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Oversteer or Understeer

Which characteristic is most common to 911's?

Oversteer or understeer?

I'd naturally think understeer since the motor and majority of the weight is in the rear but I wanted to see what everyone else thinks.

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Old 01-07-2004, 04:35 PM
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They do both at different times. But mostly oversteer. The wicked one is the off throttle induced oversteer. Kinda like driving a big rig truck, you start slowing in a turn and the cargo wants to keep on coming.

Go out to a parking lot and start a nice big fast turn. Keep turning until the tires squeel. And then lift. Don't do this near a light pole, 'cause you don't know where you're gonna end up.

If you don't want to cause a scene, do this in the rain. I think everyone ought to do this at least once.
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Old 01-07-2004, 05:06 PM
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I've read somewhere that a large majority of early 911 turbos almost always met there fate with the rear end demolished.
Old 01-07-2004, 05:10 PM
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Quote:
Originally posted by Zeke
They do both at different times. But mostly oversteer.
Thats surprising to me since I thought that it is natural for rear weighted cars to be more prone to understeer and front weighted cars to suffer from oversteer.

Personally I havent had enough seat time in my car to tell what it has more of. Perhaps its just right?
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Old 01-07-2004, 08:04 PM
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You should try the parking lot thing as Zeke suggested. Any deceleration in a corner & that big heavy engine behind you isn't going to play ball. It can be very scary & is something you never want to happen out on the road.
Old 01-07-2004, 08:10 PM
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[tic] . .but wait; that 'big heavy engine' provides more downforce, on those big fat tires[/tic]

seriously, though. ..
They are set-up from the factory to "mostly understeer".

Understeers are usually easier to (instictively) recover from; so thats how the factory set them.

(and, of course, nobody messes with the factory settings)
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Old 01-07-2004, 08:20 PM
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911s tend to understeer when they are not pushed to the limit. As you approach the limit they begin to oversteer.

Race cars are always at the limit. And street cars get into to trouble at the limit. Nothing else really matters. So it is this oversteer behaviour that has come to be both feared, revered and closely associated with the 911.

It's also why the 911 is steered with the throttle when at the limit.
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Old 01-07-2004, 08:35 PM
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Chuck, can you elaborate on "steering with the throttle"? Is that to induce oversteer to whip around corners?
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Old 01-07-2004, 08:39 PM
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My 2 cents...
I think the oversteer reputation the 911 has is based mostly on the guys that do get in trouble and lift, trailing throttle oversteer.

To answer your question...
IMHO..Compared to other sports cars...
A stock 911 may have more trailing throttle oversteer.
About the normal amount of power understeer.

I'd say a lot depends on the driver.
How he controls the weight transfer.
For ex,
Entering a turn...
Go in hot lift abruptly and load the front, oversteer.
Go in slow and on gas too early expect understeer on the apex and track out.

Again IMHO driving/racing a 911 near its limits is learning how to pitch and catch the rear weight. You can do it in any gear at any speed. You learn to drive it with the gas pedal and not the wheel.
Old 01-07-2004, 08:43 PM
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steer with throttle, the car is loose and your are loosing it, stump the gas and you will drive out of it, been their done that, it works, (well maybe not stump, i would say pressing the pedal to gain forward momentum rather then sideways momentum, or actually to get the rear wheels to bite, the your able to drive out of it even while cornering), sounds dumb but works, you could say to bring the car back in control as a drift, Kevin
Old 01-07-2004, 09:03 PM
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911's understeer until the driver screws up and then they oversteer. Of course you can intentionally get them to oversteer, but that's less common and usually for fun or show.
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Old 01-07-2004, 10:22 PM
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masraum, there was no fun or show when my car has got loose trust me, there has been may people here that has hit a off ramp to hard and the car went around, pretty common, the only way to stop it is hit the gas, those that lift off the gas find the rear facing where the front used to be, Kevin
Old 01-07-2004, 10:26 PM
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I recall watching the video of the guy at the RING driving that yellow bird ruf. I was amazed at how he was all over the gas pedal the whole time even when the car looked like it was going to loose it.
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Old 01-07-2004, 10:41 PM
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Pitch and catch should be in every 911 driverís playbook.
It is as basic as heel and toe downshifting to performance drivers.

Pitch is to lift throttle and rotate the rear while transferring weight to the front wheels.
Catch is to apply throttle to transfer the weight to the rear wheels creating more rear traction.

You may instinctively be doing it and not realize it?
You are steering the car with the gas pedal.

It can be for fun or to show off.
It can also be used for accident avoidance among other useful scenarios.

The pitch can be a huge second gear 30 degree rotation or as subtle as a 120mph 5th gear breathe to create a touch more steering.

Sorry but if you havenít mastered the pitch and catch in a 911 you are missing an important technique.

This is power oversteer.
Old 01-07-2004, 10:47 PM
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Quote:
Originally posted by Beethoven
Chuck, can you elaborate on "steering with the throttle"? Is that to induce oversteer to whip around corners?
Oversteer happens when the slip angle of the rear tires is greater than the slip angle of the front tires. Note that slip angle has nothing to do with slipping or loss of traction. It is the difference between the direction the wheel is pointed and the direction the wheel is traveling. Flex and distortion of the tires ensures these are not the same in a turn.

Rolling on the throttle causes weight transfer to the rear. More weight on the rear reduces the slip angle of those tires and reduces oversteer. Ease off the throttle, rear slip angle increases and you have more oversteer. The extreme example is the feared lift-throttle-oversteer.

Masraum, oversteer is not about showboating or loss of control. We are not talking about loss of traction or spinning the tires. A 911 operating at the cornering limit is doing a careful balancing act that is all about controlling oversteer with the throttle.

The street is no place to experiment with this. Check out a high performance driving school with good instruction. Be warned, it's likely to start an expensive addiction.
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Old 01-07-2004, 10:58 PM
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Quote:
Originally posted by smestas
I was amazed at how he was all over the gas pedal the whole time even when the car looked like it was going to loose it.
I rode in a 911 at the track that had carbs.. the pitch and catch throttle response was wonderful w/carbs from my prospective.
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Old 01-08-2004, 02:14 AM
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Quote:
Originally posted by ted
Pitch and catch should be in every 911 driverís playbook.
It is as basic as heel and toe downshifting to performance drivers.


I agree 100% that is why I don't recommend Big Willow as a students first track experiance. Much better to practice those technics at 40-50, then turn eight aor nine.

Once you can master that. you'll be ready for anything the 911 can throw at you.



Personally, Every stock 911 I've driven I thought understeered like a pig. you could induce oversteer, but the natural tendency is understeer.
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Old 01-08-2004, 02:30 AM
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"Pitch and Catch" sounds altogether too drastic to me. Sure you can "Pitch and Catch", but that's not the fast way. The fast way is to modulate the throttle to get the car to travel where you want to go. You don't want to loose traction at either end, but rather stay in the zone where one end or the other is on the verge of losing traction, but not quite there. Once you lose traction at one end or the other, you're going to be in catch-up mode until that end recovers traction -- and while you're in catch-up mode someone who hasn't lost traction will be driving away.

One of the secrets of Senna's driving technique was that he would be constantly making attitude corrections by minute throttle changes. He'd never quite be losing traction, but never quite with full traction either. It goes back to the traction circle concept. I've tried making a graph for comparison.



The big exception to this idea that I can think of is the Handbrake-turns done by rally drivers, but Rally driving is another discussion all together.
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Old 01-08-2004, 03:08 AM
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The place to learn this technique is AUTOCROSS. You don't want your first experience with lift-throttle oversteer to be on a big track at speed: you will lose it and not get it back until concrete meets rear license panel.

A well-designed autocross course will include sections where the car will oversteer, understeer, and actually encourage you to lift to rotate the car. You can also practice "both feet in" spin recoveries multiple times. I highly recommend that and any skidpad time you can beg, borrow or steal as a way to explore the unique handling of the 911.

I have yet to experience power oversteer, with only 155 HP it's tough to do unless you are in the rain (or driving on the grass as I seem to do lots).
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Old 01-08-2004, 05:51 AM
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Quote:
Originally posted by jluetjen
"Pitch and Catch" sounds altogether too drastic to me.
Hi John,
The SDR PCA term pitch and catch is just our slang for the same technique you explained.
We are all talking about the same technique.
I agree throttle steer does sound less drastic than pitch and catch when refering to this technique in 3rd, 4th or 5th gears.

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Old 01-08-2004, 06:56 AM
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