[infidel335]

I'm not debating AWD vs RWD, I'm comparing open diff vs LSD. An open diff lacks terribly in performance when compared to an LSD. An AWD car is awesome for driving all year but RWD is typically more fun, at least for me. I'm not sure if there was a question in there.

With the DTC disabled the car is very squirrely when the tires break loose in a turn. I'd like more control of the car but that could probably be achieved in more ways than one. Having a Subaru style torque biasing controller would be a performance "must have" but until one of those hits the market I think an LSD might help keep the car under control a little better. Again, I'd like to find someone that is running this setup and read any notes they've provided.

[noLimits Enterprises]

edit: Wrong thread sorry

[paradoxical3]

LSD works great on xdrive. I have about 10 days on my wavetrac and I am kicking myself I didn't do it earlier. You will need to code off the e-diff and other nannies, which you can see how to do on my blog: http://www.onelapx1.com/blog

Xdrive is really fantastic on track with a LSD; it's faster than RWD for sure. The cars I can keep up with are pretty ridiculous and I make up so much time coming out of turns at full throttle.

[cebrailbakan]

Originally Posted by paradoxical3

LSD works great on xdrive. I have about 10 days on my wavetrac and I am kicking myself I didn't do it earlier. You will need to code off the e-diff and other nannies, which you can see how to do on my blog: http://www.onelapx1.com/blog

Xdrive is really fantastic on track with a LSD; it's faster than RWD for sure. The cars I can keep up with are pretty ridiculous and I make up so much time coming out of turns at full throttle.

Appreciated brother !! Thanks a looottt

[OffensiveDriver]

Originally Posted by paradoxical3

LSD works great on xdrive. I have about 10 days on my wavetrac and I am kicking myself I didn't do it earlier. You will need to code off the e-diff and other nannies, which you can see how to do on my blog: http://www.onelapx1.com/blog

Xdrive is really fantastic on track with a LSD; it's faster than RWD for sure. The cars I can keep up with are pretty ridiculous and I make up so much time coming out of turns at full throttle.

Nice job paradoxical3 ! Your blog is the most informative bit I've read on optimizing XDrive with an LSD. Thanks for taking the time to post it. Now all I have to do is figure out how to code !

[cebrailbakan]

I think we can code it via auto-logic diagnose machine

[pavproch]

Eventually found this thread.

A Drexler LSD (lamelle - 40% slip) works just fine (rear diff, front left untouched, ie "open") on my 330i xDrive MY2011. The handling and predictability (especially while hard cornering on icy/slippery roads, DSC off, obviously) improved tenfold. At least.

But, imho LSD (of any kind - I do run a Quaife - a worm type LSD - on the other car of mine, and frankly speaking I would NOT tell Drexler from Quaife, they behave +/- the same) is only half of the fun. Shortening the diff does the second half.

I have both cars shortened quite a lot (3er - 15% both diffs, Z4 - 17% rear one) and the increase in dynamics is overwhelming. Proportionally, the milleage dropped quite a lot, too.

[putnampunk]

Originally Posted by OffensiveDriver

Nice job paradoxical3 ! Your blog is the most informative bit I've read on optimizing XDrive with an LSD. ... Now all I have to do is figure out how to code !

I feel the same way - glad to have a good review of LSD in a Xdrive system and need to re-learn code (e-diff off, turn off TPMS, turn on alarm retrofit, etc.)

[ifobd]

Originally Posted by paradoxical3

LSD works great on xdrive. I have about 10 days on my wavetrac and I am kicking myself I didn't do it earlier. You will need to code off the e-diff and other nannies, which you can see how to do on my blog: http://www.onelapx1.com/blog

Xdrive is really fantastic on track with a LSD; it's faster than RWD for sure. The cars I can keep up with are pretty ridiculous and I make up so much time coming out of turns at full throttle.

Originally Posted by paradoxical3

LSD works great on xdrive. I have about 10 days on my wavetrac and I am kicking myself I didn't do it earlier. You will need to code off the e-diff and other nannies, which you can see how to do on my blog: http://www.onelapx1.com/blog

Xdrive is really fantastic on track with a LSD; it's faster than RWD for sure. The cars I can keep up with are pretty ridiculous and I make up so much time coming out of turns at full throttle.

Resurfacing an old thread as im thinking about an lsd for my xdrive. Your blog is offline, hoping it is still around in someform elsewhere?

[AWD Addict]

Same. Bump.

[Soravia]

LSD makes car grip more, and they perform differently based on type. The center diff on xDrive IS LSD, a clutch type actuated by electric motor. Now many cars have this, used to be stated from Nissan Skyline.

Which back diff LSD directly bolts on for xDrive with 6MT? I don't want different ratios between front and back final drives.

On the other hand, which LSD (Torsen type) fits for front diff? Torsen is perfect for front because it transfers torque to MORE grippy side but doesn't LOCK in like clutch or liquid types.

[floydarogers]

Originally Posted by Soravia

LSD makes car grip more, and they perform differently based on type. The center diff on xDrive IS LSD, a clutch type actuated by electric motor. Now many cars have this, used to be stated from Nissan Skyline.

Which back diff LSD directly bolts on for xDrive with 6MT? I don't want different ratios between front and back final drives.

On the other hand, which LSD (Torsen type) fits for front diff? Torsen is perfect for front because it transfers torque to MORE grippy side but doesn't LOCK in like clutch or liquid types.

While the overall thrust of this post is correct, there are major flaws.
1) BMWs don't come with a "center" diff. It's a transfer case, and it'w always creating some windup between front/rear that is only relieved by tire slippage.
2) There are no LSD's that fit within the very special front differential case. (AFAIK)

[Soravia]

Doesn't the center transfer case have electronically actuated clutch pack?
My Mazda has it now, being FWD based the shaft runs all the time and the clutch sits on rear diff nose to "slip" torque 0-50%.

[floydarogers]

Originally Posted by Soravia

Doesn't the center transfer case have electronically actuated clutch pack?

Yes, it has a clutch pack, controlled by the DSC system. But it is not a differential like Subaru and Audi/Quattro have.

[AWD Addict]

Originally Posted by floydarogers

Yes, it has a clutch pack, controlled by the DSC system. But it is not a differential like Subaru and Audi/Quattro have.

Honestly, my WRX's awd performance blew away my 08 e92. So much more robust and predictable at wheel. And that was just a simple open diff.

With DCT on in this car, with slippery conditions, it's similar but not the same. Not as good. On pavement, it's more refined, but less gutsy and effective.

One day my perfect car will be born.

[Soravia]

Originally Posted by AWD Addict

Honestly, my WRX's awd performance blew away my 08 e92. So much more robust and predictable at wheel. And that was just a simple open diff.

With DCT on in this car, with slippery conditions, it's similar but not the same. Not as good. On pavement, it's more refined, but less gutsy and effective.

One day my perfect car will be born.

Probably because DSC is programmed to not send power to the front unless it really think it's needed. The car is supposed to behave like RWD most of the time.
WRX is FWD base sending as much as spare power it can to the rear, but never more than 50% due to the tiny diff in the back end.

Reprogramming when the clutch pack kicks in for the E9x is probably out of reach for most people. Skyline GT-R and GT-4 series used the same exact setup and they didn't send power to the front all the time either.

[woodex m.e.]

Originally Posted by Soravia

Probably because DSC is programmed to not send power to the front unless it really think it's needed. The car is supposed to behave like RWD most of the time.
WRX is FWD base sending as much as spare power it can to the rear, but never more than 50% due to the tiny diff in the back end.

Reprogramming when the clutch pack kicks in for the E9x is probably out of reach for most people. Skyline GT-R and GT-4 series used the same exact setup and they didn't send power to the front all the time either.

I'm not an expert, but I am quite certain everything you said about the WRX was completely false/inaccurate information.

[Soravia]

Originally Posted by woodex m.e.

I'm not an expert, but I am quite certain everything you said about the WRX was completely false/inaccurate information.

FULL TIME AWD, except when the wheels are turned, and the front is totally slipping? LoL.

It's very very front biased system. They sell the FWD only trims in other markets in early days.

Have you seen their rear diff? It's smaller than 1989 Mazda Miata rear diff!

[Soravia]

Originally Posted by pavproch

Eventually found this thread.

A Drexler LSD (lamelle - 40% slip) works just fine (rear diff, front left untouched, ie "open") on my 330i xDrive MY2011. The handling and predictability (especially while hard cornering on icy/slippery roads, DSC off, obviously) improved tenfold. At least.

But, imho LSD (of any kind - I do run a Quaife - a worm type LSD - on the other car of mine, and frankly speaking I would NOT tell Drexler from Quaife, they behave +/- the same) is only half of the fun. Shortening the diff does the second half.

I have both cars shortened quite a lot (3er - 15% both diffs, Z4 - 17% rear one) and the increase in dynamics is overwhelming. Proportionally, the milleage dropped quite a lot, too.

Good to know I can swap out final ratios on rear in xDrive and have no issue with AWD controller. I want to do that since the wagon is heavy and the wheels are heavy on 18x8 50 lbs each wheel and tire

[woodex m.e.]

Originally Posted by Soravia

FULL TIME AWD, except when the wheels are turned, and the front is totally slipping? LoL.

It's very very front biased system. They sell the FWD only trims in other markets in early days.

Have you seen their rear diff? It's smaller than 1989 Mazda Miata rear diff!

I guess this could be considered accurate assuming you only consider cvt powered wrx units from 2015 and up.

[Soravia]

Originally Posted by woodex m.e.

I guess this could be considered accurate assuming you only consider cvt powered wrx units from 2015 and up.

Mostly has to do with what they use to send power to the rear. Mazda uses clutch pack in the middle, similar to xDrive or Nissan ATTESA-E AWD. Mazda spin the drive shaft to the rear at all times, and the clutch pack right in front of the rear diff is activated based on when the computer wants to send power to the rear. No brakes needed to activate AWD.
Subaru use open diff, torsen diff, or clutch diff based on their trims, and send power mostly to the front (Mazda, too!).
Brake based AWD systems, regardless of transmission, just suck bad. And most of them rely so much on the front wheels, they are barely able to send power to the rear, never really on demand either.
ALL Subaru, focus on the front wheels for power, even the WRX STI with clutch center diff. The rear is afterthought, opposite of BMW, Skyline, Merc, etc.

[Impreza98]

Originally Posted by Soravia

Mostly has to do with what they use to send power to the rear. Mazda uses clutch pack in the middle, similar to xDrive or Nissan ATTESA-E AWD. Mazda spin the drive shaft to the rear at all times, and the clutch pack right in front of the rear diff is activated based on when the computer wants to send power to the rear. No brakes needed to activate AWD.
Subaru use open diff, torsen diff, or clutch diff based on their trims, and send power mostly to the front (Mazda, too!).
Brake based AWD systems, regardless of transmission, just suck bad. And most of them rely so much on the front wheels, they are barely able to send power to the rear, never really on demand either.
ALL Subaru, focus on the front wheels for power, even the WRX STI with clutch center diff. The rear is afterthought, opposite of BMW, Skyline, Merc, etc.

Taken from Subaru website:
"Available only on the WRX STI, this drivetrain is the most advanced and sophisticated of the four. With a 41/59 split, it leans more on a rear bias, which is ideal for a sport-focused drive feel. "

The earlier STI are even more rwd bias at 35/65 split. I am an owner of an 05 STI by the way.

Watched this video a while ago but if my memory is correct, the video describes the various awd system pretty well and touches on the previous generation.