Embarrasing moment for the new Q5 at an offroad test
02-09-2009, 09:14 PM
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Embarrasing moment for the new Q5 at an offroad test
Repost?<ul><li><a href="http://www.youtube.com/watch?v=mkQ5yBnS4SU&">Youtube Video - car to blame?</a></li></ul>
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02-10-2009, 06:17 AM
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The torsen diff is the centre differential and thus shifts torque front to rear and vice versa
The differentials for the front and rear axle are open differentials. Therefore if you have one wheel on the front that has traction and the other opposite wheel on the rear axle that has traction, we can assume that the centre diff is sending 50% of the torque to the front and 50% to the rear.
Now what happens is that because the front/rear are not limited slip differentials, the torque gets shifted to the wheel with less grip, in this case, the one up in the air which is no good.
This is where EDL comes into play. The system will apply the brakes to the wheel that is spinning away thus some of the torque gets shifted to the other wheel that does have traction and the car can continue to move.
Some cars do use a torsen diff for the rear like Subaru. I think long term for Audi, they'll start to use the "port differential" in the rear which is electronically controlled to shift torque dynamically, which will be available in the B8 S4.
Now what happens is that because the front/rear are not limited slip differentials, the torque gets shifted to the wheel with less grip, in this case, the one up in the air which is no good.
This is where EDL comes into play. The system will apply the brakes to the wheel that is spinning away thus some of the torque gets shifted to the other wheel that does have traction and the car can continue to move.
Some cars do use a torsen diff for the rear like Subaru. I think long term for Audi, they'll start to use the "port differential" in the rear which is electronically controlled to shift torque dynamically, which will be available in the B8 S4.