Just a quick question on the rear torque vectoring behavior on the SH:

I understand the concept of breaking-slowing (Green Arrows) the inside wheel, and speeding up (Blue Arrows) the outside wheel on a turn. This happens every time i take a turn at slower speeds.

Now when i am taking a sweeping left-hander or right-hander turn at say 80mph, what i see is exactly the opposite. The outside wheel is breaking-slowing (Green Arrows), and the inside wheel is speeding up (Blue Arrows). Maybe one of you nice folks can explain-expand on this concept, so i can understand it?

Thank you!

 

At 78mph the electric motors are decoupled from driving positive torque. The green arrows are representing power regen more than torque application. However when decoupled, the planetary and sun gears cause the 'opposite' effect you describe. The outer real wheel in that turn ( > 80mph) has / needs the most traction. SH logic applies to that wheel (focusing where more traction is). But since SH-SHAWD is not feeding positive torque, it only regens power (the green arrows). With focus on the outer rear wheel, the inner real wheel experiences equal but 'opposite' force (the blue arrows) but no positive torque is applied. In effect, negative torque vectoring is still occurring, but mostly as a regen source. The system 1st reacts to the outer rear wheel as the greater traction source (and naturally is faster than inner rear wheel in a turn) and applies the regen logic (as it cannot apply positive drive torque). THEN the opposite inner rear wheel experiences the equal but opposite force due to the planetary gears, resulting in the system displaying positive (blue arrows). It really is not getting positive torque from the system, being de-coupled, but it is displaying that opposite but equal effect.

That is my understanding and welcome anyone with a better explanation to correct my take.

 

So if i am understanding this correctly, there is NO breaking-slowing or speeding up happening over 80mph. There is however regeneration occurring.......

I am pretty sure this happens when i am taking a turn at 60-70-etc also.....I will check for sure though next time i take the car out.

Thank you Tampa!

 

There is no positive torque being applied due to the decoupling. The regen that is occurring does apply some negative torque, but I suspect due to the planetary, gears nothing significant - but does permit reverse polarity of the motors to regen power.

The physics of both rear sides can swap (when the car changes direction), so in effect there is still side to side vectoring.

If you want to make the most of the system in curves or twisties, keep it below 78mph. In a straight highway cruise, it is moot and arcs at 78mph+ the negative torque effects are nominal, but regen is primary.

Now should you loose control of the vehicle I expect all the systems will do their best to save your butt (VSA, LKAS, RDM, etc).

 

If you look at the SH-AWD section of the TLX brochure, it describes a lane change scenario where it will send more torque to the inside rear wheel for increased stability. I think that RLX SH is doing the same thing in those less tight curves.