Watching the car today in a turn, it was clear that there's an LSD on the front.

I don't see anywhere that talks about this, but I notice that the car needs three different kinds of gear oil, so I gather there's a good chance the LSD on the nose is a Torsen unit instead of a clutch pack (like the rear).

But I am having a hard time understanding how the computer would control the Torsen unit the way that it controls the clutches on the rear wheels.

Does anybody know much about how the vectoring works on the nose?

 

I don't believe there is any vectoring in the nose. I think the only thing that comes into play is the VSA. Having had Torsen in my 08 Civic Si, the feeling there was the outside front was not losing any power in a turn to the inside wheel - it actually helped rotate the car around a turn. What I feel in the SH-AWD is that the outside rear adds to the push into the turn. I will report more on this in the coming winter months when I can play with traction better than on dry or wet pavement.

The MID shows equal power to the front wheels while the rears vary depending upon what the car is doing. This reflects what Honda shows on their websites in animated demos.

 

Okay. Well, here's what I noticed in a hard left corner while the SH-AWD display was turned on.

I expected to see the right rear wheel showing quite a bit of torque.

What surprised me was that the right front wheel showed more torque than the right rear wheel, and more than the left front wheel.

I can conceive of other explanations, but it seems to me the most logical explanation is that there is an LSD on the front.

I can't claim to know for sure what I am talking about, of course.

But that's what I noticed to make me ask.

You're probably right. It'd make sense to mention it someplace if it existed, because a Torsen axle would add more than a couple hundred dollars to the price of the vehicle. And I doubt it's any kind of clutch like the rear because there's only mention of Honda MTF going to the transmission.

Maybe the vectoring of the right rear pushes the right front wheel in a way that causes it to display more torque?

 

George posts an excellent question. I too would like more info on the vectoring system.

I can attest thus far on wet rainy roads during heavy Seattle downpours, the SH-AWD system is solid. Very confident inspirations, plenty of grip. Makes me "want" to go faster than necessary. Overall very neutral handling... I recall my 1G TSX was not as inspiring on wet roads.

I am waiting for the snow as well. I too will report on the TL's handling when the snow comes down, or if I decide to go up to the mountains.

Not to sound like an Acura ad, but the 4G TL was engineered with the snow in mind; I recall the 4G TL was tested on the snow during the winters of Alaska and Minnesota: http://www.topspeed.com/cars/acura/2...l-ar80141.html

 

I'm not a 4G TL guru, but SH-AWD as introduced in the RL could go side to side on both axles. The example typically given involves the rear, but both have the capability. While driving my RL I can see that in use (not that the SH-AWD gauge is necessarily gospel). The TL's SH-AWD is a bit simpler in the back than the RL (to save cost and weight), but it should be the same up front.

 

This is not correct. The RL does not shift torque across the front axle. RL advantages include a carbon fiber reinforced drive shaft and a planetary gear acceleration device in the rear differential. This device allows for about 5.6% over drive on the outside rear wheel vs. 1.6% in the fixed ratio on the TL.

 

So basically we all seem to know that the computer's vectoring happens at the rear axle, but none of us seems to know if the front axle is a Honda Torsen LSD, which would mechanically, automatically shift torque.

Mission quest.

 

Alas, you are correct. I just re-watched the intro video:

 

George, the front axle on the SH system is an open differential. I think an LSD would take a bit away from what SH is trying to do unless it also actively distributed torque like the rear. An open front allows a litle more free spin of the outside front wheel in turning while the SH accelerates the outside rear wheel. They compliment each other nicely and it's a simpler design with less weight and complication plus it offers ideal handling for smooth dry surfaces. It's at it's worst under the opposite conditions but traction control and VSA do a great job on the front differential to assist in traction.

 

Fantastic video!

 

Thank you very much.