S3 - 4WD, How does it work...?

[DaveMK^]

Hi All,

How does the 4WD system work on an S3? I heard its not constant and only engages when it needs too?

Any explanations appreciated

Thanks

 

[Olly_K]

Yep its not a torsen diff like in bigger audis (s4/s6/s8 etc) which is a perm 50/50 split of power.

S3's - and golf r32's etc for that matter use a haldex system.....which is a re-active system. Once the front wheels start to slip, it will transfer some power to the back wheels.

You can upgrade the haldex controller to be a more pro-active system than a re-active one, so it will sense when the front wheels will start to slip and transfer power to the back earlier

 

[DaveMK^]

Perfect thanks for the fast response!

 

[Defratos]

Olly Always responds quickly

 

[voorhees]

He needs to update his sig though

 

[edward_harris]

i thought the uprated haldex controller work on throttle position not when the wheels slipped?

 

[voorhees]

i thought the uprated haldex controller work on throttle position not when the wheels slipped?

so the wheels would slip and slide and you would crash because the throttle position wasn't right?!

 

[edward_harris]

no i thought when the throttle is past a certain point it goes to 4wd instead of waiting for the wheels to slip at all

 

[simch]

He is sort of right, I believe it is due to throttle position and speed of application with the uprated haldex controller, rather than engine torque produced that prompts the haldex to kick in on the stock car.

 

[sitrials]

haldex is poo standard but with the uprated controller its a bit more fun in the wet!

 

[jojo]

From my bit of research and reading amongst this other forums, I'm led to believe the uprated Haldex controller works the same as the standard one, only making more use of the throttle position to help engage the Haldex to full on 50% throttle or more.

 

[satanmademedoit]

Where can you buy an uprated haldex controller? Are they a worthy mod?

 

[ChriS3]

He is sort of right, I believe it is due to throttle position and speed of application with the uprated haldex controller, rather than engine torque produced that prompts the haldex to kick in on the stock car.

From my bit of research and reading amongst this other forums, I'm led to believe the uprated Haldex controller works the same as the standard one, only making more use of the throttle position to help engage the Haldex to full on 50% throttle or more.

You're both right, but its not the full picture. The up-rated haldex works on a narrower slip angle than standard - so it takes less front wheel-spin to engage the haldex clutch. It also works as simch says, meaning its more predictable coming out of a corner as you get 4wd more consistently than standard. Takes away some of the understeer too.

 

[ChriS3]

Where can you buy an uprated haldex controller? Are they a worthy mod?

Most tuning companies have them - Awesome, The TT Shop, Star Performance, etc.

Makes a nice improvement to the drivability. But it depends how you drive. I only really noticed the effect when pushing hard. It won't turn the car into a drift machine, but its more stable and planted. I'd say driving style comes into it too. Some people that have it think its a waste of time and can't feel the difference.

 

[chippie]

would it not be possible to completely replace the haldex coupling to give permanent for wheel drive ?