4Drive VCDS/OBDEleven 4WD Control module - Traction Mod

[Damo H]

Got wind of this via a facebook post about an S3 owner not being happy with the understeer in his S3.

Anyway this linked me to the following forum around a mod on VCDS...

https://www.vwroc.com/forums/topic/20965-awd-increased-traction/

This appears to be the same mod others have tried for the normal VAQ Diff (So Cupra and Golf GTi PP).

@paddy6789 kindly obliged this evening to swap the settings. Wasn't expecting much, but honestly the difference it makes can't all be a placebo effect surely. Car feels more planted in general, and to me in the corners its as close to the feel the 280 with the diff had.

Very happy, however I suspect its going to have an adverse effect on economy as others have posted it appears to make the car permanent 4WD. Also the question is the impact on wear and tear of the VAQ system.

Any one else tried this on a 4drive?

 

[Butty]

I thought the 4drive had a single VAQ and that is on the rear axle? The front is just a normal open mechanical diff.
How is this mod making the 4drive permanent?

 

[Damo H]

I thought the 4drive had a single VAQ and that is on the rear axle? The front is just a normal open mechanical diff.
How is this mod making the 4drive permanent?

All the VAQ stuff is at the front of the car in the gearbox. Effectively there is some sort of electronic pump that engages/disengages the rear drive.

For the FWD Cupra that pump is used in a different way to effectively make the front diff act like an electronically controlled limited slip differential.

I’m sure someone can explain it better that I.

 

[silky16v]

All the VAQ stuff is at the front of the car in the gearbox. Effectively there is some sort of electronic pump that engages/disengages the rear drive.

For the FWD Cupra that pump is used in a different way to effectively make the front diff act like an electronically controlled limited slip differential.

I’m sure someone can explain it better that I.

The 4-drive cars don't have this in the front diff?

The propshaft turns all the time and the rear haldex regulates the back axle, nothing in the front diff disengages the propshaft

this mod is simply making the Haldex in the rear diff work harder thus feeling like more permanent 4x4

 

[Damo H]

The 4-drive cars don't have this in the front diff?

The propshaft turns all the time and the rear haldex regulates the back axle, nothing in the front diff disengages the propshaft

this mod is simply making the Haldex in the rear diff work harder thus feeling like more permanent 4x4

Oh right my understanding was that it only engaged the rear drive as and when needed and that it was just an open diff at the back.

So you’re saying is always 4wd and that the Haldex just determines how much extra power is directed rearwards.

 

[silky16v]

Oh right my understanding was that it only engaged the rear drive as and when needed and that it was just an open diff at the back.

So you’re saying is always 4wd and that the Haldex just determines how much extra power is directed rearwards.

It does only engage as and when is needed but its not coupled from the front diff the whole propshaft assembly turns all the time
the rear can free wheel and the Haldex controls the torque applied to the rear (the Haldex is part of the rear diff)

This mod is simply engaging the haldex to be more aggressive and thus being more 4wd (similar to the VAG Torsen awd, but not if you get what i mean)

personal experience I've had a RS3 8v and Audi S1 and now the Cupra 4-drive all with Haldex systems which is very very capable and safe and quite understeery (except the S1)

I also own a B5 RS4 with Torsen quattro 50/50 split, big old heavy barge but find it far more predictable and sure footed when on it and on fast open roads going through the bends you knew the limits (and could slide it around)

where as with the RS3 or Cupra you don't have that luxury to play with it at the limit as its always trying to correct you

 

[Damo H]

It does only engage as and when is needed but its not coupled from the front diff the whole propshaft assembly turns all the time
the rear can free wheel and the Haldex controls the torque applied to the rear (the Haldex is part of the rear diff)

This mod is simply engaging the haldex to be more aggressive and thus being more 4wd (similar to the VAG Torsen awd, but not if you get what i mean)

personal experience I've had a RS3 8v and Audi S1 and now the Cupra 4-drive all with Haldex systems which is very very capable and safe and quite understeery (except the S1)

I also own a B5 RS4 with Torsen quattro 50/50 split, big old heavy barge but find it far more predictable and sure footed when on it and on fast open roads going through the bends you knew the limits (and could slide it around)

where as with the RS3 or Cupra you don't have that luxury to play with it at the limit as its always trying to correct you

Ahh I thought it was the rear prop that was engaged. Every day is a school day.

The Bugatti and Lambo use Haldex but with it permanently on. Wonder if this is a similar thing or the setting they use. Certainly feels better. Will see what the fuel economy does. Certainly don’t plan on turning it back off yet. But if fuel economy plummets may have to invest in an android phone and obdeleven...

 

[kiddo]

The 4-drive cars don't have this in the front diff?

The propshaft turns all the time and the rear haldex regulates the back axle, nothing in the front diff disengages the propshaft

this mod is simply making the Haldex in the rear diff work harder thus feeling like more permanent 4x4

I understood the 4 drive system to be as you describe silky... Open front diff with prop shaft to rear diff permanently turning. If slip detected on either front wheel haldex system engages clutch between prop shaft and rear diff to engage rear wheel drive. The fwd cupras have half a haldex and are able lock drive to which front-wheel isn't slipping.

 

[Damo H]

Yeah always known the front diff is open on the 4drive. It’s why the Focus RS with its performance pack getting the LSD at the front would of been nice on this. Just didn’t realise that the rear prop was always driven and it engaged at the rear axle.

 

[Butty]

So what is the mod doing on the Haldex for front to back balance, rather than the mod on a VAQ unit on 2WD cars across an axle?
Can't see how the 4drive mod helps on understeer issues.

 

[Oldbutswift]

The other issue with bringing the rear diff more into action is potential reliability issues,since they are only designed for part time working.

 

[Damo H]

The other issue with bringing the rear diff more into action is potential reliability issues,since they are only designed for part time working.

Yeah that was my thinking, but I also though surely the clutch always being engaged would cause less stress and wear and tear than moving on and off.

 

[Jaco2k]

I even forgot I had made this mode to my car
...need to change it back now when there is snow and see if I feel any differences