Quattro's Rule !! Snow causes Traffic Havoc, its been coming down at a rapid pace this mornin
12-18-2005, 05:19 PM
#31
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I disagree with the it's difficult to spin a FWD car
It's very easy with an inexperienced driver or one that doesn't understand the dynamics of how the car behaves.
Trust me, I do. FWD automatic 1986 front end heavy 5000S around a corner. Lifted off the throttle too quickly which effectly brakes the front tires while the backend receives no braking. Front end really wants to slow down, weight distribution shifts forward, back end gets light and wants to continue the same rate of speed and now you have the back end coming around. Get on the throttle but now it's too late. You're now pointing the wrong direction.
Also I think you're preaching to the wrong crowd here. We're not that stupid that we're going to expect AWD to bend the laws of physics. People here, as true Audi quattro enthusiasts, understands what the AWD system can do and can't do.
Go and preach to the drivers who get their AWD cars and SUVs stuck in the ditch. They think AWD helps them with slowing down which it doesn't obviously. They think AWD can get them around a corner without slowing down. They are the ones that don't understand what it can do and can't do. Frankly, they are probably better off with FWD or even RWD with proper tires for the conditions.
Actually I think every new driver should take a mandatory driving course, both summer and winter. It would make the roads much safer for everybody.
Trust me, I do. FWD automatic 1986 front end heavy 5000S around a corner. Lifted off the throttle too quickly which effectly brakes the front tires while the backend receives no braking. Front end really wants to slow down, weight distribution shifts forward, back end gets light and wants to continue the same rate of speed and now you have the back end coming around. Get on the throttle but now it's too late. You're now pointing the wrong direction.
Also I think you're preaching to the wrong crowd here. We're not that stupid that we're going to expect AWD to bend the laws of physics. People here, as true Audi quattro enthusiasts, understands what the AWD system can do and can't do.
Go and preach to the drivers who get their AWD cars and SUVs stuck in the ditch. They think AWD helps them with slowing down which it doesn't obviously. They think AWD can get them around a corner without slowing down. They are the ones that don't understand what it can do and can't do. Frankly, they are probably better off with FWD or even RWD with proper tires for the conditions.
Actually I think every new driver should take a mandatory driving course, both summer and winter. It would make the roads much safer for everybody.
12-18-2005, 07:09 PM
#34
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Nonsense, you're confusing two separate effects
Weight transfer provides at best a momentary tendency to oversteer. With the same tires on each end of the car, properly inflated, it is extremely difficult to induce oversteer in a fwd car. What you describe is nothing more than areduction in understeer caused by weight transfer effects. it should be obvious that weight transfer is much less on slippery roads for obvious reasons.
Once the weight has fully transferred the front tires will develop greater slip angles and understeer will result.
I'm not preaching, I'm suggesting that quattro drive isn't magic. It's a good system but not magical.
Once the weight has fully transferred the front tires will develop greater slip angles and understeer will result.
I'm not preaching, I'm suggesting that quattro drive isn't magic. It's a good system but not magical.
12-18-2005, 07:21 PM
#35
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Because at worst if the awd has the same tires
it's obvious that it couldn't do worse than fwd.
I just assumed everyone was familiar with Road & Track's back to back testing of awd with regular against fwd with snow tires. Snow tires are a lot cheaper and ultimately more effective than awd. With snow tires you don't need awd.
My point has always been that fwd is sufficient for Canadian winter driving as long as you use four winter tires.
I also emphasize that awd offers no practical advantage over fwd in winter because getting going is not the problem, steering and braking are the issues.
I enjoy awd as much as the next guy but I get a little tired of people extolling the supposed virtues of awd when they obviously know little or nothing about what the vehicle dynamics actually are.
Essentially, for street driving awd requires a substantial weight penalty without corresponding advantages which is why very few manufacturers bother with the expense and complication of awd over two wheel drive. Audi trades on its deserved reputation based on the Quattro rally car but you may note that Audi no longer wins in that arena. Audi currently excels in rwd only Le Mans type racers!
It is required by physics that awd chassis will understeer. The reason is simple: the rear wheels always push straight forwards, just like a rwd car which always loads the front tires with extra work to do. In a rwd car the driving torque eventually overcomes the rear grip and allows the driver to turn the car by causing oversteer. In an awd situation the front tires are always trying to drive the car as well as steer, the more torque the driver tries to put through the rear wheels the more torque also goes through the front wheels, resulting in terminal understeer. This is why Porsche awd biases the drive torque heavily towards the rear, by as much as 90/10 and an awd Porsche will still understeer at the limit. This also why Porsche continues to offer their top perfromance versions in rwd only.
It is exceptionally difficult to induce a truly balanced four wheel drift in an awd car. On dry pavement it is virtually impossible. On loose surfaces it is feasible and is the main reason for very powerful rally cars to have adopted awd.
I just assumed everyone was familiar with Road & Track's back to back testing of awd with regular against fwd with snow tires. Snow tires are a lot cheaper and ultimately more effective than awd. With snow tires you don't need awd.
My point has always been that fwd is sufficient for Canadian winter driving as long as you use four winter tires.
I also emphasize that awd offers no practical advantage over fwd in winter because getting going is not the problem, steering and braking are the issues.
I enjoy awd as much as the next guy but I get a little tired of people extolling the supposed virtues of awd when they obviously know little or nothing about what the vehicle dynamics actually are.
Essentially, for street driving awd requires a substantial weight penalty without corresponding advantages which is why very few manufacturers bother with the expense and complication of awd over two wheel drive. Audi trades on its deserved reputation based on the Quattro rally car but you may note that Audi no longer wins in that arena. Audi currently excels in rwd only Le Mans type racers!
It is required by physics that awd chassis will understeer. The reason is simple: the rear wheels always push straight forwards, just like a rwd car which always loads the front tires with extra work to do. In a rwd car the driving torque eventually overcomes the rear grip and allows the driver to turn the car by causing oversteer. In an awd situation the front tires are always trying to drive the car as well as steer, the more torque the driver tries to put through the rear wheels the more torque also goes through the front wheels, resulting in terminal understeer. This is why Porsche awd biases the drive torque heavily towards the rear, by as much as 90/10 and an awd Porsche will still understeer at the limit. This also why Porsche continues to offer their top perfromance versions in rwd only.
It is exceptionally difficult to induce a truly balanced four wheel drift in an awd car. On dry pavement it is virtually impossible. On loose surfaces it is feasible and is the main reason for very powerful rally cars to have adopted awd.
12-18-2005, 07:25 PM
#36
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Nonsense, I suppose you think Porsches oversteer
because they have a rear weight bias.
Chassis balance isn't that simple.
If you doubt that, try hammering a standard US built pick up truck on any kind of road. I guarantee that you can get that puppy to oversteer at the drop of a throttle and it is really nose heavy.
Audi's, like all awd cars, must understeer at the limit because the physics say so. You can't drive the front wheels and steer them at the same time and have the chassis oversteer.
Even Porsche's awd system with torque split as much as 90% to the rear can't get away from this effect. To get your Porsche properly sideways under power only you must drive a rwd version.
Chassis balance isn't that simple.
If you doubt that, try hammering a standard US built pick up truck on any kind of road. I guarantee that you can get that puppy to oversteer at the drop of a throttle and it is really nose heavy.
Audi's, like all awd cars, must understeer at the limit because the physics say so. You can't drive the front wheels and steer them at the same time and have the chassis oversteer.
Even Porsche's awd system with torque split as much as 90% to the rear can't get away from this effect. To get your Porsche properly sideways under power only you must drive a rwd version.
12-19-2005, 05:19 AM
#39
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Perhaps you missed the initial discussion of the Road and track article
we had here a few months back ??
You do realize they were testing a FWD car shod with Winters over an AWD shod with NON winters ?
Come back to us when they compare Apples to Apples !!
* btw, the only reason why Audi got out of Rallye Racing was due to the weight penalties imposed on them as well as HP restrictions, cause of their total domination of the sport!!
Thanks for playing !!
Best Regards !!
You do realize they were testing a FWD car shod with Winters over an AWD shod with NON winters ?
Come back to us when they compare Apples to Apples !!
* btw, the only reason why Audi got out of Rallye Racing was due to the weight penalties imposed on them as well as HP restrictions, cause of their total domination of the sport!!
Thanks for playing !!
Best Regards !!