Viscous coupling & 4WD in Scenic RX4

[Bobi-BG]

Hello guys I can't find much information about 4WD system in RX4 and have to ask You
What is separation of the power on front:rear axle...is it 100%:0% or 95%:5% or other proportion in normal conditions (on the road)
Is it fast response of the viscous coupling when conditions are suitable to shift power to rear axle...what do You think, if You had impressions?
And another question...when I think about ASR and viscous coupling-the action of ASR and viscous is it in contradiction (one is for prevent sliping of the front wheels,and another is activating when front wheels start sliping )?
Any information will help me

[Alex]

Hi Bobi,

i found this page but i don't know about the truth

I will check my other documents at home ... maybe there is an information about that.

cu.

Alex

[Bobi-BG]

Thanks Alex
Hmmmm,in the link was wrote "On tarmac, the split is 60:40, the larger chunk directed at the sharp end. If the going gets tough, the ratio changes automatically to maintain traction".
In four different articles was wrote four different values (100:0, 95:5, 80:20 and 60:40 proportion of the front:rear axle in normal conditions).I am so confused

[Alex]

I think .... 100:0 or 95:5 will be correct, because the visco clutch will close at heat up and this only can happen by different rotation speed between the front and rear axle.

May be there is something to find at the original documents. I will have a look.

cu.

Alex

[fred ullrich]

Hallo Alex


hier eine Seite mit der Beschreibung der Visco-Kupplung,

bei mir habert es leider mit dem Englisch zum übersetzen.

Visco-Kupplung

Mfg


Fred ullrich

[Bobi-BG]

Why on German dudes,I can't understand much
Look what I found about viscous couplings:
http://en.wikipedia.org/wiki/Viscous_coupling
http://syncro.org/VCTest.html
http://www.autozine.org/technical_schoo ... _4wd_2.htm
But I can't still find true proportion of the power (front:rear axle).
BR,
Bobi

[Bobi-BG]

It seems to me that the power ratio on front/rear axle is this :

The four-wheel drive system is simplicity itself; in normal circumstances the front/rear drive split is 80/20, but when the ABS system detects front wheelspin, more torque is automatically transferred through a viscous coupling to the rear. Renault says the system maximises fuel economy, although that again raises the question of whether you need the extra weight of four-wheel drive in the first place. If and when you do take the RX4 off-road, the system works well; Moroccan desert terrain ranging from rocky tracks to steep, sandy hills posed no problems. There was some kickback through the steering on rough surfaces but the suspension travel and ground clearance were perfectly adequate, and the ride quality was good. It did feel a little soft on asphalt roads but not excessively so, and, with the exception of offset pedals and an awkwardly high clutch action, was a pleasant and comfortable drive.