B8 quattro AWD system explained

[Gert B Frobe]

Can anyone point me to a thread or resource somewhere that explains how the A4 B8 AWD system works exactly? I'm not sure if B8 A4s have the center diff crown gear setup or something different. I know there have been many changes (some good some bad) over the years to Audi quattro drives and I am curious where the B8 A4 fits, advantages, disadvantages, etc..

Thanks

[hyperunion]

Can anyone point me to a thread or resource somewhere that explains how the A4 B8 AWD system works exactly? I'm not sure if B8 A4s have the center diff crown gear setup or something different. I know there have been many changes (some good some bad) over the years to Audi quattro drives and I am curious where the B8 A4 fits, advantages, disadvantages, etc..

Thanks

B8 is one of the first with a 60:40 rear wheel biased mechanical drivetrain!.. it started with the b7 rs4 then improved with our years!.. only thing is a4 owners don't have access to is the b8 s4's rear sport differential option!..

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[JinDIS]

https://en.wikipedia.org/wiki/Quattr...-drive_system)
Center diff is a Torsen system
Front and rear are open diff with EDL

[A4x]

https://en.wikipedia.org/wiki/Quattr...-drive_system)
Center diff is a Torsen system
Front and rear are open diff with EDL

Are you sure about the EDL (electronic locking differential)?

Is this part of the traction control system? Seems like EDL is just using the brake on one side to lock up that wheel. Not 100% sure tho.

[JeriQo]

B8 is one of the first with a 60:40 rear wheel biased mechanical drivetrain!.. it started with the b7 rs4 then improved with our years!.. only thing is a4 owners don't have access to is the b8 s4's rear sport differential option!..

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wish i had something to say on this subject :(

[adamazing]

wish i had something to say on this subject :(

Lol.
100% torque delivery to the front wheels... no split because that creates parasitic drive-train power losses. You're putting a higher percentage of your power to the ground!


#SilverLining

[A4x]

Lol.
100% torque delivery to the front wheels... no split because that creates parasitic drive-train power losses. You're putting a higher percentage of your power to the ground!


#SilverLining

To the ground, or to the spinning wheels that lost traction?

[adamazing]

To the ground, or to the spinning wheels that lost traction?

Tomato Tomoto, lol

[JeriQo]

To the ground, or to the spinning wheels that lost traction?

i can always get slicks, son.

- - - Updated - - -

Lol.
100% torque delivery to the front wheels... no split because that creates parasitic drive-train power losses. You're putting a higher percentage of your power to the ground!


#SilverLining

hell yeah! lol

[JinDIS]

Are you sure about the EDL (electronic locking differential)?

Is this part of the traction control system? Seems like EDL is just using the brake on one side to lock up that wheel. Not 100% sure tho.

yup, EDL is a part of the braking system but its behavior also integrates with the quattro system
the downside to any open differential is that if one side slips (like on ice or snow), the other side won't receive any power. The old school method of getting around this was to apply a little bit of brakes so the wheel free spinning on ice slows down and transfers some of its energy to the opposite wheel (that has traction). EDL just does as you described (except without using all four brakes) so if one tire from the front and rear are simultaneously slipping, EDL locks those tires up with brakes so the open diff can transfer of power to the wheels that aren't slipping.

for our cars, front and rear are open differentials although other models might use a viscous coupling or a true LSD diff (torsen/audi sport differential)




For anyone still interested, I think this video best illustrates and explains how the systems work
bear in mind the setup for the SQ5 is
front: open diff with EDL
center : torsen
rear: (audi sport differential/torque vectoring)

[hyperunion]

Lol.
100% torque delivery to the front wheels... no split because that creates parasitic drive-train power losses. You're putting a higher percentage of your power to the ground!


#SilverLining

#frontwheeldrivematters

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