RL06tech

Have you ever taken a sharp 90 degree curve at a fast speed with the pedal to the metal? That is sort of the ultimate test for SHAWD. Well here is the skinny, something very scary will happen! SHAWD will do its duty sending all the torque to the rear outsde wheel, if you are going fast enough this will induce significant over-steer. Naturally your reaction is to steer into the skid to regain a straight line while still stepping on the gas so as create a gracefull power four wheel drift. BIG MISTAKE What happens is the the VSA will abruptly stop your slide, at the same time, torque is transffered to the other rear tire (since you steered into the skid) causing the car to fishtail quite violently in the other direction till VSA catches you again and your cerebellum finally figures out that releasing the gas is the sane thing to do The car does not spin out or show any inclination of flipping over but your rear cheeks expirience a brief episode of tetany (ask neuron what tetany means ). Definitly an unexpected and possibly little dangerous trait. Please note that this can only be induced by pushing the car very, very hard on a dry road. I had expirienced a much smaller version of the same thing when I overdrove it in another sharp turn an a completely water soaked road, while test driving the car. The road where I re-discovered this trait was dry but may have had a little salt or sand on it.
So there you have it SHAWD is super, but f taken to the maximum it can get a little scary! I'm wondering what would be the effect with the VSA off, but I think its a test better suited for a track rather than an empty country road.

Mike_TX

I'm not necessarily saying this is what you mean, but some people seem to think SH-AWD is some kind of magic that will keep the car from doing anything at all weird under any and all circumstances. That just isn't so.

It's an aid, not a failsafe, and you can "over-drive" it just like you can over-drive any system.

I've seen posts from people on other forums who were surprised and pissed off when they wrecked out while doing something stupid. They expected the vehicle stability control system to step in and save them no matter how much they tried to violate the laws of physics and it just didn't work that way.

I have no doubt the RL can get away from you if you drive aggressively enough ... and that fact doesn't surprise me at all! What we don't know is what shape you'd be in if you didn't have SH-AWD.
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RL06tech

All true, as stated, this quirk is under extreme conditions. However, its important to know how the system will react when you go past its limits. Moreover, SHAWD, is a system you have to "learn" to extract the most of since it is truely different from all other drive systems. All systems have their quirks which must be explored if you ever want to get the most of your ride. One thing most RL owners have probably found out driving enthusiasticly is that the RL will oversteer progressively when pushed hard in turns (like any RWD) however its good to know what happens when when you exceed its very high limits. As already proven by my little test, steering into the skid to drift the car is not the thing to do. The correct reaction is to ease off the throttle till traction is regained and then bury the accelerator. The car will not drift with VSA engaged.
I saw a video of a driving "expert" skidding a BMW 3 station wagon in front of an audience, the finale was supposed to be a 180 degree skid right in front of the stands. To the crowd's (and the driver's) dismay the car flipped over during the maneuver.

RL06tech

All true, as stated, this quirk is under extreme conditions. However, its important to know how the system will react when you go past its limits. Moreover, SHAWD, is a system you have to "learn" to extract the most of since it is truely different from all other drive systems. All systems have their quirks which must be explored if you ever want to get the most of your ride. One thing most RL owners have probably found out driving enthusiasticly is that the RL will oversteer progressively when pushed hard in turns (like any RWD) however its good to know what happens when when you exceed its very high limits. As already proven by my little test, steering into the skid to drift the car is not the thing to do. The correct reaction is to ease off the throttle till traction is regained and then bury the accelerator. The car will not drift with VSA engaged. However the VSA is nicely calibrated for less than extreme driving since it does allow for some oversteer and interferes progressively (vs toyota systems that kill any fun driving and in most models cannot be turned off). In the instance I describe, the oversteer is extreme and sudden, thus, the system goes into full "save" mode abruptly. What is unique, however, is the wagging to the other side that is caused when tourque is appropriated to the other wheel when attempting to correct oversteer in the "usual" fashion by steering into the skid. What worries me is how the system would react if VSA were off. Maybe the quirk woud not happen or it could be even more severe. I'll try some day after I clean my drawers . My best guess is that it would disappear since the VSA would not induce the precipitating counter yaw effect.
I saw a video of a driving "expert" skidding a BMW 3 station wagon in front of an audience, the finale was supposed to be a 180 degree skid right in front of the stands. To the crowd's (and the driver's) dismay the car flipped over during the maneuver.

neuronbob

My buttcheeks would done more than clench hard (tetany! ). I would have been faced with stinky poo on my RL's leather with that maneuver, had I survived.

Certainly an argument for having systems like our VSA that can be turned off manually for this sort of testing on a track.

Mike_TX

Point taken. I wasn't sure if your original post was sort of a complaint about the RL's failure to recover the way you wanted it to, or just an alert on the way it behaves under extreme conditions.

Hopefully, most of us will never need to find out about this trait firsthand, but it's good info to file away in the back of the mind.

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