sf.basilix Posted January 4, 2017 Share Posted January 4, 2017 Has anyone come across actual Subaru documentation describing what the front to rear toque split is with the 2.5i limited? Every reference I can find online specifically calls out the 3.6R and it's ability to have close to 50:50 when needed. Every time I try to find 2.5i info it's missing. Even car and driver mentions this as well. Only info any researchers provide is specifically for the 3.6R. It really makes me wonder how much is shared in the 2.5 from the 3.6 because I can tell you that my car got stuck in snow the other day with only one wheel quasi-spinning and the car not moving. In fact I would step on the gas and when it slipped it would drag the engine speed down and slow the rotation but it was not nearly enough power to break the car free. I was quite upset. Link to comment Share on other sites More sharing options...
ammcinnis Posted January 4, 2017 Share Posted January 4, 2017 Has anyone come across actual Subaru documentation describing what the front to rear toque split is with the 2.5i limited? According to the Subaru Global web site, the default torque split for the current generation "Lineartronic" CVTs is 60F/40R. Torque split is dynamically managed by the VDC and CVT controllers, and it can range from 100F/0R to 50F/50R depending on road/traction conditions. ... my car got stuck in snow the other day with only one wheel quasi-spinning and the car not moving. In fact I would step on the gas and when it slipped it would drag the engine speed down and slow the rotation but it was not nearly enough power to break the car free. Sounds like Traction Control intervening. Next time try temporarily disabling VDC. "If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland) Link to comment Share on other sites More sharing options...
sf.basilix Posted January 4, 2017 Author Share Posted January 4, 2017 Thanks for the quick reply! Unfortunately I did disable VDC but there was no difference at all. In fact I even went to a snow filled parking lot recently to try and intentionally spin the tires with VDC off and it wouldn't let me do it. I found no difference with VDC on or off in snow with my vehicle. Were you able to confirm the info above was not just for the 3.6R and also applies to the 2.5i? Link to comment Share on other sites More sharing options...
upstater Posted January 4, 2017 Share Posted January 4, 2017 They don't really confirm the torque split, because it is bad marketing for an AWD car company to tell you that the car mostly operates as a FWD car, unless there is wheel slip. The magic of Subaru AWD is that it transfers power so quickly, and substantially more effectively than most other manufacturers sometime AWD vehicles. If you want true AWD, buy a full time AWD car. It will cost you significantly in MPG's, and won't really help you much on the road in normal driving conditions, just that 1% of the time that you encounter a use for full time AWD. Stuck in snow, shut off VDC, try to keep wheel spin down to a minimum, and if it happens a lot for you, put on snow tires. The car is only as good as the tires allow it to be. A Subaru AWD car with snow tires is a beast in the snow. Short of this, get a traction aid to put under your tires to help you get going. My Legacy, without snow tires, is damn good driving in the snow. I took it out recently during a minor snow event and noticed how many FWD cars were having serious issues getting started at traffic lights after stopping, due to 3-4" of mush in the road. My car had no issues with this, it was actually better than the AWD pickups that I also saw that morning (most of which have even less weight on their rear axle = poor weight distribution). I saw several FWD vehicles spend an entire cycle of the traffic light just trying to get going from a stop. Stopping and steering, let's just say it was sloppy, and I had to slow down because the tire grip was limited. In one circumstance I was sliding toward a curb, so I stopped braking and accelerated where I wanted to go, and was able to get enough traction to redirect the car, but I learned that even with AWD the Legacy needs snow tires if you want to avoid curbs, or significantly more attention than I was paying when it comes to stopping and steering...In my defense, I was testing the traction limits to see how the car would perform with all season tires and slippery conditions. If I still lived in the hill towns 10 miles from my current house, I would do full snow tires like I used to. Now I expect a bit of wheel slip, and drive the well-maintained roads back and forth to work slower if it is snowing. If I was in a snow filled parking lot, with the stock all season tires, I would expect some issues getting going. Link to comment Share on other sites More sharing options...
personatech Posted January 4, 2017 Share Posted January 4, 2017 This is interesting, as the few times I've brought up the drive mode information screen in my '17 Limited, it always seems to show all four wheels driving the car no matter the condition - this almost to the point where I wondered why they even bothered with the graphic at all. Perhaps I should take a closer look at that screen. Link to comment Share on other sites More sharing options...
upstater Posted January 4, 2017 Share Posted January 4, 2017 The only time you will see anything interesting on that screen is if you take it out during a snowstorm/similar slippery conditions and gun it, the wheel that slips will blink momentarily, corresponding with dash warnings that there is wheel slip. Link to comment Share on other sites More sharing options...
dgoodhue Posted January 4, 2017 Share Posted January 4, 2017 The torque split is variable, so that is why Subaru doesn't market it. It is using wheels sensors and (likely) the engine load as the primary variable for engaging the AWD. If you logged the MTC in scan tool (Multiplate Transfer Clutch), you would see how often the rear wheels are engaged. The front wheels are mechanically connected and therefore engage 100% of the time. To get the torque split you divide the MTC by 2 which would give you the rear portion of the split. I saw in one post that some mention that under acceleration in dry conditions that the MTC was engage 70% so that would be 65/35 torque split. In deceleration they saw 20% so that would be 90/10 torque split. Likely those MTC value were just based of the engine load and not the wheels sensor inputs. I would imagine that if the tires were slipping the torque split would approach 50/50. They big key Subaru is that Subaru is constantly engaging the wheels and anticipating wheel sleep base on the acceleration as oppose to the old reactionary system base off of most wheels sensors that give AWD a bad name (ie RAV4, CRV that are on youtube). Link to comment Share on other sites More sharing options...
ammcinnis Posted January 4, 2017 Share Posted January 4, 2017 I saw in one post that some mention that under acceleration in dry conditions that the MTC was engage 70% so that would be 65/35 torque split. In deceleration they saw 20% so that would be 90/10 torque split. That was probably me. The MTC duty cycle observed during constant-speed cruising on level ground is typically 35 to 40%. One note, though. What you can observe via OBD/CAN is the MTC control solenoid duty cycle (0 to 100%), but we can't assume that MTC clutch friction is linear with respect to control command. Of course, Subaru has measured this in the lab, so the transfer function is no doubt well known to the engineers. Besides acceleration and deceleration, I've observed that the MTC duty cycle also varies with steering angle, which makes sense. N.B. All of my observations have been in light traffic on clear and dry roads. The last thing I need is to be "head down," staring at a screen under snowy, icy, or other marginal-traction road conditions. "If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland) Link to comment Share on other sites More sharing options...
Beamercub Posted January 4, 2017 Share Posted January 4, 2017 This is interesting, as the few times I've brought up the drive mode information screen in my '17 Limited, it always seems to show all four wheels driving the car no matter the condition - this almost to the point where I wondered why they even bothered with the graphic at all. Perhaps I should take a closer look at that screen. Perplexing. Does the 15' have this screen? Link to comment Share on other sites More sharing options...
Beamercub Posted January 4, 2017 Share Posted January 4, 2017 My last legacy was a 2006 without VDC and all 4 wheels would spin equally if I was stuck in snow.. Was actually cool to watch... They were all equal.. No difference from the front to the back... I haven't had a chance to try with my 15' 3.6 R yet, but overall I hate this car. It is a horrible car, Subaru really dropped the ball on the remodel... I'm having handling problems along with odd noises that will clearly lead to some type of failure in the future. Link to comment Share on other sites More sharing options...
cerbomark Posted January 4, 2017 Share Posted January 4, 2017 Perplexing. Does the 15' have this screen? yes... Link to comment Share on other sites More sharing options...
sf.basilix Posted January 5, 2017 Author Share Posted January 5, 2017 Thanks to all for your replies this is very helpful! Link to comment Share on other sites More sharing options...
personatech Posted January 5, 2017 Share Posted January 5, 2017 Perplexing. Does the 15' have this screen? It's the same head unit as far as I know (at least, in Limited trim). Info->Vehicle Monitor Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted January 6, 2017 Share Posted January 6, 2017 when the center differential locks up 100% it will be a 50/50 split... Link to comment Share on other sites More sharing options...
ehsnils Posted January 6, 2017 Share Posted January 6, 2017 when the center differential locks up 100% it will be a 50/50 split... It's the same on all AWD vehicles, regardless of diff or clutch pack. The difference is what torque split you have before the diff lock goes in. Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted January 6, 2017 Share Posted January 6, 2017 ^ not true a CR-V is unable to send more than roughly 40% to the rear wheels... but then again slip and grip really isn't AWD... Link to comment Share on other sites More sharing options...
sf.basilix Posted January 7, 2017 Author Share Posted January 7, 2017 It's the same on all AWD vehicles, regardless of diff or clutch pack. The difference is what torque split you have before the diff lock goes in. Not true for other vehicles and also not true for even Subaru: https://www.cnet.com/roadshow/news/not-every-subaru-all-wheel-drive-system-is-created-equal/ Link to comment Share on other sites More sharing options...
sf.basilix Posted January 7, 2017 Author Share Posted January 7, 2017 The only time you will see anything interesting on that screen is if you take it out during a snowstorm/similar slippery conditions and gun it, the wheel that slips will blink momentarily, corresponding with dash warnings that there is wheel slip. So this was interesting because I never understood why this picture existed. It seemed kind of pointless. When you wrote this I decided to try it out. I don't know if your model is newer or has an updated code but mine did not work this way. I had purposely placed one wheel on an ice patch and gun it. The display still showed all 4 wheels turn red and the VDC icon appear. I could not get it to define which wheel was slipping. Does yours do this also? I have the 2015 limited legacy. Link to comment Share on other sites More sharing options...
upstater Posted January 7, 2017 Share Posted January 7, 2017 So this was interesting because I never understood why this picture existed. It seemed kind of pointless. When you wrote this I decided to try it out. I don't know if your model is newer or has an updated code but mine did not work this way. I had purposely placed one wheel on an ice patch and gun it. The display still showed all 4 wheels turn red and the VDC icon appear. I could not get it to define which wheel was slipping. Does yours do this also? I have the 2015 limited legacy. WRX would light up for the individual wheel that was slipping, I haven't tested the Legacy yet, so not sure. Either way, I use that info panel mainly to see the oil temp so I know when the car is properly warmed up. Link to comment Share on other sites More sharing options...
Milkywitness Posted January 8, 2017 Share Posted January 8, 2017 My Legacy, without snow tires, is damn good driving in the snow. I took it out recently during a minor snow event and noticed how many FWD cars were having serious issues getting started at traffic lights after stopping, due to 3-4" of mush in the road. My car had no issues with this, it was actually better than the AWD pickups that I also saw that morning (most of which have even less weight on their rear axle = poor weight distribution). I saw several FWD vehicles spend an entire cycle of the traffic light just trying to get going from a stop. Stopping and steering, let's just say it was sloppy, and I had to slow down because the tire grip was limited. In one circumstance I was sliding toward a curb, so I stopped braking and accelerated where I wanted to go, and was able to get enough traction to redirect the car, but I learned that even with AWD the Legacy needs snow tires if you want to avoid curbs, or significantly more attention than I was paying when it comes to stopping and steering...In my defense, I was testing the traction limits to see how the car would perform with all season tires and slippery conditions. If I still lived in the hill towns 10 miles from my current house, I would do full snow tires like I used to. Now I expect a bit of wheel slip, and drive the well-maintained roads back and forth to work slower if it is snowing. If I was in a snow filled parking lot, with the stock all season tires, I would expect some issues getting going. I had the same experience in my 2.5i during our snow storm (happening right now). Accelerating from a stop on ice/slush/snow is great and I can get going while they still spin. Though I slip around a lot, and turning is scary. Granted I was doing it on Goodyear Assurance all seasons and not snow tires. Link to comment Share on other sites More sharing options...
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