Braking technique & ABS
warmpepsi is correct.
Theres a real simple way to show how effective threshold braking is. Go on a snow road in any car with ABS (evo would be great) and go about 30 then slam on the brakes going max into abs and notice how long it take you to stop.
Then go 30 again try braking right at the point before the abs kicks in (maybe go into the abs braking a bit and let off just a bit until you stop feeling the pulsing.
you'll beat the abs by a huge margin every time.
The point is that whether you're going 30 on a snowy road or 100 on asphalt, the concept is the same. The abs computer is generic. If it detects the wheels are locking up, it generically pulses the brakes until the wheels are not locking up. Your human brain and senses can outperform the computer any day all day.
Theres a real simple way to show how effective threshold braking is. Go on a snow road in any car with ABS (evo would be great) and go about 30 then slam on the brakes going max into abs and notice how long it take you to stop.
Then go 30 again try braking right at the point before the abs kicks in (maybe go into the abs braking a bit and let off just a bit until you stop feeling the pulsing.
you'll beat the abs by a huge margin every time.
The point is that whether you're going 30 on a snowy road or 100 on asphalt, the concept is the same. The abs computer is generic. If it detects the wheels are locking up, it generically pulses the brakes until the wheels are not locking up. Your human brain and senses can outperform the computer any day all day.
You also get all the nasty gunk fluid from the abs circuit getting into your clean fluid (assuming you bled the brakes before your track day, which is a good idea, but did not also flush the abs, because that is a PITA)
Going further into people talking about how abs works, if you think of the friction circle (if you haven't heard of it yet, in short, your tires can only give so much friction in an x/y chart of: acceleration, deceleration, horizontal. I'm sure you've seen a g-force thing.) Anyway, what ABS does is give up some of your deceleration axis to go towards horizontal. ABS is made to let you turn while braking for emergency situations, and because people are stupid enough to slam on their brakes when nearing an accident (so it activates so that your tires can have some traction to turn as well, so as to try and avoid the accident).
Anyway, basically the point of that story is just to further prove that if you're in ABS you aren't getting as hard of braking as you could out of it.
Anyway, basically the point of that story is just to further prove that if you're in ABS you aren't getting as hard of braking as you could out of it.
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Going further into people talking about how abs works, if you think of the friction circle (if you haven't heard of it yet, in short, your tires can only give so much friction in an x/y chart of: acceleration, deceleration, horizontal. I'm sure you've seen a g-force thing.) Anyway, what ABS does is give up some of your deceleration axis to go towards horizontal. ABS is made to let you turn while braking for emergency situations, and because people are stupid enough to slam on their brakes when nearing an accident (so it activates so that your tires can have some traction to turn as well, so as to try and avoid the accident).
Anyway, basically the point of that story is just to further prove that if you're in ABS you aren't getting as hard of braking as you could out of it.
Anyway, basically the point of that story is just to further prove that if you're in ABS you aren't getting as hard of braking as you could out of it.
I also have data from our race car that says we were able to generate about .2g's more peak braking force without ABS but that our distance used to slow an equivalent amount of speed increased due to excessive driver brake force modulation.
So yes, if you're Michael Schumacher you can probably brake better without ABS. The reality is none of us are. Even then i'd bet most F1 drivers would rather have ABS, just like most of them would rather have traction control.
So yes, if you're Michael Schumacher you can probably brake better without ABS. The reality is none of us are. Even then i'd bet most F1 drivers would rather have ABS, just like most of them would rather have traction control.
Theres times that a set of 4 locked tires will stop shorter (due to the abs pulsing, and pulsing, and pulsing), and theres times that the abs pumps right, keeps it from locking, and will stop you sooner.
As mentioned above, ABS is used as a recovery technique so that a driver can apply the brakes, but still turn the wheel to avoid an object in the road, car, etc.
I've had the abs plug near the passenger's foot come undone on track, lock up all 4 wheels and slide sideways to a stop from 120ish. Stock tires were shot and flat spotted to no end. However, braking in a straight line, I could not have stopped. It's a 35 mph right hand turn. It's close enough to call it a wash.
ABS is to keep a tire from locking, and it's much more effective than "pumping" the brakes, as you had to in previous generations of cars. The computer is much more effective than your foot, no question. However, abs is what happens when you exceed the threshold of the tire adhesion to the ground.
Bottom line: you want to brake just short of the threshold for ABS. Thats the most effective way to slow the car. You also want to brake HARD early, and lessen the pressure as you apply gas while apexing the corner.
griceiv
Quote from the study.
"To eliminate driver variability effects only one professional test driver with 17 years experience served as driver for all testing conducted for this study."
Not the way I would run a test like this but what do I know? ABS is for soccer moms not track drivers that want to get the most out of their cars.
Quote from the study.
"To eliminate driver variability effects only one professional test driver with 17 years experience served as driver for all testing conducted for this study."
Not the way I would run a test like this but what do I know? ABS is for soccer moms not track drivers that want to get the most out of their cars.
you guys crack me up. 
remember what I said about the ABS also changing the brake bias (EBD)? Everything in the evo's braking system is the same between having ABS and not having ABS, except the non ABS cars have additional proportioning valves mounted on the master cylinder to reduce the rear braking force.
http://www.stoptech.com/tech_info/wp...formance.shtml
Also the ABS system is not waiting for the wheels to "lock" and then fully releasing brake pressure. It's monitoring slip percentange and modulating brake pressure to maintain a target slip ratio.
they explain it better then i do...
http://www.stoptech.com/tech_info/wp...rakekits.shtml
But the reason you don't want to be too hard into the abs while racing is that the abs modifies the stability of the car (it makes it much more stable...aka understeer). While this is good for braking in a straight line, if you're still in abs when you attempt to turn in your senses will make you think you're still going to fast and you'll hold the brakes longer. only to find out that as soon as you let off the brakes you're going way to slow. So your lap times will be faster not using full abs into every corner because you will carry more speed into the corners.
remember what I said about the ABS also changing the brake bias (EBD)? Everything in the evo's braking system is the same between having ABS and not having ABS, except the non ABS cars have additional proportioning valves mounted on the master cylinder to reduce the rear braking force.
http://www.stoptech.com/tech_info/wp...formance.shtml
Also the ABS system is not waiting for the wheels to "lock" and then fully releasing brake pressure. It's monitoring slip percentange and modulating brake pressure to maintain a target slip ratio.
they explain it better then i do...
http://www.stoptech.com/tech_info/wp...rakekits.shtml
But the reason you don't want to be too hard into the abs while racing is that the abs modifies the stability of the car (it makes it much more stable...aka understeer). While this is good for braking in a straight line, if you're still in abs when you attempt to turn in your senses will make you think you're still going to fast and you'll hold the brakes longer. only to find out that as soon as you let off the brakes you're going way to slow. So your lap times will be faster not using full abs into every corner because you will carry more speed into the corners.
Last edited by griceiv; Aug 24, 2008 at 11:12 AM.
you guys crack me up.
remember what I said about the ABS also changing the brake bias (EBD)? Everything in the evo's braking system is the same between having ABS and not having ABS, except the non ABS cars have additional proportioning valves mounted on the master cylinder to reduce the rear braking force.
http://www.stoptech.com/tech_info/wp...formance.shtml
Also the ABS system is not waiting for the wheels to "lock" and then fully releasing brake pressure. It's monitoring slip percentange and modulating brake pressure to maintain a target slip ratio.
they explain it better then i do...
http://www.stoptech.com/tech_info/wp...rakekits.shtml
But the reason you don't want to be too hard into the abs while racing is that the abs modifies the stability of the car (it makes it much more stable...aka understeer). While this is good for braking in a straight line, if you're still in abs when you attempt to turn in your senses will make you think you're still going to fast and you'll hold the brakes longer. only to find out that as soon as you let off the brakes you're going way to slow. So your lap times will be faster not using full abs into every corner because you will carry more speed into the corners.
remember what I said about the ABS also changing the brake bias (EBD)? Everything in the evo's braking system is the same between having ABS and not having ABS, except the non ABS cars have additional proportioning valves mounted on the master cylinder to reduce the rear braking force.
http://www.stoptech.com/tech_info/wp...formance.shtml
Also the ABS system is not waiting for the wheels to "lock" and then fully releasing brake pressure. It's monitoring slip percentange and modulating brake pressure to maintain a target slip ratio.
they explain it better then i do...
http://www.stoptech.com/tech_info/wp...rakekits.shtml
But the reason you don't want to be too hard into the abs while racing is that the abs modifies the stability of the car (it makes it much more stable...aka understeer). While this is good for braking in a straight line, if you're still in abs when you attempt to turn in your senses will make you think you're still going to fast and you'll hold the brakes longer. only to find out that as soon as you let off the brakes you're going way to slow. So your lap times will be faster not using full abs into every corner because you will carry more speed into the corners.
If you're on the abs at all when braking, you need to learn how to threshold brake.
Plain and simple, if a guy kicks on his abs regularly, he needs to come in, stop the car, and think about what he's doing.
I appreciate the link to stoptech, but after 50 some odd days in an evo, and thousands of miles on track, i can confidently say I understand the braking characteristics of the Evo 8 and 9.
10? no clue.
You prefer the car to understeer?
The Evo is the first and only car I've driven on the track with ABS, but knowing what it does, none of this makes sense to me. ABS is supposed to hold the brakes at the threshold. You look at data showing the same car stopping with and without ABS(when ABS was new, they used to publish this data everywhere), the car always stops sooner with it. Given this, it would also slow you down sooner, meaning you should be able to brake later if you want to, and in a race, who wouldn't want to brake later? Someone also wrote it overheats your pads..why is that? I have stomped on the brakes in my car, and have always got it slowed down in time, and even a few times when I thought I out-braked myself. I've never locked the brakes either. I used to race a 911 with obviously no ABS, and a proportioning valve (the kind that just pinched off pressure), and would lock 'em up on that thing occasionally. Usually in the first couple laps, but it would happen. I also occasionally drove a 911 GT2 which had the full monty proportioning system, and even it would occasionally lock up a wheel or two, depending on how it was set. With the Evo being AWD, you don't see as much trail-braking as you would with a RWD car, due to you needing to power to the apex, and since the majority of the braking is done in a straight line,
the "threshold" is that much easier to hold, meaning it's easier for the ABS to work as promised. What am I missing here?
TIA
the "threshold" is that much easier to hold, meaning it's easier for the ABS to work as promised. What am I missing here?
TIA
+1000. I'm totally agreed with u. Also most people on evom are drag racer anyway
My time attack evo probably have more tracks day than most people on here. WE tested over and over evo with and without ABS. I'm telling you ABS will save us good mount of times on the road course. We can lay on the brake and not worrying about locked up.
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