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Old 11-21-2012, 10:01 AM   #14651
Commander Keen
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My guess is that I won't need to be as cautious during acceleration, but that I should handle braking and turns with the same caution. Right?
Accelerating shouldn't take too much thought.

The car knows how much acceleration you're asking for, which way you're pointing the steering wheel, where it's heading, and which wheels are slipping.

It also has the ability to reduce engine power and brake any of the four wheels while powering others.

All this lets you drive somewhat normally in bad conditions, but it's not magic and you can still lose the car in a ditch. Subaru warns not to become overly confident.
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Old 11-21-2012, 11:38 AM   #14652
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Quote:
Originally Posted by Commander Keen View Post
If we're talking about high speed, high power driving, the STI's system can definitely transfer torque more smoothly and efficiently than the Impreza's VDC.

At low speeds like in the video, VDC can move power anywhere regardless of the initial torque split. If you've seen video of the Impreza or XV crawling around off-road, a wheel in the air will often stop spinning completely as the car moves forward.
You are correct, however the locking center diff provides 4x4 like power transfer that the 50/50 limited slip center doesn't. All in all, you're good with both systems, I was just pointing out the differences between my two Subaru.
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Old 11-21-2012, 11:39 AM   #14653
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Also, sorry I wasn't clear in my original post. The front and rear LSD is on the STI not on the 2.0i
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Old 11-22-2012, 02:04 AM   #14654
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So today I filled up my subie with gas and as I drove home the Eco mileage gauge needle on the bottom of the speedometer stop working? I stopped the engine and restarted twice but still doesn't work. The needle moves when i start her up but then when i put it in drive it does not move anymore. Weird.... Anyone have that happened? Since my first service is not due for another 2500 miles (3750) I though I would wait to have it looked at. Anyone perceive any harm in waiting? I mean as far the actual mileage calculation and what not? Kind of a buzz kill on a 2013 car.
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Old 11-22-2012, 02:20 AM   #14655
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Originally Posted by mforce712 View Post
So today I filled up my subie with gas and as I drove home the Eco mileage gauge needle on the bottom of the speedometer stop working? I stopped the engine and restarted twice but still doesn't work. The needle moves when i start her up but then when i put it in drive it does not move anymore. Weird.... Anyone have that happened? Since my first service is not due for another 2500 miles (3750) I though I would wait to have it looked at. Anyone perceive any harm in waiting? I mean as far the actual mileage calculation and what not? Kind of a buzz kill on a 2013 car.
how many miles since you filled and reset the meter? it take a few miles before it starts to work again.
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Old 11-22-2012, 02:43 AM   #14656
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It takes exactly 1 mile for it to register after resetting the trip odometer.
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Old 11-22-2012, 03:20 AM   #14657
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You guys are saying open diffs f/r with a 50/50 split LSD center diff right? There's so LSD between the wheels like you'd be familiar with on a 4x4 setup. Just making sure we're all on the same page.
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Old 11-22-2012, 08:04 AM   #14658
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There is no LSD, but there is ABS and VDC which essentially means the car sends power to the wheels with grip, and cuts power to wheels that slip.

It is pretty efficient, no matter what the situation, perhaps the limitation is true off road driving (how many people actually drive their impreza offroad in the woods?)

Watch the video, a CVT Crosstrek that is pretty impressive, even with a wheel off the ground the Crosstrek did not miss a beat -- better than a 4X4 land rover wheel slip wise:

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Old 11-22-2012, 10:35 AM   #14659
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old video
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Old 11-22-2012, 10:44 AM   #14660
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Quote:
Originally Posted by kenny doggins View Post
You guys are saying open diffs f/r with a 50/50 split LSD center diff right? There's so LSD between the wheels like you'd be familiar with on a 4x4 setup. Just making sure we're all on the same page.
For the 5MT:

Front diff - open. If one tire slips VDC will brake it.

Center diff - "Continuous AWD" is a viscous coupling type where metal plates are spinning (one set connected to the front axle shaft, other to the rear shaft) in a viscous fluid. Under normal conditions the axles both spin at an equal rate, leaving the normal 50:50 split. Once you lose traction on either axle the free spinning motion will spin those plates faster than the other set. This difference in speeds will cause friction and heat in the differential which hardens the viscous fluid. As it hardens it forces the faster spinning plates to slow until the entire diff is 50:50 again. This is a VERY good system and I have never been stuck in snow (05 WRX, 08 WRX, 11 WRX).

Rear diff - open. If one tire slips VDC will brake it.

For USDM CVT and 4EAT:

Front - Open.

Center - "Active AWD" The torque distribution is constantly changing as the ECU takes multiple sensors into account. Once conditions arise that change the throttle position, yaw, steering angle, tire slip, etc, multiple clutch plates are hydraulically pressed together to alter the amount of power diverted from front to rear. SOJ and SCI say it is 60:40 normally, up to 50:50. SOA refuses to say. It is however superior to other car makers as it does not always wait for a slipping wheel, even pressing the gas pedal will transfer torque.

Rear - Open.


VDC Tip: If you are in deep snow, like coming out of a parking space, going up a steep road that isnt cleared or doing donuts, I would suggest turning OFF VDC as it will reduce engine torque as it senses slipping (to slow the wheel) but that will just bog the engine and you wont have the power needed. Turn it OFF and let the center differential do all the work. As I've said, I've never been stuck with it OFF.
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Old 11-22-2012, 11:12 AM   #14661
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Originally Posted by flyboy1100 View Post

how many miles since you filled and reset the meter? it take a few miles before it starts to work again.
I have driven it less then one mile. I never noticed that it stopped working after resetting the trip. So I will see if that's the case. Thanks for bringing that to my attention. I'll know today when I drive around.
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Old 11-22-2012, 11:26 AM   #14662
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Quote:
Originally Posted by mforce712 View Post

I have driven it less then one mile. I never noticed that it stopped working after resetting the trip. So I will see if that's the case. Thanks for bringing that to my attention. I'll know today when I drive around.
If you reset your tripometer the center display and that gauge both shut off until you accumulate new data via driving.

Then they continually adjust (usually when they first display the MPG's are very low and climb over the next 5-10 miles till it levels out)
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Old 11-22-2012, 11:43 AM   #14663
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Quote:
Originally Posted by Snow Drift

For the 5MT:

Front diff - open. If one tire slips VDC will brake it.

Center diff - "Continuous AWD" is a viscous coupling type where metal plates are spinning (one set connected to the front axle shaft, other to the rear shaft) in a viscous fluid. Under normal conditions the axles both spin at an equal rate, leaving the normal 50:50 split. Once you lose traction on either axle the free spinning motion will spin those plates faster than the other set. This difference in speeds will cause friction and heat in the differential which hardens the viscous fluid. As it hardens it forces the faster spinning plates to slow until the entire diff is 50:50 again. This is a VERY good system and I have never been stuck in snow (05 WRX, 08 WRX, 11 WRX).

Rear diff - open. If one tire slips VDC will brake it.

For USDM CVT and 4EAT:

Front - Open.

Center - "Active AWD" The torque distribution is constantly changing as the ECU takes multiple sensors into account. Once conditions arise that change the throttle position, yaw, steering angle, tire slip, etc, multiple clutch plates are hydraulically pressed together to alter the amount of power diverted from front to rear. SOJ and SCI say it is 60:40 normally, up to 50:50. SOA refuses to say. It is however superior to other car makers as it does not always wait for a slipping wheel, even pressing the gas pedal will transfer torque.

Rear - Open.

VDC Tip: If you are in deep snow, like coming out of a parking space, going up a steep road that isnt cleared or doing donuts, I would suggest turning OFF VDC as it will reduce engine torque as it senses slipping (to slow the wheel) but that will just bog the engine and you wont have the power needed. Turn it OFF and let the center differential do all the work. As I've said, I've never been stuck with it OFF.
But how do you turn off vdc? You can turn off traction control but not vdc with the button on the dash
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Old 11-22-2012, 11:49 AM   #14664
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Originally Posted by flyboy1100 View Post
But how do you turn off vdc? You can turn off traction control but not vdc with the button on the dash
VDC off *IS* the button on the dash. The button turns off the engine reduction function and TCS (or at least reduces it to an undetectable level). With the button ON the engine will slow as soon as there is slipping, the swerve light will turn on. With the button OFF nothing happens besides normal driving, enjoy the snow or track.
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Old 11-22-2012, 12:04 PM   #14665
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The manual says:

Quote:
Even when the Vehicle Dynamics Control system is deactivated, components of the brake control system may still activate. When the brake control system is activated, the Vehicle Dynamics Control operation indicator flashes.
My understanding is that power reduction and brake activation are two sub-features of VDC and when you deactivate VDC, only the power reduction is disabled or maybe just lessened.

The manual also claims that when VDC is disabled, the car behaves like one without VDC, but if it's still firing the brakes, this isn't true.

When VDC is reducing throttle, the light is steady.
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Old 11-22-2012, 02:54 PM   #14666
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I've had VDC since 2008 and when you press the button, even in deep snow or at the track, the light stays off and the power doesn't decrease. The braking is never felt, so I don't know if it's happening.
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Old 11-22-2012, 03:10 PM   #14667
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Does your 08 manual mention anything like what I quoted above? The system may have evolved since then.

There's no missing the pulsed braking, it makes the entire car ring.
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Old 11-22-2012, 03:54 PM   #14668
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For my STI if you press the VDC button, it turns off traction control, if you press and hold it it turns off the VDC. Probably different for the '12 Impreza.
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Old 11-22-2012, 05:26 PM   #14669
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Quote:
Originally Posted by Snow Drift

VDC off *IS* the button on the dash. The button turns off the engine reduction function and TCS (or at least reduces it to an undetectable level). With the button ON the engine will slow as soon as there is slipping, the swerve light will turn on. With the button OFF nothing happens besides normal driving, enjoy the snow or track.
This is wrong because I slid into a curb with the vdc off, I could hear and feel the 2 brakes on the driver's side trying to change the direction of the slide.
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Old 11-22-2012, 06:17 PM   #14670
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Quote:
Originally Posted by Commander Keen View Post
Does your 08 manual mention anything like what I quoted above? The system may have evolved since then.

There's no missing the pulsed braking, it makes the entire car ring.
Pulsing is ABS, not VDC braking a single wheel. It will pulse off power going down a hill. The 08-today systems are the same, with the system off it will not reduce engine torque and it limits intervention. With it ON, at the track, it kicked in on a turn, with it OFF it never turned activated the dash light.

Quote:
Originally Posted by ST Eye View Post
For my STI if you press the VDC button, it turns off traction control, if you press and hold it it turns off the VDC. Probably different for the '12 Impreza.
STI VDC has three modes, the rest have two.

Quote:
Originally Posted by flyboy1100 View Post
This is wrong because I slid into a curb with the vdc off, I could hear and feel the 2 brakes on the driver's side trying to change the direction of the slide.
Are you sure you didn't feel the pulse of ABS? That is not VDC.
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Old 11-22-2012, 09:28 PM   #14671
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For my STI if you press the VDC button, it turns off traction control, if you press and hold it it turns off the VDC. Probably different for the '12 Impreza.
If you press the button on a '12, it toggles VDC and if you hold it, VDC stays on and the button is ignored for the rest of the trip.
Quote:

Pulsing is ABS, not VDC braking a single wheel. It will pulse off power going down a hill. The 08-today systems are the same, with the system off it will not reduce engine torque and it limits intervention. With it ON, at the track, it kicked in on a turn, with it OFF it never turned activated the dash light.
ABS does not operate unless the driver is pressing the brake pedal. ABS reduces brake pressure to prevent lock-ups and VDC applies it to transfer torque. Both involve pulsing.

The manual confirms what flyboy is saying. The skid logo can appear while the VDC OFF light is lit.
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Old 11-22-2012, 09:30 PM   #14672
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Are you sure you didn't feel the pulse of ABS? That is not VDC.
my foot was 100% off the brake and clutch
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Old 11-23-2012, 09:43 AM   #14673
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i know the stock tires are no good on ice, but everything was really slippery last night and every time i tried to accelerate the back end wanted to swing out on me. would putting some weight back there help? like people do with pickups?
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Old 11-23-2012, 11:13 AM   #14674
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Originally Posted by ST Eye View Post
It takes exactly 1 mile for it to register after resetting the trip odometer.
You guys are absolutely correct. I guess I never noticed that before. It started working again at exactly 1 mile. Chalk it up to my being a subie newbie. Thanks for your response everyone.
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Old 11-23-2012, 03:14 PM   #14675
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Quote:
Originally Posted by flyboy1100

my foot was 100% off the brake and clutch
Stability control perhaps?
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