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Old 01-29-2013, 09:33 PM   #1
Scooby Newbie
Member#: 194453
Join Date: Nov 2008
Location: central NH
2001 Legacy 2.5 GT
Winestone Pearl

Default 1998 Legacy Outback trans swap 4EAT to 5MT write up

This is a full and complete write-up on my second transmission swap on my second gen legacy outback. I will try to be as detailed as possible for anybody that is thinking of attempting this to get an idea of the amount of work involved. This project requires a lot of mechanical knowledge, money, time, resources, and most importantly the ability to find a way around anything one may encounter. As this was my second time doing this, I ass-u-med that it would be easier the second time around. I was wrong. I hoped to get it back on the road within half a week or so, but it ended up taking a full week of searching for parts, ordering and waiting for parts, among many other problems. This is a very long and thorough write up, but I'd rather include too much info than not enough. So bare with me.....


This is the boring part, but is definitely worth including as a background. I got the car for cheap ($550) with a dying 2.5. I picked up a 2.2 engine for $300 and with the help of (specifically 987687), discovered that the 2.2 plugs right in, with little to no modifications. I got the car back on the road within a month or so and really lucked out with the engine that I got. It was in great shape. The car had some issues that needed to be addresses, but none were urgent. Brakes, exhaust, fluid changes.... There was just one problem with the engine that I got. It did not have an EGR set up (exhaust gas recirculation). This is an emissions related "fuel saver" that threw a Check Engine Light (CEL) almost immediately. So I could not pass inspection. I tried tricking the computer but nothing seemed to work. I dealt with the issue a few months later and about 10,000 miles by finding an even cheaper engine for $150. Its easy enough to replace that I didnt feel like replacing the whole manifold and welding into the headers to get true exhaust gas. I later found out from 987687 on that instead of welding into the exhaust, one can reroute to the intake past the MAF before the throttle body. Huge thanks go to the infinite help I have received from him. Anyway, this cheaper engine was not in as good shape as the first one I got. But it still ran fine so I kept it for another 7,000 miles or so. It turns out that the manual 2.2s did not come with EGR, but the automatics did. All of the 2nd gen 2.5 outbacks came with EGR I believe. At one point I tried a manual 2.5 OB ECU but it did not work, prior to finding out that it was only the 2.2 MTs that came without it. I thought that if I change the car to a manual, and the computer thinks it has a manual, then I theoretically could use an engine without EGR and it would not throw a code. After the swap I discovered that it still threw an EGR code, and later found out that only the 2.2 MTs had no EGR. So I will need to find a brain thats from a 98 2.2, and in theory I should no longer get an EGR code. *fingers crossed*

So one day the car starts acting up. I still think it is possessed because I still haven't found the problem. It idled high, around 1,000 or 1,100 RPM. While I was driving, the car would go into fail-safe mode. This retards the timing and gives the engine very little power, and doesn't let it rev past 4500 rpm in hopes to save the engine from internal damage because it thinks something is horribly wrong. The code it threw initially was P1507: Idle Air Control Valve (IACV) malfunction fail-safe. This made sense because it seemed to only happen while I came to a stop in D, when the revs would fall to idle. A high idle can also clog up an IACV. It did not happen all the time but it was too frequent. If I turned the car off and back on it would reset itself, but would usually just happen again the next time I stopped. So I had a third 2.2 that I got for $60 and mainly used for parts. I swapped over the IACV but it did the same exact thing immediately. So that probably wasn't the cause of it. I tinkered with the throttle cable to make sure that the TB wasn't open just a little too far. That did not help. I replaced the TPS (throttle position sensor) from one I grabbed at the junkyard. That did not help. It seemed that everything I tried was not working. The AT OIL TEMP light occasionally flashed 16x upon start up after going into limp mode. The owners manual says "there is a problem with the trans control. see dealer." As if............. I tried the secret handshake I got from ultimatesubaru, but could not seem to get it to work, as was the case with most of the posts on that thread.

My thoughts were, maybe the trans was putting the engine into limp mode to save the trans from damage. The 4EAT always shifted funny from the first day I drove it. It shifted hard from 1st to 2nd, and hesitated, sometimes 3 seconds or more, from 2nd to 3rd. I read that if you change the fluid a bunch of times it will cure it, but after the 3rd fluid change I just gave up. It never seemed to get any worse in the 17,000 miles that I drove it. I thought maybe the trans realized it was failing and was trying to do something about it (typical limp mode for an AT is to stay in 3rd, but it still shifted through all the gears). This was a good chance to get rid of the 4EAT while I had a chance. The rest of the car is in good shape and wanted to hang onto it. And if it was an engine issue, I could use the old 2.2 (the original replacement without EGR) to hopefully solve the issue.


The car that was swapped was a 1998 Legacy Outback Limited, 30th anniversary ed, (yes with dual sunroofs!!). I live in central NH but ended up doing the swap in PA with a warm garage and my brother and friends to help. I packed up everything that I could think of that I might need in the back of the wagon and hauled it down the 370 miles to PA with the chance of it going into limp mode. It drove fine on the highway so long as I didnt come to a stop. It actually made it the whole way without going into limp mode once. I only stopped once for gas and a bathroom break. I brought the trans, rear diff, engine, driveshaft, trans xmember, clutch, flywheel, along with many tools, fluids, and spare bolts. She was very weighed down, I hit the bump stops more than once yay for wagons! The first few days I spent waiting for some more parts and trying to diagnose the problem with my buddy Spencebot.


Here's a list of the parts I needed. I thought of mostly everything before I got started, but there were many unforeseen missing linkages and brackets that I needed. Many mistakes and chances taken....

$20- Transmission crossmember with trans mount. Ran into a big problem with this....
300- 5MT tranny and rear diff combo (ratios MUST match!) from an '00 legacy GT. 4.11 final drive.
40- driveshaft (the MT is longer than the AT)
20- short shifter (did not fit, did not use)
64- shifter linkage (from an 09 impreza)
43- heater core hoses and clamps (they were deteriorating and it would have been stupid to not to do while the engine was out
5- exhaust gaskets
32- thermostat from Subaru (I've had bad luck with aftermarket ones...)
128- Clutch kit
29- pedal assembly (just need the clutch/brake. The gas pedal is the same on the AT and MT)
45- master cylinder, slave cyl and clutch lines. Failed, ended up having to buy replacements,
30- replacement master and slave
37- starter (found at junkyard, looked at the mileage on the car i took it off of after I removed it. car had 258k on it... the starter is very tired
91- 5 qts of royal purple 75W-90 gear oil for the tranny and rear diff.
16- coolant and muffler repair kit
48- linkage for shifter that did not come with the assy
55- clutch fork with clips and boot, washer and bushing for shift linkage, and flywheel bolts (the ones that hold on the flywheel are longer than the ones that hold on the flexpate on the AT)
115- bracket on the back of the trans that hold the shifter on, clutch bolts (hold the clutch to flywheel), and CV boot repair kit (both front inner boots were torn)
15- washers and bolts that should have been on the trans. a few were missing. I knew it had been taken apart but there were also important sensors that were missing, Neutral and reverse switches, along with the speed sensor.

Total I spend more than $1,100. This was a couple hundred more than I wanted to spend. There were so many odds and ends that needed to be addressed for the swap to be a success. My main problem with this project was that I did not have one specific donor car. I grabbed all the parts from many vehicles and many different sources. This was a BIG mistake. I spent way more than I needed to and ran into so many problems. Having a donor car is not necessary, but extremely encouraged. I spent so much time and money fixing or adding stuff that should have been there in the first place. While the engine was out of the car, I replaced the timing belt and water pump with spare new parts because I did not know how many miles were on the current one. After taking it apart, it appeared pretty worn. I'm glad I replaced it. As I was doing the water pump, Spencebot regreased the pulleys which were also very worn. While the trans was out, I had my brother replace the CV boots.


Here is the process as clearly as I can remember step by step. I lost track of the days as they passed but the whole process took about a week including waiting for parts and searching for solutions.....

Started off by unloading everything from the car. Used the engine hoist to take out the engine I would be using from the cargo area. Cleaned and prepped the garage for the swap. Put the car on jack stands and started taking it apart. Started with the exhaust and heat shield under the driveshaft. I drained the rear diff and the trans fluid before taking them out. I also drained the coolant and took out the radiator. I removed everything in the engine bay so that the engine and trans could come out freely. I took out the front left axle bolt and the control arm so that the axle would come out. I left the axle on the other side in like I did with my last swap. As long as you remove the pin, it will slide out with relative ease when the trans comes out. Just remember to slide it out and slide it back into place when removing/ installing the trans. I removed the tail section of the driveshaft so that I could tackle the rear differential.

The bolts on the back of the rear diff were very rusted, but I managed to get a grip on them and break them free after some struggling. Eventually I got the diff to fall, lowering it with the jack. The front end of the diff had to be lowered first, then the whole thing had to slide forwards. This is because the studs that hold it to the rear subframe sticks out pretty far and has to slide out. After the studs were free, the diff was hanging by the 2 rear axles which did not need to be removed. After some careful prying, we got both axles free and finally the rear diff was out. While the process was fresh in my head I started putting the new diff in. In reverse order, I got both axles partially in the diff, and managed to bolt it into place. The 2 axles popped out but would not pop back in all the way. They were in the diff but not entirely secure. We ended up taking off the rear wheels and axle bolts, and with the biggest hammer we could find, hit the axles out of the hubs to force them to seat into the diff. It worked with both sides and we simply put the axle bolt back on to make it gut'n'tight. Rear diff was complete!


While I was waiting for my friend to wake up, and eventually show up, I tackled the pedal assembly and the shifter. The pedals are a huge PITA. It can be done without lowering the steering column, but it makes it a lot easier if theres more wiggle room. The black plastic cover comes off, and there are 2 bolts holding the column up. Simply remove those and it fall enough to get the pedals in and out. The AT brake pedal comes out fairly easily. I kept the switch used for the brake lights and transferred it over to the manual setup. The gas pedal has to be removed before the assy can come all the way out. The TCM (trans control module) is attached to the brake assy and will come out with it. The manual assy has the clutch and brake on the same frame, and it bolts right up to the same holes. Before installing all the way I had to remove the little black plug that took the place of the master cyl. After some wrestling past a huge bundle of wires it went in. I tightened it all up and reattached the gas pedal. Bolted up the steering column and put the plastic cover back. Heres the master cyl hole and the very crowded pedal assy

The AT shifter was fairly easy. The center console has to come out to get to all of the bolts and screws but it is relatively painless. There are 6 or so screws holding it in at the top, and the 2 bolts and pin holding the linkage to the trans. After unhooking that from underneath the AT shifter was free.

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