WRX Clutch Install on a 2014 Subaru: Drop, Torque, Clearance

What a WRX Clutch Install Takes

The steps and torque figures below are from one 2014 WRX with a push-type stage 2 clutch and a steel flywheel listed at 13.7 lb. That car’s stock disc hub was blued, and the owner tied the color to 345 lb-ft. A push-type release is what this WRX uses. A pull-type STI clutch is a different fork and a different job.

The transmission has to come back far enough for the input shaft to leave the disc. On this car it slid a couple of inches and stopped because the bellhousing was against the turbo. Dropping the tail to clear the turbo left the input shaft hung in the clutch. The case came off only after the turbo was unbolted from the up pipe and the engine and transmission were jacked back into line.

The clutch, flywheel, and fork can be changed with the transmission still under the car. On this job the transmission jack was too tall to roll the unit out, and there was still room to bolt the flywheel and a four-bolt inspection plate. The torque for that plate was stamped on the plate.

Open the throwout-bearing box before the case is on the ground. The box from the dealer on this job held a thermostat.

Torque Specs From This Install

These are the figures written down for the 2014 reassembly. The flywheel and the front crossmember each have a second number from the same car, explained under the table.

The two 17 mm front crossmember bolts are written at 103 ft-lb. On this car the wrench stopped at 80 ft-lb because the bolts felt over-torqued. The same job records the flywheel at 52 ft-lb in the short list and at 52.8 ft-lb on the install: blue thread locker, a star pattern, a pass at 26 ft-lb, then 52.8 ft-lb.

Bellhousing torque covers five 14 mm bolts and two 14 mm nuts. Thread locker goes on the flywheel bolts and the clutch-cover bolts. Fill the transmission once the case is back in the car.

Ball Joints, Axles, and the Slave

Loosen the front lug nuts, disconnect the battery and lift it out, then put the car on jack stands and pull the wheels. The front sway-bar end links come off the lower control arms. An aftermarket bar on this car also needed the sway-bar mounts unbolted before the links had room to come out.

The pinch bolt is 37 ft-lb. With it out, a screwdriver driven into the knuckle slot spreads the clamp. Penetrating oil on the joint, then a jack under the brake disc until the control arm sits level. Level keeps the ball joint from cocking in the knuckle, and it keeps the suspension from soaking up the hit. Strike the end-link mount through a block of wood.

Drain the transmission with a T70 plug and torque it to 32 ft-lb on the way back in. Pry the front axles out of the transmission.

The intercooler comes off next. On this car that was three hoses, and the bypass valve stayed on the cooler. The slave is two 14 mm bolts at 27.5 ft-lb. Set the slave on the engine with the line still attached. Pull the starter ignition wire, leave the battery cable on the starter, remove the 12 mm starter bolts, and set the starter on the engine. Starter torque is 37 ft-lb.

Downpipe and Driveshaft

Unplug the downstream oxygen sensor and take it out of the downpipe. Support the midpipe on a jack stand and leave the midpipe in the car. That stand is also what holds the driveshaft once both ends are free.

Remove the turbo heat shield. The downpipe is held to the turbo with 14 mm nuts. A heat shield that wraps the driveshaft comes off as well: four 12 mm bolts. Mark the driveshaft flange to the rear differential before those bolts come out, so the shaft can go back on the same clock. That mark is how this shaft was kept in its original position. The four flange bolts are 12 mm at 23 ft-lb. Two 14 mm bracket bolts at 38 ft-lb hold the center of the shaft. Once both ends are free, walk the shaft around the midpipe and set it on the floor.

The shifter stays in the car. Two fasteners come loose: a 12 mm nut on the side transmission stay, under the linkage, at 13 ft-lb, and a 12 mm vertical bolt on the top of the linkage at 9 ft-lb. The plugs that come off are the black connector and the gray connector on top of the transmission, by the firewall. The connectors on the side of the case stay plugged in. The transmission ground is a 10 mm bolt on the firewall next to the pitch-stop mount. The firewall end is the one with room to get a wrench on it.

Getting the Transmission Off

Put a jack under the transmission. Support the front of the engine before the crossmember bolts come out. This job used a jack stand under the oil pan so the engine would not tip as the case left.

1. Crossmember. Two 17 mm bolts hold the front crossmember to the body. Four 14 mm bolts hold the rear crossmember to the body at 51.6 ft-lb, and four more 14 mm bolts hold the transmission housing to that crossmember.
2. Bellhousing. Five 14 mm bolts and two 14 mm nuts, 36.9 ft-lb. The pitch stop and the transmission dipstick come off with them.
3. Turbo. Unbolt the turbo from the up pipe. Jack the transmission up into the tunnel and jack the front of the engine until the input shaft and the crank are in line. Pry the turbo up off the up pipe, then pry the case straight back.

A rusted dowel is a different hang-up. On a 2003 WRX wagon, one dowel had fused the case, and an afternoon of pulling did nothing. A few seconds of heat on that pin is what let the transmission come off. The 2014 separated cleanly until it met the turbo.

With the case back, the clutch fork comes out of the bellhousing, then the cover, the disc, and the flywheel. Cover bolts are 12 mm at 11 ft-lb. Flywheel bolts are 14 mm.

Flywheel and Pressure Plate

Clean the friction faces with brake cleaner. Old fork grease on this car had hardened, on the fork pivot and in the dimple where the slave rod sits, until it felt like plastic. Clean the transmission snout and the input splines, then dry-fit the throwout bearing and the disc until both slide. Grease goes on after that fit: the fork, the fork mounting rod, the slave rod, the throwout bearing, the snout, and the input splines.

Grease the splines by sliding the disc up and down the input shaft, then wipe the disc. Grease left on the friction face is what you smell later. A centering tool holds the disc on the flywheel. Check the flywheel face and the disc with a straight edge before they go on. Both were flat on this clutch.

Blue thread locker on those bolts. The short list for the same job records this flywheel at 52 ft-lb. The 13.7 lb wheel on this car sits just above the old floor for a Subaru flywheel: about 12 to 13 lb was as light as people went when they wanted to avoid false misfires, and light pulleys put a wheel in that range on the edge.

Brake-clean the pressure-plate face and wipe it before it meets the disc. The plate on this stage 2 clutch is larger than the stock plate. After the first start the new plate was rubbing the black dust shield. Prying that shield, with the car in the air, stopped the racket. The transmission stayed in the car for that fix.

Throwout Bearing Clearance

At assembly this slave bolted flat to the bellhousing. The piston did not have to be compressed, the pedal linkage did not need a change, and there was a little play between the rod and the fork. That play was gone after the clutch had miles on it.

The bearing that made that noise was a dealer piece, installed in place of the bearing that came in the clutch box. Pedal effort went back to stock, the small judder went away, and the hot-clutch smell in tight parking went away. Engagement sat a little closer to the floor than it had before the rod was shortened. The throwout bearing still has whatever wear those miles of preload put on it.

The gear rattle showed up in the higher gears on a light flywheel and dropped out as soon as the pedal went in or the throttle opened. A second 2014 WRX on the same stage 2 kit had a heavy engine-braking rattle in every gear and uneven engagement. A forged fork and a billet pivot on that car changed the engagement only a little, and the slave-rod play had not been checked.

Break-in on the first car stayed under 3,000 rpm, with easy engagement. Taking the engine to about 2,000 rpm before the clutch came out kept chatter down on the first drive. Before the rod was shortened, that clutch juddered on about every tenth start, smelled hot in parallel parking, and the pedal was only a little heavier than stock.

1. Clean and dry-fit. Brake-clean the faces, prove the bearing and the disc slide, then grease the fork, rod, snout, and splines.
2. Flywheel. Thread locker, star pattern, 26 ft-lb, then 52.8 ft-lb. Wipe spline grease off the disc and center it.
3. Pressure plate. A third of the bolt at a time, star pattern, cover bolts to 11 ft-lb.
4. Refill and listen. Fill the transmission, confirm the dust shield is clear of the plate, and recheck slave-rod play after 500 to 1,000 miles.

FAQ

What torque does a WRX clutch install use on the flywheel?

On this 2014 the flywheel went to 26 ft-lb, then 52.8 ft-lb, in a star, with blue thread locker. The short list for the same job records that bolt at 52 ft-lb.

Why does a light flywheel rattle on deceleration?

A light-flywheel gear rattle in the higher gears drops out when the pedal goes in or the throttle opens. A rub right after startup, on a larger pressure plate, was the dust shield, and prying the shield stopped it.

When should the clutch slave rod be checked?

After 500 to 1,000 miles. The rod on this car had lost its play by about 2,500 miles and was loading the throwout bearing with the pedal up. About 3/8 in off the rod restored the play.

Why does the transmission stop a few inches off the engine?

On this 2014 the bellhousing hit the turbo. Unbolt the turbo from the up pipe and line the engine up with the transmission before you pry. A fused dowel is the other reason a case will not move, and a few seconds of heat on the pin freed one on a 2003 WRX wagon.