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The Beast I Drive

RX Tranny Teardown (and rebuild?) WITH PICS

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Hey ya'll, well, Ive finally started my little project of trying to stuff 4.11 gears into an RX trans, along with the 1.59:1 low range gears from a 3.9 D/R tranny (vs. the 1.2:1 gears from the RX). The goal of this build it to get the lower, close-ratio gearset of the RX trans, plus the much lower final drive of the Legacy trans (4.11 vs. 3.70) and the lower low range, all to be able to turn my 31's better than with the standard 3.9 d/r I have now. Hopefully it will get me back close to stock gearing and an acceptable gearing for off-roading with the big tires.

 

From what I have read here, the Legacy 5 speeds use a similar setup to the RX, which is a pinion shaft inside a tube which has half the gearset on it, so theoretically the pinion and ring gear should swap (actually the entire front diff for that matter). The trick is to get the locking RX center diff to work with the Legacy pinion shaft, as Ive heard the legacy shaft is a good bit longer than the RX shaft. Ive begun taking apart one of my RX trannies tonight, and although I was quite dissapointed when I poured rust colored water out of it :-\ the bearings all look to be ok. There is a lot of rust on other parts though, but if I cant salvage this tranny I have the one from my old RX that I know is a good trans.

 

Ill be going back out to drain the fluid out of the Legacy trans after I post this, but now, for your viewing pleasure, pics of the insides of an RX trans!

 

The tailhousing off

IMG_0106.jpg

Inside the tailhousing

IMG_0110.jpg

The locking center diff mechanism

IMG_0112.jpg

The inside of the main trans body

IMG_0108.jpg

The other half of the case

IMG_0109.jpg

pulled the gears out

IMG_0116.jpg

the pinion gearset

IMG_0113.jpg

the pinion shaft/gear

IMG_0114.jpg

the input shaft/gears

IMG_0115.jpg

 

I also dicovered the speedometer gear is siezed. Unfortunately, I rotated the tranny input not knowing this, and it stripped it (being plastic and all, it didnt take much) so if anyone has an extra layin around, I could sure use it, although I dont need it as the speedo will likely be so far off with my 31" tires that I'd be better off judging speed by RPM's anyway.

 

-Bill

Edited by The Beast I Drive

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If I remember correctly those plastic speedo gears aren't too expensive from Subaru? might be worth having a new part than old plastic.

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also. other way around. RX pinion gear is shorter than the legacy one.

 

 

legacy output shaft and pinion gear:

DSCF0459Medium.jpg

 

and assembled:

DSCF0462Medium.jpg

 

extending the pinion to reach the locker is not going to be easy.

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also. other way around. RX pinion gear is shorter than the legacy one.

 

 

legacy output shaft and pinion gear:

DSCF0459Medium.jpg

 

and assembled:

DSCF0462Medium.jpg

 

extending the pinion to reach the locker is not going to be easy.

 

Aha, so the RX has the longer pinion shaft... Hmmm. Guess I just have to hope the Legacy trans I have has a Viscous center diff (which I doubt), or else I'll be having a machine shop mod mix and match pieces of the 2 pinion shafts.

 

-Bill

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All the Legacy 5 speed's I've torn down have the VC equipped center diff section. Including the '90 I dissasembled. Haven't had the good fortune to reassemble one yet - they have all been full of metal and failed bearings, etc.

 

GD

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Well the Legacy tranny I have does indeed have a Viscous center diff, and it seems to be working :banana: But I really want to use the RX locking center diff... Mainly because I want the true, locked 4wd ability.

 

Monday Im gonna start looking for a machine shop in my area that can cut/splice the rear section of the pinion shaft from my RX onto the Legacy pinion shaft, and re-temper the shaft. That way I'll be able to have what I want. Although, now that Im resorting to that, I might just have them cut/splice the 4.444 pinion gear that I pulled from the OB trans onto the RX pinion shaft..... Then I would have the ultimate low gears :banana:

 

But I think Ill just have them do the legacy shaft cut/splice for now, if I like it, I might try the 4.444's on my next tranny :brow:

 

Pics of the Legacy trans

100_0089.jpg

IMG_0117.jpg

The Viscous center diff

IMG_0123.jpg

 

Tailsection off

IMG_0124.jpg

IMG_0125.jpg

The coupler for the Viscous unit

IMG_0126.jpg

The case split

IMG_0129.jpg

IMG_0128.jpg

Gears removed

IMG_0134.jpg

The input shaft/gears

IMG_0132.jpg

The pinion gearset

IMG_0131.jpg

The pinion gear/shaft

IMG_0130.jpg

The front diff

IMG_0133.jpg

Here is a side-by-side shot of the RX pinion (top) and the Legacy pinion

IMG_0135.jpg

 

-Bill

Edited by The Beast I Drive
more pics

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"now that Im resorting to that, I might just have them cut/splice the 4.444 pinion gear that I pulled from the OB trans onto the RX pinion shaft..... Then I would have the ultimate low gears :banana:"

 

Come on, why not? If you're doing this work anyway...more bang for the buck. :burnout:

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Did a little calculating and diggin around, and it looks like the standard N/A 3.9 D/R 5-speed has a final crawl ratio of 22:1, not accounting for the tires.

 

The stock RX trans has a crawl ratio of about 16:1

 

The RX trans with the 1.59 low gears from a NA D/R and 4.11 final drive has a crawl ratio of about 23.5:1

 

The RX trans with 1.59 low gears and 4.444 final drive has a crawl ratio of almost 25.5:1

 

Obviously nothing close to a Toyota or other T-case rig, but I think I'll be having the 4.444 gears welded on now, to get the best ratio I can to offset my big tires. After crunching the numbers, it doesnt look like 4.11 will get me the gains I want, but for anyone running smaller tires, like 27's or 28's, it would probably be enough.

 

From what I have seen taking these trannies apart, you can build a 4.111 D/R AWD with the Legacy front diff, pinion shaft, and center diff, the RX case and gearset, and the N/A D/R low gears (1.59:1). This would be a bolt-together swap, the only mods required would be to clearance the ring gear to clear the low gears. As long as you have a good working Viscous center diff, it would be a very potent combo for offroading on 27's or 28's or even 31's with an EJ.

 

-Bill

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From what I have seen taking these trannies apart, you can build a 4.111 D/R AWD with the Legacy front diff, pinion shaft, and center diff, the RX case and gearset, and the N/A D/R low gears (1.59:1).

 

not really news ;)

 

the only thing I don't think has been confirmed/denied, is if an EJ pinion shaft will work with an EA output shaft (hollow one).

 

 

what year outback trans do you have? in all the decent gearing charts I could find, the only US cars to get 4.444s are the larger tire turbo cars (FXT, OBXT, Baja turbo).

 

 

also, all EJ 5MTs have a viscous center. actually, all subaru center diffs have some sort of traction device, be it a locker or viscous LSD.

 

 

anyway, a 1.6 with 4.444 would be pretty sweet. my toyota only has a 30.5:1 crawl ratio (auto), so you're getting close.

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Its not ground breaking research, I know, but I confirmed the Legacy pinion is an exact fit in the RX pinion gear tube.

 

As for the 4.444's I have, I pulled them from a 96 Auto trans. The Auto pinion shaft is 100% different from the manual pinion shafts, but since Im going to have the pinion gear cut off and welded to the RX pinion shaft it doesnt matter anyway. I saw in a chart somewhere that the Only Subarus in the US that came with 4.444 5-speed trannies were Turbo foresters, and it was only for like 2 years or something like that, like a '00 or '01 or something, I cant remember.

 

These are the ring and pinion from the OB that I pulled last year

IMG_0137.jpg

 

Here is a shot showing the differences between all 3 pinions, from top to bottom: RX 5 speed, Legacy 5 speed, Outback 4EAT

IMG_0136.jpg

 

-Bill

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Its not ground breaking research, I know, but I confirmed the Legacy pinion is an exact fit in the RX pinion gear tube.

 

that is news. SWEET! that will simplify my project this week :)

 

yea, looks like only 04-05. but my chart only goes to 05....

 

 

as long as the cut on the auto pinion gear is at the same angle....it should work. actually, that pinion shaft looks a lot closer to the MT version than I thought it did!

 

 

cool! I'll be watching this closely.

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Since Im ending up using the OB stuff for this trans, I figure I might just go ahead and build the 4.111 AWD D/R trans using the Legacy parts and my other RX trans :banana: just to do it, I dont really have anything to put it in ATM :lol:

 

Im using the Outback ring gear as well as the pinion gear, because the gear cut is slightly different from the Legacy ring gear, and I learned from Gloyale's D/R 4.111 thread that just cuz the gears *look* like they will work, doesnt mean they will, so I will just use the gears that are meant to go together.

 

The RX trans I split needs new seals and a lot of good cleaning from sitting outside, with no gear oil, and a lot of water in it. I was kinda hoping to have it built before the Hatch Patrol run, but I doubt that will happen, I will source out a shop to do the welding on the 4.444 pinion on Monday, and talk to my tranny shop about setting up the backlash.

 

I still have to go pull the NA D/R from one of my rigs to source the 1.59 low gears from, I have one that made horrendous noise driving on the road, but the low gears should be fine ;)

 

I have one more thing to consider while its apart though, should I change the stubs to 23 spline or just leave them 25 spline? I plan on putting it in the Beast, so I can always just go buy Turbo axles, but since its apart now, I have the choice.....

 

Also, if you have the cash, having the case split presents the perfect opportunity to swap in a front LSD :slobber: and I would put one in, but I dont have the cash to drop on one of those.

 

-Bill

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Having that gear put on the RX shaft might not be real cheap. I would imagine that they will have to bore the shaft *out* of the 4.444 gear and then cut down the gear on the RX shaft till the 4.444 gear can be slid over the remaining stub. I'm not sure how to lock it to the shaft but welding would only be part of it. I would likely shrink it to the shaft using an interference fit and then plug weld the end having left the shaft 1/2" shorter than would fully extend through the gear. I'm not even sure that would be strong enough. Probably would have to bevel the bottom of the gear and cut a groove in the shaft in order to get enough weld penetration on the gear.

 

I would charge a ton of money to do something like that - if I had the tools :rolleyes:. Someday when I get a lathe and mill.....

 

GD

Edited by GeneralDisorder

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Having that gear put on the RX shaft might not be real cheap. I would imagine that they will have to bore the shaft *out* of the 4.444 gear and then cut down the gear on the RX shaft till the 4.444 gear can be slid over the remaining stub. I'm not sure how to lock it to the shaft but welding would only be part of it. I would likely shrink it to the shaft using an interference fit and then plug weld the end having left the shaft 1/2" shorter than would fully extend through the gear. I'm not even sure that would be strong enough. Probably would have to bevel the bottom of the gear and cut a groove in the shaft in order to get enough weld penetration on the gear.

 

I would charge a ton of money to do something like that - if I had the tools :rolleyes:. Someday when I get a lathe and mill.....

 

GD

 

It probably wont be very cheap, but it has been done before. There was a link here somewhere to a thread on one of the new-gen boards where a guy had a 4.444 pinion gear welded to the pinion shaft of his Legacy tranny for Rallycross... Really its all just a matter of cutting in the right place, getting full penetration, properly anealing it, then properly re-tempering the shaft. I might look into having it cryo treated as well, but that probably isnt necessary, and I have no real idea what the gains from that would be, probably not worth the cost considering there will never be more than 160HP going into this trans anyway, if that much even. I have access to a lathe, and a mill, and I can do the actual machining myself, BUT I dont know how to properly do the anealing and re-tempering, and I'd rather one machinist do it all so there is no confusion and less chance for mistakes. :banana:

 

-Bill

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Hey,

 

On Axle splines, more are better. If you pull this off, you will have the most desirable DR 5 speed in the Subaru world, in the U.S.

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Hey,

 

On Axle splines, more are better. If you pull this off, you will have the most desirable DR 5 speed in the Subaru world, in the U.S.

 

well....he should drop it all in an EJ D/R case for that.

 

 

but yea.....pretty sweet.

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well....he should drop it all in an EJ D/R case for that.

 

 

but yea.....pretty sweet.

 

 

Funny you should mention that.... :grin:

If I were building my rig with an EJ motor, I would do the necessary machine work to fit the D/R equipment into the EJ case. The Early Legacy 5 speed case and the RX D/R case are so similar its not even funny, the only machining that has to be done is bore out the boss on the side of the case for the D/R lever, and machine the input snout down to flat, and drill the 3 holes to bolt-on the RX input snout. Boom, EJ D/R, with Diff-lock, for less than 1200 ;)

 

-Bill

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It wouldn't be *quite* that easy. The first input shaft bearing doesn't exist on the EJ 5 speeds due to them not having any load on that portion of the shaft (no low range gearset). It's further complicated by the casting of the EJ case not haveing as much material in that location to support the bearing with. It would likely have to have the "snout mount" section of the EA case plas'd out and welded into the EJ case. Either that or just plas off the whole EJ bell-housing and weld it to the EA case.

 

GD

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It wouldn't be *quite* that easy. The first input shaft bearing doesn't exist on the EJ 5 speeds due to them not having any load on that portion of the shaft (no low range gearset). It's further complicated by the casting of the EJ case not haveing as much material in that location to support the bearing with. It would likely have to have the "snout mount" section of the EA case plas'd out and welded into the EJ case. Either that or just plas off the whole EJ bell-housing and weld it to the EA case.

 

GD

 

Yes, I am aware that the input shaft bearing is not there on the Ej's. Hmm, I'll have to take some measurements, looking at the pics its hard to tell. Or, a custom unit could always be machined out of some billet to fit tne needs :banana:

 

-Bill

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Hey Bill,

 

Think about this. The person doing the pinion may offer a lower price if they're doing two of them at the same time. You up for something like that?

 

4.44. Hummmmmmm

 

P.S. @ 8000 rpm

 

Sincerely,

 

Doug

 

The pioneers, they're the ones with the arrows in their backs.

Edited by Quidam
Add text.

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Ok, so I've been lazy and haven't looked up a shop to do the custom cut/weld/machine work on my pinion shafts just yet. HOWEVER, Im also looking into another option.

 

In the USA there was 1 model of Subaru that came with 4.444 gears in a 5 speed manual, and it was available for 2 years. That would be the 04-05 Forester Turbo. The Ring and pinion set is available from the dealership, at a mere $317 plus tax :eek:. Not cheap, but its brand new, OEM.

 

SO, my question, is the pinion shaft in the Turbo Forester 5 speed transmission the same length, shape, and dimensions as the Early Legacy (90-94) 5 speed pinion shafts? Because if it is, then I will save up and pay up for the new pinion and ring gear from Subaru. If not, its back to the original plan.

 

-Bill

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Wow somehow I thought any kind of gear would be more money then $317. Not sure how much work you were going to have the shop do, but watch their shop rate 'cause you can end up at $317 pretty quick!

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Wow somehow I thought any kind of gear would be more money then $317. Not sure how much work you were going to have the shop do, but watch their shop rate 'cause you can end up at $317 pretty quick!

 

Thats about what they are. Maybe a *tad* more than others, but after looking for gears for the scout (~250$) its reasonable. Good luck on the swap, I am also watching this thread closely.

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