Torque-steer and AWD
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Torque-steer and AWD
Most of us understand that when you turn the axis of a rotating wheel, there's torque steer due to angular momentum. When you turn a wheel that's a driving wheel during acceleration, the torque steer is increased and that contribute to more unexpected and adverse handling of the car. That's one of the reasons why we love RWD cars. What about AWD cars?
One of the reasons why race cars place their driving wheels on the rear is to avoid torque steer, among other reasons. In implementing AWD, wouldn't that bring back torque steer? What's up with the selling point of the AWD Bimmers and WRX? I must be missing something here: it seems counter-intuitive to me. Anyone?
One of the reasons why race cars place their driving wheels on the rear is to avoid torque steer, among other reasons. In implementing AWD, wouldn't that bring back torque steer? What's up with the selling point of the AWD Bimmers and WRX? I must be missing something here: it seems counter-intuitive to me. Anyone?
Last edited by ArthurY; 07-30-2006 at 05:12 PM.
#2
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i'm no rocket scientist , but from my understanding awd stops torque steer by sending power to the rear wheels. see in awd and mainly the more advanced versions in sti's and evo's, not every wheel constantly gets equal power (thats called 4x4.) In awd if torque steer is detected power shifts to the rear, if over steer is detected it shifts to the front. also depends on the car, (i might be wrong here) but i sti is more tuned to deliver more power constantly to the rear, behaving more like a rwd once its at speed, while an evo will send most power to the front expect for matters like from a complete stop.
thats my humble understanding, though it is limited.
thats my humble understanding, though it is limited.
#3
Torque steer comes from uequal length halfshafts. It's not as bad when its in the front as it is when it's in the back like on some of the MR2's and Fiero. Even then it's not too bad under about 200 HP.
AWD just means less wheel spin under extreme situations. Modern cars put heavy sway bars in them which has the effect of lifting the inside tires around turns. Even with limited slip there is a decoupling of traction. AWD just minimizes that.
Finally rallye racing where the4 AWD cars really shine. If you've never seen what rallyes are all about, then strap on a helmet, buckle up, and watch the following two videos. Oh yeah, be sure to open them full screen and sit back about 4 feet.
WRC
Now once you've caught your breath, this one is, well, simply spectacular...Oh yeah, listen closely - almost the entire time Ari's on the gas, all 4 wheels are spinning - even when he's clocked on radar at over 150 MPH!
Pikes Peak
AWD just means less wheel spin under extreme situations. Modern cars put heavy sway bars in them which has the effect of lifting the inside tires around turns. Even with limited slip there is a decoupling of traction. AWD just minimizes that.
Finally rallye racing where the4 AWD cars really shine. If you've never seen what rallyes are all about, then strap on a helmet, buckle up, and watch the following two videos. Oh yeah, be sure to open them full screen and sit back about 4 feet.
WRC
Now once you've caught your breath, this one is, well, simply spectacular...Oh yeah, listen closely - almost the entire time Ari's on the gas, all 4 wheels are spinning - even when he's clocked on radar at over 150 MPH!
Pikes Peak
#4
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Gotta love the Pikes Peak Hil Climb! Oldest auto race in th US.
The WRC compilation video was actually produced by a member of the community at www.iwsti.com. He has one for each of the last 4 seasons. Check out the video section there for more. They are all pretty cool.
The WRC compilation video was actually produced by a member of the community at www.iwsti.com. He has one for each of the last 4 seasons. Check out the video section there for more. They are all pretty cool.
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