Welcome to the North American Subaru Impreza Owners Club Thursday March 28, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Subaru Models > Impreza Forum

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 12-23-2012, 12:23 AM   #1
motorace
Scooby Newbie
 
Member#: 339003
Join Date: Nov 2012
Default explain imprezas AWD?

from what i know about 4x4 ford trucks, which i can be wrong about, the 2 fronts wheels would be locked together with one of the rear tires, with least resistance rear, having power. thus, 3 wheels have power while in 4x4.



what does an impreza have? with the computer transferring power to slipping wheels, does that means it's similar, as in 3 wheels have power?

(or like other brand awd vehicles, where its just 1 wheel up front and 1 wheel in the back and call it awd?)
* Registered users of the site do not see these ads.

Last edited by motorace; 12-23-2012 at 12:41 AM.
motorace is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-23-2012, 07:44 AM   #2
sgoldste01
Scooby Specialist
 
Member#: 322264
Join Date: Jun 2012
Chapter/Region: Tri-State
Location: Webster, NY
Vehicle:
2012 Impreza Sp 5sp
Obs Blk Prl/Drk Gray Mtl

Default

sgoldste01 is offline   Reply With Quote
Old 12-23-2012, 08:07 AM   #3
sgoldste01
Scooby Specialist
 
Member#: 322264
Join Date: Jun 2012
Chapter/Region: Tri-State
Location: Webster, NY
Vehicle:
2012 Impreza Sp 5sp
Obs Blk Prl/Drk Gray Mtl

Default

sgoldste01 is offline   Reply With Quote
Old 12-23-2012, 08:14 AM   #4
Zeeper
Scooby Specialist
 
Member#: 299286
Join Date: Oct 2011
Chapter/Region: NESIC
Location: Upstate NY
Vehicle:
2017 Legacy Limited
White

Default

look at the AWD wiki, it depends upon whether you have a CVT or a 5 Speed which type of AWD the car has.

I don't think every single claim on the wiki document is accurate, but that has been discussed on the forum multiple times. It does give you a general idea of the different systems and how they work.

Most videos including those above show the CVT/Auto version of symmetrical AWD.

In no case is it like the systems you are describing.

http://www.awdwiki.com/en/subaru/
Zeeper is offline   Reply With Quote
Old 12-23-2012, 08:27 AM   #5
Guzzi 1
Scooby Newbie
 
Member#: 338666
Join Date: Nov 2012
Chapter/Region: MWSOC
Location: Northeast Ohio
Vehicle:
2022 Crosstrek Ltd.
Magnetite Gray

Default

Great videos! I had not seen them before. They pretty much explain why Subarus can deal with bad roads easier than many other vehicles.

John

edit: Friday night when I got off work, the roads in these parts were beyond bad. With the wind and snow, salt and plow trucks could not keep up. Thw vehicle I drive at work is a full size Ford van without posi traction. It is by far one of the worst vehicles I have ever driven in snow, rivaling that of '60's and '70's muscle cars. I can tell you with certainty that the system used with the CVT does as well as the 5 speed manual system that was in my '03 WRX. EVERYBODY around me was struggling to make up hills and I was able to drive easily. No drama. Just as if the road was dry. THAT is why Subaru owners are smiling when driving on wintery roads. ;-))

Last edited by Guzzi 1; 12-23-2012 at 08:36 AM.
Guzzi 1 is offline   Reply With Quote
Old 12-23-2012, 11:18 AM   #6
BajaGuy68
Scooby Newbie
 
Member#: 127720
Join Date: Oct 2006
Chapter/Region: Tri-State
Location: Western, NY
Vehicle:
2015 WRX
Lightning Red

Default

Loved the video's! I love my Subies and that is why I'm on my fifth one now.
BajaGuy68 is offline   Reply With Quote
Old 12-23-2012, 11:23 AM   #7
grubincan
Scooby Newbie
 
Member#: 300961
Join Date: Nov 2011
Chapter/Region: E. Canada
Location: N.B.
Default

And this one is a lot of fun too, if you have an hour to spare....


It's surprising how many vehicles have trouble on a just pair of front or rear rollers (is that a BMW xDrive that can't get off a single rear roller?) it would be nicer to see some other makes and newer models.
grubincan is offline   Reply With Quote
Old 12-23-2012, 01:13 PM   #8
Zeeper
Scooby Specialist
 
Member#: 299286
Join Date: Oct 2011
Chapter/Region: NESIC
Location: Upstate NY
Vehicle:
2017 Legacy Limited
White

Default


I like this video the best, expecially because it shows the CVT Crosstrek holding its own with a dedicated 4WD Landrover. You can see how well the Symmetrical AWD (electronic clutch version) and VDC work together to limit wheel slip and transfer power.
Zeeper is offline   Reply With Quote
Old 12-23-2012, 01:59 PM   #9
hemophilic
Scooby Specialist
 
Member#: 301213
Join Date: Nov 2011
Chapter/Region: South East
Location: Raleigh, NC
Vehicle:
2012 Imp. Sp. Ltd.
Blue/Silver

Default

^^ That's impressive.
hemophilic is offline   Reply With Quote
Old 12-24-2012, 01:20 AM   #10
ans2k
Scooby Specialist
 
Member#: 315631
Join Date: Apr 2012
Location: Bryant, AR
Vehicle:
2012 Impreza Sport

Default

Quote:
Originally Posted by grubincan View Post
And this one is a lot of fun too, if you have an hour to spare....

AWD sistems wars (testing) on rollers - YouTube

It's surprising how many vehicles have trouble on a just pair of front or rear rollers (is that a BMW xDrive that can't get off a single rear roller?) it would be nicer to see some other makes and newer models.
watching that video make me doubt a little about the legendary awd system of subaru.
ans2k is offline   Reply With Quote
Old 12-24-2012, 06:30 AM   #11
M45
Scooby Newbie
 
Member#: 333446
Join Date: Sep 2012
Chapter/Region: NESIC
Vehicle:
2013 Impreza SL CVT
DGM

Default

Quote:
Originally Posted by ans2k View Post
watching that video make me doubt a little about the legendary awd system of subaru.
i'm not sure rollers is a great indicator of much since no one ever drives on rollers.
M45 is offline   Reply With Quote
Old 12-24-2012, 10:32 AM   #12
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

Quote:
watching that video make me doubt a little about the legendary awd system of subaru.
I think a VDC-equipped Subaru would have behaved differently.
Commander Keen is offline   Reply With Quote
Old 12-24-2012, 10:51 AM   #13
Zeeper
Scooby Specialist
 
Member#: 299286
Join Date: Oct 2011
Chapter/Region: NESIC
Location: Upstate NY
Vehicle:
2017 Legacy Limited
White

Default

You don't have to think it, look at the Crosstrek video and notice that when a wheel has no traction it cuts off power to that wheel pretty much instantly. There is almost no wheel slip, and less than the 4WD Landrover!

What subaru was that in the roller video? It may not have had any traction control, only AWD?
Zeeper is offline   Reply With Quote
Old 12-24-2012, 11:06 AM   #14
Snow Drift
Scooby Specialist
 
Member#: 75071
Join Date: Nov 2004
Chapter/Region: Tri-State
Location: Long Island
Vehicle:
23 Solterra,ModelY
Old: 05 08 11 WRX, 18 STI

Default

Quote:
Originally Posted by motorace View Post
from what i know about 4x4 ford trucks, which i can be wrong about, the 2 fronts wheels would be locked together with one of the rear tires, with least resistance rear, having power. thus, 3 wheels have power while in 4x4.



what does an impreza have? with the computer transferring power to slipping wheels, does that means it's similar, as in 3 wheels have power?

(or like other brand awd vehicles, where its just 1 wheel up front and 1 wheel in the back and call it awd?)
No, all Subarus (save the BRZ and foreign kei cars) use full-time awd which is never deactivated. All 4 wheels receive power all the time unless slipping occurs where the system needs to reroute it.

2011+ Impreza 5MT

Rear Differential = Open (VDC applies brake to slow spinning wheel)
Front Differential = Open (VDC applies brake to slow spinning wheel)
Center Differential = 50/50 torque split ALL the time. A viscous coupling center differential has metal plates that are connected to either the front or rear driveshafts and are surrounded by a viscous fluid. During normal driving the metal plates spin at an even 50/50 rate. Upon either axle slipping that shaft's metal plates will begin to spin at a faster rate that the other. The shearing action of the plates and heat from friction causes the fluid to harden. The hardening fluid thus slows the spinning plate and forces all plates to spin at 50/50 again. This is a VERY good system.
Turn off VDC when in deep snow to prevent Engine Power Reduction from stalling the motor.

2011+ Impreza CVT

Rear Differential = Open (VDC applies brake to slow spinning wheel)
Front Differential = Open (VDC applies brake to slow spinning wheel)
Center Differential = Actively changing torque split (60/40 normally per SOJ and SCI). A multiplate clutch system is housed in the center differential which can be compressed based on a number of sensors (throttle position, wheel slip, steering, etc). The computer will determine how much clamping pressure to apply to the center, thus altering the amount of torque flowing between the front and rear driveshaft. A major difference between Subaru and others is that the system is not FWD until slip. The system will alter the torque split if you merely push down the gas pedal. It is not a fwd car that only kicks in the rear tires in bad situations. This system works well for normal snow driving. Not designed for off-road.
Turn off VDC when in deep snow to prevent Engine Power Reduction from stalling the motor.

Last edited by Snow Drift; 12-24-2012 at 11:12 AM.
Snow Drift is offline   Reply With Quote
Old 12-24-2012, 11:13 AM   #15
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

CVT Center Differential = None
Commander Keen is offline   Reply With Quote
Old 12-26-2012, 03:54 PM   #16
riccnick
Scooby Newbie
 
Member#: 311152
Join Date: Feb 2012
Location: Home
Vehicle:
2012 Impreza
Ice Silver Metallic

Default

Quote:
Originally Posted by Commander Keen View Post
CVT Center Differential = None
^This
riccnick is offline   Reply With Quote
Old 12-26-2012, 07:59 PM   #17
Snow Drift
Scooby Specialist
 
Member#: 75071
Join Date: Nov 2004
Chapter/Region: Tri-State
Location: Long Island
Vehicle:
23 Solterra,ModelY
Old: 05 08 11 WRX, 18 STI

Default

Quote:
Originally Posted by Commander Keen View Post
CVT Center Differential = None
Quote:
Originally Posted by riccnick View Post
^This
Uh, there is a center differential. It is built into the rear of the transmission and contains clutch packs. How do you think power is split between the front and rear axles?
Snow Drift is offline   Reply With Quote
Old 12-26-2012, 08:02 PM   #18
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

Quote:
Uh, there is a center differential. It is built into the rear of the transmission and contains clutch packs. How do you think power is split between the front and rear axles?
There is not. It is possible to combine a differential with an MPT clutch, just like the 5MT combines a differential with a viscous coupling, but this is not what the CVT has. It has only a clutch pack.
Commander Keen is offline   Reply With Quote
Old 12-26-2012, 08:46 PM   #19
Snow Drift
Scooby Specialist
 
Member#: 75071
Join Date: Nov 2004
Chapter/Region: Tri-State
Location: Long Island
Vehicle:
23 Solterra,ModelY
Old: 05 08 11 WRX, 18 STI

Default

Quote:
Originally Posted by Commander Keen View Post
There is not. It is possible to combine a differential with an MPT clutch, just like the 5MT combines a differential with a viscous coupling, but this is not what the CVT has. It has only a clutch pack.
And the clutch pack is the differential. It allows the front and rear axles to rotate at different rates or compress the packs and come to 50:50. It may not be a mechanical gear but it is a differential. You're playing semantics. If it didn't have a differential you wouldn't have AWD (unless you had two axle motors or hub motors)
Snow Drift is offline   Reply With Quote
Old 12-26-2012, 08:56 PM   #20
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

A clutch is a clutch and a differential is a differential.

A differential allows shafts to rotate at different speeds with very little power loss.

A clutch must either disengage, or dissipate the difference in motion as heat.

The CVT's rear wheels can never turn faster than its front wheels.
Commander Keen is offline   Reply With Quote
Old 12-26-2012, 09:14 PM   #21
Snow Drift
Scooby Specialist
 
Member#: 75071
Join Date: Nov 2004
Chapter/Region: Tri-State
Location: Long Island
Vehicle:
23 Solterra,ModelY
Old: 05 08 11 WRX, 18 STI

Default

Quote:
Originally Posted by Commander Keen View Post
A clutch is a clutch and a differential is a differential.

A differential allows shafts to rotate at different speeds with very little power loss.

A clutch must either disengage, or dissipate the difference in motion as heat.

The CVT's rear wheels can never turn faster than its front wheels.
So would you say the Evo 9 and 10 don't have center differentials? Their center is a clutch pack.
Snow Drift is offline   Reply With Quote
Old 12-26-2012, 09:27 PM   #22
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

Like I said before:

Quote:
It is possible to combine a differential with an MPT clutch, just like the 5MT combines a differential with a viscous coupling, but this is not what the CVT has. It has only a clutch pack.
The Evo is an example of a real center differential combined with a clutch pack. Again, this is NOT what the CVT Impreza has.

See: http://www.roadandtrack.com/car-news...ntial-you-5535
Commander Keen is offline   Reply With Quote
Old 12-26-2012, 10:45 PM   #23
Snow Drift
Scooby Specialist
 
Member#: 75071
Join Date: Nov 2004
Chapter/Region: Tri-State
Location: Long Island
Vehicle:
23 Solterra,ModelY
Old: 05 08 11 WRX, 18 STI

Default

Evo ACD is just clutch packs.
Snow Drift is offline   Reply With Quote
Old 12-26-2012, 11:05 PM   #24
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

Commander Keen is offline   Reply With Quote
Old 12-27-2012, 12:46 AM   #25
cnlson
Scooby Newbie
 
Member#: 310098
Join Date: Feb 2012
Location: South Dakota
Vehicle:
2012 Impreza PremCVT
Dark Cherry Pearl

Default

CK,
do you have an exploded view of the Rear Diff on a 12 CVT? i looked and am unable to locate one. I'm not argumentative, I'm actually really interested.
cnlson is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 01:49 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.