Tranny Swap Help

[91-SUB-Legacy]

My 91 legacy 4eat is failing slowly and i wanna do a 5mt swap but im not exactly sure what parts i will need and exactly what to do

 

Parts i know:

Tranny

Clutch

Flywheel

Pedal Assm.

Front Half of 5mt Driveline

Tranny Brace

 

Possible Parts:

TCU/Ecu

[lmdew]

Do a search for the swap. Legacy 77 has a great post with all the details.

 

A little wiring is involved but it's not bad.

 

I've done a couple.

 

You have the parts listed.

 

Larry

[idosubaru]

some year legacy's need the cruise control computer swapped as well if you have it and want to retain it. i've done later ones, not sure about 1st gen stuff. easiest way is to get an entire donor vehicle that's wrecked, blown motor, etc. i just picked up an 03 Legacy manual to be used for a trans swap for $500.

[wtdash]

Hi,

I just did this swap on my '90. I used JoshC/Legacy777's post HERE - This includes some other stuff he did but covers the transmission swap well. Read the Electrical/Wiring stuff especially so the car will start.

 

Besidese the USMB, http://bbs.legacycentral.org, NASIOC and RS25.com are all good resources for info and parts.

 

From your list:

 

Tranny - Your '91 is a 4.11 FD ratio, which should make it easier to find a donor. I used a '98 Forester. TRANS chart LINK. Any Legacy/Forester/Impreza should work up to 2000-ish that has the matching ratio. You can reuse your mechanical speedo cable -even on the newer ones. Just remove it, including the gear portion-not just the cable, from the AT and replace on the MT.

 

Clutch/Press. Plate/FW/TO and pilot bearing -confirm whether you're using a Push or Pull style. You'll need the bolts for the PP>>FW.

 

Flywheel - see above - You'll need the bolts to mount to the engine. The AT's flexplate bolts are too short. (Make sure you disconnect the TC before removing the trans.)

 

Pedal Assm. - using a Cable clutch pedal box is much easier. The good news is your '91 should be pre-drilled if you go w/a hydraulic (hydro) clutch (the Turbo model had them in '91.) I used a cable clutch w/my '98, which was originally a hydro.

 

Front Half of 5mt Driveline - Not sure about this. But a complete '95+ is too long. I ended up using the complete driveline from a '92, and changed the pinion flange on the '00 4.11 rear diff to match the older style. If you get a '95+ driveline the rear flange that mates to the rear diff won't fit your '91. Also, read this about the difference in drivelines between '90-91 and later models:

The difference in the driveline is that the 90-91 MY's had CV style joint in the center and the front & rear section are not able to be separated. The 92 and later drivelines are two piece and use a universal joint. I have run both, and ended up going to the universal joint setup because it gives more room for exhaust clearance. Here's some pictures of the different drivelines.

 

 

 

1990 - http://www.surrealmirage.com/subaru/images/swap/02/DCP_3058.JPG

 

1992 - http://www.main.experiencetherave.com/subaru/images/ej22t/35/DCP_6074.JPG

 

http://www.main.experiencetherave.com/subaru/images/ej22t/35/DCP_6075.JPG

 

Tranny Brace - I'd replace the bushings and get a new tranny mount. I used an Group N mount/Sti one and it's OK.

 

Here's a pic of some of what I bought. I got most of this from a 'pull-n-save' - the axles are for the rear diff which isn't pictured:

More parts:

Possible Parts:

TCU/Ecu - AT and MT ECUs are the same. You'll remove the TCU completely - 5speed doesn't have one.

 

Additional notes:

- All the holes are pre-drilled for the tranny mounts. Just remove the plastic/rubber covers.

Parts you'll need/suggested:

- shifter - recommend a WRX/Impreza RS

There are two parts I replaced w/new; The rear mount for the shifter - underneath the car; and the shifter joint.

 

-starter - MT not the same as AT. There is lot of interchange among years for starters.

 

-plastic surrounding the shifter/shift boot/shift knob

 

-clutch fork/release lever - must match clutch type - hydro or cable.

 

-Pitch mount

-clutch slave/master cyl. if going hydro.

-cable mounts if cable clutch and new cable for the clutch - You can move the pivot ball if needed on the trans housing - see THIS-.

 

-If you don't care about cruise or starter relay, you don't need the clutch pedal switches; brake switch should be the same as AT.

-Cruise control computers are different for the MT vs. AT. Also there were 2 relays attached to my '90's AT computer - a main and inhibitor. Only the Main relay can be reused. The MT uses a clutch relay in place of the AT's inhibitor relay. I initially pulled a '92 and it only had the Main relay. I went back and found a '90 w/both relays to get my cruise working again....get the plug, too - the AT's inhibitor plug won't work in the clutch relay.

 

GL ,

TD

Edited October 4, 2011 by wtdash

[91-SUB-Legacy]

Thank you all for the help i will be working on it as soon as i find all the parts its gonna have to be a weekend job between me and my brother because his apartment unit might get mad if he has a disabled vehicle there for longer than that

[987687]

AT and MT ECUs are the same

This is not entirely true. Sure, it'll work without swapping the ECU, and you can swap auto and manual ECUs all day long. But there are slight tuning differences between AT and MT computers.

A lot of it has to do with how it idles. I've had an auto computer in my manual car just to test it out, and it's wicked annoying in traffic. It doesn't idle down properly because it "thinks" it's an auto and if it just goes to idle like it should in a manual, the engine will stall. Also, at speed if you shift into neutral it will not idle below 1500 rpms or something.

 

So not a priority on the list of swap parts, but something that should be done eventually.