5sp manual and 5sp automatics have slightly different AWD

[godwhomismike]

I just read that the AWD on the 5sp automatic is different then the system on the 5sp manual. The automatic is rear bias with 45/55 split front to rear. The manual is a perfect 50/50 balance. This is what the Subaru website says: "AWD: Models equipped with 5-speed automatic transmission utilize an electronically controlled variable transfer clutch in conjuction with a planetary-type center differential. Rear-wheel-biased torque distribution normally configured at 45/55-split front-to-rear." Doyou guys think a 45/55 split will be more fun than a 50/50 split, or would you not really notice the difference? How do you think handling will be affected with this difference? Opinions? - Mike

[SteVTEC]

Time to hit the search button. I think this has been discussed in great depth here already, lol Steve

[godwhomismike]

I will copy what the brochure says about it when I get home, I'm at my girlfriend's house in southern NJ. ( OT - just spent the weekend driving her '91 Legacy AWD Turbo - drove it 1 hour away and 1 hour back and got to push her on the backroads and on some dirt roads, we went camping so I got to have some AWD fun. :D - Mike

[SUBE555]

It has been discussed but for sake of argument and getting a few posts in while DM isn't here ;) I'd have to say in the slick it would likely be more noticeable. The rear bias helps to promote oversteer to a slight bit but that's mostly suspension. You may notice it, but it would probably be less than you think for most people. Personally, I'd be more interested in side-to-side handling such as adding a helical front LSD. The bias is fairly close and at this point, a helical/torsen unit would give you a better handling ability, particularly pulling out of corners faster.

[Ken S]

Mike, A 5% difference in torque split will hardly be noticed. What you will notice, however is the reaction of the two systems under slippery conditions. The 5MT uses a viscous coupling that changes it's torque split only after one axle spins faster than the other. The 5EAT uses a bit more sophisticated system called VTD that uses planetary gears to split the torque 45:55 and an electronic clutch pack to move torque depending on the need. For example, the system will send more power to the rear tires when the TCU and ECU sense hard acceleration. I've only driven the 5MT VC in snow, and when it slips, you definetly can feel the power oscillate from front to rear until the system settles. I believe this is less the case with VTD. Ken

[Drift Monkey]

The TECH REFERENCE explaina the differences. [url]http://www.legacysti.com/viewtopic.php?t=591[/url] shame on you for getting posts while I away SUBE! :lol:

[NicoGamine]

[quote name='godwhomismike']I just read that the AWD on the 5sp automatic is different then the system on the 5sp manual. The automatic is rear bias with 45/55 split front to rear. The manual is a perfect 50/50 balance. This is what the Subaru website says: "AWD: Models equipped with 5-speed automatic transmission utilize an electronically controlled variable transfer clutch in conjuction with a planetary-type center differential. Rear-wheel-biased torque distribution normally configured at 45/55-split front-to-rear." Doyou guys think a 45/55 split will be more fun than a 50/50 split, or would you not really notice the difference? How do you think handling will be affected with this difference? Opinions? - Mike[/quote] This is the same setup that was on the previous generation: mechanical setup on manuals, mecanichal + electronics on automatics. Not sure which model you have in mind as non-GT automatics do not get the VTD system. The automatic gives 95/5 in normal, slip-free driving, and can give up to 45% to the rear in case of slippage. Basically, there is a hard link to the front axle (i.e. gears) and a soft link to the rear (viscous differential with adjustable plates), so the front is always getting power but the system can vary what gets to the rear. I guess the 45% comes form the system never being able to completely remove slippage in the differential. Subaru Australia has a presentation on this at [url]http://subaru.com.au/awd/flash.asp[/url] (notice they mention 50/50 for manuals but don't give numbers for the automatics). Driving the automatic and having tested the manual, the viscous system on the manual is smoother and seamless, i.e. you don't feel anything happening. The manual I tested had no understeer. With the automatic, when the slippage is sudden (from a start or if you hit an icy patch), you feel the system engage and the rear start to push. It is fun when it happens in a curve as understeer just goes away, but it can be surprising... :) Hope this helps. Nicolas

[Drift Monkey]

The ATS system is 60/40. This is much better than the Haldex system.

[Ken S]

"The automatic gives 95/5 in normal, slip-free driving" Actually, there doesn't seem to be a straight answer to this question. We've asked technicians from SoA over at Edmund's about the non-VTD torque split and were told 80/20 normally. No one seems to know for sure. Ken

[7stars]

I've read 90/10 on other sites. another reason to get the 5MT!

[godwhomismike]

According to the brochure: [b]2.5 GT model with 5-speed automatic: [u]AWD system[/u] - VTD [u]How it works[/u]: Variable Torque Distrubtion (VTD) uses electronically controlled hydraulic transfer clutch in conjunction with a planetary gear-type center differential to control power distrubution between the front and rear wheels. Under normal driving conditions, the VTD system splits power 45% front and 55% rear, to deliver more of a performance driving feel.[/b] That mean, I am happy with my choice of the Legacy GT Limited - :D - Mike

[Drift Monkey]

[quote name='Ken S']"The automatic gives 95/5 in normal, slip-free driving" Actually, there doesn't seem to be a straight answer to this question. We've asked technicians from SoA over at Edmund's about the non-VTD torque split and were told 80/20 normally. No one seems to know for sure. Ken[/quote] Well, I don't know, but on that Subaru flash site Nico posted, it clearly shows a 60/40 split, with 95% of the torque being able to be transfred to the front at any given time (rear traction loss).

[Subaru-aholic]

It is my understanding that the absolute biggest percentage of torque going to the rear wheels is 55% (a 45/55 front/rear split). Under slippery conditions, it reverts back to 50/50. Unless I am misreading what you guys and gals are writing, there seems to be some confusion on the issue. The reason behind the somewhat insignificant change of only 5% is safety, as a larger % change could upset the car. Cheers, Subaru-aholic.

[Drift Monkey]

[quote name='Subaru-aholic']It is my understanding that the absolute biggest percentage of torque going to the rear wheels is 55% (a 45/55 front/rear split). Under slippery conditions, it reverts back to 50/50. Unless I am misreading what you guys and gals are writing, there seems to be some confusion on the issue. The reason behind the somewhat insignificant change of only 5% is safety, as a larger % change could upset the car. Cheers, Subaru-aholic.[/quote] This is only for the GT autos. The base models get 60/40 split before slippage.

[NicoGamine]

[quote name='Drift Monkey'][quote name='Ken S']"The automatic gives 95/5 in normal, slip-free driving" Actually, there doesn't seem to be a straight answer to this question. We've asked technicians from SoA over at Edmund's about the non-VTD torque split and were told 80/20 normally. No one seems to know for sure. Ken[/quote] Well, I don't know, but on that Subaru flash site Nico posted, it clearly shows a 95-5 split, with 40% of the torque being able to be transfred to the rear at any given time (traction loss).[/quote] Looked for info in the tech manual and the only thing I could find is that the "duty cycle" of the transfer case on automatics without VTD is 5% to 95%, which seems to mean that it can lock (thus transfer torque to the rear) from 5% to 95% with the front. Keep in mind that in the non-VTD systems the front wheels have a "hard" connection to the transmission, so that whatever happens, they always get power, and that the best the rear can do is match the front. The funky stuff happens with the connection to the rear axle. The manuals get the viscous coupling that have a minimum decided by the type of fluid used and their clutch plates (read about different types somewhere, forget where...) and can lock up if enough slip occurs (slip heats the fluids which becomes less fluid, which tightens the thing up). The non-VTD autos get the electronic system that seems to be able to get to 95% lock, so the least power the back would get is 2.5% (5% of 50%) and the most 47.5% (95% of 50%). The VTD uses gears (i.e. a hard connection) to split torque 45/55 and electronics and a viscous coupling to vary it. As to the amount of change and upsetting the car, I think the manual's purely mechanical setup is smoother and seamless, whereas the automatic's setup (which can go form 5 to 95%) makes itself really felt. Finally :) the difference between manuals and autos might explain manuals having lower MPG numbers than autos, unlike most other cars, as the manuals are getting a bit more drivetrain friction because they are sending more power back... Nicolas

[NicoGamine]

[quote name='Drift Monkey'][quote name='Subaru-aholic']It is my understanding that the absolute biggest percentage of torque going to the rear wheels is 55% (a 45/55 front/rear split). Under slippery conditions, it reverts back to 50/50. Unless I am misreading what you guys and gals are writing, there seems to be some confusion on the issue. The reason behind the somewhat insignificant change of only 5% is safety, as a larger % change could upset the car. Cheers, Subaru-aholic.[/quote] This is only for the GT autos. The base models get 95/5 split before slippage.[/quote] And it seems (form the Subaru Australia thingy) that the most the VTD system can send to the rear is actually 64%. As a note, there are system that are more sophisticated than the Legacy's manual and base automatic setups, but none of those are available for the price Subaru is asking. On my car, 95/5 is serving me well and the only thing I would add are limited-slip differentials on the front and rear axles (rear might get done by cannibalizing an Outback, front may get done in my dreams...). Nicolas

[Subaru-aholic]

[quote name='Drift Monkey'][quote name='Subaru-aholic']It is my understanding that the absolute biggest percentage of torque going to the rear wheels is 55% (a 45/55 front/rear split). Under slippery conditions, it reverts back to 50/50. Unless I am misreading what you guys and gals are writing, there seems to be some confusion on the issue. The reason behind the somewhat insignificant change of only 5% is safety, as a larger % change could upset the car. Cheers, Subaru-aholic.[/quote] This is only for the GT autos. The base models get 95/5 split before slippage.[/quote] Perhaps my confusion came from the fact that people keep referring to VDC (which is Vehicle Dynamics Control) and not VTD (which is the Variable Torque Distribution system on the Legacy 2.5GT's 5-speed automatic). Thanks for the clarification.

[NicoGamine]

[quote name='Subaru-aholic']Perhaps my confusion came from the fact that people keep referring to VDC (which is Vehicle Dynamics Control) and not VTD (which is the Variable Torque Distribution system on the Legacy 2.5GT's 5-speed automatic). Thanks for the clarification.[/quote] Guilty as charged... :( Editing pripor posts for clarity's sake. Nicolas

[Subaru-aholic]

[quote name='NicoGamine'][quote name='Subaru-aholic']Perhaps my confusion came from the fact that people keep referring to VDC (which is Vehicle Dynamics Control) and not VTD (which is the Variable Torque Distribution system on the Legacy 2.5GT's 5-speed automatic). Thanks for the clarification.[/quote] Guilty as charged... :( Editing pripor posts for clarity's sake. Nicolas[/quote] No harm done, my friend. There are simply way too many abbreviations and acronyms within the automotive world to be expecte dot keep them all straight. Cheers 8)

[Drift Monkey]

I re-evaluated my prior staements and realized it's only 95/5 when the rear wheels slip and 60/40 normally for the ATS (2.5i models). Yeah so everyone should have it straight now. To recap: VLSD - viscous limited slip differential (5MT GT Models) - 50/50 ATS - active torque split - 60/40. If front wheels slip, 50/50 slip. If rear wheels split, 95/5. VTD - variable torque distribution - 36/64. If rear wheels slip, 50/50 split, sending more torque up front. VDC - vehicle dynamic control - takes input from an array of sensors about data including vehicle speed, engine speed, steering wheel angle, gear, and brake status to constantly monitor the conditions and to try and alleviate a potential danger before the car gets out of hand. I hope this clears up any future confusion! :lol:

[NicoGamine]

[quote name='Drift Monkey']I re-evaluated my prior staements and realized it's only 95/5 when the rear wheels slip and 60/40 normally for the ATS (2.5i models). Yeah so everyone should have it straight now. To recap: VLSD - viscous limited slip differential (5MT GT Models) - 50/50 ATS - active torque split - 60/40. If front wheels slip, 50/50 slip. If rear wheels split, 95/5. VTD - variable torque distribution - 36/64. If rear wheels slip, 50/50 split, sending more torque up front. VDC - vehicle dynamic control - takes input from an array of sensors about data including vehicle speed, engine speed, steering wheel angle, gear, and brake status to constantly monitor the conditions and to try and alleviate a potential danger before the car gets out of hand. I hope this clears up any future confusion! :lol:[/quote] Actually ;) for the automatic's ATS, I would say: ATS - active torque split - 95/5. If front wheels slip, 55/45. Now, this is from experience (how my car behaves) and other readings on the net. Nothing definite in Subaru's litterature... yet. ;) Nicolas

[NicoGamine]

Found this at [url]http://www.autoworld.com/news/Subaru/Subaru_All-Wheel.htm[/url]. Not sure how reputable/trustworthy AutoWorld is, but it is detailed and confirmed in part by Subaru: [url]http://www.subaru.com/allwheeldrive/middle.jsp?pageID=2[/url]. And we are both wrong... (he's saying 90/10 :) ) [quote]All-Wheel Drive (Automatic Transmission) Active all-wheel drive is a term coined by Subaru to differentiate the all-wheel drive system in the automatic transmission from other "reactive" all-wheel drive systems on the market today. What makes this all-wheel drive system so special is its ability to anticipate traction needs and act before a wheel slips. The mechanism that transfers torque fore and aft is contained within the transmission’s tailshaft. To the casual observer it looks just like a typical hydraulic clutch found in any automatic. The key difference in this clutch pack is its operation. It’s designed to slip according to how much all-wheel drive is needed. When an automatic’s clutch slips, it is due to a malfunction and will eventually burn up. But the multi-plate transfer (MPT) clutch uses a special friction material that easily withstands the friction loads generated during torque transfer. The MPT’s operation is controlled by the Transmission Control Unit (or TCU) and constantly changes dependent on how the vehicle is being driven. To get more all-wheel drive, the TCU increases the hydraulic pressure to the clutch for less slippage. Less all-wheel drive calls for more slip and the TCU reduces the hydraulic pressure to the clutch. Under normal, dry pavement operation torque split is about 90% front and 10% rear. This distribution helps to compensate for the car’s weight distribution and resultant smaller effective rolling diameter of the front tires. As weight transfers to the rear of the vehicle, (i.e., under acceleration), the TCU shifts the torque split more toward the rear wheels. Under hard braking, torque is directed forward. Torque distribution is changed based upon how the vehicle is being driven. Throttle position, gearshift lever position, current gear and other factors combine to influence the TCU and it, in turn, selects a software map that determines how aggressively torque split will be adjusted. Two speed sensors are used by the TCU to detect wheel slippage. One sensor monitors the front axle set, the other the rear axle set. Pre-programmed variables help the TCU differentiate between slipping wheels and normal wheel speed differentials as what occurs when cornering. A speed differential (front-to-rear) of up to 20% signals the TCU that the vehicle is cornering and torque is distributed to the front wheels to help increase traction during the turn. Anything above 20%, however, indicates to the TCU that wheel slippage is occurring and torque is then distributed to the rear wheels. Another feature of the all-wheel drive system is its interaction with the anti-lock brake system. When ABS is engaged, the transmission selects third gear, reducing the unpredictability of engine braking and, thus, reducing the possibility of wheel lock-up. But all four wheels are still connected to the engine through the AWD system and are brought back up to overall vehicle speed quicker and can, therefore, be controlled again sooner. In a two-wheel drive system if the locking wheel isn’t a drive wheel, it can only be brought back up to overall wheel speed by whatever traction exists between it and the road. The quicker a wheel is controlled the better the stopping performance[/quote] Sorry if am I beating this dead horse BUT this is something where I have seen a lot of differing opinions, just feel like clearing it up. Nicolas Edit: And this guys says it is 80/20: [url]http://www.canadiandriver.com/testdrives/02legacy.htm[/url]... This is so funny, it's as if Subaru actually WANTS people confused... :) :)

[Drift Monkey]

[quote name='NicoGamine']Actually ;) for the automatic's ATS, I would say: ATS - active torque split - 95/5. If front wheels slip, 55/45. Now, this is from experience (how my car behaves) and other readings on the net. Nothing definite in Subaru's litterature... yet. ;) Nicolas[/quote] ATS is 60/40 normaly 95/5 upon front slip according to that flash site you posted. Watch the animations closely.

[NicoGamine]

[quote name='Drift Monkey'][quote name='NicoGamine']Actually ;) for the automatic's ATS, I would say: ATS - active torque split - 95/5. If front wheels slip, 55/45. Now, this is from experience (how my car behaves) and other readings on the net. Nothing definite in Subaru's litterature... yet. ;) Nicolas[/quote] ATS is 60/40 normaly 95/5 upon front slip according to that flash site you posted. Watch the animations closely.[/quote] Man, this is a bad tread for me: I keep getting corrected... :) Main thing is we have our answer. I'm happy. Moving on now... ;) Nicolas

[Drift Monkey]

I have no idea what to think anymore. There is so much misinformation out there. Upon further research, many signs seem to point that Subaru's ATS AWD system is 90/10, yet I haven't found any official documentation. I did however found this: [url]http://www.subaru-global.com/about/awd/2321.html[/url] This system for manual transmission vehicles combines a centre differential with bevel gears and a viscous coupling type limited slip differential (LSD). Normally, the centre differential distributes the torque at a ratio of 50:50 to the front and rear wheels for extremely stable driving and maximum traction. Where the balance of traction is lost when front or rear wheels slip, viscous LSD automatically redistributes torque to maximise grip, so full traction and driveability are always available. [url]http://www.subaru-global.com/about/awd/2322.html[/url] Active Torque Split AWD is a system that makes the most of stable driving performance of automatic transmission vehicles under any road conditions. Vehicle conditions such as variations in front and rear tyre grip, vehicle speed, and so on, are constantly monitored by sensors. Based on torque distribution readouts and directly coupled to front and rear tyres, it dramatically stabilises traction performance. Electronic Control MP-T (MultiPlate Transfer) is a device that increases AWD stability and driving pleasure by controlling the distribution of torque to the front and rear wheels in real time, responding directly to driving conditions. [url]http://www.subaru-global.com/about/awd/2323.html[/url] V-T-D AWD is an AWD system for automatic transmission vehicles that provides positive, sporty driving by making improvements in turning-in while maintaining the basic driving safety performance of Subaru AWD. The system uses complex planetary gear type centre differentials that distribute the basic torque at a ratio of 35 for the front wheels and 65 for the rear. Distributing more torque to the rear wheels reduces the tendency to understeer when accelerating while cornering to provide smoother, more confident handling. Torque distribution is also optimally controlled to suit road conditions. This system provides both sporty driving and stability under any road conditions by automatically equalizing the front and rear wheel torque distribution to a maximum ratio of 50:50.