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1993 Legacy Automatic Trans Replacement

Posted: Tue Apr 29, 2003 5:21 pm
by frood
I've done a bunch of looking into things, and am fairly sure I know what's happening.

First, as far as I can tell, A 1993 Impreza's _transmission_ is a direct replacement for a 1993 Legacy, BUT the front differential is not. It looks like the 1993 Imprezas used a 4.11 but my 1993 Legacy uses a 3.9 . This leads me to my questions...

1) Is it possible, while swapping the 93 Impreza Trans to my 93 legacy, to just unbolt the front bellhousing/3.9 differential case from my transmission, pull it out, and put the whole bellhousing and diff/case on the donor transmission? What is involved? Just remove those 8-10 bolts and pull? It looks really easy, but looks can be deceiving.

1b) If I do this, won't I need to also swap the transmission gear from my 93 legacy to the 93 impreza donor trans?

2) Lets say it's too tough to swap the front diff case. If I get the 4.11 rear differential in addition to the 4.11 front diff and trans, will the 4.11 rear diff from the 93 impreza bolt right on to my 93 legacy?

2b) If I swap both front diff/transmission and rear diff, will my speedo be right? I would think so, as the transmission

3) How do I get to the torque-converter to flywheel bolts?

4) Are the 4 trans mounting bolts on the EJ18 and EJ22 engines the same? They look it, but I'm not sure.

I'll be honest, I wouldn't mind having a 4.11 on my car instead of a 3.9 though it looks like it'll add a bunch of work time and another $100. It only increases cruise RPM from 2800 to 2950 and it should give me some needed torque in 1 and 2.

And a confession, I am now considering doing the trans swap myself (-gasps-) . I'm AMAZED at how much room there is to work around the transmission on a Subaru. I had a 1987 Supra and I wouldn't have dreamt ever dropping a trans, because there's no bloody room (2" back of engine to firewall). But if I were so inclined, I could hug the transmission in the Legacy there's so much room.

Oh, and I want to thank everyone -tons- who has been assisting. Especially Cipher. I've learned a TON about this now, and am rapidly becoming 'proficient' in Subaru-ese. ;) And I love the overall simplicity and interchangability of their parts.

Posted: Tue Apr 29, 2003 7:17 pm
by vrg3
I'm not well versed in Subaru transmission work, but I don't think the front differential can be removed from the transmission. Your best bet, if you're using a 4.11 Impreza transmission, is probably to put in a 4.11 rear diff using the appropriate driveshaft (I don't know which one).

Your speedometer would be off, but that can be corrected, I think. I think the speedometer works by having a gear in the transmission spin a cable that goes to the instrument cluster. In the cluster itself is the mechanically driven gauge and the vehicle speed sensor that the ECU uses.

If you correct the speedometer, there is a risk that your ECU would get upset, since it is supposed to be able to interpolate what gear you're in. I don't know if that would really affect driveability much, but it could set off a CEL at the least. You might have to "un-correct" the signal as it goes to the ECU.

The EJ18 and EJ22 use the same 4 bolt pattern.

I've never done a tranny swap on a Legacy, but my brother and I did convert his '86 Supra from automatic to manual, and it actually wasn't that hard a job. If you think it looks easier on the Legacy than on the Supra, go for it yourself. :)

Posted: Tue Apr 29, 2003 9:39 pm
by ciper
Wait, we should research on NASIOC. Specifically I swear I read in the conversion forum that someone changed the ratio of the Front differential.

However I do know its possible to swap ring and pinion between diffs....

Posted: Wed Apr 30, 2003 2:01 am
by frood
Ack. So I crawled around under the 1993 Impreza. The only badging on the differential case was in raised lettering cast with the case itself that said "363" but that can't be a ratio. The lowest I was aware of was, like, 3.5 something on a SVX. Figures; my car has two badges that clearly state 3.90, but this one doesn't have any. :x

I DID do one smart thing; I got the VIN. =) So I hope to be able to call Subaru and ask them what ratio it is. Anyone know of a nice Subaru dealership that would do this for me?

(Oh, and am I to understand that I'm the ONLY cheeky monkey surrounded by a hoarde of JELLO addicts?!?!?! I think not...)