60-0 braking distances

[Meza]

What's the best way to do a decent (ie shortest possible) stop from 60mph? I'm in a VVC coupe btw. With ABS is it just a case of stomping on the pedal as hard as possible and letting it do the hard work?

[Tatts]

Originally Posted by Meza

I'm in a VVC coupe btw. With ABS is it just a case of stomping on the pedal as hard as possible and letting it do the hard work?

Yep! Sure is!

[Si]

not imo, to me the abs in a mgr comes on too early, i find i can stop faster if you hit the brakes hard but try to keep from the abs interfeering.

not a doubt in my mind that abs will stop quicker in the event of a skid but if you can avoid it then do


simon

[Rob]

Originally Posted by Meza

What's the best way to do a decent (ie shortest possible) stop from 60mph? I'm in a VVC coupe btw. With ABS is it just a case of stomping on the pedal as hard as possible and letting it do the hard work?

Drive into a large tree?

Seriously though, if abs cuts in the wheels have already locked. If my gcse physics serves me correctly, would it not be better to brake to the point just before abs cuts in, so the wheels don't skid at all?

Of course being able to judge this exact point in reality would be virtually impossible, so in real situations relying on abs might be the best bet.

[Si]

in a acctual emergency most ppl just stand on the brakes anyhow

but in testing perposes like i said it's best not to use the abs

[Gra]

I always thought it was best to control your stopping speed by hammering the brake pedal as hard as possible until your ABS kicked in and then releasing the pedal slightly and then hammering them again.....but I swear there was something on 5th Gear or one of those type of motoring programs that tested the theory and came up with the conclusion that stomping the brake pedal and locking up the wheels (as best you can with ABS) stopped you a reasonable amount quicker than trying to control it because of the extra friction with the road surface? It obviously helps if you're trying to stop in a straight line though...and I'm sure a dry road would be an advantage as well...

[Meza]

I think ABS is designed to get the best possible braking (in average dry conditions) and should reduce the brake force *just* before the wheels stop turning, and then keep modulating it to keep the wheels just on the edge of max grip without actually starting skidding.

But I suppose in the real world, spongy brake fluid, sticky calipers, old ABS pump could naff it all up so you get a bit of skid.

Tree idea - nice one No ta though!

[Gra]

Oddly enough (speaking of trees) I watched a rather flash Merc get nerfed into a tree outside our office today....fortunately he wasn't doing much more than maybe 5 or 10mph when he hit it, but it was still enough to cave a rather large chunk of the front of his car in...

[Meza]

Actually this reminds me, in a vehicle control course I did at Silverstone I got to play in an Audi with and without ABS on to experience the difference. From what I can remember without ABS the stopping distances were shorter (and a lot more fun, noisey and smellier!), BUT you stop in a straight line and have no choice in the matter!
With ABS on the stopping distances weren't as good, but you could still steer.

So that reminded me - ABS is NOT to stop you quickly, but to keep control of the car.

So I'm going to answer my own question here, to get the best 60-0 stopping distances pull the ABS fuse out.

[Perspective]

ABS is the safest and best form of braking most of the time and for the vast majority of drivers and is why it is fitted to so many cars today. By 'managing' the breaking and still providing you with the ability to steer during braking it is a good and safe system. To get the best from an ABS system simply hit the brake pedal as hard as you can and let it sort it out from there. On and off (cadence) braking should not really be used with an ABS system as the whole point of ABS is to automate the provision of cadence braking.

However, in the dry and sometimes in the wet a good driver without ABS should be able to better the stopping distance of an ABS equiped car more often than not by using cadence braking techniques, a human version of ABS if you like. This requires skill and feel but can be very effective and is something I have used in the past, most memorably when trying to stop my non ABS equiped Cavalier in the 80's ramming into the back of a bus on a road which was covered with Diesel (just!). Its all about releasing the braking for a split second just as you feel the wheels lock and then reaplying them again as soon as the wheels start to turn. If used well you should still be able to steer too, but it does require a good feel for you car and also good reactions.

Like heel and toeing there are different forms of cadence braking. I tend to prefer to brake hard initially then balance it with a softer brake application near the lock point, others just stamp on and off the brake pedal quickly, which I feel is a little rock ape, though no less effective. I did my advanced drivers test at 19 and found it very useful but I also did a number of fast road driving courses, which were even better and bsed on many of the Police best practices and other courses. They allow you to focus on these skills and get so much more from you car in a very safe and controlled manner.

The thing I like to do most of all, and something which can be used to demonstrate balance and feel for a car is brake hard (though safely and only on a quiet, empty road) so the passenger feels the brakes come on but as you slow gently release the brake pressure until you stop, but without the jerk or rocking you usually associate with such braking. The passenger does not jerk back into their seat if, they simply glide back in as one smooth motion so as you come to a stop they don't feel it. If done well your foot should be virtually off the brake as the car stops, one fluid movement from application to stopping, lessoning the brake pressure as the car slows to a stop. Very satisfying and something used by good drivers all over the world, and I am sure many on this site too.

[sadtosee]

It's also worth noting that ABS systems have improved a lot over the years. The latest systems seem to react a lot faster and probably out perform even the most skilled professional driver.

There is also a difference on cars equipped with EBD (Electronic Breakforce Distribution). On an EBD equipped car find a quiet bit of road (or ideally a closed track) with a grass verge even with the road. Drive with one set of wheels on the grass and another on the tarmac upto about 30mph. Then slam the brakes on - on a car equipped with a good ABS/EBD system the car should stop perfectly in a straight line. Look back at the grass and you should not see any significant marks on the grass because all the braking will have been done by the wheels on the tarmac.

[ZR120]

People Always get confused with ABS, they think that as the B stands for braking, it must be all about braking and stopping. But ABS was not introduced for this, and will never make the car stop any faster, you will always be able to match it in a car not fitted with ABS. ABS is solely to increase control during brakin, any other car would lock the front wheels up under brakin, then you would lose your stearing, but in a ABS car, the wheels are able to turn (not locked up) so you are able to steer clear of the danger.

EBD is a program to help make sure that all wheels contribute evenly to the brakin to help the car stop evenly

[cosb6]

60-0 times are very much related to Vehicle weight...

If you fit 10 cars with the same sized tyres, and all cars have decent brakes (ie good enough to lock the wheels at 60mph if desired)... then all the cars will stop in the order of the lightest first..... you may get slight variations of course if different suspension matters....

If you add ABS into the equation, the best ABS System will probably stop quicker than similar weighted cars... but the heaviest will take longer to stop....

If the brakes are capable of locking the wheels, they are therefore taking out the maximum amount of energy they can. The rest is taken out between tyres and the road, and this is a pretty fixed rate to....

So the more momentum, the longer it takes to stop!

[Perspective]

Originally Posted by cosb6

60-0 times are very much related to Vehicle weight...

SNIP

So the more momentum, the longer it takes to stop!

Ah yes, but what if you have a 500 kilo anchor in the boot that your able to throw out and hook into the tarmac eh, not so cleva now is ya

Always thinking.....ish......

[MGJohn]

I believe it's been compulsory for new cars to be fitted with ABS (Advanced Braking System) for a few years now. I don't think I've ever noticed the ABS on my MG ZS. It's there though, just never noticed it. Those ZS brakes are really just how I like them to be on a car. I like them.

Driving my Vitesse turbo fairly fast over a rough, uneven and slightly damp grassy field track then hitting the brakes hard provided me with the best demonstration of how an ABS can work ever. That Vitesse's brake pedal went up and down like a manic Yo-Yo.

However, in an extreme stamp test over a rough grassy track, that pedal went mental under my right foot at speed but the car still pulled up in a dead straight line. Remarkable! I tried the same on a non-ABS fitted car and it was like doing a handbrake turn......

For the vast majority of drivers, ABS is a very good thing.

[Meza]

It's anti-lock not advanced I think.

[Northerner]

ABS on ice though can be a bit of a nightmare!

[DunRovin]

Originally Posted by Northerner

ABS on ice though can be a bit of a nightmare!

Driving on ice can be a bit of a nightmare.

There is more to the stopping effect of ABS than just the ability to steer. For a start it takes the tyre out of skid and back to grip - which is why you can steer but also more puchase on the surface. It moves the tyre round from the hot melting contacting area to a fresh cooler area. In aquaplane it allows some of the buildup of static water under the wheels to be dispersed with the rotation of the tyre, there are other effects too.

In some circumstances some very expert or flukey humans might be able to do better sometimes, but the machines will usually be the best.