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How the VW Golf GTI Performance Pack (PP) “Front Differential Lock” (VAQ) works.

rafal83

New member
Location
Poland
that power is above what the car can cope with with out any wheelspin...

Usually you should try the best tyres Conit sport contacts or PS4,s...then suspension etc ..

You can reduce the intervention of the XDS (ESP light) by adjust a setting in the ABS unit (labelled expanded difflock) to "weak"...this will allow the VAQ unit to do its job better.

when you spin the wheels..the left (when sitting in the car) wheel will spin faster then the right one as the VAQ unit is on the right side of the gearbox....& the left drive shaft is lighter shaft is therefore spins easy..the right drive shaft goes through the VAQ unit & has the extra weight/mass of the clutch's to spin therefore slower... before the ABS sensors tell the VAQ to operate..
I have PSS, but in winter time I run Dunlops that generetes more wheel spin - true. Some poly bushes and torque arm insert as well installed already. I tried many settings in XDS (weak, standard, strong), also changed VAQ into "increased traction" in module 32. I can say that changing to increased traction helped a little, but didn't cure. I also have the feeling that something might be wrong with suspension and it tends to twist into right under hard acceleration even without esp/xds intervention - no wheel slip. BTW, do you know what does "Haldex clutch status - degree of blockage" mean in advanced measuring module 32? Maximum value i was able to achieve was 24,8% and it locks up even when car is in neutral and i press hardly accelerator.
 

alper

Ready to race!
Hi, great post and piece of information! I'm coming from Seat community in Europe owing stage 2 Leon Cupra which uses the same system as Golf PP. I tried recently to understand better VAQ due to the problem i have with torque steer. During hard acceleration my left wheel gets too much torque, spinning faster than right. Even at high speed over 100km/h when (full load) I checked with VCDS - left wheel spins faster, then ESP light on the dash tries to (perhaps) brake it and so on....at the end it pulls to the right. In my simple understanding the VAQ should efficiently manage torque between both wheels, but sounds is not like this. Despite some mechanical suspension failure what can cause such an effect? Are there any adaptations in ESP that should be done? I did many times basic settings in module 32, but it didn’t change. There are no errors, nothing. Or 500NM of torque combined with 400HP is too much for this car.

This is definitely not normal even for a 400bhp/500Nm car. Those are typical stage 2 numbers that several GTI and Cupra owners run, some of them while also regularly tracking their cars, without experiencing any of the issues you describe: Intense torque steer, even above 100% km/h, and car feeling as it wants to turn to the right without any lights coming on? To my knowledge and personal experience with a slightly weaker stage 1, both the VAQ and the chassis are well capable of keeping the car on its track at these power levels, so it sounds as something in your car needs looking at.

Did you buy it new and have full knowledge of the status and settings of all systems? Has it been particularly abused in any way? I guess not as you'd have mentioned it but just in case...
 

rafal83

New member
Location
Poland
The car is 3 years old and I'm the only owner. I had 2 years ago slightly left rear hit while i tried to drift on the snow, but it ended up with scratched left rim, left rear bearing replacement (became noisy) and alignment of course. I have replaced springs, control arm bushes and made few alignments in the meantime since that time. The only moment recently when car was good it was just after stage 2 (ironic) TCU and ECU remap - late summer 2017. It was combined that also with another alignment. My feeling is that even with unequal torque distribution chassis should manage straight line acceleration quite well as you said, so I'm susspecting these direction also. I will keep you posted if i discover anything new.

Coming back to the topic. There is at the beginning of the thread information about 3 VAQ settings in Cupracer cars. Do you thing is the same what you could change by using VCDS in module 32? There are also 3 settings called: reduced noises, standard and increased traction.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
T
Coming back to the topic. There is at the beginning of the thread information about 3 VAQ settings in Cupracer cars. Do you thing is the same what you could change by using VCDS in module 32? There are also 3 settings called: reduced noises, standard and increased traction.
They use "Motorsports" specific software, so it will be different to the road car software in the VAQ..

However just log all changes & change on setting from the strongest to the weakest & see if it makes any difference in the direction that you want..ie reducing torque steer..
 

alper

Ready to race!
The car is 3 years old and I'm the only owner. I had 2 years ago slightly left rear hit while i tried to drift on the snow, but it ended up with scratched left rim, left rear bearing replacement (became noisy) and alignment of course. I have replaced springs, control arm bushes and made few alignments in the meantime since that time. The only moment recently when car was good it was just after stage 2 (ironic) TCU and ECU remap - late summer 2017. It was combined that also with another alignment. My feeling is that even with unequal torque distribution chassis should manage straight line acceleration quite well as you said, so I'm susspecting these direction also. I will keep you posted if i discover anything new.

Coming back to the topic. There is at the beginning of the thread information about 3 VAQ settings in Cupracer cars. Do you thing is the same what you could change by using VCDS in module 32? There are also 3 settings called: reduced noises, standard and increased traction.
I see, there could be something tracing back to that incident then it's my only guess. As you know, with 400bhp you can break traction very easily yes, but it only happens in a straight line, there is no torque steer or other weird behavior.

No idea if it's the same setting as on Cup race cars but I know switching to "increased traction" made a noticeable difference during cornering, for the better.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
Corrected the info on the order of stacking the clutch plates as there could be three ways to make the clutch pack...I thing I have got it right now...will have to slightly alter the drawing...

Just so little info out there on the details...
 

rafal83

New member
Location
Poland
I've just started battle with torque steer and VAQ from analysis and data stand point. Herewith print screen from logs - Conditions: slightly wet tarmac, winter tires and hard acceleration from stand still, not WOT, but hard enough to lose traction and trying to manage this. Car pulled to th right, you can see how big difference is between left and right wheels. Does VAQ work ok basing on the figures you see? Another question is why the front axle speed difference is so low (max 3,3 km/h) while left and right wheels speed difference are higher (even up to 17km/h)?
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
Finally got the drawing & description of the internals of the clutch pack/basket 100% accurate....

so please re-read that section..& it is marked, is the edit...
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
I've just started battle with torque steer and VAQ from analysis and data stand point. Herewith print screen from logs - Conditions: slightly wet tarmac, winter tires and hard acceleration from stand still, not WOT, but hard enough to lose traction and trying to manage this. Car pulled to th right, you can see how big difference is between left and right wheels. Does VAQ work ok basing on the figures you see? Another question is why the front axle speed difference is so low (max 3,3 km/h) while left and right wheels speed difference are higher (even up to 17km/h)?
If you remember in my post I quote the Borg Warner testing of the VAQ for a simulator which found that the VAQ unit oscillating very quickly from side to side as it tried to figure out which wheel to put the power down to?...You have just proved it again with your data.....;)

Also I suspect that as the VAQ unit is on the right hand side of the gearbox when siting & facing the front..that it will pull the car that way....

Re the data...the data is not 100% as the time stamps are way out for each line...are you using an older VCDS cable & not the new "V2"...
 

bluefox280

New member
Location
Broomfield, CO
golfdave said:
The FDL activates when an ABS sensor identifies a spinning front wheel (inside wheel when cornering).
When cornering, and the traction control light is flashing:
a.) is the VAQ / FDL operating during when the light flashing?
b.) is the VAQ / FDL is operating prior to light flashing but the car is being overdriven and wheel spin is still occurring?
c.) none of the above - if so, please elaborate when engagement occurs (is there a visual indicator of operation)

- Erik
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
When cornering, and the traction control light is flashing:
a.) is the VAQ / FDL operating during when the light flashing?
b.) is the VAQ / FDL is operating prior to light flashing but the car is being overdriven and wheel spin is still occurring?
c.) none of the above - if so, please elaborate when engagement occurs (is there a visual indicator of operation)

- Erik
There is NO visual indicator of when the VAQ unit is operating....

The VAQ unit would be operating when one wheel has more grip than the other & before the other traction control systems (however it may in certain conditions operate the other traction control systems to help lock up the VAQ unit)....the blinking lights on the dash are for the those other traction control systems & not the VAQ....
 

bluedoggiant

Ready to race!
Location
MD/GA
Yes & no...

what the problem is the transition between the XDS intervening & the FDL taking over...

The XDS will want to intervene first as its a safety system & is higher priority compared to the FDL unit...so the car will try to sort the lack of grip out with XDS/ABS etc first..

However in certain situations you want the FDL to be active & sort out the grip & the XDS to turn off.....

So you have to "back off" (set to weak) the XDS to allow the FDL to operate....in these conditions..


This is only for certain conditions & not "all the time"..way to many variables to list here...
Golfdave, amazing information in your first few posts in this thread.

So I’m gathering that by turning XDS off, you allow the VAQ to work more, but you need the XDS to “pre load” the VAQ.

So does this mean the XDS is essential to the VAQ operation and therefore you should not turn off XDS? And because you want the VAQ to work more than XDS, the XDS “weak” setting is most optimal? Even more so than turning it off completely?

I have my VAQ set to increased traction, torque limiter off, ESC Off, VAQ set to Sport in infotainment System. Did some tests with XDS off and strong and can definitely see a few mph improvement blasting out of corners with it off.

Thanks!
 

stockton2007

Go Kart Champion
Location
NJ
Golfdave, amazing information in your first few posts in this thread.

So I’m gathering that by turning XDS off, you allow the VAQ to work more, but you need the XDS to “pre load” the VAQ.

So does this mean the XDS is essential to the VAQ operation and therefore you should not turn off XDS? And because you want the VAQ to work more than XDS, the XDS “weak” setting is most optimal? Even more so than turning it off completely?

I have my VAQ set to increased traction, torque limiter off, ESC Off, VAQ set to Sport in infotainment System. Did some tests with XDS off and strong and can definitely see a few mph improvement blasting out of corners with it off.

Thanks!
What security code did you use to access 32 - differential lock to set van to increased traction? Thanks!!
 

plac

GTI Master
Location
SF Bay Area, CA
confused about PP and 2018 GTI's. Did I hear right that the PP diff is not available whatsoever on 2018 GTI's?

I know my GTI SE has "GTI" on my brake calipers, but not sure if they are golf R brakes??
 

Clem604

Ready to race!
confused about PP and 2018 GTI's. Did I hear right that the PP diff is not available whatsoever on 2018 GTI's?

I know my GTI SE has "GTI" on my brake calipers, but not sure if they are golf R brakes??
2018 GTI's in the SE and Autobahn trim get the VAQ differential and the PP/Golf R brakes as standard.
 

Visceral

Ready to race!
Location
Northbrook, IL
Just reviving this thread by golfdave because it has so much good information in it. To the point though, has anyone messed around with the XDS settings and found meaningful differences? Understand there are maybe 3 or 4 choices... I don't have a VCDS so going by what I recall from previous posts on this.
 

TheJokker

Ready to race!
Location
jacksonville
I would like to add to the comment that many dealers are not familiar with the need to replace the differential fluid. I took my 2016 to be serviced last September and the Service Manager remarked I was only the second person who requested a fluid change. The dealer had to reschedule my appointment not once but twice because they did not have the specific fluid in stock and it was two and a half months later before it was eventually serviced. Total cost was $246.00
 
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