Different technologies in Subaru rear LSDs?

When I've had I my wife's 03 OBW's rear in the air (brake job, putting synth fluid in the diff) I noticed that rolling the wheel on one side cause the opposite to roll in the same direction. Doing the same test on my 06 WRX wagon however, cause the opposite wheel to rotate backwards like an open diff. So, either they use different designs or one of them is not LSD or has failed. My guess is, my WRX has a viscous rear LSD and some different syle LSD in in the Outback.

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1 Lucky Texan
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Sorry to bring the bad news but 03 OBW has the real thing (viscous rear LSD) while 06 is about the cutoff when subaru on stronger yen ever ditched LSDs on most of the lineup save for STI (that had a mechanical LSD out back anyway, pun intended)

So it's highly likely that your WRX only has one "real" diff and that is between the axles. The rear is simulated by the system that breaks a spinning wheel.

If Mercedes could swing it in ML fhi could do it in a wrx just as well.

The only compact with (an active) rear diff currently sold that I know of is juke. If nissan brings a turbo version I could see wrx owners potentially be switching in droves.

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Hmmm, rear LSD is listed for my car at 2 sources, but you have a good point about it maybe being part of the ABS system or something. I have no indication of VCD or VTD or any other 'alphabet soup' system being on the car. I'd kinda expect the WRX could have a viscous LSD in the rear - it would show as open under the condotions I tested it - I THINK - since the viscous fluid must heat-up from spinning a wheel before torque begins being transferred. But what system is in the Outback then? Are there Outbacks in junk yards with awesome mechanical rear diffs in them? I just found it curious.

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1 Lucky Texan

Anybody else?

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1 Lucky Texan

Well, it wouldn't surprise me in the least if Subaru ditched the mechanical LSD for an electronic LSD. The mechanical systems were highly reliable and competent, but cost a lot to implement.

Yousuf Khan

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Yousuf Khan

I'm R&Ring the rear shocks on her OBW today and I confirmermed that the rear diff will move the other side in the SAME direction as the side you rotate. This is with the frone wheels on the ground. I'm not sure if the drive shaft was moving. I'll try to look later (I'm only about 1/4-1/3 in the project right now).

Almost every thing I've read recently seems to indicate both my cars would have viscous rear diffs. The OBW MAY have a different technology diff with the 'cold weather' package. It seems Subaru has had in-out- in-out optional/standard rear LSD changes thru the years. Neither of my cars have any of the electronic vehicle control stuff. (except for the 4EAT's center c;utch-pack of course).

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1 Lucky Texan

OK - here are the conditions; front wheels on the ground and chocked, igntion off (key out), trans in PARK, both rear wheels off the ground.

Pulling back on the bottom of either rear wheel (as if car was moving forward) cause the opposite rear wheel to move in the SAME direction and the drive shaft rotates counter-clockwise as viewed from the rear (looking forward under the rear of the car).

there is a number 2041 on the cast part of the rear diff. and a coupla arrow shapes cast in the metal that point to some bosses where a bolt goes in on the side. On the end cap/plate (where the fill and drain plugs are) there is the number 13 and a star. I couldn't see any other designations or important marks.

03 H6 Outback with cold weather options. (heated seats, mirror, wiper area)
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1 Lucky Texan

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