Handling Question
Three Wheelin'
Joined: Jul 2007
Posts: 1,649
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From: NJ
Lifting the trottle in a turn near the limit of adhesion was a dangerous situation mainly with pre 993 models. This was not only due to the weight transfer but also because the older models, with a traditional semi trailing arm set up would actually turn the rear wheels outward ( in the trailing throttle mode). During a turn, with the outside rear wheel (with more weight than the inside) would contribute significantly to steering the rear of the car outward. At the limit this could/would be disasterous.
Nordschleife Master
Joined: Oct 2004
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From: Vacuuming Cal Speedway
Originally Posted by 996toomey
If you like sport on try putting shocks in the softer of the 2 settings (shocks off). Also slight trail braking is necessary to keep the weight forward during turn in. Do not get on gas hard until steering wheel is straightened out.
Nordschleife Master
Joined: Oct 2004
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From: Vacuuming Cal Speedway
Originally Posted by 911Dave
I don't completely understand the physics myself, but increasing tire pressure increases its load capacity, which affords it better shape retention on hard cornering, as well as crisper turn-in.
If you do a web search on understeer, you'll find countless references to using tire pressure to increase/decrease understeer or oversteer.
Here's an article at Tire Rack
Here's a list of handling corrections
Here's the most concise explanation I found:
"Using tire pressure to eliminate oversteer and understeer by balancing slip angles between front and rear:
Slip angle is the difference between the vector drawn thru where a tire is aimed and the vector drawn thru its actual direction of travel. Slip angle is determined by how much your contact patch distorts in cornering and you can change that by changing tire pressure. Increasing pressure will reduce contact patch distortion and reduce slip angle.
Neutral steer occurs when slip angles are balanced front to rear.
Oversteer occurs when rear slip angles exceed front slip angles.
Understeer occurs when front slip angles exceed rear slip angles.
Balance between front and rear is what matters, so you can reduce oversteer by increasing rear pressure OR decreasing front pressure and you can reduce understeer by increasing front tire pressure OR decreasing rear tire pressure."
If you do a web search on understeer, you'll find countless references to using tire pressure to increase/decrease understeer or oversteer.
Here's an article at Tire Rack
Here's a list of handling corrections
Here's the most concise explanation I found:
"Using tire pressure to eliminate oversteer and understeer by balancing slip angles between front and rear:
Slip angle is the difference between the vector drawn thru where a tire is aimed and the vector drawn thru its actual direction of travel. Slip angle is determined by how much your contact patch distorts in cornering and you can change that by changing tire pressure. Increasing pressure will reduce contact patch distortion and reduce slip angle.
Neutral steer occurs when slip angles are balanced front to rear.
Oversteer occurs when rear slip angles exceed front slip angles.
Understeer occurs when front slip angles exceed rear slip angles.
Balance between front and rear is what matters, so you can reduce oversteer by increasing rear pressure OR decreasing front pressure and you can reduce understeer by increasing front tire pressure OR decreasing rear tire pressure."
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Burning Brakes
Joined: Mar 2005
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Originally Posted by joolsbourne
You could just fill it with fuel and try again. Vast difference in handling with full fuel tank. Less skipping at the front.
Three Wheelin'
Joined: Oct 2004
Posts: 1,696
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From: Stevenson Ranch, CA
Originally Posted by jrgordonsenior
Can you apply throttle when you're on your brakes in your car? I ask because I can't in mine, it's just cuts out. A friend loaded the GIAC sofware and said it eliminated the throttle cut off allowing him to trailbrake with some maintainance throttle which is desirable.
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From: Los Angeles, CA
Originally Posted by Lori
Recently, during a somewhat spirited drive on twisty country roads the front end kind of my Carrera S felt like it was skipping across the slightly uneven though otherwise smooth pavement. Is this normal?
A little throtle while the wheel is turned can unload the front end to where it may skip a bit...
What speeds are we talking about when this occured?
Real understeer is interesting... the wheel is turned and the car wants to go straight.
Attend PDE (PSDS) and learn a bit more of vehicle dynamics
Three Wheelin'
Joined: Jul 2007
Posts: 1,649
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From: NJ
What's the difference between oversteer and understeer?.......
Oversteer is when the driver is calm but the passengers are scared. Understeer is when the passengers are calm but the driver is scared
Oversteer is when the driver is calm but the passengers are scared. Understeer is when the passengers are calm but the driver is scared
Race Director
Joined: Mar 2006
Posts: 15,362
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From: Tampa
Lori, you experiance understeer or sometimes it is call push. I HIGHLY suggest you go to your local clubs DE (Drivers Ed) track day and/or auto cross to learn more about how to control a Carrera in these conditions. I have been doing DE's and Autox's now since last November and will probably do 10 of them this year. I have learned a vast amount about car control and set up (tire pressure and alingment) and still have so much more to learn as I push my limits.
Race Director
Joined: Mar 2006
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From: Tampa
Originally Posted by Lori
I really do want to go to PDE.
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Burning Brakes
Joined: Mar 2005
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Originally Posted by mdrums
I did PDE back in March of this year. Best present my wife ever gave me and money well spent. You will get awesome instruction, gain knowledge and confidence in your newly learned skills and you cars abilities. Take the 2 day course though...it is the only way to go and extremely well worth it.
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From: Los Angeles, CA
Originally Posted by Lori
Porsche has a 2 day women's PDE. I wonder how it differs (other than the obvious) from the regular 2 day PDE.