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gearing to 4.11 questions


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25 replies to this topic

#1 greggbrat

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Posted 05 March 2004 - 10:54 PM

I am now the proud owner of a 1982 Brat/EA81 carb motor/4 speed maual D/R tranny......lots of rust and lots of work to get it road/off-road ready. I have a few questions about gearing it to 4.11 differentials.

I read through the message boards about various options but it didnt really answer all my questions. Basically I want to convert my 82 brat to 4.11 gears on both front and rear. I know the 4.11 gears are available from a select few subarus. (exactly which models I am not certain but I gather the RX/RS models had them)

1. Can I put the 4.11 gears from an RX/RS model directly into the rear differential of my 82 Brat?

2. Is it possible to remove the 4.11 differential gears from an RX/RS model single speed transfer case/tranny and install them into my D/R tranny front differential on my 82 Brat?

3. Are there any newer D/R trannys (ie. outback, forester, baja, etc) that have 4.11 front differential gears......and could this tranny be mated to my EA81 motor?

I appreciate any and all help with these questions.

Thanks,
Gregg

#2 Qman

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Posted 05 March 2004 - 11:15 PM

You can use a 4.11 differential. The trans is another story. You can use a 4 sp single range trans from a Gen1 Brat. They were 4.11 however, they are not D/R.

#3 baccaruda

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Posted 06 March 2004 - 12:00 AM

maybe he could yank the gears from one of those at least?

#4 oddcomp

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Posted 06 March 2004 - 12:30 AM

i may be wrong but i would think if all he is changing is the differential gearset and got the shims corect that it "should" work

#5 Mike W

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Posted 06 March 2004 - 12:41 AM

Boy that'd be funny if the swap worked. Can't believe no one has tried it yet and that makes me skeptical. Can't wait to hear the results.

#6 greggbrat

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Posted 06 March 2004 - 12:48 AM

It would be great if the front diff gear swap worked........but I dont have the parts to find out for sure. Does anyone have the detailed specifications on the 4 speed D/R tranny? And the detailed specifications on an RS/RX (or any other tranny) tranny that has 4.11 gears......if I had the gears sitting side by side the answer to this question would probably be obvious.

#7 calebz

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Posted 06 March 2004 - 12:54 AM

Originally posted by greggbrat
It would be great if the front diff gear swap worked........but I dont have the parts to find out for sure. Does anyone have the detailed specifications on the 4 speed D/R tranny? And the detailed specifications on an RS/RX (or any other tranny) tranny that has 4.11 gears......if I had the gears sitting side by side the answer to this question would probably be obvious.



The 4 spd D/R has a 3.90 front/rear diff.. There are a couple of different 1st and 2nd gear sets.. specs are listed in a few posts around here somewhere.

The RX tranny is 3.70

Don't know what the RS.. I am assuming you are referring to the Impreza RS.. or maybe the Loyale RS?.. if its the loyale, its 3.70 for the 90 turbo model.. 3.70 for the NA auto models and 3.90 for the NA manual

#8 the sucker king

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Posted 06 March 2004 - 01:51 AM

Originally posted by Qman
You can use a 4 sp single range trans from a Gen1 Brat. They were 4.11 however, they are not D/R.



were the gen1 wagons 3.9?

#9 carfreak85

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Posted 06 March 2004 - 03:35 AM

Like stated above, the RX/RS had 3.7 gears. All autos had 3.7 gears. N/A cars had 3.9 gears. Only the newer N/A cars have 4.11 gears.

#10 GLCraig

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Posted 06 March 2004 - 03:43 AM

I either heard or read somewhere that some australian ea81s got a d/r 4speed with 4.11 gears. But trying to get one of those gear sets would probably cost more then you paid for your brat. If you have all kinds of money to burn you could probably have a 4.11 or even a 4.44 ring and pinion machined for you.

#11 Dr. RX

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Posted 06 March 2004 - 12:27 PM

There is a ring and pinion shop up across from Paine Field in Everett, WA., I'm sure that they could cut a ring gear that would match the pinion gear to get a 4.11 ratio, but I wouldn't want to pay the bill.

#12 Rooinater

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Posted 09 March 2004 - 07:00 PM

well ken is right. that's mainly what you can do to get the 4.11. but you have no dual range. the only reason i have the dual range and still have 4.11 gears... is i had the whole drivetrain redone. it has 2 t-cases and a bunch of other stuff. which without lifting your car won't really work and the way i have it is probably over kill for you.

#13 subie94

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Posted 19 February 2005 - 05:48 PM

i guess this could be a silly question but is having 4.11:1 gears good?

#14 Jibs

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Posted 19 February 2005 - 06:28 PM

Thats funny, I had asked mudrat this the other day as well. Getting 4.11 gears into the rear diff isn't hard, but the tranny is a different thing all together. You could use an All wheel drive tranny, but you wouldn't get the D/R properties. As said above, you could have someone machine shop them, but the bill would be outrageous.

#15 TROGDOR!

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Posted 19 February 2005 - 08:30 PM

Nobody mentioned exactly where to find 4.11 gears.

First of all, all autos were NOT 3.7!!! At least for the EA82-type cars, all nonturbos were 3.9 and all turbos were 3.7- this includes manual AND automatic. Except for the XT's- all 4cyl XT's are 3.7. I've owned a couple autos that were 3.9 and have seen dozens in the junkyard that are 3.9 as well- I even went from 3 speed AT to 5 speed Dual Range and the gear ratios from the factory rear diff matched up perfectly.

As for the 4.11 gears (besides the gen1 Brat single range)- all 1990-91 nonturbo Legacys came with 4.11 gears, and all 1992-94 nonturbo manual trans Legacys also had the 4.11's. Newer gen Legacys may use them as well. The rear diff from an early gen Legacy is a direct bolt-in to an older gen Subaru.

If you had a junk 4.11 Legacy trans to tear apart, the gears would be worth looking at to see if they'll fit the EA8x front differential. Most likely they won't but if you had the parts laying around, it's worth a look.

#16 JWX

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Posted 20 February 2005 - 02:06 AM

First of all, all autos were NOT 3.7!!! At least for the EA82-type cars, all nonturbos were 3.9 and all turbos were 3.7- this includes manual AND automatic. Except for the XT's- all 4cyl XT's are 3.7. I've owned a couple autos that were 3.9 and have seen dozens in the junkyard that are 3.9 as well- I even went from 3 speed AT to 5 speed Dual Range and the gear ratios from the factory rear diff matched up perfectly.


where'd you find this out at? all of my FSMs say 3.7 for autos

#17 Qman

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Posted 20 February 2005 - 02:14 AM

Nobody mentioned exactly where to find 4.11 gears.

First of all, all autos were NOT 3.7!!! At least for the EA82-type cars, all nonturbos were 3.9 and all turbos were 3.7- this includes manual AND automatic. Except for the XT's- all 4cyl XT's are 3.7. I've owned a couple autos that were 3.9 and have seen dozens in the junkyard that are 3.9 as well- I even went from 3 speed AT to 5 speed Dual Range and the gear ratios from the factory rear diff matched up perfectly.

As for the 4.11 gears (besides the gen1 Brat single range)- all 1990-91 nonturbo Legacys came with 4.11 gears, and all 1992-94 nonturbo manual trans Legacys also had the 4.11's. Newer gen Legacys may use them as well. The rear diff from an early gen Legacy is a direct bolt-in to an older gen Subaru.

If you had a junk 4.11 Legacy trans to tear apart, the gears would be worth looking at to see if they'll fit the EA8x front differential. Most likely they won't but if you had the parts laying around, it's worth a look.


To clarify, the 90-94 auto non turbo Loyales were 3.90. Not all EA82's as stated above.

#18 TROGDOR!

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Posted 20 February 2005 - 10:37 AM

Has anyone ever owned a nonturbo auto with a 3.7 final drive? I've owned two that had a 3.9 ratio (one was an 88 GL, the other a 92 Loyale), and have seen probably 50 more in junkyards. When I first got the Loyale I put an auto trans from an 86 GL wagon in it, and surprise, it also had a 3.9 final drive. I pulled another one for a friend out of an 87 GL wagon- it was also 3.9. I've never seen nor heard of a nonturbo 3.7, except in an XT.

Maybe we need to have the 4WD auto owners on the board look at their rear diffs so we can figure out which ratio they really are.

#19 Caboobaroo

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Posted 20 February 2005 - 11:12 AM

My RX had a 4EAT and it was a 3.70 gearing....

So what is this about gen 1 Brats with s/r 4-speeds having 4.11 gearing? Very interested, me didn't know this, even though I own a updated gen 1 FSM... Then what about my '79 4wd wagon? Is it 4.11 as well? I looked at it awhile ago and I remember it having a 3.90 tag on the rearend.

#20 ballitch

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Posted 20 February 2005 - 01:44 PM

my 86 gl has 3.90 gears.

#21 MorganM

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Posted 22 February 2005 - 11:49 AM

where'd you find this out at? all of my FSMs say 3.7 for autos

1988 Subaru owners manual has a pretty good chart.

#22 JWX

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Posted 22 February 2005 - 12:26 PM

my FSM is an 88, but the only owners manual I have is 87. and the FSM says 3.7 for autos

#23 bushbasher

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Posted 22 February 2005 - 11:36 PM

theres a guy who rallies an rx in australia who swapped the guts from a wrx tranny into his ea82 5spd ft4wd box including the 4.11 diff. I remember him saying its a bolt-in affair between ej and ea internals, and that if you swap everything at once you can make it work. I dont know if you can mix and match and keep your current Dual range though.

#24 kingbobdole

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Posted 23 February 2005 - 12:51 AM

Ok,
I'm so lost. Anyone know what a 2wd xt turbo 5 speed would have? Is there a difference between 2wd cars and 4wd cars?

#25 MorganM

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Posted 23 February 2005 - 11:17 AM

theres a guy who rallies an rx in australia who swapped the guts from a wrx tranny into his ea82 5spd ft4wd box including the 4.11 diff. I remember him saying its a bolt-in affair between ej and ea internals, and that if you swap everything at once you can make it work. I dont know if you can mix and match and keep your current Dual range though.


I was talking on the phone with mudrat79 about similarities between EJ and EA tranny internal parts and assemblies. He too thought most (if not all) of it would swap.

Now I dont know if this would necisarily be an upgrade for seriouse offroading unless you retain the 5MT Dual Range's low range reduction gear in addition to the WRX 4.11 drive gear ratio. Would seem to be a superior upgrade for rally/auto-x however in any case.

Good stuff !_!




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