Parts List
Part 2: Parts, Tools, & Materials
Here is an overview of the parts you need. Make sure what you're doing is cross-compatible with your Forester model. Things like the 5MT transmission crossmember are Forester-specific due to the subframe spacers that the Impreza does not have. Remember axle compatibility and push/pull style clutch years. Impreza 5MTs are much more readily available than Forester 5MTs because Foresters have shorter gear ratios (4.11 and 4.44), so this write-up is geared towards swapping an Impreza transmission. I swapped a 3.90 in mine from an '04 WRX, but shortly blew the main shaft out- be careful buying used transmissions!
Mechanically, everything is a direct bolt-in. Subarus are like Legos and a lot of parts are cross-compatible between different years and car models.
Basic Parts List:
1. Transmission
2. Matching ratio rear diff
3. 5MT driveshaft (4EAT/6MT driveshaft is too long)
4. Matching front axles- for the Impreza, '02-early '04 axles were female and '04-'07 axles were male.
5. Clutch/flywheel/pressure plate- clutch system must match if you have a push or pull style clutch. I sprang for an XTD Stage 3 six-puck clutch and matching pressure plate. It sucked. I replaced it with an organic clutch.
6. Clutch master/slave cylinders and clutch lines- make sure slave cylinder is for your push/pull style clutch system.
7. 5MT pedal box- anything from '02-'07 Impreza or Forester will work. I used a pedal box from an '04 which has fancy silver pedal pads. The accelerator pedal is completely separate from the clutch/brake pedal box so don't worry about DBW compatibility.
8. 5MT shifter assembly (make sure you get the right wide vs narrow shifter)- shifter assembly includes shifter and shift knob, rubber gasket, pivot bushing and bolts, lower shifter ball bushing and rear shifter bushing/bracket assembly, and the other half of the shifter assembly (sometimes left attached to the trans). This is a good time to upgrade to an aftermarket short shifter since the stock Forester shifter is so tall! This is also a good time to upgrade all your shifter bushings.
9. Trans mount (good time to upgrade to Group N)
10. Forester-specific 5MT transmission crossmember- good time to upgrade to stiffer crossmember bushings
11. Forester-specific interior shifter trim & shift boot
12. 5MT starter- the starter bolts onto the bell housing of the trans and is different for 4EAT and 5MT vehicles.
The easiest method of obtaining these parts is buying a used "transmission swap" package deal from an Impreza owner who is doing an STi 6MT swap. These package deals normally include the trans, rear diff, driveshaft, axles, and starter and will run you anywhere from $800-$1500 depending on year and mileage. This way, you know all of the drivetrain parts are from the same car with the same amount of mileage in the same condition. Avoid the '02 5MT because it had weak gears. I suggest finding the lowest mileage 5MT you can from a stock car that doesn't have performance mods putting more torque on the transmission. I bought an '04 WRX 5MT swap package, but little did I know the transmission had a bad main shaft rear brake plate.

Be careful buying used transmissions.
The following section is where things deviate. If you want to get rid of everything 4EAT, you'll remove the TCU which is also the ABS controller on *some* 4EAT vehicles. On my vehicle, removing the TCU did NOT remove ABS. For some vehicles, you'll need a 5MT wiring harness and 5MT ABS unit if you want to do this whole swap. It also eliminates some other electrical issues which will be discussed later.
More specific parts list:
1. 4EAT flex plate bolts are too short to serve as flywheel bolts. The part number for the flywheel bolts is 800610740 and you need 8 of them.
2. Extra bolt for the 5MT clutch/brake pedal box that bolts up under the dash. The tapped hole is already there with an inserted plastic plug. The bolt is part number 901000267.
3. Extra clevis pin & spring pin for the clutch pedal linkage, part numbers 736016020 and 051108001.
4. Two flange nuts for where the master cylinder connects to the clutch pedal box linkage through the firewall, part number 023808000.
5. Bolts for attaching the pressure plate to the flywheel, part number 800508310 and you need 6 of them at least for the '02 flywheel. '02-'04 are identical but I can't speak for '05+.
6. You'll probably want to press a new pilot bearing into a used flywheel. The pilot bearing is part number 806212020.
7. You also might want to replace the rear main seal while the output shaft of your engine is exposed. Rear main seal for the EJ253 is part number 806786040.
8. The transmission axle seals probably need replacing. I can't find the part number for this one.
9. The rear differential axle seals also probably need replacing. The part number for the '03+ Impreza rear diff axle seals is 806735240 and you need 2 of them.
I'm sure I'm missing some random nuts and bolts so feel free to chime in. You reuse your 4EAT bell housing bolts and some of the bolts from the 4EAT transmission crossmember and mount. Your used crossmember, mounts, and other small parts should come with the attaching bolts, ask your parts seller.
Tools:
I was fortunate that my uncle lent me access to a hydraulic lift, air power, and a variety of quality Matco tools and impact sockets as well as all kinds of wrenches. An electric impact wrench made undoing tight bolts a lot quicker than the breaker bar, but even the impact wrench couldn't undo that long lateral link bolt. :icon_eek: We had to pull out the breaker bar for that one.
The following tools are absolutely necessary, in my opinion:
1. Breaker bar
2. 32mm socket for undoing axle nuts
3. Ball joint puller tool
4. 50-150ft/lbs torque wrench
5. High quality or impact socket set
6. Torx T-70 bit for undoing the transmission drain plug
7. Bit for undoing the rear diff drain plug. I used the 1/2" breaker bar socket and didn't have any problems, but the specific plug fits better and you don't risk munting the plug.
8. Hydraulic lift really makes things so much easier. There was no way I would have been able to swap the mechanical parts in less than a week without the lift. I HIGHLY recommend you find some way to get access to one of these for 7 days or so.
9. Gloves (sort of optional); I say sort of optional because I don't like working with gloves to retain the bare-handed touch sense, but I wore gloves when working around the sharp exhaust heat shields and while pulling the engine and transmission.
10. Safety glasses for protecting your eyes from falling dirt.
11. Oil catch pan for catching dripping ATF- when you pull the trans, ATF will pour out of the 4EAT tail shaft as well as the ATF cooler lines.
12. Steel-toed boots; optional but extra insurance in case you drop something heavy, which I nearly did a few times with slippery fluids on my hands. A torque converter with the starter gear-toothed edge doesn't feel so good when you drop it on your foot.
Materials:
1. 75W-90 gear oil, without limited slip modifiers because the 5MT doesn't like the modifiers.
2. Anti-seize compound.
3. Tape and a permanent marker for labeling engine compartment wires.
4. Waterproof grease for installing the axles. Those are a big pain to remove, one was so stuck in the hub I had to cut the axle in half and take the hub to the shop to get the stub pressed out.
5. Tons of shop rags for soaking up spilled ATF and oil. An ATF-soaked rag wrapped around a stick makes a great torch. :biggrin:
6. Mineral spirits for cleaning up parts
7. Fast Orange or other pumice hand cleaner for getting grease off your hands
8. Clothes you don't care about getting oil and grease all over