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VAQ Differential Discussion

grambles423

Automotive Engineer
Location
Alabama
Car(s)
2008 GTI
Taken from a Technical Memorandum. Even though there isnt any true technical mechanical discussion, its a good functionality approach so we can get into the mindset of what is to come:


Electronically controlled front-axle transverse differential lock (VAQ)
For the vehicles developed in the MQB system – and for the first time
in front-wheel drive production vehicles – an electronically controlled
front-axle transverse differential lock (VAQ) will be available. VAQ
passed grueling endurance tests at the 24-hour race at the Nürburgring
in the past two years. The electronically controlled front-axle transverse
differential lock is a powerful addition to the familiar ASR, XDS and ESP
control systems. The new system is based on a multi-plate coupler that
is located between the differential cage and the right drive shaft. The
pressure required to actuate the VAQ is produced and regulated by an
electrically-powered hydraulic pump. A control unit continually adjusts
for the optimal locking power as a function of the driving situation.


For example, this prevents slip of the wheel with the least grip in a split
friction (split-μ) situation or slip of the wheel on the inside of the curve in
turning situations. In dynamic driving, VAQ applies the drive torque to the
wheel on the inside of the curve and the outer wheel on the road according
to the different vertical wheel forces. The vehicle remains very neutral
right up to its performance limits by this so-called torque vectoring effect.
Curves can therefore be driven more precisely and with greater stability
than ever before with a front-wheel drive car. The traction disadvantages
of front-wheel drive vehicles are essentially eliminated. Significantly more
agile driving behaviour and higher speeds through curves also generate
even more driving fun and better performance.

Discuss
 

Soflogtimk6

Go Kart Champion
Location
GunKatas house
Sounds amazing. Want to drive one to see what is is like. It talked about corners but will traction hold that well from launch going straight?
 

DAS_STIG

Banned
Location
Chicago
theoretically, if the surface under both tires is the same when launching, this shouldn't make a difference. realistically we all know that one tire might have some loose gravel under it or be going over a manhole cover or something else, so it might help out a bit here and there. corners will be where you should really notice the difference.
 

Soflogtimk6

Go Kart Champion
Location
GunKatas house
Damn so it will still suck trying to launch. I really want a MK7 gti but I have had a mk4 and currently a mk6 and I am done with Fwd. I'll wait for the r or get an awd Audi.
 

grambles423

Automotive Engineer
Location
Alabama
Car(s)
2008 GTI
As Dybz said, the LSD will really help ALOT in corners. Straight line...not so much. However, I have never experienced much torque steer even with K04 power levels in a straight line (~380tq). Out of corners I get ALOT of push in understeer due to traction which is where the LSD would really shine.
 

RacingManiac

Drag Race Newbie
Location
MI
Reading this, it sounds like the Haldex system for AWD applied to FWD. Haldex is something VW has done for a while so it probably isn't a huge stretch for VW to move it to this application(instead of front/rear axle slip, you get left-right wheel slip). The advantage is obviously the system can still decouple the left-right wheel so adverse camber, bumps or whatnot that tend to cause the preloaded or mechanically torque sensing type diff to lock/unlock won't happen with this.
 

grambles423

Automotive Engineer
Location
Alabama
Car(s)
2008 GTI
Reading this, it sounds like the Haldex system for AWD applied to FWD. Haldex is something VW has done for a while so it probably isn't a huge stretch for VW to move it to this application(instead of front/rear axle slip, you get left-right wheel slip). The advantage is obviously the system can still decouple the left-right wheel so adverse camber, bumps or whatnot that tend to cause the preloaded or mechanically torque sensing type diff to lock/unlock won't happen with this.

Yep. You are correct. It IS a Haldex based system.
 

grambles423

Automotive Engineer
Location
Alabama
Car(s)
2008 GTI

PRRGG1

Drag Racing Champion
Location
USA
Would the VAQ help traction in snow, or is that more of a XDS function?
 

golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate

PRRGG1

Drag Racing Champion
Location
USA
Thanks VERY much golfdave -- lots to learn there. Just what I was looking for. (y)
 

PRRGG1

Drag Racing Champion
Location
USA
I must say that I've never owned a car that corners as solidly and predictably as my new GTI. It's pretty amazing and great fun, whether it's making a quick turn at speed at an intersection or taking on a wide sweeper. I'm assuming that it's the VAQ doing its thing, although ESC is probably lending a hand too. All-in-all, pretty darn cool. :giggle:
 

ucfquattroguy

Go Kart Newbie
Location
Florida USA
It's honestly a bunch of factors.
Mk7 GTI has a pretty good spring/damper setup out of the box compared to previous versions.
MQB platform is stiffer than previous.
VAQ plays a part when it comes to front-end bite during corner exit.
ESC is fairly decent. I've only had hard intervention when I've blatantly (and on purpose) did something to provoke it.
 
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