess and say that the reason ABS can't stop as fast as the World's Best Driver (that's IF ABS is slower, there is evidence for both sides), it is because ABS is designed with steering in mind, and allows for any extra force sharp steering motions might add.

Edit: made it more interesting for Funnybear

Havn't we done the Moose example already?

Imagination people. We want old ladies, Athletic trees, drunk hunting on a saterday night. . . . or is that just me.

As a side note: a very funny bear we have here, and a total lunatic

It's too hot to think here now, so I can't bring anything to this discussion at the moment

*sigh* I try.

It's got cold here again. I think summer is over. Good old british weather. The only country where global warming will take one look and consider it a wasted effort.

Quote from george_tsiros :

If you brake using ABS, then you are limited by the ABS.

If you brake without ABS, you are limited only by your skills.

if you jump out of an aeroplane with a parachute, you are limited by the parachute.

If you jump out of an aeroplane without a parachute, you are limited only by your skills.

Quote from jtr99 :

Ah, Shannon, I would love to hear the other guy's side of this particular story, mate.

Sorry can't find the guy now he must've moved house? basically I was driving at least 4 car lengths behind him/her at normal road speeds in wet conditions.

As soon as lights went orange (they were 3 or 4 car lengths before lights, he slams on brakes ( when most ppl would just go through and not worried, giving the guy behind time to stop etc) and pulls up with front half of car over control line. Leaving me not a lot of room to dodge him.

It was single lane road wet dark and 2 am? Oh and maybe I should mention I was in utility with a bit of weight in it at the time

Cheers
ShannonN

Quote from Blowtus :

if you jump out of an aeroplane with a parachute, you are limited by the parachute.
If you jump out of an aeroplane without a parachute, you are limited only by your skills.

Does "bad analogy" ring any bells?

Quote from ShannonN :

As soon as lights went orange (they were 3 or 4 car lengths before lights, he slams on brakes ( when most ppl would just go through and not worried, giving the guy behind time to stop etc) and pulls up with front half of car over control line. Leaving me not a lot of room to dodge him.

Which is why I believe Red Light Cameras and Speed Cameras are so wrong I can’t count how many times I've seen people slam on their brakes even when they aren't doing anything wrong.
He probably couldn't remember if there was a camera box on that intersection or not and decided not to risk it so lets just slam on the brakes - anything to avoid that pesky fine.

Why do I have this opinion? Well because I think speed cameras aren't an effective deterrent against speed related offences:
1. those that speed regularly know where they are mostly and are looking for them all the time and therefore are distracted from other potential accident causing situations around them. They also normally speed until they see one then slow down then after they have passed it speed up again straight away, so it obviously doesn't act as a deterrent for repeat offenders.
2. there too convenient, as in the fine comes in the mail and there is no confrontation with a burley officer on the side of the highway (much more effective I think).
3. people that don’t really speed can be over cautious about speeding and do erratic things (which can lead to accidents) when they see a camera because of the constant publicity about speeding.

I believe that while speed maybe a factor in a lot of accidents, a greater factor is wreck less driving, low skill in emergency situations and inconsiderate drivers who think they own the roads and therefore take unnecessary risks.
I think speed cameras are just the easy way out (i.e. low cost, low maintenance and high revenue generating) It would be far better if going for a car licence was much tougher and required advance driver training and education, also I feel a greater police presence on the streets is more effective than cameras, I'm not saying they shouldn't use cameras but they shouldn't be a replacement for a real police presence on the roads either...

Quote from george_tsiros :

Does "bad analogy" ring any bells?

I thought it made it's point well enough
Being 'limited' by something that does a better job than you, is not really a problem...

Quote from Glenn67 :

Speed Cameras are so wrong I cant count how many times I've seen people slam on their brakes

Apparantley biker deaths have increased on (very quiet) roads in Scotland where speed cameras have been installed because they're coming off trying to slow for them illepall

Speed cameras are wrong because people slam the brakes?

Hm.

I say stop/yield signs are wrong as well, because i've seen people brake too hard when they approach an intersection.

The roads would be great if it wasn't for the other people. I think youshould have one designated driver per country. I claim Britain.

Where did i read that the dude who designed how road-going would be regulated, didn't even know how to drive?

Doesn't seem so...

Quote from Funnybear :

The roads would be great if it wasn't for the other people. I think youshould have one designated driver per country. I claim Britain.

Can you drive me to work today?

Yep. But can you wait until I've taken the other 4,684,006 people before you on the list.

I think I need a bigger car.

Back ON topic, here is are a chart I found on Todd Wasson's site:

Quote from wheel4hummer :

Back ON topic, here is are a chart I found on Todd Wasson's site:

Posted above by Shotglass.

But wasn't the original topic about braking with locked wheels to escape danger/evade accident? Not about slip ratios...