Clutch swap!!!

Well around 35k miles my faithful OEM clutch started to give up the ghost.  I first noticed it on the coldest days in the highest gears, and eventually once 2nd started to slip even on warm days I knew it was time.

Now lots of folks decide to upgrade their clutches when they replace them.  Of course it's a good time to do it--you're "in there" and there's really no better time.  But there's always a down side.  One of the down sides is that the "+1" clutch is capable of handling more transmitted torque than the OEM clutch, which is relatively weak.

"WEAK?" you say... "why would someone WANT a weak clutch?"  Well, in an all wheel drive car such as the Subaru Impreza  it's important to always keep in mind where the failure mode is.  For MANY folks, even those running on OEM clutches, the weak point ends up being the GEARBOX.  There are two main reasons for this: a) all wheel drive means a LOT more traction.  Instead of burning rubber, the tires dig in and bite, and b) the five-speed manual transmission is not the strongest unit to begin with.   Take those two inherent factors, and add in a grippy, aggressive clutch and the result is that quite a few folks have crunched their MT5s within weeks of fitting an aftermarket clutch.   Keeping the clutch as the failure point or "fuse" could mean the difference between replacing a 200 dollar OEM clutch vs. replacing a 2000 dollar transmission.

Another downside of the +1 clutch is drivability.  Generally with a +1 it puts you in the "sport" range, which are typically still organic material discs.  This means they're still pretty drivable, but NOTHING will have smoother engagement or better slip characteristics than the OEM clutch.

Also ALL of the +1 clutches I've seen for the EJ20x  Subaru engines have been at least twice the cost of the OEM clutch... i.e. 400 vs. 200.  For me, that's a great benefit.

Last but not least, it is my opinion that you REPLACE a clutch that slips due to normal wear and use, and you UPGRADE a clutch that slips even when brand new.  People have trapped over 110 mph in the quarter mile on an OEM clutch, which means they can actually hold quite a bit of torque.

So...  I decided to go OEM clutch as a replacement.

One thing I considered was going to a lightweight flywheel for the increased response it offers.  I really liked what adding a lightweight crank pulley did for my car, and this is a further  extension of that same kind of mod.  The downsides to the LW fly are the possibility of throwing a misfire CEL, the need to slip the clutch a bit more especially while starting uphill or with a loaded car, and the increased cost of buying one. On the other hand, when replacing a clutch it is always a best practice to resurface the flywheel, and having a brand new flywheel ready to swap on eliminates the necessity of stopping your swap job and bringing your original clutch somewhere to be Blanchard ground, another expense.

I decided to go with the ACT StreetLight 13lb flywheel.  This is not terribly light, nor terribly heavy, offers a good level of drivability, and is very competitively priced around $250.

So here are some pictures and comments of the process:

first, gain access to the underside of the TMIC.

take off the starter, the IC brackets, the "dogbone" aka tranny pitch stop, the clutch slave cylinder, and the ground strap.  unplug all electrical connections going to the tranny and make sure cable mount points are free.

remove the downpipe and midpipe for easy access.

remove the cotter pins, and the castle nuts on the bottom ball joints where the lower control arm meets the knuckle.  we freed the ball joints by hammering on the LCA right near the bolt with a 3lb ball pein hammer.  we just smacked them a few good times and they were broken loose, after which it was just a matter of pulling down on the LCA to clear the bolt portion.  we found this process a LOT easier once we removed unbolted the front sway bar end links.

tying the knuckle forward and out of the way makes it a lot easier to work on the halfshafts.

knock the pins out carefully with a drift and pull the halfshafts off the spindles.

driveshaft safety loop gets removed, then the driveshaft is disconnected from the rear differential via these four bolts.

disconnect the shift linkage completely.

drop down the tranny crossmember. at this point the only thing holding the tranny in place is the engine block. you should be able to move it around a bit as the engine rocks on its mounts.

unscrew the cover plate, insert the 6mm bolt, and pull out the clutch fork pivot shaft. we used a pair of pliers and a prybar as shown.

tranny out of the car!

clutch assembly exposed and ready for swap.

old clutch disc out. yes, it got a bit hot at some point in its life! probably as it was slipping at 5k rpms while WOT towards the end…

the flywheel wasn’t too bad looking, but it did have some score marks where it was touched by the rivets of the clutch disc.

setting home the pilot bearing with a high tech bearing press.