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3.90 or 4.11

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Up until recently I was under the assumption that all automatic 89-94 AWD legacies had 4.11 gears.I need to replace the rear diff on my offroader because I grenaded it.So I thought I would go up to pull and save and grab one off an automatic legacy because the yards are littered with automatic legacies.However it was a different story when I got there.Every single auto legacy barring two 250K+ cars had 3.90 rear gears.Before that I had only seen 4.11 on automatic 1st gen legacies.So can anyone tell me if there is any rhyme or reason to which cars had 4.11's  and which cars had 3.90's? Like I said up until recently  I thought auto/turbo EA cars were 3.7,All other 4x4 EA stuff was 3.90,manual legacies were 3.90 and auto legacies were 4.11.

 

Or did all of those auto have a 3.90 swapped in for some strange reason?

I know for gen2 outback autos got 4.44, legacy autos got 4.11. H6 outbacks got the 4.11.

 

Does cars101 have gearing info?

Cars101 doesn't have that info.

 

Like Dave says, a manual 96-99 outback will be 4.11, a manual 95-99 GT also has 4.11.

90-94 manual = 4.11

 

90-91 Auto = 4.11

 

92-94 auto = 3.9

Yep I have a Manuel first gen with 4.11 that's my 90

My mom has had two first gen autos one 90 4.11 one 91 4.11

Edited by mikaleda

About this:

 

...  I thought auto/turbo EA cars were 3.7,All other 4x4 EA stuff was 3.90 ...

 

I've seen Rear LSD Differentials on Gen II Leones (EA81's) with 3.889 ...

 

 

LeoneTurboCollage.jpg

 

... "Almost" 3.90, isn't it?

 

Kind Regards.

jeszek, if you want to talk about oddball stuff,  :) 

 

- you can pull the viscous unit from the manual trans and use higher-numbered gears in the rear (4.44 instead of 4.11 for example) to bias the torque to the rear

 

- there is a variety of subaru front diff with a non-viscous limited slip

 

and what i am hoping ends up being my oddball

 

- you can put the VDC center diff into a non-VDC 4EAT trans and get an all-the-time 45/55 torque split (no VDC, and maybe a manually lockable AWD clutch)

i'm pretty sure gloyale is right.

but to be sure, check legacy central.

 

http://bbs.legacycentral.org/viewtopic.php?t=32148

 

 

what ratio do you need???

95 - 99 will bolt right in and both 3.9 and 4.11 were used then too.

 

I think he needs from 90-94 so it has the male stubs.

 

95+ use the female type where the axle ends stick into the diff.

About this:

 

 

I've seen Rear LSD Differentials on Gen II Leones (EA81's) with 3.889 ...

 

Hmm......That sticker doesn't say 3.889.  Why does he think that's the ratio.

 

I'm pretty sure it's just regular ole 3.9

 

I can't even figure out what combo of # teeth R+P would make 3.889?

 

 

Ring gears range from 37 teeth to 42

pinions range from 9-11

 

No combination of these would yeild 3.889

 

A 17 tooth pinion with a 66 tooth ring would be almost 3.889....but not quite even..3.882...and there is no way you can fit a 17/66 tooth ring & pinion into a r160

 

Anybody got any documentaion or explanation?

Edited by Gloyale

3.889 would be so close anyway I think you could drive pavement all day every day and it would be no nevermind.

A 9/35 gives 3.888888888888, is that in the realm of possibility? That's get written 3.889.

 

Not a lot of pinion teeth though, but I do see planty of examples on the net (nissans, toyotas).

Hmm......That sticker doesn't say 3.889.  Why does he think that's the ratio.

 

I'm pretty sure it's just regular ole 3.9  ...

 

 

A 9/35 gives 3.888888888888, is that in the realm of possibility? That's get written 3.889.  ...

 

Sorry for Hijack the Thread.

 

See this post:

 

Caboobaroo, I make 3.90 LSD rear diffs all the time, I just replace the open diff in the 3.90 with a LSD diff from a 3.70. It bolt right up to the ring gear so it if a simple conversion. There is some grinding required to the housing though.

 

I really doubt if you or anyone else could tell the difference between a 3.889 and a 3.90. In fact I bet if you count the teeth on the Datsun/Nissan you find it has the same as the Subaru. Subaru just choose to round it up, and Datsun didn't.

 

Taken from this thread: http://www.ultimatesubaru.org/forum/topic/12263-lsd-on-gen-1-brat/?do=findComment&comment=104047

 

 

This is LeoneTurbo's Build Thread, with more Photos:

 

~►  http://www.ultimatesubaru.org/forum/topic/109465-84-4wd-wagon-new-daily-driver-with-future-ej-swap/

 

Kind Regards.

Edited by Loyale 2.7 Turbo

A 9/35 gives 3.888888888888, is that in the realm of possibility? That's get written 3.889.

 

Not a lot of pinion teeth though, but I do see planty of examples on the net (nissans, toyotas).

 

Seems like a very low # on the ring gear.  But I suppose  it could be. 

 

I have alot of old Fuji literautre and NEVER seen a listing of 3.889.  But I guess I can't say for sure it doesn't exist.

 

 

I really doubt if you or anyone else could tell the difference between a

3.889 and a 3.90. In fact I bet if you count the teeth on the

Datsun/Nissan you find it has the same as the Subaru. Subaru just choose

to round it up, and Datsun didn't.

 

Subaru didn't just round up.  All 3.9 ratio diffs I've taken apart, and all in the literature, are a 39/10 ring pinion count......exactly 3.9

Edited by Gloyale

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