2017 S3's Updated/New Haldex System - Rear Wheel Biased

[salvadorik]

Audi of America's rep discusses (see the link to the video below) the changes made to the refreshed 2017 Audi A/S3 compared to their 2016 MY counterparts. Other than virtual cockpit and other small changes I believe the coolest improvement is the new rear wheel baised Haldex system. The rep mentions that in dynamic mode an S3 behaves essentially like a rear wheel baised car with most of the torque split to the rear wheels. If this is true (I have no reason to believe it is not) it should be just a matter of having the Haldex system flashed with new a piece of software for those of us with 2015-16 MY wanting to have this system. Anybody who can shed more light on this? Is the 2017 S3s Haldex system update only software related or it is more involving than that?

Here is the youtube video with the rep's discussion: https://www.youtube.com/watch?v=fWQZrYScdO8

[mroberte]

All the reviews I've read so far had stated that many couldn't not tell a difference in the new haldex system at all.

Sent from my SM-N910V using Tapatalk

[marcg611]

I'm guessing the difference is only when you put quattro in dynamic and either on a track or wet/snow where you could feel the more rear biased. Audi should have offered an upgrade to a "twinster" type coupling like the Focus RS gets to get the torque vectoring.

[HurrayFive]

Software only change for sure. Making that kind of hardware change this close to the end of the 8V's life cycle is nowhere close to cost effective. It would also be easy to limit the software changes to '17+ models via subtle ECU, TCU, and Haldex controller architecture adjustments; effectively rendering any backwards compatibility impossible without 3rd party intervention.

At best, in certain "at the limit" driving scenarios, you might feel this change in your butt compared to a '15 or '16. Compared to aftermarket ECU & TCU tunes that already exist, this is nothing though. I can throw the 3 sideways all day long the way it sits now. That said, don't expect to be able to flash the revised software any time soon, and likely ever without 3rd party help.

[salvadorik]

Thank you guys. I guess you are right in a sense that you wont feel too much unless you are pushing the car hard. It is probably this feeling of having a rear wheel biased car just makes feel too excited. Lets wait and see then.

[Rob2k68]

It'll be easier to change the Haldex ECU than flash the software on it - just changed mine from rev D to rev H as been having some wheelspin issues. Can't feel any difference with the later software version on it although this change of revision was from pre facelift cars.

[RudyH]

I was JUST about to post about this....more so why doesn't Audi have it in the S3 yet!

Was thinking about the GLA AMG, and dropping it to a reasonable Sportback / Avant / wagon height from it's useless ride and saw the rear limited slip option. Then at the end of pricing I was like, man I could get a really nice RS3...
To the Audi dealership tonight I go to see if they have the 2017's in

[BP11]

It'll be easier to change the Haldex ECU than flash the software on it - just changed mine from rev D to rev H as been having some wheelspin issues. Can't feel any difference with the later software version on it although this change of revision was from pre facelift cars.

Tell me more about this. So the rev D and rev H are software versions? And the dealership did this for you?

[Hockenheim]

Is this the same for the 2018 A3 Quattro?

[TheDude420]

I don't have any info about the changes in the Haldex system for the 2017+ S3's but here's some info about the Haldex system for those not informed. This post is meant to be informative not to put down anyone's A3/S3/RS3 (I own an S3 and love it). The MQB platform uses a Haldex all wheel drive system. The majority of the time 100% of power is sent to the front wheels making it front-wheel drive. The system is capable of sending up to 50% of power to the rear wheels when needed. I may be wrong but I think the only times you get power to all four wheels is when you launch the car (for models with launch control) and when the car senses there is front wheel slippage in rain or snow. It then goes back to front-wheel drive mode. Early Haldex systems (Volkswagen) would send 90% of power to the front wheels and 10% to the rear with up to 50% to the rear when needed. Another iteration of the Haldex system sent 95% of power to the front wheels and 5% to the rear with up to 50% to the rear when needed. Other Audi models have a more traditional AWD system where power is always sent to all four wheels. Some models like the new RS7 are capable of sending more power to one wheel while cornering for better performance. I'm not an expert and this is just what I've learned from reading and watching videos about the Haldex AWD system in our cars.

TLDR: Our A3/S3/RS3's are labeled as Quattro and are capable of AWD in certain conditions but are usually in FWD mode.

[Spinnetti]

haldex is just a clutch on a fixed system. Its functional but not as good as torsen system. Regardless, it can never do more than 50% torque to the rear as its a fixed ratio system. The later software may give more rear torque in more conditions, but you can set that to some extent on the earlier models too. I set mine to the max traction and its decent.

[Hockenheim]

I believe when you put your car into sports mode it goes 50\50 permanent

[Spinnetti]

I believe when you put your car into sports mode it goes 50\50 permanent

I can confirm it doesn't at least PFL anyway. Dunno about the 17's. If you go in with vagcom or another tool and set the engagement to its max setting it definitely engages the rear more and we know 50/50 is max, so by default it doesn't. Prolly the only real difference is the default software setting anyway I bet. Anybody with a newer car than can go in and look at the default?

[S3_Miles]

I can confirm it doesn't at least PFL anyway. Dunno about the 17's. If you go in with vagcom or another tool and set the engagement to its max setting it definitely engages the rear more and we know 50/50 is max, so by default it doesn't. Prolly the only real difference is the default software setting anyway I bet. Anybody with a newer car than can go in and look at the default?

Is there harm in having it set to max engagement? (I forgot the name of the menu setting...I use Carista). Essentially you are telling the haldex pump to constantly run to apply fluid pressure to the rear diff. Is there harm in this? Has anyone ran theirs longterm in this mode?

[PitchS4]

I can confirm my FL was set to standard by default

[Spinnetti]

Is there harm in having it set to max engagement? (I forgot the name of the menu setting...I use Carista). Essentially you are telling the haldex pump to constantly run to apply fluid pressure to the rear diff. Is there harm in this? Has anyone ran theirs longterm in this mode?

Well, 2 things. One is, you aren't telling it to constantly do anything. The factory settings vary by market and all 3 settings are withing factory parameters. You are simply picking the more rear aggressive setting. I set mine there the second I learned of it and will never change it. Its still a FWD car until it detects slip, it just slips less on the max setting.

[S3_Miles]

Well, 2 things. One is, you aren't telling it to constantly do anything. The factory settings vary by market and all 3 settings are withing factory parameters. You are simply picking the more rear aggressive setting. I set mine there the second I learned of it and will never change it. Its still a FWD car until it detects slip, it just slips less on the max setting.

Got it. Ok that makes sense.

I got the order of operations out of order.

I assumed rear engagement full time. The truth (what you are saying) makes more sense in that ONCE slip is detected, rear becomes engaged but just more "briskly"

[Hockenheim]

Can someone please explain which is the best option for performance\traction?

[AlexQS]

Can someone please explain which is the best option for performance\traction?

Hey Man, Interesting screen shot. Is that what OBDeleven looks like?

I’m curious what your goals are.

I used to have a Mini Cooper S. I got into the habit of immediately turning the traction control off every time I started the car. The reason is that I found the traction control to be way too intrusive in the Mini. I hated when the computer would cut the throttle at what seemed like the worst moment.

A3 seems much better to me. I’ve tried driving for a week in each mode (just with dash button). I can’t really tell the difference.

Will one of these modes make Haldex engage more often? I’m wondering if that’s your goal?

[Hockenheim]

I need as much power to the rear wheels as possible at all times!

[XMetal]

I need as much power to the rear wheels as possible at all times!

Sorry for having to say this, but if that is your goal, then you bought the wrong Audi!

[AlexQS]

I need as much power to the rear wheels as possible at all times!

Me too! I’m curious if you’ve found any solid information about this yet.

I’ve been searching around and I may try the mod to change AWD Logic. I hear there are three settings: Standard, Increased Traction and Reduced Noise.

Still there’s little information about what these settings actually do. On VW Vortex forum I found someone who claims they compsred these settings back to back on a snowy hill, trying to limit other variables. I’m sure it’s true, that the car went up the snowy hill with less wheel wheel spin when using the Increased Traction setting. But that doesn’t explain why or how, it’s only a result of one scenario.

My theorie (which I can’t prove) is that this Increased Traction setting causes the rear wheels to engage with a lower criteria from the sensors. There’s always “a little” difference between the precise amount of rotation of each wheel, and I figure there’s a certain threshold of variance which trips the switch for rear wheels so to speak. And I think it also works to anticipate causes of wheel spin to engage in a preventative way, I.e. a certain amount of throttle position, steering angle, etc. So if there’s a way to make the rear engage more often, I’m all for that.

Interestingly enough, a couple of guys who track their cars found no difference in handeling nor lap times with the setting on or off. That makes some sense to me from what little I remember of the physics classroom and HPDE events I did many years ago.

Am curious to know your results with trying the settings. Hoping to get VAG-COM soon so I can try.

[Spinnetti]

Me too! I’m curious if you’ve found any solid information about this yet.

I’ve been searching around and I may try the mod to change AWD Logic. I hear there are three settings: Standard, Increased Traction and Reduced Noise.

Still there’s little information about what these settings actually do. On VW Vortex forum I found someone who claims they compsred these settings back to back on a snowy hill, trying to limit other variables. I’m sure it’s true, that the car went up the snowy hill with less wheel wheel spin when using the Increased Traction setting. But that doesn’t explain why or how, it’s only a result of one scenario.

My theorie (which I can’t prove) is that this Increased Traction setting causes the rear wheels to engage with a lower criteria from the sensors. There’s always “a little” difference between the precise amount of rotation of each wheel, and I figure there’s a certain threshold of variance which trips the switch for rear wheels so to speak. And I think it also works to anticipate causes of wheel spin to engage in a preventative way, I.e. a certain amount of throttle position, steering angle, etc. So if there’s a way to make the rear engage more often, I’m all for that.

Interestingly enough, a couple of guys who track their cars found no difference in handeling nor lap times with the setting on or off. That makes some sense to me from what little I remember of the physics classroom and HPDE events I did many years ago.

Am curious to know your results with trying the settings. Hoping to get VAG-COM soon so I can try.

That's basically it. Its really quite simple. Just like a manual transmission car with a clutch, the Haldex is nothing more than a computer controlled clutch for the rear axle. Max 50% engagement, and the computer controls when it locks up and how much. On the strongest setting you can really feel it kick in, especially with launch control (Stage II in my case). Its never satisfying as something like an S4, but still pretty fun. If you really want a good AWD system, you have to go with models that are not transverse engines. Those have the Torsen based models A4 and up), and you can mod those (with gearsets) to change the torque distribution if desired, though I never felt the need to.

[rex_racer]

Interestingly enough, a couple of guys who track their cars found no difference in handeling nor lap times with the setting on or off. That makes some sense to me from what little I remember of the physics classroom and HPDE events I did many years ago.

You also have to keep in mind that above a certain speed threshold the Haldex disengages all together. At track speeds this would imply it would become weight distribution more than anything.

[Spinnetti]

You also have to keep in mind that above a certain speed threshold the Haldex disengages all together. At track speeds this would imply it would become weight distribution more than anything.

Well, in a straight line and with enough traction AWD does nothing for you. Low speed corner exit with 400+ hp on the other hand , that quattro is nice to have :)

[AlexQS]

You also have to keep in mind that above a certain speed threshold the Haldex disengages all together. At track speeds this would imply it would become weight distribution more than anything.

That makes sense to me too. I don’t see a lot of difference in the way one drives FWD or RWD. When in a situation with lots of body roll (mid-corner), one would want to have precise throttle control for weight distribution.

Had an older Porsche Boxter prior to A3. Really had to get off brakes a little sooner before initial turn in. A3 being a little nose heavy, it feels more confident to me when keeping the weight a little more forward at initial turn-in. Obviously a limit to this as understeer can be caused by too much braking while turning too.

Once past apex and accelerating differences between FWD and RWD seem negligible to me. RWD can accelerate into decreasing radius corner, and may reach a point where back end steps out and doing donuts. FWD may reach a point where inside front wheel just spins. I’m thinking that in a low speed tight turn, that Haldex would engage at this point even on standard setting.

Haldex was kaput when I bought my 2015 A3 just a few months ago. Was fixed under free used car warranty. Before it was fixed, experienced severe understeer when making near 90’ turns around 40mph in wet (wide road in the middle of no-where). As soon as beginning to accelerate, front end just lit up and plowed. After Haldex repaired, no longer have this problem, above situation would now result in car simply staying planted or perhaps a nice predictable 4-wheel drift. Interestingly enough, my 2015 FWD Passat in same situation would not have understeered as much. Makes me think suspension in A3 was designed/engineered to get that little push from rear in various scenarios. I’m betting Caster-Angle would be the big difference,...not sure but would be interesting to see if suspension geometry is slightly different between FWD A3 vs A3 quattro... sorry just rambling on here

Anywho, I run an extra 2 or 3 PSI in rear tires on A3 now, and I feel it handles fairly predictably. Still want to get VAG-COM to change a few things like linear throttle, and also try to eliminate the lag at initial start off from a dead stop. Even when using launch control, there’s a moment of hesitation after I release brake before car takes off.

[AlexQS]

That's basically it. Its really quite simple. Just like a manual transmission car with a clutch, the Haldex is nothing more than a computer controlled clutch for the rear axle. Max 50% engagement, and the computer controls when it locks up and how much. On the strongest setting you can really feel it kick in, especially with launch control (Stage II in my case). Its never satisfying as something like an S4, but still pretty fun. If you really want a good AWD system, you have to go with models that are not transverse engines. Those have the Torsen based models A4 and up), and you can mod those (with gearsets) to change the torque distribution if desired, though I never felt the need to.

Ya I thought my theorie was close at least. Thanks. So the torsion version of diff on A4 and above is cool. I mistakenly thought A3 had same setup till just after I bought it. Oh well, there’s some years and refinement in Haldex now. They’ve been using it at least since R32 Rabbit I think.

[Spinnetti]

Ya I thought my theorie was close at least. Thanks. So the torsion version of diff on A4 and above is cool. I mistakenly thought A3 had same setup till just after I bought it. Oh well, there’s some years and refinement in Haldex now. They’ve been using it at least since R32 Rabbit I think.

All the transverse engine cars are haldex, the longitudinal engines Torsen (what I think of as the "Real" quattro, though quattro is just a brand name). The R8 uses a 3rd system with a viscous coupling different that either of the other systems.

[Hockenheim]

So anyone know which would be the best setting for sport\handling???

[steve111b]

Driving on snow covered highways I found the following with my 2010 gen 4 A3:
acceleration - stable
cruising - less stable
coasting and changing lanes - unstable

My first discovery was that the Haldex was engaging on small throttle inputs. So I tried to keep the Haldex active and use weight transfer to improve things - no luck.

My next discovery (which took years) was selecting full time 50/50 awd. On the gen 4 cars drivers can use Sport or traction control off. This gave me:
acceleration - stable (no change)
cruising - stable
With the car now stable I could increase the speed by 20 km/hr (say from 80 to 100).
coasting and changing lanes - stable
This was a large improvement, way more than the cruising increase.

Also did some testing on snow at 40 km/hr. With the car coasting (40 km/hr) I turned the wheel to make the car turn 90 degrees. Next I did the same thing with the car in full time awd. Turning the wheel the same amount as my first attempt, the car turned one car width sooner.

In the Summer I never saw any difference when I used full time awd. The gen 5 cars are different and my 2018 RS3 does not work like my old gen 4 car.

[steve111b]

An update

It looks like I was able to notice the Haldex working on the gen 4 car because the shocks were worn. On my new RS3 I could not notice the Haldex working like the previous car. After I had the magride recalibrated at the dealer I immediately noticed an improvement in how the car drove. Next I wondered if this improvement was in my imagination. So I did some testing and can say the car drives better in many ways.

Firstly, the car has better front end grip in the snow. Next, I believe the ESC is more useful. But then it gets weird. Two years in I noticed drive train slack. It was not a big deal so I decided to figure out when it occurred and alter my driving to cover up the problem. The drive train slack has completely disappeared. Another thing I have noticed recently is the shifts at higher RPM were not crisp. They are now. And I think the worn shocks on my old car gave less grip in the snow. This explains a mystery that I could not figure out. My 225/18 winters on the RS3 give me the same grip as the 205/16 winters on my old A3. A skinny soft winter should give more grip than a wide hard one. Finally, I find manual shifting to be smoother. The car does not pitch as much.

If my shocks stay perfect because they are recalibrated every two years I doubt that I will ever be able to notice the Haldex working. I have a theory how the Haldex works, but cannot confirm any of my theory.