| Jimmy S. | 12-30-2001 04:07 PM |
How do you take turns? Couple of questions....
1. Do you brake into the turn then accerlate out?
2. Is it true the AWD only kicks in when accelerating?
3. Do you brake the entire turn?
4. Does it depend on the turn?
5. Do you accelerate the entire turn?
What i do is downshift to slow down before the turn and if needs be tap the brake once or twice then accerlate hard out and shift out of it....i was wondering if this is the correct way because even with the AWD (i know its not a superpower but thought it would help just a bit more;)) i have gotten a bit squirrly. I still have the stock tires on and that might be it but i do a lot of canyon runs and would like to know if there is a better way then how im doing it. thanks!!!!!!
--Jimmy
2. Is it true the AWD only kicks in when accelerating?
3. Do you brake the entire turn?
4. Does it depend on the turn?
5. Do you accelerate the entire turn?
What i do is downshift to slow down before the turn and if needs be tap the brake once or twice then accerlate hard out and shift out of it....i was wondering if this is the correct way because even with the AWD (i know its not a superpower but thought it would help just a bit more;)) i have gotten a bit squirrly. I still have the stock tires on and that might be it but i do a lot of canyon runs and would like to know if there is a better way then how im doing it. thanks!!!!!!
--Jimmy
| Fitz | 12-30-2001 05:47 PM |
First off, get rid of those stock tires. Both you and your car are being limited by them. Secondly, there are a couple of sites you can check out. [url]www.turnfast.com[/url] is just one of them that comes to mind off the top of my head. [url]www.corner-carvers.com[/url] is a good one too. There are so many people on here that could give you abetter answer than I, Patrick Olsen, wac, Pilot, and RyanC come to mind for experienced pavement bunnies. Speaking of which, are you talking pavement, dirt, snow?? Let's go with pavement for now, because I'm pretty terrible at the rest; realistically speaking I'm not all that great on pavement either. But I digress...
Try do do all your braking prior to entering the corner. Trail brake/throttle brake ONLY if you have an idea what the end result is going to be and if you feel you need to shift the position of the car mid corner. Keep a constant pressure on the gas pedal so that you don't upset the suspension. Power out of the corner. Like I said, the other people as well as those sites can explain it better.
Fitz
Try do do all your braking prior to entering the corner. Trail brake/throttle brake ONLY if you have an idea what the end result is going to be and if you feel you need to shift the position of the car mid corner. Keep a constant pressure on the gas pedal so that you don't upset the suspension. Power out of the corner. Like I said, the other people as well as those sites can explain it better.
Fitz
| bbbradley | 12-30-2001 05:55 PM |
Take a driving school!!!!!!!!!!!! Don't wreck your car, or kill someone trying to learn this on public roads! There are tons of car clubs that offer driving schools.
/bill
/bill
| Jimmy S. | 12-30-2001 05:55 PM |
ya im talking about pavement....no snow or gravel etc.....
so keep constant pressure on the gas? what if the car feels like its gonna slide or your gonna lose the backend? i always feel like its gonna go out on me for some reason....
thanks again!
--Jimmy
so keep constant pressure on the gas? what if the car feels like its gonna slide or your gonna lose the backend? i always feel like its gonna go out on me for some reason....
thanks again!
--Jimmy
| SubEd | 12-30-2001 06:21 PM |
Follow bbbradley's advice....
Ed
Ed
| Subie Gal | 12-30-2001 06:24 PM |
[url]www.drivingtechniques.co.uk[/url]
and there are some good books out there to read & learn from as well.. it's difficult to explain, takes time to learn.
beefing up the suspension, sway bar, struts, etc.
will totally help... but i agree first and foremost...
get better rubber.....
your tires are your CONTACT with the surface you're driving on
why not make them BETTER, grippier, w/fantastic feedback?
i'm babbling....
take your time... learn little by little
and please do not do this in public places
there are schools, classes, etc. for this kind of thing.
visit [url]www.scca.org[/url] to find an organization near you.
have fun & be safe
Jamie
[url]www.subiegal.com[/url]
and there are some good books out there to read & learn from as well.. it's difficult to explain, takes time to learn.
beefing up the suspension, sway bar, struts, etc.
will totally help... but i agree first and foremost...
get better rubber.....
your tires are your CONTACT with the surface you're driving on
why not make them BETTER, grippier, w/fantastic feedback?
i'm babbling....
take your time... learn little by little
and please do not do this in public places
there are schools, classes, etc. for this kind of thing.
visit [url]www.scca.org[/url] to find an organization near you.
have fun & be safe
Jamie
[url]www.subiegal.com[/url]
| subyguy2 | 12-30-2001 10:10 PM |
Yes, all wheel drive is only in operation when power is aplied. If there is no throttle, how can power be transfered if there is none to be transfered. AWD is not a computer system like stability control, it is simply the design of the drivetrain. Someone correct me if Im wrong:)
Chris
Chris
| Patrick Olsen | 12-30-2001 11:18 PM |
Re: How do you take turns? Couple of questions....
[QUOTE][i]Originally posted by SolidForce [/i]
[B]1. Do you brake into the turn then accerlate out?
2. Is it true the AWD only kicks in when accelerating?
3. Do you brake the entire turn?
4. Does it depend on the turn?
5. Do you accelerate the entire turn?[/B][/QUOTE]
1. Yes
2. It doesn't matter
3. No
4. Yes
5. See #4
[QUOTE][i]Originally posted by SolidForce [/i]
[B]What i do is downshift to slow down before the turn[/B][/QUOTE]
There's your first mistake - you should never downshift [i]in order to[/i] slow down, you should downshift [i]while[/i] you slow down. (That's done via heel and toe work, which is a whole other subject). The car has brakes for a reason. Use your brakes to slow the car down, not the transmission.
As Fitz already pointed out, generally all your braking should be done in a straight line, and your braking should finish right before you turn into the corner. When I'm at an open track event with my car on a road course, that's how I enter a turn - I have the car very close to the limit and so braking in a straight line is very important. What happens if you brake while turning when you're driving at the limit? [url]http://www.submariner.org/thepno95/Video%20clips/LRP%20August%202000/thecrash.mpg[/url] - that's a bad thing. Ask me how I know.
Now, when I'm on the street, I'm not driving at the limit, so I sometimes fudge the "only brake in a straight line" rule. But I only use the brakes lightly if I'm driving fast thru a corner. Even on the street, where I leave a much larger margin of safety, I realize (and you need to realize) that if I were to jam on my brakes mid corner the car is going to at the very least become unstable, and could swap ends.
So, the short answer is brake leading into the corner, ease out of the brakes right as you turn in, then use the throttle to set the car as you go through the corner. At some point during the turn (it varies from situation to situation) you should be able to go to WOT to power out of the corner. If you entered the turn properly, you should not have to brake during the turn, nor should you be coasting through the turn.
I'm not much of one for reading about this kind of stuff, so I haven't checked out the links posted by the others. Hopefully those sites address understeer, oversteer, and the physics governing weight transfer in a corner and how it affects your car's grip. You [i]really[/i] need to understand those concepts or eventually you'll crack up your car during one of those canyon runs. If you have a chance, I [b]strongly[/b] encourage you to get to a high performance driving school of some sort. IMHO the best way to learn these concepts is on the track in a controlled environment (as those who posted before me said). I would suggest some organizations to look into in your area, but I'm not sure where "Offending people is priority one" is. :rolleyes:
Pat Olsen
'97 Legacy 2.5GT sedan
[B]1. Do you brake into the turn then accerlate out?
2. Is it true the AWD only kicks in when accelerating?
3. Do you brake the entire turn?
4. Does it depend on the turn?
5. Do you accelerate the entire turn?[/B][/QUOTE]
1. Yes
2. It doesn't matter
3. No
4. Yes
5. See #4
[QUOTE][i]Originally posted by SolidForce [/i]
[B]What i do is downshift to slow down before the turn[/B][/QUOTE]
There's your first mistake - you should never downshift [i]in order to[/i] slow down, you should downshift [i]while[/i] you slow down. (That's done via heel and toe work, which is a whole other subject). The car has brakes for a reason. Use your brakes to slow the car down, not the transmission.
As Fitz already pointed out, generally all your braking should be done in a straight line, and your braking should finish right before you turn into the corner. When I'm at an open track event with my car on a road course, that's how I enter a turn - I have the car very close to the limit and so braking in a straight line is very important. What happens if you brake while turning when you're driving at the limit? [url]http://www.submariner.org/thepno95/Video%20clips/LRP%20August%202000/thecrash.mpg[/url] - that's a bad thing. Ask me how I know.
Now, when I'm on the street, I'm not driving at the limit, so I sometimes fudge the "only brake in a straight line" rule. But I only use the brakes lightly if I'm driving fast thru a corner. Even on the street, where I leave a much larger margin of safety, I realize (and you need to realize) that if I were to jam on my brakes mid corner the car is going to at the very least become unstable, and could swap ends.
So, the short answer is brake leading into the corner, ease out of the brakes right as you turn in, then use the throttle to set the car as you go through the corner. At some point during the turn (it varies from situation to situation) you should be able to go to WOT to power out of the corner. If you entered the turn properly, you should not have to brake during the turn, nor should you be coasting through the turn.
I'm not much of one for reading about this kind of stuff, so I haven't checked out the links posted by the others. Hopefully those sites address understeer, oversteer, and the physics governing weight transfer in a corner and how it affects your car's grip. You [i]really[/i] need to understand those concepts or eventually you'll crack up your car during one of those canyon runs. If you have a chance, I [b]strongly[/b] encourage you to get to a high performance driving school of some sort. IMHO the best way to learn these concepts is on the track in a controlled environment (as those who posted before me said). I would suggest some organizations to look into in your area, but I'm not sure where "Offending people is priority one" is. :rolleyes:
Pat Olsen
'97 Legacy 2.5GT sedan
| ANZAC_1915 | 12-31-2001 12:08 AM |
[quote]Yes, all wheel drive is only in operation when power is aplied. If there is no throttle, how can power be transfered if there is none to be transfered. AWD is not a computer system like stability control, it is simply the design of the drivetrain. Someone correct me if Im wrong [/quote]
You're wrong. AWD systems work as you decelerate, and make the car a little more stable when slowing down.
The only difference is you're transferring power from the wheels back up the drivetrain.
Glenn
You're wrong. AWD systems work as you decelerate, and make the car a little more stable when slowing down.
The only difference is you're transferring power from the wheels back up the drivetrain.
Glenn
| rsquire | 12-31-2001 02:44 AM |
very very old rule of fast driving ;)
Slow in... fast out
ie go in relatively slowly ( depends on the corner) get your line spot on and then accelerate out.
Slow in... fast out
ie go in relatively slowly ( depends on the corner) get your line spot on and then accelerate out.
| kaos200 | 12-31-2001 02:56 AM |
[QUOTE][i]Originally posted by Glenn Wallace [/i]
[B]
You're wrong. AWD systems work as you decelerate, and make the car a little more stable when slowing down.
The only difference is you're transferring power from the wheels back up the drivetrain.
Glenn [/B][/QUOTE]
What?
its called All Wheel [b]DRIVE[/b]
the system wont do squat for decelerating
what it WILL do, is have an effect when downshifting, instead of only a pair of wheels being disrupted at a time, all of them are, and as long as the car is setup correctly, (and the driver knows what he/she's doing) react controllably... (read, usually if at the limit, and downshifting (NOT GOOD) the tires will start to slide, if all four are sliding, its better than just two sliding which can cause major over/understeer depending on the drive wheels.)
how do you figure that "transferring power from the wheels back up the drivetrain" does ANYTHING to make the car more stable?
Id really like to hear your explanation of that:rolleyes:
[B]
You're wrong. AWD systems work as you decelerate, and make the car a little more stable when slowing down.
The only difference is you're transferring power from the wheels back up the drivetrain.
Glenn [/B][/QUOTE]
What?
its called All Wheel [b]DRIVE[/b]
the system wont do squat for decelerating
what it WILL do, is have an effect when downshifting, instead of only a pair of wheels being disrupted at a time, all of them are, and as long as the car is setup correctly, (and the driver knows what he/she's doing) react controllably... (read, usually if at the limit, and downshifting (NOT GOOD) the tires will start to slide, if all four are sliding, its better than just two sliding which can cause major over/understeer depending on the drive wheels.)
how do you figure that "transferring power from the wheels back up the drivetrain" does ANYTHING to make the car more stable?
Id really like to hear your explanation of that:rolleyes:
| johnfelstead | 12-31-2001 07:14 AM |
kaos200, less of the attitude would be a good start, we are all friends here (i hope).
Trying to explain this stuff on a BBS is very, very dificult so i wont even try to. :lol:
Read the driving techniques web site, it's good. I wrote some of the articles on there, the best AWD driver in the world wrote most of it.
Glenn is absolutely correct, AWD systems work in all states and all transitions. There are many diferent types of AWD system available. The system in your Skyline is an active system using variable torque depending on attitude/load and slip angle. The system in the Impreza varies depending on model.
rsquires 22B for example has an electrically variable centre VC that you can play with manually as you drive. If your are skilled you can make the car respond diferently by the second by varying the settings.
The standard UK impreza has a fixed centre diff ratio and a rear LSD with open front LSD, that will handle more neutrally but isnt as controlable at the limits when you have a skilled driver.
The Impreza 2.0i N/A has an open front and rear diff with a fixed ratio centre diff. This again responds diferently.
My rally team GroupA Escort Cosworth utilises a high N/M centre VC and a 50/50 rear/front torque split. The road going Escort Cosworth uses a 65/35 torque split and a much milder centre VC. These 2 cars handle completely diferently.
All these cars do utilise the AWD system during cornering, acceleration, deceleration and anything in between. I dont have time to explain the mechanics of this (translates to cant be bothered) but thats the reality.
Your Skyline uses computer controlled AWD that works as a RWD car until the computer system decides to start feeding torque to the front diff. You cant compare it to normal AWD non assisted systems. Even when 100% RWD the front diff still does alter the cars handling due to the momentum in the drivetrain and the front diff charicteristics.
Limit braking in an AWD car is far more eficient than a 2WD car due to the stability and torque transfer charicteristics of the AWD system. Before it was banned, F1 cars experimented with linking the front and rear wheels for improved braking. Just a few years ago Benetton utilised a system in their F1 car that had a front diferential completely independant of any power input. All it did was link the two front wheels together via torque shafts into the small diff mounted in front of the drivers feet. They did this to take advantage of the increase in braking torque you can use by linking the two front wheels together. They abandoned this after one season as the weight of the system and the increase this caused to roll centre height outweighed its advantages in that aplication.
Not a lot of people know this but when i setup a powerfull GT car using a ramp type diff, i specify diferent ramp angles inside the diff for acceleration and deceleration. There are two ramps that control how the diff works, one for under load and one for under drag. Transmition setup is incredibly important for all states of attitude a car with see.
Trying to explain this stuff on a BBS is very, very dificult so i wont even try to. :lol:
Read the driving techniques web site, it's good. I wrote some of the articles on there, the best AWD driver in the world wrote most of it.
Glenn is absolutely correct, AWD systems work in all states and all transitions. There are many diferent types of AWD system available. The system in your Skyline is an active system using variable torque depending on attitude/load and slip angle. The system in the Impreza varies depending on model.
rsquires 22B for example has an electrically variable centre VC that you can play with manually as you drive. If your are skilled you can make the car respond diferently by the second by varying the settings.
The standard UK impreza has a fixed centre diff ratio and a rear LSD with open front LSD, that will handle more neutrally but isnt as controlable at the limits when you have a skilled driver.
The Impreza 2.0i N/A has an open front and rear diff with a fixed ratio centre diff. This again responds diferently.
My rally team GroupA Escort Cosworth utilises a high N/M centre VC and a 50/50 rear/front torque split. The road going Escort Cosworth uses a 65/35 torque split and a much milder centre VC. These 2 cars handle completely diferently.
All these cars do utilise the AWD system during cornering, acceleration, deceleration and anything in between. I dont have time to explain the mechanics of this (translates to cant be bothered) but thats the reality.
Your Skyline uses computer controlled AWD that works as a RWD car until the computer system decides to start feeding torque to the front diff. You cant compare it to normal AWD non assisted systems. Even when 100% RWD the front diff still does alter the cars handling due to the momentum in the drivetrain and the front diff charicteristics.
Limit braking in an AWD car is far more eficient than a 2WD car due to the stability and torque transfer charicteristics of the AWD system. Before it was banned, F1 cars experimented with linking the front and rear wheels for improved braking. Just a few years ago Benetton utilised a system in their F1 car that had a front diferential completely independant of any power input. All it did was link the two front wheels together via torque shafts into the small diff mounted in front of the drivers feet. They did this to take advantage of the increase in braking torque you can use by linking the two front wheels together. They abandoned this after one season as the weight of the system and the increase this caused to roll centre height outweighed its advantages in that aplication.
Not a lot of people know this but when i setup a powerfull GT car using a ramp type diff, i specify diferent ramp angles inside the diff for acceleration and deceleration. There are two ramps that control how the diff works, one for under load and one for under drag. Transmition setup is incredibly important for all states of attitude a car with see.
| johnfelstead | 12-31-2001 07:42 AM |
just a quicky to add here.
[QUOTE]As Fitz already pointed out, generally all your braking should be done in a straight line, and your braking should finish right before you turn into the corner. When I'm at an open track event with my car on a road course, that's how I enter a turn - I have the car very close to the limit and so braking in a straight line is very important. [/QUOTE]
This is the biggest single mistake known to man on a race track. (no offence intended :eek: ;) ) If you drive in this way you will be pretty safe but you will never be as fast as you could be or get close to the limits of your tyres.
You should not come of the brakes before you turn in, what that does is unload the front tyres right at the point where it needs a high loading to make the best turn in. The name of the game is to keep the tyre right at it's maximum G loading. This is all explained in a diagrame called a G-G diagramme. At all times the tyre should be at 100% G, as you transition from braking into the cornering phase you need to make the tyres G load transfer smoothly from one load direction to another. Keeping the load at 100% G is what seperates the gods from the also rans. Even Senna couldnt manage this at 100% but he could keep it at high 90's ALL THE TIME!
If i can i will scan in a typical G-G plot for you tonight. Jackie stewart is a master at teaching this stuff. All transitions need to be smooth and blend together. As you get more experienced you'll change the way you take diferent types of corners, some i am braking hard into right up to the apex, others i am trail braking (thats where you are on the brakes lightly all the way through the turn), others i am on the brakes and the power at the same time using the brakes to control the front and the power to control the rear.
The only way to learn this stuff is to go and play, a good limit handling coach will be a big help. Lots of race school instructors havent a clue on this kind of thing unfortunately. People like Don Palmer and Simon De Banke really understand this kind of thing and are used by F1 drivers as coaches, Don Certainly has been, Simon beet current F1, WRC and BTCC drivers in a head to head shoot out on a limit handling course recently, pity he is a fat git or he could be pretty good in a race car. ;)
My personal weakness is Left Foot Braking, i need time and a good coaching sesion to get my head round this fully.
[QUOTE]As Fitz already pointed out, generally all your braking should be done in a straight line, and your braking should finish right before you turn into the corner. When I'm at an open track event with my car on a road course, that's how I enter a turn - I have the car very close to the limit and so braking in a straight line is very important. [/QUOTE]
This is the biggest single mistake known to man on a race track. (no offence intended :eek: ;) ) If you drive in this way you will be pretty safe but you will never be as fast as you could be or get close to the limits of your tyres.
You should not come of the brakes before you turn in, what that does is unload the front tyres right at the point where it needs a high loading to make the best turn in. The name of the game is to keep the tyre right at it's maximum G loading. This is all explained in a diagrame called a G-G diagramme. At all times the tyre should be at 100% G, as you transition from braking into the cornering phase you need to make the tyres G load transfer smoothly from one load direction to another. Keeping the load at 100% G is what seperates the gods from the also rans. Even Senna couldnt manage this at 100% but he could keep it at high 90's ALL THE TIME!
If i can i will scan in a typical G-G plot for you tonight. Jackie stewart is a master at teaching this stuff. All transitions need to be smooth and blend together. As you get more experienced you'll change the way you take diferent types of corners, some i am braking hard into right up to the apex, others i am trail braking (thats where you are on the brakes lightly all the way through the turn), others i am on the brakes and the power at the same time using the brakes to control the front and the power to control the rear.
The only way to learn this stuff is to go and play, a good limit handling coach will be a big help. Lots of race school instructors havent a clue on this kind of thing unfortunately. People like Don Palmer and Simon De Banke really understand this kind of thing and are used by F1 drivers as coaches, Don Certainly has been, Simon beet current F1, WRC and BTCC drivers in a head to head shoot out on a limit handling course recently, pity he is a fat git or he could be pretty good in a race car. ;)
My personal weakness is Left Foot Braking, i need time and a good coaching sesion to get my head round this fully.
| Lurker | 12-31-2001 09:11 AM |
[QUOTE]its called All Wheel [b]DRIVE[/b]
the system wont do squat for decelerating
[/QUOTE]
Just my attempt to explain: the purpose of braking is to bleed away the energy present in a moving vehicle to reduce it's velocity. The primary means of doing this, unsurprisingly, is through the vehicle's braking system, which converts the energy into heat via friction. However, the AWD system of our Subaru's also bleeds off energy through inefficiencies in the system (three diffs, four halfshafts, a driveshaft, etc). Whenever you are off of the power, [i]even if the vehicle is in neutral or clutch-in[/i], the drivetrain is still connected to the wheels, and is thus is consuming energy. This energy must come from the vehicle itself, which is thus losing speed as well.
Or at least that's what I figure... :cool:
the system wont do squat for decelerating
[/QUOTE]
Just my attempt to explain: the purpose of braking is to bleed away the energy present in a moving vehicle to reduce it's velocity. The primary means of doing this, unsurprisingly, is through the vehicle's braking system, which converts the energy into heat via friction. However, the AWD system of our Subaru's also bleeds off energy through inefficiencies in the system (three diffs, four halfshafts, a driveshaft, etc). Whenever you are off of the power, [i]even if the vehicle is in neutral or clutch-in[/i], the drivetrain is still connected to the wheels, and is thus is consuming energy. This energy must come from the vehicle itself, which is thus losing speed as well.
Or at least that's what I figure... :cool:
| Patrick Olsen | 12-31-2001 11:12 AM |
[quote][i]Originally posted by johnfelstead [/i]
[b]If you drive in this way you will be pretty safe but you will never be as fast as you could be or get close to the limits of your tyres.
You should not come of the brakes before you turn in...[/b][/quote]
First, I'm doing open track events, not racing, so being safe is about 1000x more important than getting right to the limit of my tires. Second, the guy who originated the post was talking about driving on the street, where being safe is about 1,000,000x more important than getting to the limit of one's tires.
With that said, clearly you are correct. I didn't phrase it very well, but later in my post I said "ease out of the brakes right as you turn in" - a very brief reference to the transition from braking to turning. That was one of the things my instructor was telling me to work on at one of the open track events I attended this summer. It's all about being smoooooooth in transition to prevent upsetting the tires (or "tyres", as the silly Brits would say ;) ).
So, I know exactly what you're getting at, John, but based on the tone of the original post I'm going to stick to what I said the first time. :)
Pat
[b]If you drive in this way you will be pretty safe but you will never be as fast as you could be or get close to the limits of your tyres.
You should not come of the brakes before you turn in...[/b][/quote]
First, I'm doing open track events, not racing, so being safe is about 1000x more important than getting right to the limit of my tires. Second, the guy who originated the post was talking about driving on the street, where being safe is about 1,000,000x more important than getting to the limit of one's tires.
With that said, clearly you are correct. I didn't phrase it very well, but later in my post I said "ease out of the brakes right as you turn in" - a very brief reference to the transition from braking to turning. That was one of the things my instructor was telling me to work on at one of the open track events I attended this summer. It's all about being smoooooooth in transition to prevent upsetting the tires (or "tyres", as the silly Brits would say ;) ).
So, I know exactly what you're getting at, John, but based on the tone of the original post I'm going to stick to what I said the first time. :)
Pat
| Fitz | 12-31-2001 11:44 AM |
Ditto with Pat on that one John.. do we really want Jimmy... rather.. does Jimmy really want to be trail-breaking on his first session out?? :) Sounds like he should take a driving school or two prior to touching that brake pedal in the corners.
I would like to see a copy of the G-G diagram if you get a chance to post it. I use trailbreaking a lot in the Hillclimbs I race in. It really helps to get the car lined up in the corners. I haven't experimented with left foot breaking a lot, but hope to learn more about it up at Tim O'Neils on the 19th and 28th respectively.
Thanks,
Fitz
I would like to see a copy of the G-G diagram if you get a chance to post it. I use trailbreaking a lot in the Hillclimbs I race in. It really helps to get the car lined up in the corners. I haven't experimented with left foot breaking a lot, but hope to learn more about it up at Tim O'Neils on the 19th and 28th respectively.
Thanks,
Fitz
| Jimmy S. | 12-31-2001 03:11 PM |
wow guys thanks for all the response!
| johnfelstead | 12-31-2001 03:13 PM |
1 Attachment(s)
Point taken chaps, i do get carried away sometimes. ;):D
OK, below is the g-g diagramme for Senna from Adelaide, 1987.
all the lines are the plots for the car as its going through braking, accelerating and cornering left and right.
Max braking G is 3G's :eek:
Max acceleration is 1.8G's :eek:
Max cornering is 3G's :eek:
This diagramme alone shows you what a violent place a grand prix car was with sticky tyres and huge aero downforce. I hope it makes sense. I'll dig out a plot for a road car on road tyres to compare in a minute.
OK, below is the g-g diagramme for Senna from Adelaide, 1987.
all the lines are the plots for the car as its going through braking, accelerating and cornering left and right.
Max braking G is 3G's :eek:
Max acceleration is 1.8G's :eek:
Max cornering is 3G's :eek:
This diagramme alone shows you what a violent place a grand prix car was with sticky tyres and huge aero downforce. I hope it makes sense. I'll dig out a plot for a road car on road tyres to compare in a minute.
| johnfelstead | 12-31-2001 03:31 PM |
1 Attachment(s)
next is the same car/tyre/track combination but using a normal driver and a race driver. You can see how the race driver takes the tyre closer to its limits. The diference isnt that massive really but your talking small diferences between the great and the average.
| johnfelstead | 12-31-2001 03:35 PM |
have a look at the 2nd diagrammes again.
can you see how the race driver is braking during cornering whilst the road driver is braking in a straight line?
(top middle of the diagramme)
can you see how the race driver is braking during cornering whilst the road driver is braking in a straight line?
(top middle of the diagramme)
| Lurker | 12-31-2001 03:36 PM |
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You mean here?
| Lurker | 12-31-2001 03:41 PM |
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The "normal" driver also seems to spend a lot of time near the origin, which the "race" driver seems to avoid like the plague.
Am I reading these correctly?
Am I reading these correctly?
| johnfelstead | 12-31-2001 03:43 PM |
yes, exactly.
The road driver has a very flat curve and hardly uses a combination of braking and cornering. He doesnt go near that area of the tyres available grip.
The road driver has a very flat curve and hardly uses a combination of braking and cornering. He doesnt go near that area of the tyres available grip.
| johnfelstead | 12-31-2001 03:45 PM |
good stuff this isnt it. thank god i am not talking to myself. :lol:
Powerful engine in that isuzu. :lol:
Anyone who says F1 drivers dont earn their money just doesnt understand the forces these guys feel. (i exclude the pay drivers, they are crap and i should be driving in there place. :D )
Powerful engine in that isuzu. :lol:
Anyone who says F1 drivers dont earn their money just doesnt understand the forces these guys feel. (i exclude the pay drivers, they are crap and i should be driving in there place. :D )
| kaos200 | 12-31-2001 03:52 PM |
[QUOTE][i]Originally posted by johnfelstead [/i]
[B]
Glenn is absolutely correct, AWD systems work in all states and all transitions. There are many diferent types of AWD system available. The system in your Skyline is an active system using variable torque depending on attitude/load and slip angle. The system in the Impreza varies depending on model.
[/B][/QUOTE]
I still do not agree here, the awd system simply wont make a difference in stability during deceleration unless the engine is coupled to the trans and providing a sort of loading force on all 4 wheels. (ie, engine braking)
[B]
Glenn is absolutely correct, AWD systems work in all states and all transitions. There are many diferent types of AWD system available. The system in your Skyline is an active system using variable torque depending on attitude/load and slip angle. The system in the Impreza varies depending on model.
[/B][/QUOTE]
I still do not agree here, the awd system simply wont make a difference in stability during deceleration unless the engine is coupled to the trans and providing a sort of loading force on all 4 wheels. (ie, engine braking)
| kaos200 | 12-31-2001 03:56 PM |
[QUOTE][i]Originally posted by Lurker [/i]
[B]
Just my attempt to explain: the purpose of braking is to bleed away the energy present in a moving vehicle to reduce it's velocity. The primary means of doing this, unsurprisingly, is through the vehicle's braking system, which converts the energy into heat via friction. However, the AWD system of our Subaru's also bleeds off energy through inefficiencies in the system (three diffs, four halfshafts, a driveshaft, etc). Whenever you are off of the power, [i]even if the vehicle is in neutral or clutch-in[/i], the drivetrain is still connected to the wheels, and is thus is consuming energy. This energy must come from the vehicle itself, which is thus losing speed as well.
Or at least that's what I figure... :cool: [/B][/QUOTE]
I agree with you, that the connected parts of the system, even when disconnected (neutral or clutch in) are taking away energy and slowing the car slightly quicker, but this does NOT inherently mean that the car is decelerating with more stability.
[B]
Just my attempt to explain: the purpose of braking is to bleed away the energy present in a moving vehicle to reduce it's velocity. The primary means of doing this, unsurprisingly, is through the vehicle's braking system, which converts the energy into heat via friction. However, the AWD system of our Subaru's also bleeds off energy through inefficiencies in the system (three diffs, four halfshafts, a driveshaft, etc). Whenever you are off of the power, [i]even if the vehicle is in neutral or clutch-in[/i], the drivetrain is still connected to the wheels, and is thus is consuming energy. This energy must come from the vehicle itself, which is thus losing speed as well.
Or at least that's what I figure... :cool: [/B][/QUOTE]
I agree with you, that the connected parts of the system, even when disconnected (neutral or clutch in) are taking away energy and slowing the car slightly quicker, but this does NOT inherently mean that the car is decelerating with more stability.
| johnfelstead | 12-31-2001 03:59 PM |
OK, you stick with that idea but you are wrong. :lol:
Have a think about my example of the benneton front braking system, that had no link to an engine, it just linked both front wheels via a differential. Now apply that on the rear axle too. Now apply that front to rear. No engine, just diffs and torque transfer shafts.
does it make sense now?
Have a think about my example of the benneton front braking system, that had no link to an engine, it just linked both front wheels via a differential. Now apply that on the rear axle too. Now apply that front to rear. No engine, just diffs and torque transfer shafts.
does it make sense now?
| stimpy | 12-31-2001 04:25 PM |
Lets simplify this a little bit.
If you remove all the weight transfer for just a moment, we can see what's going on with our awd during a corner. Imagine yourself in your favorite sweeper corner; mid-corner. You are accelerating around and need to adjust the car's orientation a little. You get off the gas a little and the engine slows down the car some. Car remains fairly stable because the engine-braking is acting on all four wheels when you let off the throttle.
Situation number 2:
Imagine hitting that same sweeper, same position. This time you are in an rx7. Again, you are accelerating around the corner and need to adjust the car's orientation. You get off the gas and the engine grabs ahold of those rear wheels and slows down the car. The car now becomes loose in the rear (remember, we are disregarding weight transfer here) because it is effectively engine-braking with ONLY the rear wheels.
In this example, the awd was actively modifying the way the car drove while decelerating.
-Jon
[url]www.nothingserious.net[/url]
If you remove all the weight transfer for just a moment, we can see what's going on with our awd during a corner. Imagine yourself in your favorite sweeper corner; mid-corner. You are accelerating around and need to adjust the car's orientation a little. You get off the gas a little and the engine slows down the car some. Car remains fairly stable because the engine-braking is acting on all four wheels when you let off the throttle.
Situation number 2:
Imagine hitting that same sweeper, same position. This time you are in an rx7. Again, you are accelerating around the corner and need to adjust the car's orientation. You get off the gas and the engine grabs ahold of those rear wheels and slows down the car. The car now becomes loose in the rear (remember, we are disregarding weight transfer here) because it is effectively engine-braking with ONLY the rear wheels.
In this example, the awd was actively modifying the way the car drove while decelerating.
-Jon
[url]www.nothingserious.net[/url]
| kaos200 | 12-31-2001 04:41 PM |
Stimpy, I dont know if you directing that post towards me, but if so reread my posts, I was agreeing with you!:p
What I am saying is that, [I]just because [/I] a car has awd, it wont be more stable, when the engine in NOT connected, or in a straight line.
What I am saying is that, [I]just because [/I] a car has awd, it wont be more stable, when the engine in NOT connected, or in a straight line.
| kaos200 | 12-31-2001 04:45 PM |
[QUOTE][i]Originally posted by johnfelstead [/i]
[B]OK, you stick with that idea but you are wrong. :lol:
Have a think about my example of the benneton front braking system, that had no link to an engine, it just linked both front wheels via a differential. Now apply that on the rear axle too. Now apply that front to rear. No engine, just diffs and torque transfer shafts.
does it make sense now? [/B][/QUOTE]
I understand what you are saying, I still dont see how it makes the car more Stable?
[B]OK, you stick with that idea but you are wrong. :lol:
Have a think about my example of the benneton front braking system, that had no link to an engine, it just linked both front wheels via a differential. Now apply that on the rear axle too. Now apply that front to rear. No engine, just diffs and torque transfer shafts.
does it make sense now? [/B][/QUOTE]
I understand what you are saying, I still dont see how it makes the car more Stable?
| stimpy | 12-31-2001 04:59 PM |
Ok kaos200, I guess I am not seeing exactly what you do and don't agree with. Is it that you are just saying that just because it has awd it doesn't GUARANTEE it will handle in a certain way? If so, thats a given. Best example of that I can think of is using a front one-way pulley on my awd R/C touring car. This is more or less adding an LSD (I forgot which type of LSD) to the front of the car and prevents engine braking from acting upon the front wheels. Now when you let off the throttle, it is engine braking like a rwd and becomes unstable in corners.
-Jon
[url]www.nothingserious.net[/url]
-Jon
[url]www.nothingserious.net[/url]
| kaos200 | 12-31-2001 05:22 PM |
ok, I guess we went off track there.
What I disagree with, is that [B]engine "UNcoupled"[/B] awd makes the car inherently more stable, and aid in deceleration. (atleast to a point that can be noticed)
Engine connected, I would agree, that under most circumstances, the car will react more neutrally since all 4 wheels are reacting the same way. That could be called more stable if you wish. But lets not all go thinking that awd will save your behind in a lift-off throttle situation! (because, well, I found it doesnt:p )
What I disagree with, is that [B]engine "UNcoupled"[/B] awd makes the car inherently more stable, and aid in deceleration. (atleast to a point that can be noticed)
Engine connected, I would agree, that under most circumstances, the car will react more neutrally since all 4 wheels are reacting the same way. That could be called more stable if you wish. But lets not all go thinking that awd will save your behind in a lift-off throttle situation! (because, well, I found it doesnt:p )
| stimpy | 12-31-2001 05:30 PM |
Gotcha! ;) All things considered, I guess there really isn't that much different from an awd or rwd car when they are both in neutral HOWEVER most people I know don't hit the corners hard in neutral :p
Now, back to topic. Here are two books which I believe to have some good theory within:
[U]Secrets of Solo Racing[/U] by Henry A. Watts
[U]Going Faster!: Mastering the Art of Race Driving[/U] by Carl Lopez and Skip Barber Racing School
-Jon
[url]www.nothingserious.net[/url]
Now, back to topic. Here are two books which I believe to have some good theory within:
[U]Secrets of Solo Racing[/U] by Henry A. Watts
[U]Going Faster!: Mastering the Art of Race Driving[/U] by Carl Lopez and Skip Barber Racing School
-Jon
[url]www.nothingserious.net[/url]
| kaos200 | 12-31-2001 05:33 PM |
[QUOTE][i]Originally posted by stimpy [/i]
[B]HOWEVER most people I know don't hit the corners hard in neutral :p
[/B][/QUOTE]please please please tell that to my friend, he constantly just takes his car into neutral, and half way through the corner, decides to put it back into gear.
I honestly dont want to drive with him, its annoying as hell!:lol:
[B]HOWEVER most people I know don't hit the corners hard in neutral :p
[/B][/QUOTE]please please please tell that to my friend, he constantly just takes his car into neutral, and half way through the corner, decides to put it back into gear.
I honestly dont want to drive with him, its annoying as hell!:lol:
| 2WDrift | 12-31-2001 07:09 PM |
bad bad bad
Tell him that unless he has the gracefulness of Senna, his clutch reengagement from neutral is going to upset the weight transfer, not counting the synchro crunch of his likely non-heel/toe, and that eventually he'll go nose or rear end off a slick curve.
Gary
Gary
| TOMMY B | 12-31-2001 08:15 PM |
Well I take a more simpler approach to cornering;
If I'm not scaring my self, I must be going fast enough ;)
Remember the golden rule: "Drive Fast and Take Chances" :)
RALLY ON /////////////////////
If I'm not scaring my self, I must be going fast enough ;)
Remember the golden rule: "Drive Fast and Take Chances" :)
RALLY ON /////////////////////
| cRayZee | 01-02-2002 01:18 PM |
[QUOTE]Remember the golden rule: "Drive Fast and Take Chances" [/QUOTE]
as long as don't take away other people's chance to live and drive safely. :)
solidforce: dood, you gotta come down for one of the sd auto-X's. We're having a practice auto-X on the 19th, i think, you get like 6-8 runs! That's a great way to learn about driving. Also, did you go to the scic driving clinic sometime in the summer? I learned quite a bit that day. Learned how important braking was and how to apply throttle on a turn. One thing i did when i was making turns was punching the gas when i wanted to accelerate and let it go completely when i felt a bit of understeer then punch again and repeated if necessary--- BAD-- totally disrupts the weight transfer. What the guy @ the driving clinic told me was to feather the throttle and have smooth transitions :).
Ever since i started autoX-ing, i've calmed down a lot when driving in public roads. Autox-ing i just so much fun and you feel so much safer being in a controlled area. I've seen one too many accidents with friends when i've gone canyon driving, and i really don't like pushing that hard on public roads anymore...
Here's my friend's camaro SS when we went driving @ angeles crest hwy in LA just last September.
[IMG]http://ieng9.ucsd.edu/~cohren/pics/car.jpg[/IMG]
as long as don't take away other people's chance to live and drive safely. :)
solidforce: dood, you gotta come down for one of the sd auto-X's. We're having a practice auto-X on the 19th, i think, you get like 6-8 runs! That's a great way to learn about driving. Also, did you go to the scic driving clinic sometime in the summer? I learned quite a bit that day. Learned how important braking was and how to apply throttle on a turn. One thing i did when i was making turns was punching the gas when i wanted to accelerate and let it go completely when i felt a bit of understeer then punch again and repeated if necessary--- BAD-- totally disrupts the weight transfer. What the guy @ the driving clinic told me was to feather the throttle and have smooth transitions :).
Ever since i started autoX-ing, i've calmed down a lot when driving in public roads. Autox-ing i just so much fun and you feel so much safer being in a controlled area. I've seen one too many accidents with friends when i've gone canyon driving, and i really don't like pushing that hard on public roads anymore...
Here's my friend's camaro SS when we went driving @ angeles crest hwy in LA just last September.
[IMG]http://ieng9.ucsd.edu/~cohren/pics/car.jpg[/IMG]
| LateApex | 01-02-2002 04:54 PM |
Jimmy,
I agree with cRayZee, you should come down to SD. You can caravan down with me if you want. I get the feeling sometimes that people think the auto-x events are some sort of competition. I don't treat them that way at all, even though some friendly ribbing and joking goes on.
I know I'm not going to have top time of day, and considering I run in IS2(SD local class) with all the Miatas, I have about a snowball's chance in hell of winning the class. Everytime I go, I learn a little more about my car, and I hope I improve my time every run.
Trying to be fast through the canyons is fun, but really not a good way to learn to drive the car. I mean, are you using a stopwatch and doing timed runs? Judging a fast run from a slow run is nearly impossible on feel alone. I've taken timed laps before and it felt like a real crappy run, and it was my fastest all day. What feels fast isn't always fast. Just my $.02.
btw, some great stuff in this thread. :)
I agree with cRayZee, you should come down to SD. You can caravan down with me if you want. I get the feeling sometimes that people think the auto-x events are some sort of competition. I don't treat them that way at all, even though some friendly ribbing and joking goes on.
I know I'm not going to have top time of day, and considering I run in IS2(SD local class) with all the Miatas, I have about a snowball's chance in hell of winning the class. Everytime I go, I learn a little more about my car, and I hope I improve my time every run.
Trying to be fast through the canyons is fun, but really not a good way to learn to drive the car. I mean, are you using a stopwatch and doing timed runs? Judging a fast run from a slow run is nearly impossible on feel alone. I've taken timed laps before and it felt like a real crappy run, and it was my fastest all day. What feels fast isn't always fast. Just my $.02.
btw, some great stuff in this thread. :)
| Coati | 01-03-2002 12:13 PM |
Yeah! You should definitely come down this month. It's all just for fun and education.
You'll probably be faster than me, if nothing else.:lol:
Coati(DFL WRX)
You'll probably be faster than me, if nothing else.:lol:
Coati(DFL WRX)
| SubaFastR | 01-05-2002 12:24 PM |
Well, downshifting mid corner is a great way to inuce drift.
Kevin:D
Kevin:D
| nasachris | 01-05-2002 03:28 PM |
The Virginia Chapter of the National Auto Sport Association (NASA)will be hosting a High Performance Driving Event as well as a 2.5 hour endurance race at Virginia International Raceway on Feb 16-17. If you are a track junkie or want to bring your street car to the track this is your chance. All you need is your car and a helmet. You'll get over two hours of track time for the weekend and free admission into the Valentines 200 enduro race.
For this event in February NASA's schedule is set up so that you can sleep in on Sunday morning if you so choose because the endurance race starts at 8:30am and goes until 11:00am. You don' t have to be at your driver's meeting on Sunday until 11:00am unless you want to come early and watch the race. This is a good thing because your entry into the NASA event buys you admission into the speed party on Saturday night where you will get free food and beverages (some of which you have to be 21 to get), a Gran Turismo Tournament where the winner wins a free HPDE at a future NASA event, and of course pictures with the lovely NASA Trophy Girls.
You paddock next to real racers.
The benefits to the new driver are numerous but the main things that can be derived from such close proximity to racers is that these guys have the best tips on performance gains for low bucks and excellent suggestions of driving technique based upon their experience. You may be paddocked next to a semi pro driver or you may have a $250,000 race rig blocking out the wind with a Ferrari Challenge car inside.
Racing demands that everything about the weekend operate at a higher level. NASA's flagging and communications, control, tech and emergency services have operated as a team for several years and ensures a "racer" level of safety for both the racers AND the HPDE students. In 2001, NASA had six events and not one metal bending incident in the HPDEs. NO ONE on the east coast can make this claim.
Instructors. NASA has three levels of training for their instructor corps. It is an elite corps of instructors that understands and operates under a standardized system. Except for the BMW and Porsche clubs, no other organization uses this type of system. Most use a hodgepodge of instructors with no particular system and as a result have difficulty controlling actions of the students on track. Recently an organization with no structure had 90 offs and wrecked 2 cars. If you care about yourself or your car you need to attend an event with some sort of standardized system. It is not a good idea to have 35 people on track at 120mph plus without everyone being on the same page.
NASA's HPDEs count toward a racing license. You can do the HPDEs and never go racing but it's nice to know you have it if you want to.
t.
Get your entry info at [url]www.nasaracing.net[/url]
Peace,
Chris
For this event in February NASA's schedule is set up so that you can sleep in on Sunday morning if you so choose because the endurance race starts at 8:30am and goes until 11:00am. You don' t have to be at your driver's meeting on Sunday until 11:00am unless you want to come early and watch the race. This is a good thing because your entry into the NASA event buys you admission into the speed party on Saturday night where you will get free food and beverages (some of which you have to be 21 to get), a Gran Turismo Tournament where the winner wins a free HPDE at a future NASA event, and of course pictures with the lovely NASA Trophy Girls.
You paddock next to real racers.
The benefits to the new driver are numerous but the main things that can be derived from such close proximity to racers is that these guys have the best tips on performance gains for low bucks and excellent suggestions of driving technique based upon their experience. You may be paddocked next to a semi pro driver or you may have a $250,000 race rig blocking out the wind with a Ferrari Challenge car inside.
Racing demands that everything about the weekend operate at a higher level. NASA's flagging and communications, control, tech and emergency services have operated as a team for several years and ensures a "racer" level of safety for both the racers AND the HPDE students. In 2001, NASA had six events and not one metal bending incident in the HPDEs. NO ONE on the east coast can make this claim.
Instructors. NASA has three levels of training for their instructor corps. It is an elite corps of instructors that understands and operates under a standardized system. Except for the BMW and Porsche clubs, no other organization uses this type of system. Most use a hodgepodge of instructors with no particular system and as a result have difficulty controlling actions of the students on track. Recently an organization with no structure had 90 offs and wrecked 2 cars. If you care about yourself or your car you need to attend an event with some sort of standardized system. It is not a good idea to have 35 people on track at 120mph plus without everyone being on the same page.
NASA's HPDEs count toward a racing license. You can do the HPDEs and never go racing but it's nice to know you have it if you want to.
t.
Get your entry info at [url]www.nasaracing.net[/url]
Peace,
Chris
| Patrick Olsen | 01-08-2002 09:20 AM |
Geez, nasachris, that really long post of yours that doesn't really relate to this topic looks familiar. I wonder why that is??? Oh, that's right, because I just read your own thread you started [url]http://i-club.com/forums/showthread.php?s=&threadid=131975[/url] that says exactly the same thing. :rolleyes:
If that was unintentional, please edit your post here to remove it from this thread. If it was intentional, ummm, don't double post. I could see double posting in separate forums - maybe one thread in the Motorsports Forum and one in the Mid Atlantic Forum - I've done that before myself to let people know about events at VIR. But to put two identical posts in different threads in the same forum is kind of obnoxious.
Pat Olsen
'97 Legacy 2.5GT sedan
If that was unintentional, please edit your post here to remove it from this thread. If it was intentional, ummm, don't double post. I could see double posting in separate forums - maybe one thread in the Motorsports Forum and one in the Mid Atlantic Forum - I've done that before myself to let people know about events at VIR. But to put two identical posts in different threads in the same forum is kind of obnoxious.
Pat Olsen
'97 Legacy 2.5GT sedan
| Lurker | 01-08-2002 09:35 AM |
[QUOTE]I agree with you, that the connected parts of the system, even when disconnected (neutral or clutch in) are taking away energy and slowing the car slightly quicker, but this does NOT inherently mean that the car is decelerating with more stability.[/QUOTE] Well, when you think about it, the two limited-slip differentials in our cars also help reduce uneven tire lock-up. In this way, couldn't our AWD system be thought to act as a form of ABS? If, for example, your rear tires tried to lock up during heavy braking (bad), the center diff would try to connect those rear tires to the front tires, which would help maintain braking balance. Does that make any sense? :confused:
On second thought, it's too early to be making tech posts.
;) (<- I'm not winking I'm falling asleep)
On second thought, it's too early to be making tech posts.
;) (<- I'm not winking I'm falling asleep)
| johnfelstead | 01-08-2002 11:50 AM |
Get your butt in an active transmision WRC car and play with the ramps. You will soon be convinced that AWD does improve stability under braking.
| Lurker | 01-08-2002 11:55 AM |
That's a luxury most of us will never be able to indulge in, unfortunately. :rolleyes:
| johnfelstead | 01-08-2002 11:57 AM |
:devil: :D
| Axiochus | 01-08-2002 08:26 PM |
...because this thread popped up again...
I don't know if anyone mentioned it above (I'm too lazy to re-read everything right now), but there is a great technical discussion of cornering in this month's Racecar Engineering (available at your local Border's or other large book store).
It's the article at the very back of the issue, and it's written by an "expert". FWIW, according to him, you should be on the brakes (with a diminishing amount of force) until mid corner.
It's not exactly on point with most of the discussion here, but it's worth the read if you can put up with all that boring technical babble!
Matt.
I don't know if anyone mentioned it above (I'm too lazy to re-read everything right now), but there is a great technical discussion of cornering in this month's Racecar Engineering (available at your local Border's or other large book store).
It's the article at the very back of the issue, and it's written by an "expert". FWIW, according to him, you should be on the brakes (with a diminishing amount of force) until mid corner.
It's not exactly on point with most of the discussion here, but it's worth the read if you can put up with all that boring technical babble!
Matt.
| johnfelstead | 01-08-2002 08:48 PM |
i said that ages ago. :lol: :D
| Axiochus | 01-08-2002 09:02 PM |
USA = Short Attention Span (atleast, that's what F1 Bernie says).
:)
:)
| gumby647 | 01-08-2002 10:32 PM |
[QUOTE]My personal weakness is Left Foot Braking, i need time and a good coaching sesion to get my head round this fully.[/QUOTE]
Just do what I did, crash a motorcycle at Daytona, smash your right foot to bits and drive an auto tranny car with just your left foot for 4 months. Now as long as I have small enough shoes on I can use my left foot smoothly when needed.
As far as braking going into a corner goes I don't see why it's not safe to do it. I was always taught to learn the technique first and then add speed. John pointed out that you should brake into the corner to keep the tire at 100% grip. Let me add that when you brake the cars weight shifts forward compressing the front suspension. When you let off the suspension rebounds and as cornering load increases the suspension compresses agian. Proper braking should see the brakes let off as cornering load increases and when seen from the out side the noise of the car should not go up and down. I think proper technique at 9/10ths is safer than sloppy driving at 10/10ths. Just my $02 on that.
If you don't belive that diffs, and therefore awd, can affect a cars stability underbraking ask yourself why anyone would go through the trouble of making a 1.5 or 2 way diff. It's not just for backing your RX-7 into corners by down shifting too hard, however much fun that may be. :devil:
Just do what I did, crash a motorcycle at Daytona, smash your right foot to bits and drive an auto tranny car with just your left foot for 4 months. Now as long as I have small enough shoes on I can use my left foot smoothly when needed.
As far as braking going into a corner goes I don't see why it's not safe to do it. I was always taught to learn the technique first and then add speed. John pointed out that you should brake into the corner to keep the tire at 100% grip. Let me add that when you brake the cars weight shifts forward compressing the front suspension. When you let off the suspension rebounds and as cornering load increases the suspension compresses agian. Proper braking should see the brakes let off as cornering load increases and when seen from the out side the noise of the car should not go up and down. I think proper technique at 9/10ths is safer than sloppy driving at 10/10ths. Just my $02 on that.
If you don't belive that diffs, and therefore awd, can affect a cars stability underbraking ask yourself why anyone would go through the trouble of making a 1.5 or 2 way diff. It's not just for backing your RX-7 into corners by down shifting too hard, however much fun that may be. :devil:
| bpitas | 04-22-2002 01:06 PM |
Effects of AWD during braking
I have an absolutely irrefutable source of information that PROVES that deceleration stability is increased with AWD.
First, buy a Playstation 2 and Grand Tourismo 3 A-spec. Then by any AWD car, and upgrade the center diff to a racing model, which basically adds adjustability to the stock center diff. You can upgrade it to either a 1.5way or 2way. Once you install the new racing center diff, you'll be able to adjust the level of lock separately for both acceleration and deceleration. PROOF that AWD works during deceleration!!!
Seriously though, the instruction manual for GT3 does a great job of explaining why having a limited slip in the center and front/rear diffs increases stability. Basically visualize the inscribed arcs of the four wheels going through a turn. All four wheels would inscribe a slightly different radius turn. So the Subaru AWD, under deceleration, tries to keep all four wheels (actually both back and one front, so 3 wheels) turning the same rate. So if you start to spin at all, and the wheels aren't locked up, the wheel to the outside of your spin will try to spin slightly faster than the other 3, and the AWD will *resist* this increase in speed and in essence try to pull things back into line. This is similar to what the Active Handling on my C5 Corvette did, which is to selectively brake whatever wheel is necessary to pull the car back into neutral handling...
I'm not 100% up on viscous limited slips, but I know that clutch-pack types (like on the back of most american muscle cars) work by having a bunch of alternating discs of friction material and steel packed together tightly enough that they keep the wheels turning the same speed unless you apply sufficient torque differential, like the different arcs of the rear wheels when taking a turn on an asphalt road.
Since the limited slip has a tendancy to keep the wheels rotating at the same speed, that means that it in effect has a tendancy to *prevent* them from inscribing arcs of different radius, which means it will work to keep the car in a straight line. Keeping the car in a straight line is also known as keeping it "stable".
In our Subarus (at least the US spec 2002s) you have a limited slip in the rear, which would try to keep the rear wheels spinning at the same rate, adding some stability. But you also have a limited slip in the center, and if I remember viscous couplings at all, it would also try to keep the wheels from turning at different rates, although the pressure in our center diffs might not be sufficient to have much locking effect when the rotational differentials are as small as they are with wheels running different radius arcs...
Anyone who knows viscous LSDs want to elaborate on this a little more???
-B
First, buy a Playstation 2 and Grand Tourismo 3 A-spec. Then by any AWD car, and upgrade the center diff to a racing model, which basically adds adjustability to the stock center diff. You can upgrade it to either a 1.5way or 2way. Once you install the new racing center diff, you'll be able to adjust the level of lock separately for both acceleration and deceleration. PROOF that AWD works during deceleration!!!
Seriously though, the instruction manual for GT3 does a great job of explaining why having a limited slip in the center and front/rear diffs increases stability. Basically visualize the inscribed arcs of the four wheels going through a turn. All four wheels would inscribe a slightly different radius turn. So the Subaru AWD, under deceleration, tries to keep all four wheels (actually both back and one front, so 3 wheels) turning the same rate. So if you start to spin at all, and the wheels aren't locked up, the wheel to the outside of your spin will try to spin slightly faster than the other 3, and the AWD will *resist* this increase in speed and in essence try to pull things back into line. This is similar to what the Active Handling on my C5 Corvette did, which is to selectively brake whatever wheel is necessary to pull the car back into neutral handling...
I'm not 100% up on viscous limited slips, but I know that clutch-pack types (like on the back of most american muscle cars) work by having a bunch of alternating discs of friction material and steel packed together tightly enough that they keep the wheels turning the same speed unless you apply sufficient torque differential, like the different arcs of the rear wheels when taking a turn on an asphalt road.
Since the limited slip has a tendancy to keep the wheels rotating at the same speed, that means that it in effect has a tendancy to *prevent* them from inscribing arcs of different radius, which means it will work to keep the car in a straight line. Keeping the car in a straight line is also known as keeping it "stable".
In our Subarus (at least the US spec 2002s) you have a limited slip in the rear, which would try to keep the rear wheels spinning at the same rate, adding some stability. But you also have a limited slip in the center, and if I remember viscous couplings at all, it would also try to keep the wheels from turning at different rates, although the pressure in our center diffs might not be sufficient to have much locking effect when the rotational differentials are as small as they are with wheels running different radius arcs...
Anyone who knows viscous LSDs want to elaborate on this a little more???
-B
| Mako | 04-22-2002 07:56 PM |
cross posts or whatever
patrick O--yawn--who cares? ease up there, turbo:rolleyes:
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