AWD GT4, How does it work? Anyone? Options

[neoklis]

Hey guys,

As per the topic above, does anybody know how the AWD on the GT4 works? The reason why i am asking is that i always thought it was 50:50.
The car does not spin on tarmac no matter what you do to it. But on gravel or when the road is wet, the car can spin unbelievably and it seems that most of the power is on rear wheels as the tail of the car travels on either side depending on the direction of the front wheels. The car never gets out of control though (like when you overspin a rear drive car)

Any further info on this would be helpful
Thanks

This post has been edited by neoklis: Mar 16, 2004 - 5:35 AM

[Mike]

give me your car and I'll find out for you

[neophile]

Hi

Your car has an epicyclical centre differential with 50-50 % F/R distribution.

It also has a torsen rear differential and central viscous coupling, which could explain why it feels different on gravel compared to tarmac.

Check out this site for more info.

[Akimbo]

[neoklis]

wow, that was the first site i came up with when i was finding info for the GT4 2 years ago. I never saw the articles though. Although i am not quite sure on how everything works, i can see now the technology put into the GT4.
Still though can get why the rear of the car spins more in gravel or wet road. Shouldnt the 50:50 and all the systems mentioned maintain the stability of the car in such cases. In any case I really have no problem with that. I was just worried if there is a problem somewhere and the car behaves like that.

[Sh0gunkid8721]

[WannabeGT4]

[neophile]

Your car is working exactly as it is supposed to (and being a st205, looks good while it does it ).

Let me explain my basic understanding of how it works:

As you may already know, differentials let the wheels in a car spin at different speeds. This is very good especially when cornering, since the outside wheels need to spin more than the inside wheels. Without differentials, cars would be very rough riding and would wear parts out very quickly.

Being a 4WD rally inspired car, the ST205 has Limited Slip differentials. This is a good thing. In a car with a standard differential (no LSD) the wheel with the least resistance spins - so if you have a 2wd car with one wheel in mud, and one on tarmac, the diff will transfer lots of power to the wheel on mud (since it can turn easier). This is good during cornering, but not when you want to get out of a mudhole

A Limited Slip Differential allows wheels to turn at different speeds, but only to a certain point, then it "limits the slip" and sends the same power to both wheels. This is the best of both worlds, since you can still corner etc, but when one wheel is losing grip, the other wheel still gets power to help give you traction.

The ST205 actually uses a very good type of LSD called Torsen Differential (which stands for Torque Sensing) and as the name suggests, it senses difference in torque between wheels instead of wheel rotation - it is quite expensive but responds instantly.

Now if you're still awake, there's one more thing to know The ST205 also has a central LSD (a different type called a viscous coupling) which basically sits in the middle of the drive shaft between the front and back wheels. Under normal driving conditions this transfers 50% of power to the front wheels, and 50% to the rear. However if either the front or back wheels lose traction, it can transfer power to the ones with more grip - changing the ratio up to 20:80. This would be why you have noticed a diffence in handling between tarmac and gravel surfaces.

As I said, this is just my basic understanding of how it works (I'm no mechanic), but I hope this helps

[uzthedentist]

if you want loadsa info then check out the gt4 of uk website forums. www.gt4oc.com.
btw if your car is handling poorly u might wanna get your fig 8 links checked

[neoklis]

[uzthedentist]

fig8=figure 8. its the lower suspension arms. they go quite often on the st205