New thread for the Quattro cornering subject...
11-12-2001, 03:09 PM
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New thread for the Quattro cornering subject...
I'm no expert on this, so I'm going to simply stir the debate.
Anyhow, the comment about AWD not enhancing cornering seems strange. After all, as a car enters a turn it will put extreme horizontal (centrifugal force) pressures on the tires. If any slippage occurs, you have 3 other tires attempting to create forward momentum. Forward momentum decreases the horizontal pressures, thus lessening the chance of the vehicle losing control.
With 2WD, you have 2 tires that are essentially dumb; not creating forward momentum. The rear end swings out and the front tires are counter-steered. This counter-steer helps the vehicle go sideways and eventually forward.
The reason Rally drivers get the vehicle sideways prior to the turn is to minimize the attack angle. The more compass degrees you travel, the more likely centrifugal force will win over. They actually get the vehicle moving forward before they enter the turn. This proves that forward momentum lessens the centrifugal force. Otherwise they'd just keep going sideways over the cliff.
That's my first hack at it. Let's keep the debate tactful and informative. Please!
Anyhow, the comment about AWD not enhancing cornering seems strange. After all, as a car enters a turn it will put extreme horizontal (centrifugal force) pressures on the tires. If any slippage occurs, you have 3 other tires attempting to create forward momentum. Forward momentum decreases the horizontal pressures, thus lessening the chance of the vehicle losing control.
With 2WD, you have 2 tires that are essentially dumb; not creating forward momentum. The rear end swings out and the front tires are counter-steered. This counter-steer helps the vehicle go sideways and eventually forward.
The reason Rally drivers get the vehicle sideways prior to the turn is to minimize the attack angle. The more compass degrees you travel, the more likely centrifugal force will win over. They actually get the vehicle moving forward before they enter the turn. This proves that forward momentum lessens the centrifugal force. Otherwise they'd just keep going sideways over the cliff.
That's my first hack at it. Let's keep the debate tactful and informative. Please!
11-12-2001, 03:53 PM
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My thoughts go to aggressive street driving, not rally...
Total force on the tires consists of acceleration vector and cornering vector. The sum must remain below the static friction (simplistically put).
You have less torque per tire, to more tires, with Quattro. Your tires are thus closer to each other in total force, and more likely to remain below traction, allowing a normal "on rails" tracking of teh corner. If they slip, Quattro is more likely to be able to control slip with less reduction of total torque to the road.
With FWD or RWD, all the power is through 2 tires. Higher torque thus reduces the cornering force you can apply before exceeding the grip. If you slip, ESP has to cut back on half of your power, not one quarter.
You win in at least these two ways.
More dynamic driving, I do not yet understand well enough to pose an explanation. No doubt someone else will.
You have less torque per tire, to more tires, with Quattro. Your tires are thus closer to each other in total force, and more likely to remain below traction, allowing a normal "on rails" tracking of teh corner. If they slip, Quattro is more likely to be able to control slip with less reduction of total torque to the road.
With FWD or RWD, all the power is through 2 tires. Higher torque thus reduces the cornering force you can apply before exceeding the grip. If you slip, ESP has to cut back on half of your power, not one quarter.
You win in at least these two ways.
More dynamic driving, I do not yet understand well enough to pose an explanation. No doubt someone else will.
11-12-2001, 05:08 PM
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Re: New thread for the Quattro cornering subject...
It's basically about distributing torque out to four tires instead of two; it's much easier to break the wheels loose when a given amount of torque is fed to two wheels instead of four.
Look at it this way:
If you take a quattro A6 and a front wheel drive A6, get them both up to the exact same speed, and then coast both through the same slippery (rain, ice, etc.) corner, they'll pretty much be able to coast through the corner at the same speed (with some difference due to the extra weight and distribution of the quattro system and so on). That's pure roadholding.
If you take the same two cars, get them both up to the exact same speed, and then drive through the same slippery (rain, ice, etc.) corner under full power, it's MUCH more likely that the front wheel drive car will overpower the traction that the two tires can provide. In a front wheel drive car, you'd possibly end up understeering (plowing) through the corner if the front tires lose grip. In a rear wheel drive car, you'd possibly end up oversteering (skidding) through the corner if the rear wheels lose grip. I use both these features to great effect in my 911 at the track.
Look at it this way:
If you take a quattro A6 and a front wheel drive A6, get them both up to the exact same speed, and then coast both through the same slippery (rain, ice, etc.) corner, they'll pretty much be able to coast through the corner at the same speed (with some difference due to the extra weight and distribution of the quattro system and so on). That's pure roadholding.
If you take the same two cars, get them both up to the exact same speed, and then drive through the same slippery (rain, ice, etc.) corner under full power, it's MUCH more likely that the front wheel drive car will overpower the traction that the two tires can provide. In a front wheel drive car, you'd possibly end up understeering (plowing) through the corner if the front tires lose grip. In a rear wheel drive car, you'd possibly end up oversteering (skidding) through the corner if the rear wheels lose grip. I use both these features to great effect in my 911 at the track.
11-12-2001, 05:12 PM
#4
I just came from the track. The quattro was awesome. MR2 event at Big Wlllow.
Perfect example. I had this Viper driver all day. The car could out run me and probably out brake me all day. But we would get into corners and I would be WOT and pulling away. He would go 1/2 throttle and spin off the track. I dont consider this a real match, he was not a very good driver. It was a lot of fun he would leave me on the straights, pick a bad line, I'ld catch ,he'd leave me again, bad line again,but as our speed increased his lines caught up with him and off he would go.
I could hold an inside line that no one on the track could at WOT. Only quattro could do this.
How this relates to driving on the street. Who knows.:-)
<img src="http://members.aol.com/bandrscen/a14.jpg">
I could hold an inside line that no one on the track could at WOT. Only quattro could do this.
How this relates to driving on the street. Who knows.:-)
<img src="http://members.aol.com/bandrscen/a14.jpg">
11-12-2001, 05:25 PM
#5
Compare testing of a Porsche 996 C2 vs. the heavier C4....
Skid pad numbers are better for C4 and slalom is equal with the heavier C4 reeling it in. Same motor, same chassis; but better overall results with the C4. That is without traction limiters that are found in the real world. Quattro everytime, please. 
11-12-2001, 06:35 PM
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Yep, I can attest, saw him go by and followed best I could...
Quattro lines were different and Brian's line was awesome. But the best part was when it started to sprinkle a bit in the afternoon. Those of us with squirrelly mid-engined cars started packing up but Brian's eyes lit up and back to the track he went.....There was an undeniable quattro difference!
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11-12-2001, 06:44 PM
#9
The Pilot Sports are toast,cupped and growling, hydroplane city on the way home.
But 15K and 4 track days they should be. Brakes held up fine, I was good to them.
i know what ESP does now. I was in a continuous downpour at about 65 MPH and I could feel it cycling thru the wheels trying to keep control with those bad tires.
i know what ESP does now. I was in a continuous downpour at about 65 MPH and I could feel it cycling thru the wheels trying to keep control with those bad tires.