Quattro

AugustusMaximus

Could someone help explain to me the difference between standard Audi quattro system and the system used on its S and RS models.

Do I understand it right that for the most part, the standard Quattro models are for the most part FWD, but only send torque to the rear wheels when the computer deems necessary. On the other hand, the quattro system on the RS models primarily sends torque to the rear wheels in preference to the front wheels ?

mickdw

I dont know. I do know that I had a TT and the power was certainly at the rears too at all the right times.

ikillcopiers

You're getting a bit confused between the two variants of quattro available with Audis at present.

The original quattro system uses a north-south engine configuartion, it's a pure mechanical
setup with Torsen diffs.
The ratio of power distribution is fixed between axles (eg 40% to front, 60% to rear).
It does not change with respect to conditions.
All Audis with north-south engines (A/S/RS4, A/S/RS6, A/S/RS5, A/S8) use this system.
This is the "proper" quattro system that is universally praised, it provides consistent and
predictable handling.
On some of the S & RS models the power distributions *may* be different, but they
will be fixed, as it is a mechanical system.

The second system available is a Haltec system, this is on the east-west engine Audis,
and also the 4 Motion VW's.
It's an electronically managed system that runs in FWD most of the time and pushes
power to the rear also when the computer deems it appropriate.
It's not the Audi developed quattro system, and can lead to unpredictable handling.
This is the system in the A/S3 and TT.
The TTRS may have a different tune of this system, but it's still not a proper quattro.

To be short, if you want quattro, buy a north-south engined Audi with quattro, and then you will understand
the well lauded handling it provides.
But the A/S3 & TT are not the proper quattro, they are dilutions of the brand.

It's a shame, but this is what happens in the world where Porsche goes a builds a bloody jeep....

mickdw

I didnt think that any of the normals cars were running the full mechanical system anymore. The system in the TT I had was good in my opinion and readily sent power to the back. Must try the other cars to see.

AugustusMaximus

ikillcopiers wrote: »

You're getting a bit confused between the two variants of quattro available with Audis at present.

The original quattro system uses a north-south engine configuartion, it's a pure mechanical
setup with Torsen diffs.
The ratio of power distribution is fixed between axles (eg 40% to front, 60% to rear).
It does not change with respect to conditions.
All Audis with north-south engines (A/S/RS4, A/S/RS6, A/S/RS5, A/S8) use this system.
This is the "proper" quattro system that is universally praised, it provides consistent and
predictable handling.
On some of the S & RS models the power distributions *may* be different, but they
will be fixed, as it is a mechanical system.

The second system available is a Haltec system, this is on the east-west engine Audis,
and also the 4 Motion VW's.
It's an electronically managed system that runs in FWD most of the time and pushes
power to the rear also when the computer deems it appropriate.
It's not the Audi developed quattro system, and can lead to unpredictable handling.
This is the system in the A/S3 and TT.
The TTRS may have a different tune of this system, but it's still not a proper quattro.

To be short, if you want quattro, buy a north-south engined Audi with quattro, and then you will understand
the well lauded handling it provides.
But the A/S3 & TT are not the proper quattro, they are dilutions of the brand.

It's a shame, but this is what happens in the world where Porsche goes a builds a bloody jeep....

Thanks. I was originally under the impression that the Haltec system you speak of is the system which is being used on the B7 A4 for instance.

vw4life

haldex is not real 4 wheel drive,but does the job

no good for off road though

tossy

Its not haltec its haldex,Haldex are the Swedish company who make the 4wd system called 4motion in the VAG cars like the R32,TT etc,The S3 is also a 4motion car but the Haldex controller (ECU) is set up to split the power more evenly between the front and rear.It is a very easy Job to uprate the Haldex controller in any of the other 4motion cars (i have one on my shopping list for a while now)

The 4wd system in all other 4wd Audis is the quattro or torsen system,there are about 5 different generations of this set up as it advanced during the years.

The only exceptions i can think of are the likes of the Touareg,Pheaton and the B5 passat 4motion all these VW cars also use the Torsen set up the same as the quattro.

Old school 4wd VW's were also similar to the quattros of the era but the VW's were called syncros.

AugustusMaximus

Just out of interest, but is there any system out there which I guess would contain 3 actives diffs so that the computer can determine where the torque goes between all 4 wheels ?

Would make it interesting for the fact you could set all the torque to go to the rear wheels alone for etc.

tossy

vw4life wrote: »

haldex is not real 4 wheel drive,but does the job

no good for off road though

Haldex is is capable of driving all 4 wheels at once,that makes it real 4wd in my book obviously no good for off road considering we are talking about cars.

peasant

tossy wrote: »

Old school 4wd VW's were also similar to the quattros of the era but the VW's were called syncros.

Except that the Syncros didn't have torsen diffs but a viscous coupling instead

tossy

peasant wrote: »

Except that the Syncros didn't have torsen diffs but a viscous coupling instead

Good point,my bad.

VeVeX

The haldex system is not called 4motion thats what VW tagged their 4wd cars as.

Audi use the quattro tag on all cars that have four wheel drive the fact that there are different systems used in Audi vehicles that provide four wheel drive is irrelevant.

Is the R8 not quattro because it uses a haldex system? maybe its 4motion :P

Pdfile

VeVeX wrote: »

The haldex system is not called 4motion thats what VW tagged their 4wd cars as.

Audi use the quattro tag on all cars that have four wheel drive the fact that there are different systems used in Audi vehicles that provide four wheel drive is irrelevant.

Is the R8 not quattro because it uses a haldex system? maybe its 4motion :P

i think you know too much :rolleyes:

HashSlinging

troll.

tossy

VeVeX wrote: »

The haldex system is not called 4motion thats what VW tagged their 4wd cars as.

That's what i meant Keith,i never said the haldex system was called 4motion,maybe my wording wasn't right.

tossy wrote: »

Haldex are the Swedish company who make the 4wd system called 4motion in the VAG cars.

VeVeX wrote: »

Is the R8 not quattro because it uses a haldex system? maybe its 4motion :P

It doesn't matter what the R8 is it doesn't need a fancy badge to help it sell

Matt Simis

AugustusMaximus wrote: »

Just out of interest, but is there any system out there which I guess would contain 3 actives diffs so that the computer can determine where the torque goes between all 4 wheels ?

Would make it interesting for the fact you could set all the torque to go to the rear wheels alone for etc.

TorSen can send 80% to the rears (or front) and with Torque Vectoring rear diffs as on the B8 S4 and BMW X6 can then fine tune more torque between rear wheels too. Older TorSen S4s can put in a different (Aftermarket sports orientated) rear diff to increase this torque split to 88%.

Haldex can effectively send near 100% to either front or rears, its default mode is 95% front. The reason its looked down upon (incorrectly on the new gen systems) is it historically slower to react than TorSen as a computer has to sense, interpret and then act on a signal. The time to do this is milliseconds however. Like the Sports Diff mentioned above, there are aftermarket Haldex controllers out too.


From reading forums the one remaining critique of Haldex vs Torsen is its lack of predictability when horsing around in a snowy carpark for instance with Haldex. Torsen will always do the same and let the ass spin round if you want it. Haldex tends to spin up the fronts faster then it can redistribute to the rear. None of this is very applicable to the road it would appear, but is the fuel of internet debates afterall.

VeVeX

Matt Simis wrote: »

TorSen can send 80% to the rears (or front) and with Torque Vectoring rear diffs as on the B8 S4 and BMW X6 can then fine tune more torque between rear wheels too. Older TorSen S4s can put in a different (Aftermarket sports orientated) rear diff to increase this torque split to 88%.

Haldex can effectively send near 100% to either front or rears, its default mode is 95% front. The reason its looked down upon (incorrectly on the new gen systems) is it historically slower to react than TorSen as a computer has to sense, interpret and then act on a signal. The time to do this is milliseconds however. Like the Sports Diff mentioned above, there are aftermarket Haldex controllers out too.


From reading forums the one remaining critique of Haldex vs Torsen is its lack of predictability when horsing around in a snowy carpark for instance with Haldex. Torsen will always do the same and let the ass spin round if you want it. Haldex tends to spin up the fronts faster then it can redistribute to the rear. None of this is very applicable to the road it would appear, but is the fuel of internet debates afterall.

Sometimes I think the transfer of power to the rear is actually a little too aggressive. The system notes a difference in rotational speed front to rear then lashes a load of power to the rear. In straight lines on slippy roads it causes the back of the car to fish tail slightly. Probably wouldn't be ideal if you were mid corner.

This is a fairly good video of a haldex based car launch.

http://www.youtube.com/watch?v=3QikviXOW8s

Matt Simis

VeVeX wrote: »

https://www.youtube.com/watch?v=3QikviXOW8s

Looked pretty in control and composed (and quite clearly fast!). I wonder did it have an uprated Haldex controller?

AugustusMaximus

Matt Simis wrote: »

TorSen can send 80% to the rears (or front) and with Torque Vectoring rear diffs as on the B8 S4 and BMW X6 can then fine tune more torque between rear wheels too. Older TorSen S4s can put in a different (Aftermarket sports orientated) rear diff to increase this torque split to 88%.

Haldex can effectively send near 100% to either front or rears, its default mode is 95% front. The reason its looked down upon (incorrectly on the new gen systems) is it historically slower to react than TorSen as a computer has to sense, interpret and then act on a signal. The time to do this is milliseconds however. Like the Sports Diff mentioned above, there are aftermarket Haldex controllers out too.


From reading forums the one remaining critique of Haldex vs Torsen is its lack of predictability when horsing around in a snowy carpark for instance with Haldex. Torsen will always do the same and let the ass spin round if you want it. Haldex tends to spin up the fronts faster then it can redistribute to the rear. None of this is very applicable to the road it would appear, but is the fuel of internet debates afterall.

Is there a reason why the Haldex system gives so much of the power to the front wheels as standard ? I would have thought that outside of driving on snow or ice that more of the power to the rear as standard would be a better system.

Just to be sure, the B7 has the standard Torsen Quattro system ?

testicle

ikillcopiers wrote: »

It's a shame, but this is what happens in the world where Porsche goes a builds a bloody jeep....

That's not fair. Lamborghini have been building tractors for years.

Matt Simis

AugustusMaximus wrote: »

Is there a reason why the Haldex system gives so much of the power to the front wheels as standard ? I would have thought that outside of driving on snow or ice that more of the power to the rear as standard would be a better system.

Just to be sure, the B7 has the standard Torsen Quattro system ?

Basically FWD has lots of advantages over RWD for normal road use, though RWD is more sport orientated.

All the A4s and above use mechanical (Torsen) Quattro, including the B7. The B8 does too, but with the Sports Diff as an option.

ikillcopiers

Sorry about the mispelling of Haldex earlier, potatoe/potato.

My own opinion is that handling is the ability of a car to do what it is told,
not what it thinks.

Predictability is a key factor is this, that's why I don't like computery 4WD
and traction systems.

testicle wrote: »

That's not fair. Lamborghini have been building tractors for years.

Not quite the same, that's what Lamborghini started doing (and lots of trucks and stuff too).

How he started at cars was he actually had a Ferrari at one stage and went back to the
man Enzo complaining the clutch was too hard.
Enzo said something along the lines of "what would you know, you build bloody tractors".

After a short bout of experimentation the branch of Lamborghini we all know and love
was born.....

galwaytt

AugustusMaximus wrote: »

Is there a reason why the Haldex system gives so much of the power to the front wheels as standard ?

'cos that's what VAG tells it to ! The Haldex diff doesn't actually know which end is up/down/front/back - it's the way the engineers choose to use it that makes the difference.

AugustusMaximus wrote: »

I would have thought that outside of driving on snow or ice that more of the power to the rear as standard would be a better system.

Nope, the opposite, actually. FWD is an inherently understeering condition, which is more stable, and is deemed safer, for Joe & Josephine Public
RWD is inherently.........not which is why petrol heads like 'em.

Here's one with no Haldex (but is Swedish ! )...no LSD either I'd wager, no: electronics, EBD, APR, ABS, FI, Flappy paddle gearbox, wide wheels, engine at the front, front wheel drive, on loose............seems to work quite well. Oh, and 2-stroke as well - just for the Green Party, that !

https://www.youtube.com/watch?v=1lJQzrWprQE

galwaytt

ikillcopiers wrote: »

Predictability is a key factor is this, that's why I don't like computery 4WD and traction systems..

....tut tut........they used to say that about carbs vs fuel injection. Turbo's v's n/a.

You have both

Fancy giving them up, and going back to trembler coils and magneto's ?? :P

My definition of handling is it is what the car actuallydoes - not the mechanism of it's decision to do it, whether act of driver/ecu/God, take your pick......

ikillcopiers

galwaytt wrote: »

....tut tut........they used to say that about carbs vs fuel injection. Turbo's v's n/a.

You have both

Fancy giving them up, and going back to trembler coils and magneto's ?? :P

My definition of handling is it is what the car actuallydoes - not the mechanism of it's decision to do it, whether act of driver/ecu/God, take your pick......

You're putting words in my mouth now!

1. I don't have a computery 4WD system, it's proper Torsen quattro
2. ESP, I can turn that off!

You know yourself I have a 944 for the real driving experiance

As regards what a car does, the most predictable handling machine I ever had
was a Ford Fiesta van - understeeeeeeeeeeeer everywhere.
Does that make it a good handling machine though?

I agree we need a bit of progress for everyday cars, but for driving pleasure there
is a balance to be struck.
At least when you see a guy flat out in something old school you know that guy
can drive, but with something with all the modern electric controls it's hard to know.

That's my opinion, and as we all know, opinions are like arseholes.....