| Rick_James |
Hey is the MDX AWD or just 4wd when you engage the VTM?
I can't remember |
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| ByeByeChrysler |
| only up to 18 mph |
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| Rick_James |
| Ok,, so the MDX is really "only" front wheel drive and is 4x4 only when you engage the VTM, but only good when only going up to 18mph. Correct? |
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| Fabvsix |
Rick,
Do a search as this topic has been beaten to death. Acura's web site also have a comprehensive video explaining it in detail.......:1: :1: :1: |
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| JL_SS |
quote:
Originally posted by Rick_James
Ok,, so the MDX is really "only" front wheel drive and is 4x4 only when you engage the VTM, but only good when only going up to 18mph. Correct?
The quick version:
The MDX is FWD until slip is detected, then torque is shared with the rear wheels. If you drop to D1 or D2 and hit the VTM button you will lock in AWD until you hit 18 mph. |
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| pianoman41 |
It is FWD under most driving conditions.
It is AWD as needed (slip) at any speed.
It is fully locked AWD (50/50 split) when VTM lock button is engaged and in D1/D2/R and speed is under 18mph. |
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| timbrwolf9 |
| It is my understanding that it is AWD while accelerating and front wheel drive while cruising. That is why the city gas mileage sucks so bad. |
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| dipersp |
I'm sorta with timbrwolf9. My "understanding" was that it starts transferring torque to the rear wheels under ANY acceleration, as that's when slip occurs. More acceleration, more to the rear. Thus, as he stated, during crusing, you should be all FWD.
The VTM button, as others stated, locks all 4 wheels under 18 mph in 1, 2 and R. Good for getting out of trouble (Or as I learning, parallel parking on top of a snow bank when there's no spots left in town!) |
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| JL_SS |
quote:
Originally posted by dipersp
I'm sorta with timbrwolf9. My "understanding" was that it starts transferring torque to the rear wheels under ANY acceleration, as that's when slip occurs. More acceleration, more to the rear. Thus, as he stated, during crusing, you should be all FWD.
The VTM button, as others stated, locks all 4 wheels under 18 mph in 1, 2 and R. Good for getting out of trouble (Or as I learning, parallel parking on top of a snow bank when there's no spots left in town!)
That is correct. The longer version: VTM-4 has 3 conrol modes: VATC (vehicle acceleration torque control), LSD (limited slip differential), and LOCK (lock). VATC - the torque disribution to the rear wheels is a function of acceleration rate. LSD - torque distribution to the rear wheels is based on the differences in speed and acceleration between the front and rear wheels. Lock - Fully locks the rear differential clutches up to 6mph (while in R,D1,or D2) and reduces the torque to the rear wheels to 0 linearly from 6 to 18mph.
The control modes can act together to provide the best control. |
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| dipersp |
:bingo:
Sounds about right to me. I thought I remembered something about VTM reducing torque at the rear wheels at certain speeds. Thanks for clarifying. |
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| mdxforever |
Nice explanation. If I may add..
It really doesn't have the 'D' in the LSD. Its an electronic 'D' so to speak, which simulates the 'LS' part of it, although with much better response time and precision than a LSD.
And only the last mode (lock) needs manual intervention to engage/disengage it, rest all are automatic and seamless. Even in lock mode it will vary the troque to rear wheels between 0-6-18mph automatically. |
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| JL_SS |
quote:
Originally posted by mdxforever
Nice explanation. If I may add..
It really doesn't have the 'D' in the LSD. Its an electronic 'D' so to speak, which simulates the 'LS' part of it, although with much better response time and precision than a LSD.
And only the last mode (lock) needs manual intervention to engage/disengage it, rest all are automatic and seamless. Even in lock mode it will vary the troque to rear wheels between 0-6-18mph automatically.
Right, LSD is really electronically controlled mechanical clutches, but Honda still refers to it as LSD in the manuals. |
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| EXCALIBUR |
MDX4now,
Nice video. Q: What is all that white stuff? Could it be snow?:confused: |
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| Bimerman |
Yes, the video does shows that X is AWD. But, how come the traction control is not functional?
:mad:
To tell you the truth, I am kinda disappointed since I thought it would handle snow better than what is shown on the video.
I have BMW 325xi. In 2003, DC had about 2 feet of snow, and the xi handled snow batter than X.:2: |
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| JL_SS |
quote:
Originally posted by Bimerman
Yes, the video does shows that X is AWD. But, how come the traction control is not functional?
:mad:
To tell you the truth, I am kinda disappointed since I thought it would handle snow better than what is shown on the video.
I have BMW 325xi. In 2003, DC had about 2 feet of snow, and the xi handled snow batter than X.:2:
Depends on the year of the MDX. Traction Control is new this year. |
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| MDX4now |
Was that a joke regarding whether or not that was snow? Did you watch the video?!
No, it's not snow, it's moon dust from the planet Zoltar. I don't mean to be sarcastic, but really?!
And what is this talk of traction control? The video showcased a 2004 MDX Touring, and as far as I know, the VSA was improved over my 2003, but I believe the VTM-4 in the 2004-6 works very similarly to my 2003, but with some slight improvements.
In the video, it seemed as though the guy driving should have used the VTM-4 Lock button to provide 50/50 traction getting up the driveway. |
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| Echo2625 |
quote:
Originally posted by MDX4now
Here it is:
http://video.google.com/videoplay?d...496569130&q=mdx
This video is a fine example of just how bad the Michelin Cross Terrains are in snow.
I switched to the Goodyear Forteras and have much better traction/control in all weather conditions. Better ride as well. We had a ton of snow last winter and nothing stopped my X...not even close! |
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| JL_SS |
quote:
Originally posted by MDX4now
Was that a joke regarding whether or not that was snow? Did you watch the video?!
No, it's not snow, it's moon dust from the planet Zoltar. I don't mean to be sarcastic, but really?!
And what is this talk of traction control? The video showcased a 2004 MDX Touring, and as far as I know, the VSA was improved over my 2003, but I believe the VTM-4 in the 2004-6 works very similarly to my 2003, but with some slight improvements.
In the video, it seemed as though the guy driving should have used the VTM-4 Lock button to provide 50/50 traction getting up the driveway.
Excalibur is in Hawaii. He doesn't see much snow.
Acura/Honda has added traction control to VSA with the 2006 model year MDX and Pilot.
It looks like he did use the VTM-4 Lock at first but it probably turned itself off after he gained some speed and he didn't turn it back on. I believe it's mostly a funtion of the CT's not being great winter tires. The tires spin fine but get no traction. With a decent set of tires, I think it would have done much better. |
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| shootist |
That video may have been an example of:
Q. What's the difference between a really good Four Wheel Drive and a really bad Four Wheel Drive?
A. A really good Four Wheel Drive will get you much further into the woods before you get hopelessly stuck.
I never use VTM4 lock to get into a situation- only to get out of a situation. If you use VTM4 to get in, you may need VTM 4 Plus to get out. (You don't have VTM4 Plus) |
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| EXCALIBUR |
quote:
Originally posted by JL_SS
Excalibur is in Hawaii. He doesn't see much snow.
The closest thing we have to snow in Hawaii is *shave ice* aka snow cone. Merry Christmas 2005!!! |
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| Bimerman |
quote:
Originally posted by JL_SS
Acura/Honda has added traction control to VSA with the 2006 model year MDX and Pilot. [/B]
Are you saying traction control is NOT standard on 05?:confused: |
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| anjan |
quote:
Originally posted by Bimerman
Are you saying traction control is NOT standard on 05?:confused:
That's wrong information. Of course MDX has had "VSA with Traction Control":rolleyes: Yahoo Autos states for the 2005 MDX -
quote:
VSA(R) Vehicle Stability Control System Operated Via Engine Power Reduction, ABS and Traction Control Measures Lateral Acceleration and Yaw Rate
For others wondering about the effectiveness of the AWD system in MDX obviously live in an area where 2 inches of snow causes emergency situation :D They are only as good as the tires and the stock ones on MDX are not as good. As far as BMW vs MDX, my boss drives a 330xi and when driving together in really bad weather I was told to take the lead because it was having difficulty plowing through 7-8 inches of snow. Come to Western NY and we'll see which one wins Bimmerman :2: |
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| JL_SS |
quote:
Originally posted by anjan
That's wrong information. Of course MDX has had "VSA with Traction Control"
Sorry, My Bad - I came across some wrong info. MDX has had traction control integrated with VSA since the 2003 model year. |
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| Bimerman |
quote:
Originally posted by anjan
For others wondering about the effectiveness of the AWD system in MDX obviously live in an area where 2 inches of snow causes emergency situation :D They are only as good as the tires and the stock ones on MDX are not as good. As far as BMW vs MDX, my boss drives a 330xi and when driving together in really bad weather I was told to take the lead because it was having difficulty plowing through 7-8 inches of snow. Come to Western NY and we'll see which one wins Bimmerman :2:
I have never said that my BMW will win. One of reasons for me to own the X is so that I would not have to slip and slide on snow. Since I am a new X owner, I have never seen what it could do on snow. But, from the video footage, I know my 325xi can do better than that. :D |
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| JL_SS |
quote:
Originally posted by Bimerman
I have never said that my BMW will win. One of reasons for me to own the X is so that I would not have to slip and slide on snow. Since I am a new X owner, I have never seen what it could do on snow. But, from the video footage, I know my 325xi can do better than that. :D
It's really hard to tell anything without the details. All we see is 8 to 10" of snow. Is it light? is it heavily saturated? Is there a layer of ice underneath? Obviously the road is plowed - Is the stufff at the beginning of the driveway that they are having the most trouble with hard packed snow from the plow passing by? |
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| hammermdx |
| My guess is the MDX would have flipped and possibly been totaled...The MDX does not have the same balance as an X5. Amazing video....if it's authentic :4: |
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| DaleB |
quote:
Originally posted by hammermdx
My guess is the MDX would have flipped and possibly been totaled...The MDX does not have the same balance as an X5. Amazing video....if it's authentic :4:
I guess that's like saying, "Phew! I only have to worry about skidding on my doors with a bimmer!"
Too much steering input at high speed, with a high center of gravity....questionable road surface....
One thing about physics, it has no favorites. |
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| anjan |
quote:
Originally posted by hammermdx
My guess is the MDX would have flipped and possibly been totaled...The MDX does not have the same balance as an X5. Amazing video....if it's authentic :4:
I'm sure this assertion is based on very scientific tests run in your backyard? :confused: The last BMW X5 with a rollover test by NHTSA was done back in 2003 which still stands because there have been no redesigns. It got a three star rating only. MDX is ranked among the highest in SUVs with a four star rating.
When I test drove the X5 before buying my 2005 MDX, the car came across as severely rough around the edges with the handling of a boat and certainly not deserving of the BMW badging. And it was a surprise because I like BMW's handling and was sure that I would buy their SUV. |
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| hammermdx |
DaleB and anjan,
All I'm saying is that the X5 didn't flip over according to the video, (if you believe it is authentic), any vehicle at high speed, rough road surface, questionable driver would result in a flip! |
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| DaleB |
quote:
Originally posted by hammermdx
DaleB and anjan,
All I'm saying is that the X5 didn't flip over according to the video, (if you believe it is authentic), any vehicle at high speed, rough road surface, questionable driver would result in a flip!
Without totally dupliacting all conditions I don't see how you could tell 'which' vehicle is most likely to flip.
What cars are balanced on their sides to see if one will continue to flip over?
The bimmer is also outfitted, it would appear, for rally conditions. Not stock. I don't know that for a fact, of course. Just also going by appearances. |
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| mdxforever |
Its the driver not the car, especiallly in this particular case. He saved it. And things like traction control, stability control, dynamics control need a good flow of torque in a situation where additional torque to the correct wheels(and not braking) willl help.
Watch the slow motion part of the video carefully. The X5 flips twice, once on each side and lands back again on all four feet both the times. As it flips both times, look at the wheels on the ground. They are spinning, and they are spinning fast, which means the driver has slammed the throttle because he knows only torque from the engine will help the stability control put the right amount of torque on the right wheel. The driver is also doing another thing. He is turning the wheels, into the flipping side. Smart (and quick!) move. A combination of these two maneuvers saved it. I feel the terrain(loose dirt) might have helped too.
Although the condition of the suspension after this incident would be questionable.
Consumer reports and NHTSA dont test keeping in mind an expert driver or assume that the driver is holding on to his/her nerves and actually thinking and strategizing his/her next move in microseconds.
Would it have been the same with the X ? Theoritically yes but I dont know. and I am not going to try it :p |
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| Bimerman |
quote:
Originally posted by mdxforever
Its the driver not the car, especiallly in this particular case. He saved it. And things like traction control, stability control, dynamics control need a good flow of torque in a situation where additional torque to the correct wheels(and not braking) willl help.
Watch the slow motion part of the video carefully. The X5 flips twice, once on each side and lands back again on all four feet both the times. As it flips both times, look at the wheels on the ground. They are spinning, and they are spinning fast, which means the driver has slammed the throttle because he knows only torque from the engine will help the stability control put the right amount of torque on the right wheel.
In BMW cars, there is a Dynamic Stability Control (DSC) button which is always 'on' by deafult. DSC gives the ability to drive your car to the limits of adhesion without fear of losing control. Another name for it is traction control. However, depending on the driving style the driver has the option to turn it 'off'. This is why you see X5 wheels spinning on the ground.:p |
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