4EAT Q's

MPtyza · Post by **MPtyza** » Wed Nov 30, 2005 3:18 pm

Well, I believe I need a transmission soon. My second gear only works when it wants to, which for now is about 85% of the time.

I did a lot of research on Suby auto transmissions about 2 years ago when my friend needed one for her SVX, but since then I've forgotten a lot of it. From what I remember, most of the 4EAT's are basically the same except for the final drive ratio. What I'm unsure about is whether or not the actual transmission itself is exactly the same. Like is an auto from an AWD Impreza exactly the same as the Legacy unit? Would I have to use a 90-94 Legacy trans, or could I use one from a newer one? I know to look out for the diff ratio, but my stock ratio is 3.900, right? My rear diff no longer has the sticker that says it, so I figure that I might as well make sure. I know to swap the rear diff as well if going to 4.111 or 4.444's. Is there anything to look out for when selecting a donor from the U-Pull it?

Also, somewhat related, is a clunking coming from the rear when moving slow (about 5mph) rear diff related at all?

Sorry for all the questions, I just want to make sure before I go up to the U-Pull it and yank one.

MPtyza · Post by **MPtyza** » Thu Dec 01, 2005 12:56 am

Well, 3rd and 4th are gone now, and 2nd works most of the time, so I guess I'm gonna have to replace it sooner than I thought

Manarius · Post by **Manarius** » Thu Dec 01, 2005 2:58 am

Clunking from rear may be rear half shafts...check your boots. And yes, you can use new ones..but you need a rear dif to match. You'll also need to make sure that it has a power mode...because your ECU is going to be looking for that with the swap.

As I recall, 91 SS's were 3.900.

206er · Post by **206er** » Thu Dec 01, 2005 3:09 am

5mt swap. [/Thread]

Manarius · Post by **Manarius** » Thu Dec 01, 2005 3:29 am

206er wrote:5mt swap. [/Thread]

That's a little harder than just putting in a new 4EAT and dif...

MPtyza · Post by **MPtyza** » Thu Dec 01, 2005 8:21 pm

206er wrote:5mt swap. [/Thread]

yeah, I'd love to, but I really can't afford it right now, and don't know how to drive stick yet

206er · Post by **206er** » Thu Dec 01, 2005 11:10 pm

Manarius wrote:
206er wrote:5mt swap. [/Thread]
That's a little harder than just putting in a new 4EAT and dif...

what would you know. If all the parts were there I'd rather swap a 5sp than try to put a 4eat back in. plenty of junk on the 4eat to deal with also. torque converters, bleck! plus the 5mt is way easier to deal with.
not to mention that you then have a 5sp! well worth it especially on a SS.
you could end up bucks ahead over a 4eat, plus a cable 4.11 5mt is way more common to find than a 3.9 4eat. FWIW I payed $350 for my complete swap from 4eat.(I didnt have to change the diff) exedy stage 1 clutch off ebay for $160.
hit up frank(blackbart), he might still have some 5mt swaps left. hes in PA also, dont know how close to you.
this would seem to be a good opportunity to learn stick.
just my 2 c.

Manarius · Post by **Manarius** » Fri Dec 02, 2005 12:22 am

206er, I'm not denying that a 5MT swap would be better..but it would be more work. You'd have to redo the pedals, get clutch parts, get a MT ECU, etc. It'd be a lot easier to just get a 4EAT and bolt it up and plug it in.

555BCTurbo · Post by **555BCTurbo** » Fri Dec 02, 2005 2:04 am

Manarius wrote:get a MT ECU, etc.

Actually, the ECU is the same for both Auto and Manuals because the Automatics have a separate transmission computer, or TCU, which is located next to the ECU.

MPtyza · Post by **MPtyza** » Sat Dec 03, 2005 9:00 am

Yeah, it'd be a great opportunity to learn, but now just isn't a good time for me. I'd just rather drop in another auto and be done with it for a while. Maybe when I'm no longer in debt and all that I'll swap to a 5MT. I have thought of it.

MPtyza · Post by **MPtyza** » Tue Dec 06, 2005 7:48 pm

OK, I checked my local U Pull-It, and there is only one AWD 4EAT legacy, but it has 253,000 miles on it. There are however, several 93-95 AWD 4EAT Impreza's with significantly lower mileage in there. So that brings up the question again, is the Impreza 4EAT a drop-in option? Would everything work correctly straight from the drop-in?

Also, my available gears seems to be changing every several days. At first I had no 2nd, but still had 1st, 3rd, and 4th. Then I only had 1st and 2nd. Now since I've lost reverse, I only have 2nd, 3rd and 4th?

My dad suggested changing the tranny fluid, but would that fix my problem? I've been meaning to do it anyway, just gotta find a place to do it.

93Leg-c · Post by **93Leg-c** » Sat Dec 10, 2005 7:33 am

On my previous bc, a '93 NA AT, besides changing the tranny fluid, my mechanic cleaned out this metal box-like thing inside the tranny pan (sorry, but I don't recall what it's called right now). It was full of gunk from normal (possibly abnormal) wear and tear of the syncros and stuff. He said that it had to be clear for the tranny fluid to get through otherwise the tranny will start malfunctioning.

It did help the tranny work better but because the passage way was almost completely blocked, the damage couldn't be "fixed" just by a fluid change. The car went thousands of miles more till it got into the accident.

So, for a short term fix, it may help (no guarantee). But your tranny is acting up more than mine was so I'd probably say, do it, but also start looking for another tranny.

legacymax · Post by **legacymax** » Tue Dec 13, 2005 4:55 am

OK, the turbo legacy 4EAT is the same transmission that is in the SVX. The Turbo and SVX 4EATs have one extra clutch in the main body and in the trail housing. So, it is not the same as the impreza/legacy nonturbo 4EAT. And, the transmission computer is different too.
You can get a push button shifter kit for it. Transgo also makes a shift kit for it which makes it shift very fast for the 1-2 and the 2-3 shift. I have an external trany filter and cooler which helped will keeping the shift points the same even during the hardest driving.
-max

MPtyza · Post by **MPtyza** » Tue Dec 13, 2005 7:41 pm

Yeah, I knew it was different from the NA Legacy and Impreza transmission, but I was asking if the Impreza AWD transmission would drop right in and work normally. Is the TCU really different? I've got an NA Legacy TCU in at the moment. Why exactly would the TCU be different for the Turbo? Is it because of the extra clutch packs?

Post by **Legacy777** » Tue Dec 13, 2005 7:56 pm

The TCU differences are probably just in the shift logic. You could probably run the turbo trans on a standard TCU, and vice versa.

legacymax · Post by **legacymax** » Wed Dec 14, 2005 3:07 am

Well, the tranny computer is very specific to the transmission and also the sensors that effect the transmission and they varied from year to year.
-max

MPtyza · Post by **MPtyza** » Thu Dec 15, 2005 3:12 pm

Alright, since I'm doing my engine/transmission swap, or at least getting the two this Saturday, I need to know by Friday night, if the Impreza auto transmission will be a drop in and run thing, or if I'll run into some problems with it. Sorry I keep asking this, but I need to know for sure by then. Thanks

Post by **Legacy777** » Thu Dec 15, 2005 6:46 pm

I don't know if you're going to find someone who is going to give you a definitive answer.

All you can do is look at the two TCU diagrams, see if the pin outs are the same, if they are, things should work fine. If you're hesitant or cautious....grab the TCU from the impreza.

MPtyza · Post by **MPtyza** » Thu Dec 15, 2005 9:58 pm

Heh, yeah, I was poking around some AWD auto Imprezas last time I was at the yard, and I couldn't find the damn TCU at all. I looked all around up in where it is for the Legacy, but no luck. I'm currently looking for pinout diagrams to cross reference though. Good idea there, thanks.

MPtyza · Post by **MPtyza** » Fri Dec 16, 2005 6:43 pm

Hmm, I was just comparing the pinouts for the Legacy and Impreza TCU's, and the TCU for the Impreza only has two connectors where as the Legacy has three. I suppose that there is an indication that I can't use the Impreza transmisson. damn

Post by **Legacy777** » Fri Dec 16, 2005 8:36 pm

Not necessarily.

What you need to identify is the pinouts. The TCU connector and what shape it is, doesn't mean shit.

As long as the two transmissions have the same inputs/outputs and they are at the same locations on the B15 & B16 transmission connectors, you're fine.

You need to keep digging.

MPtyza · Post by **MPtyza** » Sat Dec 17, 2005 1:12 pm

ohh, shit, I've been looking at the TCU pinouts, not the connectors on the transmission.

Post by **Legacy777** » Sun Dec 18, 2005 5:20 am

It will be easier to check the type of pinouts at the TCU, since it will be in an I/O type page. But you need to check the connector at the transmission for physical fitment issues.

MPtyza · Post by **MPtyza** » Tue Dec 20, 2005 6:06 pm

OK, I've got a tranny from a '93 AWD Impreza, but being a dumbass, I never thought about the diff ratios. I have no idea what it is for the '93 AWD auto. I've searched around NASIOC and I believe it to be a 4.11, but I can't find a definate answer, so does anyone here know for sure if it is a 4.11?

MPtyza · Post by **MPtyza** » Sat Jan 14, 2006 10:57 am

Ever since the swap with the Impreza tranny, I've only had 1st, 2nd, and 3rd gears, along with reverse. It always shifts into 2nd at 3000, and into 3rd at 3500 RPM, unless I mess around with manual mode. It also doesn't downshift on its own until I slow to near a complete stop. The power light never comes on when I floor the gas pedal. I've been thinking that the Impreza tranny doesn't want to play nice with the Legacy TCU, but I wasn't quite sure if that's the problem or not. Anyone got any ideas about this? I was going to get the TCU from the donor Impreza from the junkyard, but they finally rotated their inventory, and there is only one Impreza, and it's burnt out. (Has nice '94 Legacy Turbo wheels with brand new tires

)

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4EAT Q's

4EAT Q's