3.2 Quattro? is it Haledex?

[robbie_boy]

Hello everyone

I'm looking at getting a A3 to add to the family tradition of owning all audis.
I'm driving a 04 A4 right now and was wondeirng if the A3 3.2 is actually a full quattro or is it a Haledex?
My dad has a A3 2.0T and it has the Haledex and I seem to like it but I was looking for a little more power with the 3.2.

Any input would be great

Thanks,
Rob

[A4A4A4]

It's haldex. If you want more power get a 2.0T and tune it.

[b6onboost]

The TT and A3 models have both 2.0T/3.2 mounted transversely and use Haldex.

All other Audi Models use Torsen.

[robbie_boy]

Ok great
Thanks for the info

[LWNY]

Audi's new longitudinal layout cars does not use torsen. They have moved onto the crown differential.

[ceese]

It's haldex. If you want more power get a 2.0T and tune it.

Unless you want real power than get a 3.2 and tune it.

[0396]

ok... experts, I just noticed this posting and after reading it. I have a simple question... what is a Haledex and or full quattro system?

Can some one educate me?

Thanks

[LWNY]

ok... experts, I just noticed this posting and after reading it. I have a simple question... what is a Haledex and or full quattro system?

Can some one educate me?

Thanks

full time quattro has the output of the transmission go to a differential that splits the output to the front and rear axle. This differential drives both axle, and when one starts speeding up, then other slows down. This allows for the front wheel to take a different path from the rear (as when going around corners). But if one axle starts slipping, the other stops rotating and your car would not move. Thus Audi has the TORque SENsing locking differential where with the onset of low grip, the layout of the gears in relation to each other causes them to bind up, thus the front and rear axle would rotate together. There is no slip required from the axle with lower grip in order for the differential to lock up, thus you would not feel any sense of instability. But due to the way the gear has to encounter resistance from the ones it is driving, if the driven wheel are on ice, the gear would not encounter resistance, thus it would not be able to lock up. This means these TORque SENsing differential cannot cope with surface grip that are too extreme. Newer ones are clutch based with front to rear and rear to front torque transfer ratio that are different from each other, thus allowing for higher difference between front and rear surface grip and asymmetrical max torque transfer characteristics. Plus, given it is clutch based, it could implement electronic lockup if it so desires. The old differential, being a symmetrical design, transfers torque to the front and rear equally. Newer designs, has the driving gear placed at different distance relative to turning center, thus the gear turns the rear gear with a higher leverage than the front gear, allowing for asymmetrical torque transfer ratio. This unit is completely mechanical.

As for the Haldex units, the output from the transmission are directly linked to the front axle, so they are driven 100% of the time at the exact rate the transmission is driving them. There is also another output gear from the transmission that goes to the rear of the car where the haldex clutch is based. Under normal situation, the clutch is only lightly engaged, thus only 5% of the output goes to the rear wheel. When ABS sensors senses a front wheel is slipping, it will close down on the clutch and more and more power is transferred to the rear axle, thus allowing the rear wheels to drive the car more and more. Due to the reactive nature of the unit, it will usually require some slipping of a front wheel before the rear takes over, thus it never feel as secure. The older units also pressurizes the oil to close the clutch via a pump that relies on the different rotational rate of the front and rear axle, thus you need more rotational difference to create more pressure, with the most pressure created when there is actual slip in the front axle. Newer units has an electrical pump to create the clutch pressure. Since this unit is electronics based, it can take readings from many sensors such as throttle depression rate, lateral sensor, steering angle, etc and prediction what kind of driving situation you are likely in and pre-engage the clutch if it deems you will likely need it. Plus, the front and rear are turning at their most different in corners, so clutch pressure would be there. Thus if you are accelerating out of a corner, it could have engaged the rear and transferred much of the power to the rear even before any wheel encounters any slip. If you catch the car off guard, it might not have the rear wheels engaged and it could be less stable than other times where it predicted the situation. The max power split would be at best 50:50 when the clutch are fully locked since the front axle are fully engaged to the transmission.

Note, cars like the Veyron and Aventador uses Haldex based AWD, but it is set up in reverse, with the rear wheels being fully connected to the transmission and the front wheel driven based on clutch engagement.

[0396]

I must be old school....I'm a skier and thus perfer the 50 /50 split. Are there any auto mfg that still utilizes the old methods?

Thanks

[oc cc]

Subaru does I believe

[LWNY]

I must be old school....I'm a skier and thus perfer the 50 /50 split. Are there any auto mfg that still utilizes the old methods?

Thanks

Even in skiing, you would apply different weight distribution when you want to do different thing. Tighten that turn, increase to 60/40 (not that these correlate with each other). Anyway, in automobile, rear biasing on cars usually is to counter the front weight bias of the cars, thus giving it a balanced handling. In your ski analogy, it would be as if your boot center is mounted 30cm ahead, thus you not being able to edge the shovel into performing a turn because you cannot put enough flex into it, and you just end up skidding forward. So by applying more of a skid in your tail to position the skis at the angle you want to go and digging in (or if such a ski does exist, it would have wide rear shovel to do the initiating of the turn), you thus could compensate for the front weight bias of your setup.