Driving misconceptions
01-26-2004, 11:31 PM
#1
Race Director
Thread Starter
Driving misconceptions
In order to stop continuing the hijacking of the 'downshifting problems' thread, I'd like to start a new thread on the misconceptions people have regarding how to setup and drive a 944.
Disclaimer: I am by no means an expert professional race car driver. However, based on my research, reading many perforamnce driving books, speaking with 'the experts' and limited driving experience (autox and DE), I have opinions about how proper driving techniques and car setup. Also: these are things that shouldn't be tried on the street: attend car control clinics, autocrosses, driver's ed events, and racing schools: that's where performance driving is meant to be done!
If you disagree with what I say, please respond, and explain. If you agree, please comment as well. And most important, please post other misconceptions that you know of! The board is a great resource of information: so please contribute!
So, let me start with these:
1. Downshifting is not for slowing down the car Use brakes to slow the car down, not the engine.
For more information, and a lively discussion on proper downshifting techniques, See this thread.
2. A firmer suspension is always better.Not necessarily so. It's all about balance! Firm up the front too much, and you're in for a good amount of understeer. While extreme understeer is easier to recover from for a typical driver, it isn't your friend on the racetrack. (You've gotta slow down in order to stop understeering: something you want to do as little as possible on the track!) I've seen many people adjusting their shocks at autocrosses: setting their fronts to Full FIRM, BABY! For venues like autox, you want the front to be significantly softer, so your car can 'bite' with the fronts, and give you the traction needed to plant it and get a little oversteer to help turn in the corner.
3. My car handles like it's on rails. If you feel your car handles like it's on rails, then you're not going fast enough. In order to get around a corner fast, you need to have your tires slidiing a little. Not drastic, but a 5 to 10 degree sliip angle of your car will actually help get you around the corners! NOTE: DO NOT TRY THIS ON THE STREET. Learn about slip angles on the track, at an autocross or at a car control clinic.
4. The faster I shift from gear to gear, the quicker I will accelerate Not true! The time you gain by shifting fast is countered by the jerkyness of the improper technique. Up shifting and downshifting should be smooth: hold the shifter as if you were holding an egg. Use only minimal force to move the shifter out of the gear, through the neutral plane, and into the next gear. Release the clutch smoothly. This will not upset the balance of the car like a slam! bam! shift would.
Obviously, this is just a start. Hopefully we'll have some lively discussion on proper car setup and techniques. Again, I am no expert.
So, bring on the comments, misconceptions, whatever!!
Regards,
-Z-man.
Disclaimer: I am by no means an expert professional race car driver. However, based on my research, reading many perforamnce driving books, speaking with 'the experts' and limited driving experience (autox and DE), I have opinions about how proper driving techniques and car setup. Also: these are things that shouldn't be tried on the street: attend car control clinics, autocrosses, driver's ed events, and racing schools: that's where performance driving is meant to be done!
If you disagree with what I say, please respond, and explain. If you agree, please comment as well. And most important, please post other misconceptions that you know of! The board is a great resource of information: so please contribute!
So, let me start with these:
1. Downshifting is not for slowing down the car Use brakes to slow the car down, not the engine.
From Speed Secrets by Ross Bently, pg. 20
Downshifting is one of the most misunderstood and misued techniques in driving. What is the real reason for downshifting? Many drivers think it's to use the eninge to help slow the car down. Wrong again! The engine is meant to increase your speed, not to decrease it. In fact, by using the engine to slow the car you can actually hinder accurate brake modulation and balance. Race drivers, and good street drivers, downshift during the approach to a corner, simply to be in the proper gear, at the optimum engine rpm, to allow maximum acceleration out of the corner.
Again, the reason for downshifting is not to slow the car. I can't emphasize this enough. That's what brakes are for. Too many drivers try to use the engine compression braking effect to slow the car. All they really achieve is upsetting the balance of the car and hindering the braking effectiveness (if the brakes are right at the limit before locking up and then you add engine braking to the rear wheels, you will probably lock up the rear brakes), and more wear and tear on the engine. Brake first, then downshift.
Downshifting is one of the most misunderstood and misued techniques in driving. What is the real reason for downshifting? Many drivers think it's to use the eninge to help slow the car down. Wrong again! The engine is meant to increase your speed, not to decrease it. In fact, by using the engine to slow the car you can actually hinder accurate brake modulation and balance. Race drivers, and good street drivers, downshift during the approach to a corner, simply to be in the proper gear, at the optimum engine rpm, to allow maximum acceleration out of the corner.
Again, the reason for downshifting is not to slow the car. I can't emphasize this enough. That's what brakes are for. Too many drivers try to use the engine compression braking effect to slow the car. All they really achieve is upsetting the balance of the car and hindering the braking effectiveness (if the brakes are right at the limit before locking up and then you add engine braking to the rear wheels, you will probably lock up the rear brakes), and more wear and tear on the engine. Brake first, then downshift.
2. A firmer suspension is always better.Not necessarily so. It's all about balance! Firm up the front too much, and you're in for a good amount of understeer. While extreme understeer is easier to recover from for a typical driver, it isn't your friend on the racetrack. (You've gotta slow down in order to stop understeering: something you want to do as little as possible on the track!) I've seen many people adjusting their shocks at autocrosses: setting their fronts to Full FIRM, BABY! For venues like autox, you want the front to be significantly softer, so your car can 'bite' with the fronts, and give you the traction needed to plant it and get a little oversteer to help turn in the corner.
3. My car handles like it's on rails. If you feel your car handles like it's on rails, then you're not going fast enough. In order to get around a corner fast, you need to have your tires slidiing a little. Not drastic, but a 5 to 10 degree sliip angle of your car will actually help get you around the corners! NOTE: DO NOT TRY THIS ON THE STREET. Learn about slip angles on the track, at an autocross or at a car control clinic.
4. The faster I shift from gear to gear, the quicker I will accelerate Not true! The time you gain by shifting fast is countered by the jerkyness of the improper technique. Up shifting and downshifting should be smooth: hold the shifter as if you were holding an egg. Use only minimal force to move the shifter out of the gear, through the neutral plane, and into the next gear. Release the clutch smoothly. This will not upset the balance of the car like a slam! bam! shift would.
Obviously, this is just a start. Hopefully we'll have some lively discussion on proper car setup and techniques. Again, I am no expert.
So, bring on the comments, misconceptions, whatever!!
Regards,
-Z-man.
Last edited by Z-man; 01-26-2004 at 11:47 PM.
01-26-2004, 11:35 PM
#2
Unbannable
Rennlist Member
Rennlist Member
I've always noticed that at the autocrosses, the cars that look like they are going the fastest are actually the slowest, and the cars that look like they are the slowest are actually the fastest. 
I guess that's a comment?
BB.
I guess that's a comment?
BB.
01-26-2004, 11:38 PM
#5
Unbannable
Rennlist Member
Rennlist Member
Originally posted by ilikemy944
I usually look like I am going slow at an autocross, and I usually am...
I usually look like I am going slow at an autocross, and I usually am...
BB.
01-27-2004, 12:14 AM
#6
Nordschleife Master
Good information for a especially unexperienced driver who wants to get better (me).
About point 4, its funny thats mentioned. My friends and i always give a kid we know crap for the way he shifts his car. He used to literally slam the gear**** into position, it was so rough and stiff. I can only imagine the damage on the shift linkage. We used to joke that he minus well kick the damn thing into gear with his foot!
And i think Mario Andretti stated point 3 the best when he said...
"If everything seems under control, you're just not going fast enough."
About point 4, its funny thats mentioned. My friends and i always give a kid we know crap for the way he shifts his car. He used to literally slam the gear**** into position, it was so rough and stiff. I can only imagine the damage on the shift linkage. We used to joke that he minus well kick the damn thing into gear with his foot!
And i think Mario Andretti stated point 3 the best when he said...
"If everything seems under control, you're just not going fast enough."
01-27-2004, 12:15 AM
#7
Nordschleife Master
Firmer is always better - but only to a point - for racing - on smooth tracks - as long as you have the same spring rate all around. Or at least a spring rate that makes the car handle the way you want it to.
My car has way too much body roll. I know it's inhibiting my ability to go faster on the track. Both AutoX and DE.
My car has way too much body roll. I know it's inhibiting my ability to go faster on the track. Both AutoX and DE.
Trending Topics
01-27-2004, 12:20 AM
#8
Burning Brakes
Join Date: Nov 2003
Location: Bay Area, California
Posts: 1,208
Likes: 0
Received 0 Likes
on
0 Posts
I have always like downshifting and letting the engine help decelerate the car. I have not been on the track yet but when I do I will remember that advice to not downshift for braking. It makes sense because the engine is not very good at slowing the car, at least not as good as the brakes.
One friend told me downshifting and engine braking was hard on the valves. Is this another reason to avoid engine braking?
One friend told me downshifting and engine braking was hard on the valves. Is this another reason to avoid engine braking?
01-27-2004, 12:26 AM
#9
Instructor
Join Date: Apr 2002
Location: Sydney, Australia
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
My 2 cents...
I couldn't agree more with point 1. I have this argument with people all the time. Engines produce extremely low power on overrun, but brakes have enormous power. Thousands of horsepower, in fact. Brakes are designed to slow you down, so use them and leave your engine for speeding up.
A firmer suspension is definitely not better - for traction. In fact, a softer suspension will give you more mechanical grip by allowing the tyre to stay in closer contact with the road surface. However, a softer suspension will also allow more body roll, which destroys tyre contact with the road surface because the tyre won't sit flat with the road, reducing grip. So it's a catch-22. The stiffer the suspension, the better the tyre contact patch shape on the road, but the softer the suspension, the better the rubber will grip the surface. Getting the compromise right will give you the fastest lap times. I have raced production cars, where the rules force you to stay with standard anti-sway bars (roll bars). This means your only methods of reducing body roll, dive, and squat to keep the tyre on the ground effectively is to increase spring and damping rates. This DOES NOT HELP traction. It's a trade-off. So testing is required to find the right balance.
The only reason Formula 1s have 3000lb springs is that they are highly aerodynamic devices and can't tolerate any changes in their tiny ride heights. If the designers had any other option, they'd soften the springs.
Altering the stiffness from front to read and side to side is necessary to control handling balance, but is a different topic to suspension firmness in itself.
3. I prefer a car that talks back to me right up to the point where the tyres slide and then some. If it's on rails it means I can't feel anything, and I have no idea where the limits are. People rave about tyres with high levels of grip, but I'd rather a tyre with slightly less grip but more feel. I guarantee you can go faster when you can feel what the tyre is doing than when you simply have high grip levels (being on rails).
4. I think the faster you shift, the better. So long as you can do it smoothly. Because all speed comes from smoothness.
Race cars have tiny flywheels and dog gears so they can make the shifts as close to instantaneous as possible. But don't go slamming your road gearbox around quickly if your flywheel isn't sized accordingly, or you will induce roughness that will slow you down.
Clayton
I couldn't agree more with point 1. I have this argument with people all the time. Engines produce extremely low power on overrun, but brakes have enormous power. Thousands of horsepower, in fact. Brakes are designed to slow you down, so use them and leave your engine for speeding up.
A firmer suspension is definitely not better - for traction. In fact, a softer suspension will give you more mechanical grip by allowing the tyre to stay in closer contact with the road surface. However, a softer suspension will also allow more body roll, which destroys tyre contact with the road surface because the tyre won't sit flat with the road, reducing grip. So it's a catch-22. The stiffer the suspension, the better the tyre contact patch shape on the road, but the softer the suspension, the better the rubber will grip the surface. Getting the compromise right will give you the fastest lap times. I have raced production cars, where the rules force you to stay with standard anti-sway bars (roll bars). This means your only methods of reducing body roll, dive, and squat to keep the tyre on the ground effectively is to increase spring and damping rates. This DOES NOT HELP traction. It's a trade-off. So testing is required to find the right balance.
The only reason Formula 1s have 3000lb springs is that they are highly aerodynamic devices and can't tolerate any changes in their tiny ride heights. If the designers had any other option, they'd soften the springs.
Altering the stiffness from front to read and side to side is necessary to control handling balance, but is a different topic to suspension firmness in itself.
3. I prefer a car that talks back to me right up to the point where the tyres slide and then some. If it's on rails it means I can't feel anything, and I have no idea where the limits are. People rave about tyres with high levels of grip, but I'd rather a tyre with slightly less grip but more feel. I guarantee you can go faster when you can feel what the tyre is doing than when you simply have high grip levels (being on rails).
4. I think the faster you shift, the better. So long as you can do it smoothly. Because all speed comes from smoothness.
Race cars have tiny flywheels and dog gears so they can make the shifts as close to instantaneous as possible. But don't go slamming your road gearbox around quickly if your flywheel isn't sized accordingly, or you will induce roughness that will slow you down.
Clayton
Last edited by gnosis; 01-27-2004 at 03:18 AM.
01-27-2004, 12:28 AM
#10
Heard this from one of my FSAE professors who tracks his 87 911 SC:
"Watch newer drivers at the corners. The car bobs just a little bit as they heel-toe, meaning they aren't keeping constant pressure on the break pedal. More often than not, the front end rises up, meaning they aren't breaking as hard as they can be; don't do this."
He stressed that alot too. It's all about making fluent motions and transitioning from one movement to the next smoothly. If you aren't smooth, you aren't fast.
"Watch newer drivers at the corners. The car bobs just a little bit as they heel-toe, meaning they aren't keeping constant pressure on the break pedal. More often than not, the front end rises up, meaning they aren't breaking as hard as they can be; don't do this."
Because all speed comes from smoothness.
01-27-2004, 12:42 AM
#11
TRB0 GUY
Rennlist Member
Rennlist Member
Join Date: Nov 2003
Location: Daphne, AL
Posts: 3,769
Likes: 0
Received 0 Likes
on
0 Posts
ok, this is the last time I'm posting about engine braking, i swear, lol... Maybe the words of Carroll Smith will better explain how I view engine braking... He admits that it is no longer needed on H-pattern, traditional manual transmissions, as modern brake pad material is more than sufficient to stop any car. However, he says that "rowing down through the gears... to save the brakes" is merely the "'traditional' way" of things. "The technique is not difficult to master and is a source of great satisfaction to the purists among us." THAT is exactly what I've been trying to say. Not needed, just still prefered by some. Fair enough? 
As for the "firmer is better" idea... that isn't the way I was tought. Once again, I believe a lot of this is opinion and preference. Chassis setup, within reason, dictates the limit characteristics of a car. For example, a firmer suspension setup will allow the car to corner faster, but only to a point. After that point, you might not hurt the cornering capability, but you will get your *** handed to you on the track... why? An ultra-stiff setup will not give far warning before the car swaps ends. If you find the point where the suspension's stiffness meets the tires' holding limit, while still keeping it as soft as possible, the car will begin to slide out before spinning your *** around with snap-oversteer. Also, body roll can play a good role in weight transfer to the outside tires, to a point.
-Kevin
As for the "firmer is better" idea... that isn't the way I was tought. Once again, I believe a lot of this is opinion and preference. Chassis setup, within reason, dictates the limit characteristics of a car. For example, a firmer suspension setup will allow the car to corner faster, but only to a point. After that point, you might not hurt the cornering capability, but you will get your *** handed to you on the track... why? An ultra-stiff setup will not give far warning before the car swaps ends. If you find the point where the suspension's stiffness meets the tires' holding limit, while still keeping it as soft as possible, the car will begin to slide out before spinning your *** around with snap-oversteer. Also, body roll can play a good role in weight transfer to the outside tires, to a point.
-Kevin
01-27-2004, 01:04 AM
#12
Instructor
Join Date: Apr 2002
Location: Sydney, Australia
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
Sure you can go down the box in sequence while you're braking, and use the engine revs (via heel-toe technique) to spin the box up to match the gears so they go in easy and take the strain off your synchros. But that isn't a braking technique. It's just getting the car in the right gear for when you have to accelerate. Some people go through all the gears, some miss a few on the way down. Doesn't matter so long as you're smooth.
Now, Kevin, some replies to your suspension comments.
"A firmer suspension will allow the car to corner faster, but only to a point" is incorrect, for the reasons I stated in my earlier post. Firm does not equal better by any simplistic measure.
Snap oversteer is caused by weight transfer. It can be adjusted by suspension stiffness across the car, but stiffness per se does not cause oversteer. Relative stiffness has an effect, though. Likewise, body roll does not cause weight transfer. In fact body roll does not affect weight transfer in the slightest.
Clayton
Now, Kevin, some replies to your suspension comments.
"A firmer suspension will allow the car to corner faster, but only to a point" is incorrect, for the reasons I stated in my earlier post. Firm does not equal better by any simplistic measure.
Snap oversteer is caused by weight transfer. It can be adjusted by suspension stiffness across the car, but stiffness per se does not cause oversteer. Relative stiffness has an effect, though. Likewise, body roll does not cause weight transfer. In fact body roll does not affect weight transfer in the slightest.
Clayton
01-27-2004, 01:14 AM
#13
TRB0 GUY
Rennlist Member
Rennlist Member
Join Date: Nov 2003
Location: Daphne, AL
Posts: 3,769
Likes: 0
Received 0 Likes
on
0 Posts
Hey Z-Man... this is a good thread by the way, kudos on that, this has been some good debating here!... are you planning on going to the 944Fest?
Technoduck... nice quote! (Mario seems to have so many) I think that one is going in my AIM profile soon
iloveporsches... amen to that... smooth is the key word on the track: smooth = stable, and keeping the car stable allows for greater speeds at the track!
I'm not expert either, and don't claim to be... just stating my opinions and facts as they were tought to me
-Kevin
Technoduck... nice quote! (Mario seems to have so many) I think that one is going in my AIM profile soon
iloveporsches... amen to that... smooth is the key word on the track: smooth = stable, and keeping the car stable allows for greater speeds at the track!
I'm not expert either, and don't claim to be... just stating my opinions and facts as they were tought to me
-Kevin
01-27-2004, 01:21 AM
#14
Nordschleife Master
In fact body roll does not affect weight transfer in the slightest
For example, you take a car with a lot of body roll and a soft rear suspension. You take a super hard and fast left hand turn. The weight all transfers to the right side, and the body rolls to the right as well as the car yaws (turns) to left. If you now have to change direction (such as in a chicane) you have to get all the weight to the other side and fast. If the rear is too soft, you get this feeling that is it bouncing back and forth or that the momentum of the car's body wants to push the tires in a direction you don't want them to go in. Its really hard for me to explain, but when I'm in my car I can feel it 100%.
Clayton - you are in a Clubsport so unless you have driven an 86 944t with a stock 86 suspension, you might not understand what I mean.. but admit it, even the CS could benefit from a slightly stiffer suspension - although it might make driving on the public roads unbearable!
Also, I think that if you increase your mechanical grip with Slicks, the suspension will sway more, especially the rears, and so you need to match it with stiffer sways and springs. Whereas before, the rear tires might start to drift a bit when the rear suspension hit a certain G loading, now the wheels (slicks) are holding the car in the corner, and the suspension and weight of the car is wanting to go further outside of the turn.
does that makes any sense? it does in my head.. maybe I didn't explain it properly..
01-27-2004, 01:39 AM
#15
Instructor
Join Date: Apr 2002
Location: Sydney, Australia
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
Re not having driven an 86 944T, let me give you a brief understanding of where I'm coming from. I've driven soft and firm road cars on the road, on the track, and in tarmac rally events. I've raced a Group N production race car (a Toyota MR2 with 580/700lb springs), and I've also raced a 2 litre Super Tourer (like the ones in the British Touring Car Series about 5 years ago - 330HP, 1050kgs, AP Racing brakes the size of wagon wheels, 6 speed sequential box so you have to go through each gear whether you like it or not and if you pick a gear in the wrong direction you instantly either bog the engine and lose two seconds or exceed the rev limit and grenade the engine (depending on which direction you went), with no synchros and you don't even use the clutch unless you feel like being friendly to it because they cost a fortune and everyone says "please try not to use the clutch because we didn't bring a spare"). All are enormously different, as you are no doubt aware. The 968CS is on the soft side for the track (note body roll in pic at left) but it's not bad in terms of body roll for the road. My point is I'm not just making comments from experience with a 968CS, and I can understand fully what an 86 944T would be like.
I think the best way to see what forces are responsible for what in car handling is to get one of the many good books that spell out the equations needed to calculate spring rates, weight transfer, etc. You will see, for instance, that the amount of body roll does not enter into the calculations for weight transfer and vice versa, ergo body roll HAS NO EFFECT on weight transfer. You can't argue the maths. Perception is one thing, and sure you will feel like you're experiencing much more weight transfer if your car is rolling when it turns, but this is just perception.
Stick with maths and you can't go wrong. It really helps you fight misconceptions about what physical properties of your car relate to its handling traits.
By the way, my tyre guys encouraged me to go to 1000lb spring rates on the MR2, and I lost 4 secs a lap (on a 1:50 lap). Stiffness didn't help traction one bit. Once I had enough spring rate to keep a good deal of the tyre contact patch on the road, more was only preventing the tyre from staying firmly in contact with the road surface.
If you want to go slower, just blindly keep making your car stiffer. You'll wonder why it feels so "solid" but your lap times suck.
Clayton
I think the best way to see what forces are responsible for what in car handling is to get one of the many good books that spell out the equations needed to calculate spring rates, weight transfer, etc. You will see, for instance, that the amount of body roll does not enter into the calculations for weight transfer and vice versa, ergo body roll HAS NO EFFECT on weight transfer. You can't argue the maths. Perception is one thing, and sure you will feel like you're experiencing much more weight transfer if your car is rolling when it turns, but this is just perception.
Stick with maths and you can't go wrong. It really helps you fight misconceptions about what physical properties of your car relate to its handling traits.
By the way, my tyre guys encouraged me to go to 1000lb spring rates on the MR2, and I lost 4 secs a lap (on a 1:50 lap). Stiffness didn't help traction one bit. Once I had enough spring rate to keep a good deal of the tyre contact patch on the road, more was only preventing the tyre from staying firmly in contact with the road surface.
If you want to go slower, just blindly keep making your car stiffer. You'll wonder why it feels so "solid" but your lap times suck.
Clayton