DC2slpr

Lol! Lots of good answers here..

Fabrik8

You asked....

DC2slpr

That is exactly what I was looking for. So if it is a clutch type, the clutches are unlocked during strait line driving with no wheel slip? Can the tq biased be changed dynamically without wheel slip? Sorry, I'm not too familiar with how a planetary gear set is used as a tq biasing center diff.

Are there center diffs where the clutches lock the two outputs together unless they are "opened" or over powered? - like a clutch type rear diff?

I'll leave the crown types alone for now haha.

BTW - I care about the topic - all the useless comments in this thread and I get accused of trying to boost my post count?

Fabrik8

No, the clutches are not unlocked. They are locked but aren't doing anything because there is not relative motion because there is no speed difference. A clutch-type center diff (there are viscous center diffs as well, etc.) works like the clutch type rear diffs you're talking about, where the outputs are locked together until there is a speed difference. So if you start with a 35/65 torque split (for example) in a straight line with no wheel slip, you'd add/subtract from that as the limited slip function shifts torque to the front or rear as you have a front/rear slip condition.

You can't change the torque split dynamically without wheel slip, because limited slip differentials don't function until there is a speed difference. Until then, the diff has the normal front/rear torque split from the difference in output gear ratio. So something like an STi has a 35/65 torque split until there is a slip condition. Then things get complex.

So if you wanted dynamic torque split without wheel slip, you'd need some variable gear ratio in the diff, or artificially create a speed difference between the two shafts without having a difference in wheel speed.

Born-Sinner

http://en.wikipedia.org/wiki/Torque_vectoring

?

Fabrik8

Yes, they vector torque during wheel slip. During normal operation they use the mechanical torque split built into the differential, like I mentioned above. They are basically controlling the clutch operation (or other means based on the diff design) to transfer torque during slip conditions. There really isn't any need to dynamically transfer torque under normal conditions, until you lose traction or overpower the tires with engine torque.

Born-Sinner

Yes I agree. Torque vectoring does allow for better handling while working with VSA. On SH-AWD I notice when climbing a steep hill under normal throttle, the system directs more torque to the rear wheels to better assist the climb. It is a very intelligent system if you ask me. On the RLX they also use torque vectoring to assist you through turns no matter what condition it is. It literally feels like you are floating(smooth) through a turn in that car. Maybe I can post a video later to show it's unique functions. On the ODMD, it allows you to monitor the SH-AWD system which is pretty cool to watch while driving especially in the snow/ice.

JDM74

This is possibly the poorest written article on a technical subject I have ever read on Wikipedia. It reads like some 11th grade Subaru fanboi wrote it for his class paper. The guy that wrote this thing sucks at technical writing. I would suggest reading this one instead:

http://en.wikipedia.org/wiki/Quattro...-drive_system)

Fabrik8

Yes. As someone who has had to do a lot of technical writing in the past, I agree.

Yardjass

I couldn't even get through the second section. What a terrible fucking article.