Project Summary:

This installation will replace the factory clutch, with an option to also replace the factory flywheel. The pictures were taken from a 1999 Impreza 2.5RS coupe, but should also apply to any model Impreza.
There were absolutely no instructions whatsoever with the kits. This project is not recommended for the faint of heart nor for the mechanically-challenged. The instructions are geared towards those (like myself) who do not have access to a real garage with fancy equipment like lifts and engine hoists. This installation was done in a home garage, but is also suitable on any firm level surface.

Materials Required:

1 ACT Street clutch kit or equivalent (from Powerhouse Racing, iSR Performance, Teague's Auto), consisting of:

Pressure plate
Clutch disc
Release (throwout) bearing
Pilot bearing
Installation tool

1 Lightweight flywheel or equivalent (optional, from Suby Sports, Adam & Sons, iSR Performance)

2 Exhaust header gaskets (optional)

Shop rags, garage creeper, cardboard boxes to line the ground (optional)

Liquid Wrench (optional, strongly recommended)

Tools Required:

10mm, 12mm, 14mm, 17mm, 21mm socket (ratchet) wrenches

14mm deep socket wrench

18" or longer breaker bar

4" and 6" socket wrench extensions (optional)

10mm, 12mm, 14mm, 17mm open-ended wrenches

1 or more 2-ton floor jack(s)

2 2-ton jackstands

Large prybar(optional)

Here is a less painful way of doing a clutch. In a snapshot:
1. Remove battery and windshield washer reservoir. Drain coolant, remove fans and radiator, and use a piece of plywood or thick cardboard to protect the A/C condenser.
2. Remove exhaust header bolts and let header dangle.
3. Disconnect engine mounts and pitching stopper.
4. Use a jack under the tranny and another one under the oil pan, and have a friend or two help with pulling the engine forward (you'll have a good 6" to move it).
5. Continue with clutch work.
6. Put everything back together in reverse order.
This method makes it unnecessary to remove the exhaust pipes, drive axle, and some other tranny-related details. Or you may read on for detailed instructions...

Let's Start

Disconnect the negative terminal from the battery. Wrap the cable in a rag to prevent any shorts. This is not aboslutely necessary, but is a good precautionary measure! Next, make sure you have all the parts necessary in the clutch kit. Then jack the car up and rest the car as high as possible on jackstands at all four corners using the recommended jack points. Spray rusted or siezed bolts with Liquid Wrench or WD-40. Allow the car to sit until the exhaust pipes and headers are cool to the touch. The catalytic converter may still be warm, but that's OK. Drain coolant from the engine and radiator. Remove the fans and radiator. Remove the battery and windshield washer reservoir.

Disconnect the electrical plugs on the right side of the engine. Remove the bolt and nut from the transmission dogbone (pitching stopper). Using an engine hoist or a floor jack on the oil pan, lift the engine up off the crossmember so the bolts will clear the crossmember. Place a piece of plywood or thick cardboard (to use as a shield) between the engine and the A/C condenser.

Slide the engine forward enough to provide room to get to the pressure plate bolts and release bearing with your hands. The radiator and fans were removed to provide the necessary room for the engine to side forward. The engine will only be connected to the car by various hoses. In the picture (left), you can see the stock pressure plate (red arrow), stock flywheel (blue arrow), dogbone (green arrow), and the hydraulic clutch cylinder (orange arrow).

Insert the Installation Tool into the clutch disc. Remove all the bolts from the pressure plate. Use a suitable tool to jam the pressure plate (or flywheel) and prevent movement while you remove the bolts. Remove the pressure plate, followed by the clutch disc. Use the handy installation tool to carry the clutch disc out. You will now see the flywheel (picture at right). If you are replacing the flywheel, remove the eight flywheel bolts (green arrow) and flywheel from the engine crankshaft. You will have to find something to jam into the gear ring to prevent the flywheel from moving. Note the alignment pins (one shown by red arrow). A flywheel resurfacing is highly recommend (most auto shops should provide this service). If you are installing a lightweight flywheel, be sure to have the clutch surface finished beforehand (and the flywheel balanced).

Compare the two flywheels. The stock flywheel (left) weighs 25 lbs, while the Exedy lightweight flywheel (bottom) weighs 12 lbs. Note that the clutch faces for both flywheels are facing away from you. (Forgot to take pictures of the other size.) Install the new pilot bearing onto the flywheel. Use a suitable drift and hammer to gently tap the bearing into place until flush.

Compare the two clutch discs. The OEM Exedy stock clutch disc (left) is in excellent shape even after 25,000 miles. Both clutch discs are very similar in design and construction. Word is that the ACT clutch kit uses an Exedy disc as well, hence the similarity. No further prep is required for the clutch disc.

Finally, compare the two pressure plates. The only real difference is that the fingers on the ACT pressure plate (right) are thicker and wider than the stock pressure plate (left). No further prep is required for the pressure plate.

Install the alignment pins in the flywheel, if applicable. Then install the flywheel onto the engine crankshaft. Torque flywheel bolts to 53 ft-lbs. Use the installation tool to hold the clutch disc onto the engine crankshaft, and install the new pressure plate. The installation tool holds the clutch disc until the pressure plate takes over. Torque pressure plate bolts to 12 ft-lbs. Remove the installation tool once the pressure plate is secured (see picture). Remove the old release bearing from the actuator fork on the transmission side (picture missing). There is a small steel retaining clip on each side that secures the release bearing. Install the new release bearing, and secure using the retaining clips.

Here's the hard part. Carefully pull the transmission housing back towards the engine, using the two long bottom bolts as a guide. Use a floor or transmission jack to angle the transmission so that it mates up square with the engine. Crank the engine a bit by hand and/or wiggle the transmission and engine if the pilot shaft doesn't seem to mate properly with the crankshaft at first. Once the transmission and engine are close, use the long top bolt to pull them together. Reinstall the long transmission bolts, along with the starter and cable guide brackets. Note that the two longest bolts go into the top of the transmission housing (one through the starter flange). Reinstall the two nuts on the two long lower bolts. Guide the engine back into the crossmember. Torque transmission bolts and nuts to 37 ft-lbs, and starter bolt and nut to 30 ft-lbs. Reinstall engine mount nuts on the crossmember. Reinstall the dogbone (pitching stopper) bolt and nut.

Reinstall the air box support. Reinstall the air box. Reinstall the exhaust header. Don't forget about the exhaust header gaskets, and make sure to use the 14mm stainless steel nuts (the zinc plated nuts are for the bottom transmission bolts). Reinstall the windshield washer fluid reservoir and battery. Reinstall the radiator and fans. Fill radiator with new antifreeze mixture. Reconnect the negative battery terminal. Be prepared with the remote if you have an alarm. Start the engine and let it run for a few minutes (as part of the radiator refill procedure). Then turn it off and let the engine cool down. Top up the radiator as necessary, and fill the radiator overflow tank to the "MIN" level. Restart the engine and be prepared for a low engagement zone (close to the floor) when popping the clutch!

Standard disclaimer: This information is being provided as an educational and informational service for the Subaru community. I do not make any warranties, but I will be happy to help with questions about these modifications. Please proceed at your own risk!