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Diff swappage


4x4_Welder
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Ok, I have an EA81 4speed that won't be needing it's ring and pinion, and an EJ 5speed that has 4.111 gears. Can i just crack the cases and swap the 3.90 set into the EJ trans, or is it more in depth than that? I see lots of people running the lower gears in the d/r 5speeds, but don't know about going the other way. I have a dial indicator and in/lb torque wrench for setting the gears up.

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pure speculation but there are ej trans with 3.9 in them and i doubt they changed anything so my guess is it's possible.

 

but why? do you want to put the ej trans into your ea81 or something? i think it would be easier to put in the matching 4.111 rear diff than to swap the gears in the trans.

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I am doing an EJ swap on an EA82 wagon along with an EJ speed. The car is for road use only, so I'd like a taller gear. I have a 3.90 rear diff I can throw in it, and an EA81 4speed that is going into a project vehicle that only requires the rear output, so I can raid the ring and pinion out of it. I'm not making the 8hour round trip to go grab the matching rear diff for this thing, and Legacys seem to be a bit rare around here so not much luck finding the right one in a junkyard.

 

Might be a moot point now, might have found transport to get the matching diff.

Edited by 4x4_Welder
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Diffs are the same......BUT

 

you must swap pinion gears as well as the rings. Pinion gears are integral to the lower shaft of the transmission. Lower shafts of the EA81 4spd, EA82 5spd, and the AWD EJ boxes are all completely different.

 

So no, you cannot simply swap ratios.

 

I did build a 4.11 ratio D/R AWD using EA82 D/R front case and upper shaft, and EJ lower shaft, shift forks, and rear case(AWD section).

 

But it blew out second gear pretty dramatically, there seems to be a difference int he cut of the teeth on EJ 1st and 2nd gears.

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Yeah, I finally got my brain to realize that Subarus are different. I got the 4.111 rear diff that goes with this five speed, and will be installing that. I'm going to be running 195/55R16 tires, so they'll help make up for going from a 3.70 gearset and 185/70r13s, but not by a whole lot. It'll still be spinning faster than I'd like, but it'll be quick for sure.

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Diffs are the same......BUT

 

you must swap pinion gears as well as the rings. Pinion gears are integral to the lower shaft of the transmission. Lower shafts of the EA81 4spd, EA82 5spd, and the AWD EJ boxes are all completely different.

 

So no, you cannot simply swap ratios.

 

So what you are saying is I can take the diff out of my 94 Imprezas 5 speed S\R trans(4.11), implant it into my E82 5spd D\R trans as long as i swap the pinon gears as well as the rings?

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The pinion gear shaft is also the countershaft in the transmission, it's a bizarre setup unlike most any other one. It's got other gears on it, and as has been mentioned there may be differences in that part. It's been done, it can be done, you just have to be careful.

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4sp's are very different to 5sp's.. so no interchangeability that I know of. EA82 5sp vs EJ 5sp is a different story. But no, ratios cant just be swapped between the two. I would of thought to 10+ times I've said this along with others saying would of been enough for people to be able to read and understand. oh well

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4sp's are very different to 5sp's.. so no interchangeability that I know of. EA82 5sp vs EJ 5sp is a different story. But no, ratios cant just be swapped between the two. I would of thought to 10+ times I've said this along with others saying would of been enough for people to be able to read and understand. oh well

 

I see so the P\T is a 4 speed and the FT is a 5, im new to these old subaru parts so excuse me for not knowing. My plans are to put the e82 trans in my 94 Imp L so here is another question for you if you dont mind. Which trans would you recommend for off road use the FT or the PT? Or are they both relativly the same?

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4sp's are very different to 5sp's.. so no interchangeability that I know of.

 

The actual *diff*, the carrier, and spider gears and such are the same. And rings can be interchanged between them.............

 

But in the end, since the pinions cannot be swapped, what would be the point of it.......by default you can't use the 4spd ring because you'd need the pinion as well.

 

 

 

But in theory, you could install an OBX or some other type of EJ limited slip front diff (using original ring gear) in you're 4spd D/R because the actual "diff" is the same unit. not sure why youd want to...but....in theory.

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