[wwrx]

Hi,

Does anyone know for sure if 2011 3.6R comes with rear LSD? I saw a brochure for 2010 and it clearly was saying that 2010 3.6R comes with rear LSD. So far in 2010 only two Subarus were equipped with rear LSD - STI and Outback 3.6R. We bought 2011 3.6R. It looks exactly the same as 2010 but SOA brochure doesn't say anything about rear LSD. Have they removed it in 2011 or it's still there and not marked in official brochure?

Thanks!

P.S. Sorry if that's not the right forum for that question.

 

[Nickshu]

I believe the rear LSD was dropped from the Outback for Gen-4. Not 100% sure about the 2010, but I know it was not included on the 2011-present.

IIRC Subaru elected to use the traction control system to act to limit wheel slip "virtually" rather than "mechanically" with an actual LSD, claiming that the results are basically the same. Certainly for slipping, but probably not for handling/cornering, but the Outback is not really a performance car.

 

[Pool Runner]

Pretty sure all Outbacks are open front & rear differential. But technically the traction control acts as a pseudo limited slip as when combined with an open type differential and wheel slip occurs, the ABS/brakes will be applied to the spinning wheel which will "limit the slipping" and send some power to the wheel with traction.

 

[cardoc]

I believe the rear LSD was dropped from the Outback for Gen-4. Not 100% sure about the 2010, but I know it was not included on the 2011-present.

IIRC Subaru elected to use the traction control system to act to limit wheel slip "virtually" rather than "mechanically" with an actual LSD, claiming that the results are basically the same. Certainly for slipping, but probably not for handling/cornering, but the Outback is not really a performance car.

I tend to disagree with that statement.

Sleeper VDC

The pics are graphs from my 3.0. The 3.6 is capable of high output due to the variable cams and is easily tuned on stock build.

Then: 2011 Subaru Legacy Research Page

No LSD. VDC became standard equipment and controls traction via engine, transmission and ABS controls. The 3.6 does have the VTD center diff. That's a PLUS.

 

[wwrx]

I believe the rear LSD was dropped from the Outback for Gen-4. Not 100% sure about the 2010, but I know it was not included on the 2011-present.

Yeah, I'm pretty sure that I saw "Rear Limited Slip differential" under 3.6R drive train description in 2010 specs as I compared it to 2011 and haven't seen LSD in 2011 specs... Unfortunately non of 2010 spec web links are working now . Both 2010 and 2011 are Gen4. So either they really dropped rear LSD starting 2011 or some official specs (2010 or 2011) are wrong.

I found that thread and there is some mixed info on that: http://www.subaruoutback.org/forums/104-gen-4-2010-present/22895-2010-rear-limited-slip-2.html

And here some forum members say that rear VLSD really doesn't make that much difference if there is already a VDC system: Does rear limited slip differential make a lot difference? - Subaru Forester Owners Forum

 

[wwrx]

Pretty sure all Outbacks are open front & rear differential. But technically the traction control acts as a pseudo limited slip as when combined with an open type differential and wheel slip occurs, the ABS/brakes will be applied to the spinning wheel which will "limit the slipping" and send some power to the wheel with traction.

Yep, that hiow it works although it's not the same as having an LSD but probably it won't matter for an Outback anyway.

 

[Novablue]

The only thing I (slightly) worry about is mechanical lockers are proven and work and can be built to last for a long time (properly maintained). Computer controlled components don't seem to last as long because as Scotty said:

"The more they over-think the plumbing, the easier it is to stop up the drain."

Sure the VLSD might work "the same" but will it last as long as a mechanical LSD?

 

[1 Lucky Texan]

mechanical, maybe not, but some folks say the viscous LSD is worn-out by 60K miles so, yeah, electronic can last longer tham VLSD. I don't think the cars have come with mechanical lockers since the late 80s (maybe STi has-maybe never on Outbacks)

there is also the possibility that someone will find a way (if it hasn't been done already) to 'hack' and re-flash a ROM to make the electronic version more versatile in some way. Some serious off-roader might want different reaction from the electronic system than someone in snow or rain, etc.

 

[wwrx]

mechanical, maybe not, but some folks say the viscous LSD is worn-out by 60K miles so, yeah, electronic can last longer than VLSD.

I'd agree on that as VDC just uses brakes instead of real front or rear LSD

I don't think the cars have come with mechanical lockers since the late 80s (maybe STi has-maybe never on Outbacks)

Not sure 100% but I think WRX had rear VLSD (at least the manual one) before MY2008. I also had 06 WRX . I own 2009 STI and there are front and rear Torsen LSDs there. But I agree these cars are an exception as most of the road cars don't have LSDs nowdays. Audis don't have rear LSDs also unless you order this YAW controlling rear diff as an option.

Some serious off-roader might want different reaction from the electronic system than someone in snow or rain, etc.

For serious offroad you may want a real LSD anyway.

 

[Bobaru]

It's definitely true that the marketing materials and info for the 2010 MY said that there was a limited-slip rear differential in the 3.6R cars. But then this statement disappeared for 2011. This naturally raised some questions, from both 2010 owners and (at the time) prospective 2011 buyers. I recall someone posting some service-manual info that seemed to pretty conclusively show that the 2010 never really had a rear LSD. So my guess was just that the marketing folks got it wrong to begin with.

 

[wwrx]

It's definitely true that the marketing materials and info for the 2010 MY said that there was a limited-slip rear differential in the 3.6R cars. But then this statement disappeared for 2011. This naturally raised some questions, from both 2010 owners and (at the time) prospective 2011 buyers. I recall someone posting some service-manual info that seemed to pretty conclusively show that the 2010 never really had a rear LSD. So my guess was just that the marketing folks got it wrong to begin with.

I see, thanks for the info! Maybe they just copied the LSD statement from Gen3 H6 Outback or Gen3 Lagacy GT 5MT/Auto specs...? They had somewhat similar (by SOA description) drivetrain with 3.6R - 5EAT VTD central diff with 45/55 normal split... Actually this drive train is one of the reasons why we purchased 3.6R instead of 2.5i CVT which is 90/10 normal split FWIK (if I'm not mistaken here).

 

[Novablue]

I see, thanks for the info! Maybe they just copied the LSD statement from Gen3 H6 Outback or Gen3 Lagacy GT 5MT/Auto specs...? They had somewhat similar (by SOA description) drivetrain with 3.6R - 5EAT VTD central diff with 45/55 normal split... Actually this drive train is one of the reasons why we purchased 3.6R instead of 2.5i CVT which is 90/10 normal split FWIK (if I'm not mistaken here).

Yes you are mistaken. The CVT system can send up to 50% power to the rear instantly and on demand as shown in the Freessm thread. The power of the 3.6 is the main difference on between how the cars react on the road. The center diff is also different so there can be some debate there.

Of course there have been many locked threads on that question.

 

[wwrx]

Yes you are mistaken. The CVT system can send up to 50% power to the rear instantly and on demand as shown in the Freessm thread.

Yes, I'm aware of that... Same with any other 90/10 "on-demand" system (non-Subaru) when there is a slippage detected under front wheels. 90/10 is a _normal_split when there is no actual or predicted loss of traction under any wheel. With 45/55 center diff you may get more that 55% on the rear. Is there a central diff in 2.5i CVT at all? It's probably just a clutch pack.

 

[Green LTD]

Just a clutch pack. The 3.6 also is activated by a clutch pack. And the manuals have a clutch, but no active front to rear transfer. By the way, the transfer may vary from 90/10 to 50/50, but several things affect the pressure sent to the clutch pack, including throttle input, not just "actual or predicted loss of traction".

 

[rasterman]

mechanical, maybe not, but some folks say the viscous LSD is worn-out by 60K miles so, yeah, electronic can last longer tham VLSD. I don't think the cars have come with mechanical lockers since the late 80s (maybe STi has-maybe never on Outbacks)

there is also the possibility that someone will find a way (if it hasn't been done already) to 'hack' and re-flash a ROM to make the electronic version more versatile in some way. Some serious off-roader might want different reaction from the electronic system than someone in snow or rain, etc.

+1.

I think the whole industry is getting away from mechanical ones because they're expensive, difficult to service, have limited lifetimes and nonlinear wear rates.

Brakes are waaay easier to check and maintain, and I have faith in the idea that the controlled brake "virtual" LSD system will cost less and perform better in the long run.

It may not be as safe for laying rubber patches, but nobody does that in an outback anyway.

shh Cardoc... easy there...

 

[Primotenente]

Just a clutch pack. The 3.6 also is activated by a clutch pack. And the manuals have a clutch, but no active front to rear transfer. By the way, the transfer may vary from 90/10 to 50/50, but several things affect the pressure sent to the clutch pack, including throttle input, not just "actual or predicted loss of traction".

- The 3.6. is not activated by a clutch, it is always active
- The manuals don't have a clutch - except for the transmission - they have a viscous limited slip differential

 

[rasterman]

- The 3.6. is not activated by a clutch, it is always active
- The manuals don't have a clutch - except for the transmission - they have a viscous limited slip differential

Ahh but it is a clutch. Just not one that you have to manually operate with a pedal.

The clutch is what is always active, changing the amount of torque borrowed from the front to supply the rear.

 

[Primotenente]

Ahh but it is a clutch. Just not one that you have to manually operate with a pedal.

The clutch is what is always active, changing the amount of torque borrowed from the front to supply the rear.

For the manual: No.

 

[Green LTD]

Yes primo, in the manual the clutch is between the engine and the tranny, and the viscous differential has little plates in it too. The 3.6 has an electronically controlled clutch that varies the torque distribution in the geared transfer case of old design, it CAN'T transfer torque without it. (it is arguably a hardier design, but the 2.5 doesn't need it, and rarely does one notice the supposed "sportier" feel of the default 45/55 split unless you really enjoy juicing it around curves, which some do). It also has clutch packs in it's auto transmission......

 

[wwrx]

From what I know 3.6R does have a clutch in the central diff. It locks the center differential. So, 2.5i CVT - no center diff, just clutch, 3.6R - center diff with a clutch. Center diff can transfer torque from front to rear and from rear to front without a clutch but if it's an open diff the max torque will be transferred to the axle that has loss of traction and we normally want an opposite. That's why there is a clutch there - to make it work as a LSD diff (lockable). There is still a difference between systems at how they perform close to the traction limit but I agree that most Outback owners won't feel a difference.

I'm not sure 100% but I think my old 06 WRX with 5MT didn't have a clutch in the center diff (with 50/50 normal split), just a VLSD as a center diff and VLSD in the rear. Don't know about 5MT non-turbo Imprezas or Legacy/Outbacks.

New STI's have lockable (LSD+clutch) center diff with 35/65 normal split, front and rear Torsen LSDs and VDC on top of that.