quattro - What Type?

[Garry Houseman]

I have a 2014 A4 2.0 tdi 177 quattro, could anyone explain what type of awd system it is and how it works, cheers

 

[jdp1962]

It's a permanent 4WD system, using the "torsen" technology detailed here. It's the current evolution of the original system, and is different from the temporary 4WD "Haldex" system used on the A3.

 

[Chris90]

I guess its this system?

Vectoring quattro system[edit]
Audi's new sport differential, debuted 'torque vectoring' to quattro generation V. The Audi sport differential allowed the dynamic allocation of torque across the rear axle of the debut vehicle: the B8 (2008) S4, and is now an optional addition to all quattro vehicles, which continue to use the 40:60 asymmetric Torsen (Type "C") centre differential. The sport differential replaces the normal open rear differential while the front axle still rely on an open differential with EDL.[4]

The torque vectoring rear axle differential is designed and manufactured by Magna Powertrain,[5] and is being offered on Audi A4, A5, A6 and their derivatives (including RS models). The Sport Differential selectively distributes torque to the rear axle wheels thereby generating a yaw moment, which improves handling and also stabilizes the vehicle when it oversteers or understeers, thereby increasing safety.

The sport differential operates by using two superposition ("step up") gears at the differential, which are operated via multi-plate clutches each side of the differential crown wheel. When required by the software (using lateral and longitudinal yaw sensors, the ABS wheel sensors, and a steering wheel sensor), the control software (located in a control unit close to the rear differential), actuates the relevant clutch pack. This has the effect of taking the output shaft drive through the step-up gear to the attached wheel, while the other shaft continues to drive its wheel directly (i.e., the clutch pack not actuated). The higher speed output shaft produces increased torque to the wheel, producing a yaw (turning) moment. In normal operation increased torque is delivered to the wheel on the outside of the turn thereby increasing the vehicles turning moment, in other words, its willingness to turn in the direction pointed by the steering wheel.

 

[DeanoC]

I guess its this system?

Vectoring quattro system[edit]
Audi's new sport differential, debuted 'torque vectoring' to quattro generation V. The Audi sport differential allowed the dynamic allocation of torque across the rear axle of the debut vehicle: the B8 (2008) S4, and is now an optional addition to all quattro vehicles, which continue to use the 40:60 asymmetric Torsen (Type "C") centre differential. The sport differential replaces the normal open rear differential while the front axle still rely on an open differential with EDL.[4]

The torque vectoring rear axle differential is designed and manufactured by Magna Powertrain,[5] and is being offered on Audi A4, A5, A6 and their derivatives (including RS models). The Sport Differential selectively distributes torque to the rear axle wheels thereby generating a yaw moment, which improves handling and also stabilizes the vehicle when it oversteers or understeers, thereby increasing safety.

The sport differential operates by using two superposition ("step up") gears at the differential, which are operated via multi-plate clutches each side of the differential crown wheel. When required by the software (using lateral and longitudinal yaw sensors, the ABS wheel sensors, and a steering wheel sensor), the control software (located in a control unit close to the rear differential), actuates the relevant clutch pack. This has the effect of taking the output shaft drive through the step-up gear to the attached wheel, while the other shaft continues to drive its wheel directly (i.e., the clutch pack not actuated). The higher speed output shaft produces increased torque to the wheel, producing a yaw (turning) moment. In normal operation increased torque is delivered to the wheel on the outside of the turn thereby increasing the vehicles turning moment, in other words, its willingness to turn in the direction pointed by the steering wheel.

That's an option on the Quattro setup to move torque left and right at the rear. Standard Quattro moves it front and back and then does left and right torque vectoring via the application of the brakes.

It's a great addition.

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[jdp1962]

I love my sports diff!

 

[DeanoC]

I love my sports diff!

I'm with you. Superb piece of kit!

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[Chris90]

So what does the stock one do? front/rear split with application of the brakes?

 

[DeanoC]

So what does the stock one do? front/rear split with application of the brakes?

There are a fair few versions but this gives you an idea:

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[Chris90]

I see.

Do love the quattro and the feel it gives on the road through corners etc. But when the back end starts to overtake the front (especially if your going round a long corner at a decent speed) unless you immediately lift off, the 4wd system/traction control can get confused and keep all 4 wheels spinning until the point your at 1/4 opposite lock and past the point of no return. had a couple of times where its become a tank slapper because the traction failed to kick in and see the car was effectively in a 'skid'.

 

[DeanoC]

I see.

Do love the quattro and the feel it gives on the road through corners etc. But when the back end starts to overtake the front (especially if your going round a long corner at a decent speed) unless you immediately lift off, the 4wd system/traction control can get confused and keep all 4 wheels spinning until the point your at 1/4 opposite lock and past the point of no return. had a couple of times where its become a tank slapper because the traction failed to kick in and see the car was effectively in a 'skid'.

It's like any car where you need to figure how to handle it. To be fair if you have all 4 wheels spinning round a corner then there is not much any tech is going to do.

Most tank slappers are started by lift off oversteer and then continued by the driver fighting the slide while the car is trying to do the same so you end up with over correction and the weight moving around all over the place.

I have had a few brown trouser moments where the back has stepped out but powering out and keeping a firm grip of the wheel has always corrected it

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[Dippy]

There's no torque vectoring on the OP's car.

I suffered LOOS on my Subaru WRX - the one and only time I have been to A&E as a patient (not that I remember - I was unconscious )
That's part of the reason I have driven Audis since. I have never had LOOS from any of my quattro cars.

 

[xpoweruk]

I see.

Do love the quattro and the feel it gives on the road through corners etc. But when the back end starts to overtake the front (especially if your going round a long corner at a decent speed) unless you immediately lift off, the 4wd system/traction control can get confused and keep all 4 wheels spinning until the point your at 1/4 opposite lock and past the point of no return. had a couple of times where its become a tank slapper because the traction failed to kick in and see the car was effectively in a 'skid'.

Never had that happen in my non sports diff S4

 

[jdp1962]

There's no torque vectoring on the OP's car.

I suffered LOOS on my Subaru WRX - the one and only time I have been to A&E as a patient (not that I remember - I was unconscious )
That's part of the reason I have driven Audis since. I have never had LOOS from any of my quattro cars.

"LOOS"?

 

[Chris90]

Never had that happen in my non sports diff S4

Had it a few times and can get it to do it everytime if the road surface is greasy or wet.

Unless its because got some poor Kuhmo's on the rear and rainsports on the front.

 

[xpoweruk]

 

[xpoweruk]

Had it a few times and can get it to do it everytime if the road surface is greasy or wet.

Unless its because got some poor Kuhmo's on the rear and rainsports on the front.

quattro needs 4 tyres the same or you create imbalance (as you have discovered)

 

[Garry Houseman]

thanks for the help fellas!

 

[Garry Houseman]

It's a permanent 4WD system, using the "torsen" technology detailed here. It's the current evolution of the original system, and is different from the temporary 4WD "Haldex" system used on the A3.

thank you

 

[Dippy]

"LOOS"?

Lift-Off OverSteer (but I suppose it should have been LOO?)

 

[jdp1962]

Lift-Off OverSteer (but I suppose it should have been LOO?)

Thanks, @Dippy. Given the earlier reference to brown trousers, I was imagining it was something to do with bowel movements when on (over) the limit.

 

[Roadrunner146]

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