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kep

Go Kart Champion
Location
Boston
Car(s)
Mk7 Golf R, NA Miata
DAD6D883-35D4-4913-8D5F-68483B3859B5.gif



Every time I’ve driven a GTI on track, I’ve found the diff to be very impressive, so it surprises me that people have decided to have a vendetta against them.

But back on topic, what’s the lightest weight fleshlight? I don’t want too much weight handicap while lapping.
 

BadHombre760

Autocross Champion
Location
Vegas
Car(s)
Slow FWD VW Hatch
View attachment 258666


Every time I’ve driven a GTI on track, I’ve found the diff to be very impressive, so it surprises me that people have decided to have a vendetta against them.

But back on topic, what’s the lightest weight flashlight? I don’t want too much weight handicap while lapping.
did you just assume my gearbox?

 

DrFunkalupicus

Autocross Champion
Location
Topeka
Car(s)
2016 VW GTI S
I still have no pp….
 
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Reactions: kep

Escape Hatch

Autocross Champion
Location
USA
Car(s)
Mk7 GTI
It is and it does. That's irrefutable. What's your point?

Turn xds off and you'll feel the delay even on the street. Oh wait, you can't, because you don't even own a GTI.

And yes, you can feel when the VAQ gets too hot, the car starts to power on oversteer. More so at Roebling and FIRM, less so at Daytona or Sebring.

I've autocrossed and tracked both my 18 S and 19 Rabbit for the last 5 years.

What experience do you have? Or are you just repeating what your friend's, cousin's brother told you, since you don't even own a GTI, which is hilarious given your comment above. Have you actually tracked a GTI with VAQ? If not, then STFU you poser little bitch.
Such a pleasant guy.
 

GTIfan99

Autocross Champion
Location
FL
View attachment 258666


Every time I’ve driven a GTI on track, I’ve found the diff to be very impressive, so it surprises me that people have decided to have a vendetta against them.

But back on topic, what’s the lightest weight fleshlight? I don’t want too much weight handicap while lapping.
No vendetta here. I have both an 18 S with no diff and a 19 Rabbit with. I greatly prefer with VAQ. In conjuction with setting it to increased traction. I've played around with xds off, weak standard and strong. Weak and normal work best for me. Some Canadian dude doing TT's swears by XDS on strong and VAQ increased traction, but most that track a VAQ car have come to the same conclusion, you need xds to provide some preload. Ever want to feel the difference these systems make, just pull the ABS fuse. You'll see how effective they are.

Your post was assholish, I responded in kind. Maybe don't act so sure about a car you don't own and track?

I'm glad I have VAQ, but I'd rather have a true LSD. VAQ has its limitations. Mainly it starts to not provide as much lock as it heats up.

Now, let's all start fighting over clutch vs gear types of mechanical LSDs. Go.......
 
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golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
I have noticed this is somewhat common in your entire tech explanation for the VAQ. This is consistent with the quality of sourcing for all the material you cite: marketing releases, race car user manual, a white paper, and a grad school thesis. These things are often contradictory, misleading and superficial.

If you are interested in learning how this front differential solution really works--which it seems you are. I recommend buying one, and data logging it, and trying to break it. From my experience there is nothing you can read on the internet that will give you any idea of this solution functions in the wild

Again, point out in my how to guide on the VAQ unit where I am wrong, & provide proof from Borg Warner or VW...


Your logic is:- that to understand how items on the car work you have to own one....


How does your logic regarding mechanics at main dealers or independent garages work???.....


Is the mechanic only allowed to work on the exact same car that they own....or do they own one of every type???


Many people who own cars have no idea how it functions, or how to repair it, or the correct basic mechanical terminology....


I've been owning, driving, modifying, fixing, etc. VAG cars (Audi, Seat, Skoda, VW) for the past 28yrs....many of the cars that I've worked on & driven down twisty back roads I don't own...
 

jay745

track sl00t
Location
Chicago
Car(s)
2 vw's
Jeez guys what the fuck. There's no need for name calling and insulting people.

The pp e-lsd is certainly cool technology and great for most. The 1% who track their car will wish they didn't have it and had a mechanical LSD. It's still an open diff at the end of the day. They do overheat on the track too.
 

Oversteermybagel

Go Kart Champion
Location
Boston
Car(s)
mk7 2017 GTi Sport
Again, point out in my how to guide on the VAQ unit where I am wrong, & provide proof from Borg Warner or VW...


Your logic is:- that to understand how items on the car work you have to own one....


How does your logic regarding mechanics at main dealers or independent garages work???.....

That is a misinterpretation of the words I said. You wouldn't expect someone to become a master mechanic from reading an owners manual.

In case you are curious about learning more I will document some of the things that are misunderstood or misrepresented in your guide. Maybe it'll help someone and maybe it'll spark curiosity in others. Anyway there are numerous errors, I understand that you said you want proof of operation from VW or Borg Warner but frankly most of the info about how these systems work simply can't be figured out from reading marketing material that is posted on the internet. Here are a few:

What about the “preload” problem?
The worst case scenario for any LSD or the FDL unit is that of "zero load". This could be described as having the car on level ground with all the wheels pointing straight ahead & all on ice, meaning there is no grip/torque difference between the driven wheels.
There is no 'worst case scenario' for any LSD. A car on level ground with all the wheels pointing straight ahead with no grip/torque difference between the driven wheels is not interesting. In this case the differential solution is irrelevant. In this specific case (no grip difference between driven wheels) a force to the input shaft of a locked diff, or an open diff, or a VAQ, or a wavetrac the end result is the same: the wheels spin at the same speeds when any power is applied.

The real interesting case for a differential is when considering a car navigating a corner, an ideal limited slip differential is one that redirects as much power from the less loaded wheel to the more loaded wheel without putting either wheel into slip. This is challenging because the wheels have to travel different distances. Any limited slip differential acts by applying a braking torque to the wheel spinning at a higher velocity and an accelerating torque to the lower velocity wheel. The real challenge is getting this just right such that as you navigate the corner you don't put a wheel in grip into a slide by either braking a wheel that has traction or accelerating a wheel that has traction too much that it starts sliding--both of these will result of loss of stability in the front end. The benefit of getting it right is more forward drive on power and greater chassis stability on deceleration. An overly weak LSD you might have poor drive out of a corner where an overly strong LSD will upset grip experienced for the entire drive axle. No limited slip differential solution is always going to provide a correct solution here. There is no magic spend money button: its all comprises and fine tuning

The FDL unit is not supposed to have this problem as its an electrohydraulic clutch pack diff lock. Unfortunately, it still has a “preload” type problem as it still requires a minimum amount of torque imbalance in Nm between the driven wheels to lock up.

This is simply not true. There is no minimum amount of torque imbalance between the driven wheels to lock up. Anyone who has played around with obd11 logs would know this. From any stop the car actually applies current to the clutch pack. Sitting at a stop light with the wheels at a stop the axle is always locked and as soon as you take off from the light the car starts unlocking as appropriate. People who have done data logging will see that there are predictive algorithms at play which also lock the wheels based on throttle and steering angle before any difference in wheel speed or slip happens. Figuring out exactly how these predictive algorithms work isn't something you will ever be able to do by reading the white papers. If you are really interested you are going to have to reverse engineer this.
If the driven wheels cannot provide enough grip for this then the cars existing XDS+ systems within the ABS unit will be used to apply pressure to the brakes & create a torque imbalance between the driven wheels.
XDS+ is not required to get the VAQ to work. Anyone who has done datalogging with various XDS systems enabled would know this.

The FDL unit fitted to the Seat TCR car has an externally adjustable preload setting, with the recommended range being 50Nm (37lbft) to 100Nm (74lbft). Cold measured is 15% higher than warm measure, & preload decreases approx. 15% after 50kms of running. (info from the Seat Leon Cup Racer TCR owners manual)
This is not true. See our previous discussion. This was a result of you confusing the differential in the SEQ cars with that of the DSG cars.

Unfortunately, they hit problems with the FDL (FXD) set up, quote:- “The FXD system is the most difficult to recreate due to extreme variations in driveline behaviour - The FDL system will not be implemented due to far to rapid driveline behaviour". They also found on the simulated hill tests that, quote:- "the torque that is applied upon the clutch pack coupling is varying a lot when the system oscillates & goes from zero to maximum several times. This affects the whole driveline behaviour". Basically, the unit in this configuration is very “reactive” but also “proactive” i.e. it reacts before. The driveline was oscillating like mad, as the unit tried to figure out which wheel to send the torque to! This resulted in huge differences in the recorded torque & angular velocities. This is all because it takes data from many sources, so is constantly adjusting, more so than in the other configurations & backs up my reasoning as to why they added a “bleed container” to remove air from the oil due to aeration.

Its not a good look or good form to quote papers out of context without sourcing the name or author of the paper

Wavetrac LSDs have a device in the centre of the diff which responds in zero load situations, quote:- "Precisely engineered wave profiles are placed on one side gear and its mating preload hub. As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. Very quickly, this creates enough internal load within the LSD to stop the zero axle-load condition."

Wavetrac is clear to not call their devices lockers. If you look at the friction area on the wavetrac you can probably get an idea of how much power can be transferred in the zero load case. Also, plenty of videos available of wavetrac not being able to move the car with one wheel in the air. This doesn't necessarily make it a bad limited slip differential.

Please note that this engine has a maximum specified torque of 410Nm, so the FDL unit is applying half, or more, of the engines torque figure as “preload” during braking.

You have confused the engine torque applied at the flywheel with the torque applied to the clutches of multi-plate differential. These are not the same thing and operate at different leverage ratios. There is no relevance between the two as suggested.

By altering the XDS settings you affect the FDL directly

These are separate systems and don't talk. You don't effect the operation of the FDL by changing XDS settings it still responds to the same inputs in the same way. This is clear from data logging.

It will not repeatedly react the same if you drive around the same corner at the same speed with the same weather conditions. This is because it takes in data NOT from the torque acting on the driveshafts to the FDL unit or the open diff, but from numerous other sources (see section on “How does the FDL work electrically?”).

For the same speed, G load, steering angle, yaw, and wheel speeds it will behave exactly the same


The fact of the matter is that electronic controlled multi-plate clutch differentials have numerous advantages over the classic mechanical only clutch and gear type LSDs. Not being able to directly sense torque is also a potential drawback (that being, said who knows, the center diff in the Subaru STI previously had both a torsen and a e-LSD in one package and now its just the e-LSD with the torsen still existent but mechanically disabled since 2018). We are seeing in modern high performance sports sedans and sports cars a big movement away from mechanical LSDs. Whether we like it or not these solutions are the future. Among about half of the GT4 racecar field you have electronic diffs. If you go buy a new GT3 RS you have an electronic diff. These e-LSDs can evaluate more relevant information that will never be considered by a mechanical only solution and are far more tunable in real time for tire wear and track conditions. Things like yaw, wheel angle, and G loading are all relevant in terms of deciding how much to lock. In terms of the unit in this car, I have not seen any empirical data on the VAQ vs any of the mechanical only solutions but I would love if someone has collected any data to show where each system shines. I have also seen reports of people complaining about overheating but haven't seen anyone actually prove their issues were diff caused (and not tire), again I would love to see this info because it contradicts my experience.

To this day these units continue to be used in IMSA IMPCC 2hr-4hr races. In europe they are used in longer endurance races. If you look at the tech video FCP euro did on old RS3 LMS DSG you will see that the VAQ has no additional cooling on the TCR cars which use 265mm Michelin slicks. From twelve years ago there was this quote from the haldex folks:
"The Haldex FXD prototype caused no technical down time and showed no signs of fatigue during the entire 24-hour race. " [Haldex’s new innovative electro hydraulic differential lock, Haldex FXD, debuts in the Volkswagen Scirocco #116 at the 24-hour Nürburgring Race]

If anyone has data to share i'd love to see it
 
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DrFunkalupicus

Autocross Champion
Location
Topeka
Car(s)
2016 VW GTI S
Hey since this may in the spirit of this thread, do any of the XDS+ changes in OBD11 make any appreciable difference?
 

golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
That is a misinterpretation of the words I said. You wouldn't expect someone to become a master mechanic from reading an owners manual.

In case you are curious about learning more I will document some of the things that are misunderstood or misrepresented in your guide. Maybe it'll help someone and maybe it'll spark curiosity in others. Anyway there are numerous errors, I understand that you said you want proof of operation from VW or Borg Warner but frankly most of the info about how these systems work simply can't be figured out from reading marketing material that is posted on the internet. Here are a few:


There is no 'worst case scenario' for any LSD. A car on level ground with all the wheels pointing straight ahead with no grip/torque difference between the driven wheels is not interesting. In this case the differential solution is irrelevant. In this specific case (no grip difference between driven wheels) a force to the input shaft of a locked diff, or an open diff, or a VAQ, or a wavetrac the end result is the same: the wheels spin at the same speeds when any power is applied.

The real interesting case for a differential is when considering a car navigating a corner, an ideal limited slip differential is one that redirects as much power from the less loaded wheel to the more loaded wheel without putting either wheel into slip. This is challenging because the wheels have to travel different distances. Any limited slip differential acts by applying a braking torque to the wheel spinning at a higher velocity and an accelerating torque to the lower velocity wheel. The real challenge is getting this just right such that as you navigate the corner you don't put a wheel in grip into a slide by either braking a wheel that has traction or accelerating a wheel that has traction too much that it starts sliding--both of these will result of loss of stability in the front end. The benefit of getting it right is more forward drive on power and greater chassis stability on deceleration. An overly weak LSD you might have poor drive out of a corner where an overly strong LSD will upset grip experienced for the entire drive axle. No limited slip differential solution is always going to provide a correct solution here. There is no magic spend money button: its all comprises and fine tuning



This is simply not true. There is no minimum amount of torque imbalance between the driven wheels to lock up. Anyone who has played around with obd11 logs would know this. From any stop the car actually applies current to the clutch pack. Sitting at a stop light with the wheels at a stop the axle is always locked and as soon as you take off from the light the car starts unlocking as appropriate. People who have done data logging will see that there are predictive algorithms at play which also lock the wheels based on throttle and steering angle before any difference in wheel speed or slip happens. Figuring out exactly how these predictive algorithms work isn't something you will ever be able to do by reading the white papers. If you are really interested you are going to have to reverse engineer this.

XDS+ is not required to get the VAQ to work. Anyone who has done datalogging with various XDS systems enabled would know this.


This is not true. See our previous discussion. This was a result of you confusing the differential in the SEQ cars with that of the DSG cars.



Its not a good look or good form to quote papers out of context without sourcing the name or author of the paper



Wavetrac is clear to not call their devices lockers. If you look at the friction area on the wavetrac you can probably get an idea of how much power can be transferred in the zero load case. Also, plenty of videos available of wavetrac not being able to move the car with one wheel in the air. This doesn't necessarily make it a bad limited slip differential.



You have confused the engine torque applied at the flywheel with the torque applied to the clutches of multi-plate differential. These are not the same thing and operate at different leverage ratios. There is no relevance between the two as suggested.



These are separate systems and don't talk. You don't effect the operation of the FDL by changing XDS settings it still responds to the same inputs in the same way. This is clear from data logging.



For the same speed, G load, steering angle, yaw, and wheel speeds it will behave exactly the same


The fact of the matter is that electronic controlled multi-plate clutch differentials have numerous advantages over the classic mechanical only clutch and gear type LSDs. Not being able to directly sense torque is also a potential drawback (that being, said who knows, the center diff in the Subaru STI previously had both a torsen and a e-LSD in one package and now its just the e-LSD with the torsen still existent but mechanically disabled since 2018). We are seeing in modern high performance sports sedans and sports cars a big movement away from mechanical LSDs. Whether we like it or not these solutions are the future. Among about half of the GT4 racecar field you have electronic diffs. If you go buy a new GT3 RS you have an electronic diff. These e-LSDs can evaluate more relevant information that will never be considered by a mechanical only solution and are far more tunable in real time for tire wear and track conditions. Things like yaw, wheel angle, and G loading are all relevant in terms of deciding how much to lock. In terms of the unit in this car, I have not seen any empirical data on the VAQ vs any of the mechanical only solutions but I would love if someone has collected any data to show where each system shines. I have also seen reports of people complaining about overheating but haven't seen anyone actually prove their issues were diff caused (and not tire), again I would love to see this info because it contradicts my experience.

To this day these units continue to be used in IMSA IMPCC 2hr-4hr races. In europe they are used in longer endurance races. If you look at the tech video FCP euro did on old RS3 LMS DSG you will see that the VAQ has no additional cooling on the TCR cars which use 265mm Michelin slicks. From twelve years ago there was this quote from the haldex folks:
"The Haldex FXD prototype caused no technical down time and showed no signs of fatigue during the entire 24-hour race. " [Haldex’s new innovative electro hydraulic differential lock, Haldex FXD, debuts in the Volkswagen Scirocco #116 at the 24-hour Nürburgring Race]

If anyone has data to share i'd love to see it


The above post is proof that the writer has not read & understood, any of the info that I have posted about the VAQ unit.

Heads against bricks walls, springs to mind...

Most people now will agree that to continue with this is pointless & a waste of time.
 

TimCv1

Go Kart Newbie
Location
CO
Car(s)
GTI mk 7
Every time I’ve driven a GTI on track, I’ve found the diff to be very impressive, so it surprises me that people have decided to have a vendetta against them.

The VAQ does torque-vectoring, not just transfer. Not sure why people think that's inferior to a traditional LSD....
 
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