docboy

I just saw this video over at Temple of Vtec: http://www.vtec.net/news/news-item?news_item_id=879935

http://www.youtube.com/watch?v=Yidka...ayer_embedded#

IMHO, absolutely awesome video of the SH-AWD in action on snow/ice hills and track. Very nice clips of the TL 6MT in action. As the TL carves the snow/iced curves, I can see the TL slip a bit with thereafter SH-AWD adjustments. But it then appears rock steady on the straight line.

Per Jeff at TOV, all seasons and winter tires were used on the TL 6MTs. All of the SUVs wore standard OEM all seasons.

The MDX in particular was awesome on the 30% grade hill test. Pitty the useless Lexus; the Audi Q7 was almost successful, though I gather it looked like the Q7 may have made it up the incline if given a 2nd chance.

I dare say I would never try the above on my 1G TSX.

Acura would be very smart IMHO to use this video in their ads/commercials.

winstrolvtec

Good job docboy, I was just about to put this up, in fact I just deleted it. Now I don't have to edit. Hopefully this quiets those who swear by the more constant 4WD type systems and who think SH only excels in dry handling. Unless a system has active torque vectoring it can't compete. The only exception comes at the first sec or two of start up under slippery or icy conditions being front based but otherwise I believe SH is superior in every way.

Olu

Great video. I can't believe the MDX was wearing OEM all season tires. Pretty impressive.

One thing for sure. I love the beak!! I think it's absoultely perfect on the ZDX

JAB00

Nice vid. The TL looked very muscular and athletic. The SH-AWD must be so nice. I am in DC where the region is getting pounded with snow. the AWD could come in handy.

kingofire

There is also an excellent thread about this video in car talk(I just found out about this place today)

https://acurazine.com/forums/car-talk-5/2010-acura-winter-driving-event-763099/

StonedCL

iTrader: (1)

I call BS.. there is no way it got up that same ice all the cars where sliding down that quick w/o any sliding.. Someone ran over there and threw some salt on that ice B4 the MDX started... No matter what aWD system the car has that is ICE the acura tires did not lose grip once after the begining.. NO way...

'06 Anthracite TL

So, you're saying that Acura intentionally faked the test in front of a bunch of journalists?

Cosmoslux

The power is transferred to the tires with grip - the ones not on the ice strip.

docboy

That's a very bold accusation. What is your proof?

So you are saying salt was placed prior to the MDX's run? I suppose some amount of salt (of course, less than what was placed for the MDX) was placed prior to the Q7's turn, and that NO salt was placed prior to the RX's trial?

Momyc

The Q7 started to made it up when the front left wheel got a grip on the asphalt !
When all left side wheels were on ice , it was sliding down ...

Olu

Nah, I don't think so. I think the test was set up perfectly for a torque vectoring system which can send almost all of it's power to an individual wheel. It would have been more interesting to see the same test with same grade, up a surface with a random mix of snow and ice.

winstrolvtec

It's important to take the time to understand how these systems works and how they differ. Besides rear power transfer, SH can also transfer up to all of the available rear power completely to one rear wheel and drive that one wheel only, if necessary. It's the active vectoring that allows it to do this and allows the MDX to cruise up that slope.

Even though most other systems allow for some brake or mechanical intervention to slightly drive one wheel more than the other, it's only momentarily and stutterish as it's reactive based not proactive. The power cannot freely be distributed among the rear wheels. It's not designed to be a constant and doesn't drive in these forms for any duration, it's only a limited engaged traction assist because they still have to function at an even power divide among each pair of wheels and we can see those results.

For what its worth, the MDX SH system only allows for 50% rear power transfer and then up to 100% of that to either wheel during cornering but on hill grades, like in the video, it allows up to 70% rear power. Grade logic senses the degree of incline and can adjust the system to route more power to the rear wheels. It is not just in mechanics where SH is superior, that also allows it's electronics and control systems to open up a whole new set of interactions as well.

kingofire

I am no engineer or claim to know about the AWD system but after watching that video numerous times I have summized that its a blatant operator error or an intentional error. Whenever I see the others gaining momentum it feels as though the driver lets up on the gas and the car starts to slide downwards. When its the MDX there seems to be constant acceleration and when it gains momentum there is more throttle response given to get it to move up and over. But again this is a novice view of a foreign language.

winstrolvtec

Honestly the vid may be a bit biased whether done intentionally or not. The 20% hill grade sign was filmed in front of all the cars 30% grade hill tests excpet for the MDX, so that is a little misleading. The driver also should have been able to get the Q completely up the hill at that point but also only by means of zigzagging. I think he may have been exaggerating his efforts since he was already basically cheating in the first place. Watching closely, the car had no chance run normally and didn't move anywhere until a part of it's left tire hit pavement, and not ice, multiple times. The test may also be partial to the SH system but the message and capability differences still very loud and clear.

erick3

nah; the sh-awd has the ability to push power or torque to any side/wheel it needs to. if you look closely, only the left side the ramp is iced. it's perfect for the sh-awd to show it's true colors. i say it's legit.

TechnoCat

One of the triumphs of marketing-engineering over real-engineering is that bizarre concept that 100% of the torque can be pushed anywhere. Those are just marketing words, folk. The original Audi ur-Quattro could do that, because all it means is that the one wheel will use the traction, not that the others are disconnected.

Think through manual lockers on a pickup; now all four wheels are locked together (and you cannot turn easily). Any one wheel with the traction will use it. And the other three will spin at the same rate.

How much "torque" has been "vectored" to the one wheel? Well, technically, nothing has been "vectored" at all. And all four wheels had the same amount of torque (100%) available. Only one of them was able to use it though. Torque is force, and only one wheel had any opposition, so it was the only wheel to impose the torque. But that doesn't mean the torque was vectored.

If you have an LSD in place (and the system is relying on it), you can't keep the ratio at 1-to-1; it's more like 2-to-1; your tractionless wheel will go (e.g.) twice as fast as the grippy wheel. Up to your limiter or the torque of the grippy wheel, which is again at 100% for all technical purposes.

SH-AWD seems to have some cool gearing in-place to move that ratio around on corners, in an effort to ensure that the wheels have an optimized amount of push on them and different speeds. But in really bad ice/snow conditions, the concept of "100% torque to any wheel" is meaningless; any lockable 4WD system has that, because torque cannot exist without resistance.

George Knighton

They didn't need grip. The right rear wheel was what was pushing the car up the hill.

The driver just had to point it correctly.

It's not ice. It's a no-grip surface designed to provide zero adhesion.

There's two things that bug me unrelated to SH-AWD's excellence.

(1)I think I could've got the Audi up the hill with a little patience. I'm not saying it's anywhere near as good as SH-AWD, but I don't think we really tried very hard to really get it up the 20%.

I'm not saying it would've made it up the 30%. :-)

(2)It's very disappointing to see that the Lexus ABS did not work properly to keep the car stopped and pointed correctly. It seems to me there are multiple system failures on the Lexus, and I don't think I'd buy one of those.

winstrolvtec

Other AWD systems do have the ability to transfer power as well but it's not the same. For example, most forms of Quattro even have the ability to transfer more power to the rear compared to SH but it does not do so actively and variably and cannot drive on it as a constant like the MDX does in the video.

SH actively transfers both to the rear and side to side, not only in it's mechanics but electronically controlled as well. Throttle input actively transfers power to the rear and steering input dictates how the rear power gets appropriated. It's a lot more complicated than this but it's a general idea. VSA and traction control dictate the transfers beyond that in bad conditions. There is no locking out or heavy resistance of a wheel or set of wheels required to transfer anything that most other systems need.

Others only do so when traction is lost or there is very little on the front, rear or one side that it then shifts to it's opposite. Some systems do this by braking, others by mechanics. This only lasts for seconds and they always want to default back to normal operation and percentages even if full traction is not regained.

They are reaction based and do not work effectively nor efficiently enough to put them up the icy hill grade. They work sporadically to assist in regaining full traction, SH can actually actively overdrive one rear wheel as a constant like in the video. The difference is the "active" rear differential. Any system equipped with an active rear differential should be able to that as well.

It works beyond just cornering too. It is a part of VSA and can transfer whatever torque is available as needed before the brakes are applied as a last resort. Heavy throttle places more power in the rear and again no slip or loss needed, it's completely variable and active. It's sensory, input and computer controlled.

The MDX normally allows 50% rear transfer but Grade logic works with SH and allows 70% rear power for hills. So it's not just an active side to side it's also front to rear. Yes it is front based and needs what might be an extra step but it's still an another active transfer and if it were a 50/50 AWD in base form and could still send another 20% to the rear actively, it would still benefit greatly from that. Because of that ability why not just allow more front power for efficiency when it's not needed in the rear? Makes sense.

Most newer systems with active rear differentials still don't allow for any active rear transfer, only the active side to side. Some might allow up to 85% or even 100% rear transfer but it's only reactive and is not used for dry handling.

Anything that can aid in dry handling is going to be effective in bad weather as well. 100% transfer to one wheel is not meaningless for snow and icy conditions and the reality and proof of that is right there in the video. There is no doubt that for start ups the more constant 4WD systems and their reactive based transfers might be better suited but that only last a few seconds and is rather meaningless as you are not getting stuck with SH anyway. SH is better suited for snow and icy hills and conditions while actually driving because of the active transfers. I would much rather have that going for me instead.

BEAR-AvHistory

Agree, my 1998 4X4 dual range transfer case pickup would have no problem at all with that hill.

TechnoCat

There is no such thing as "transferring power" on a wheel with no grip. None. If you lock them (or just have a single rod with two wheels welded on), there's no "transfer" from one side to the other.

The Marketing Literature Engineering has worked on you. In the other thread you even implied it doesn't matter that it's open for a second because it recovers! I tell you what... if you'll fly out to Seattle this month (on a weekend), I'll arrange a hard-core test afternoon with an S4 and a TL SH-AWD 6MT, and possibly a 335ix. Very different systems, and you'll finally know what you're talking about!

And, FWIW, I don't expect you to like your TL less. The SH-AWD is astonishing in dry hard curve-driving. I just expect you to wind up realizing that there are some things that other systems really are better at.

ggesq

iTrader: (1)

There is no need for two of these threads. Please continue this in the thread already existing in Car Talk in the Off Topic section of the forum. Thanks.