Replaced the Clutch in my 06 WRX: A reflection more than a DIY

[06wrx4me]

So I spent yesterday replacing the clutch in my 06 WRX, installing Group-N pitch stop and motor mounts and here is my story:

Disclaimer:

* First and foremost I want to say that this is an involved job. I have a whole host of tools both manual and air powered, a lift, transmission jacks etc, etc; have replaced over a dozen transmissions and clutches and a WRX clutch is one very very involved job. I now fully understand why they charge soo much to do it at a shop. So if you are contemplating replacing the clutch in your wrx and all you have is a basic tool kit and a couple hundred bucks, or like to cut corners, this job is not for you.

Tools required:

* A full set of open end wrenches in metric.
* A full set of ratcheting box end wrenches in metric.
* A full set of Sockets in metric deep reach both 3/8" and 1/2" drive.
* A full set of sockets in metric standard reach 3/8" and 1/2" drive.
* A whole host of ratchet extensions in 1/2" and 3/8"
* T70 torx
* A 1/2" breaker bar.
* A 3/8" breaker bar.
* A 1/2" torque wrench.
* A 3/8" torque wrench.
* Pry bars, bunch of sizes.
* Needle nose pliers.
* Transmission jack or Jack with tranny adapter.
* Various stands.
* Screw drivers etc.
*** 1/2" air impact will save lots of time

The beauty of this job is that shy of the lug nuts you need very few sizes to do the whole job. Pretty much the entire job can be done with the following tool sizes: 8mm, 10mm, 12mm, 14mm, 17mm, 19mm with the only 19mm things being the castles nuts on the ball joint IIRC.

The Parts list:

Required:

* Clutch kit (I used Exedy 15804)
* Flywheel (OEM SUBI is what I used)
* Gear oil (5 qts I did the rear end too)
* Cotter pins for the castle nuts (the only thing I forgot and had to go get)
* Can of brake clean
* Synthetic grease
* Down Pipe gasket
* axle seals
* Antisieze
* A Good manual
* Beer...for medication

Optional:

This is a great "while you are there" job. After the transmission is out, and in the process of taking it out, you touch everything. I put in group-n motor mounts and changed the pitch stop to group N while I was there, but I already had changed the shifter bushings and transmission mounts otherwise this would be the opportune time. This is the best time to change the motor mounts because the rear bolt that is usually obstructed by the tranny is fully exposed and you only have to jack up the engine since the transmission is out.

* Motor mounts
* Pitch stop
* Shifter bushings
* All tranny mounts (You have to remove the crossmember from the tranny so you can replace them all on a bench)
* Down pipe and exhaust
* Intercooler
* Sway bars and end links
etc, etc.

Whats so different about the 06+?

The 2006+ WRX clutch system was swapped from pull to push. What that means within the scope of this job is that there are a couple fewer steps.

* There is no clutch fork release rod you need to take out
* There are no spring pins holding the axles in that need to be punched out
* The clutch kit part #'s are different.

Gettin down and dirty:

I can't stress enough the importance of a good manual, I had the factory Subaru Workshop manual.

Under the hood (Do this first):

* Now the first step is to pop the hood and get the intercooler off.
* Also disconnect the negative cable of the battery (you are taking the starter off afterall).
* Remove the down pipe heatshield.
* Remove the down pipe bolts and nuts you can get too.
* Remove the starter.
* Remove the slave cylinder and zip tie out of the way.
* Undo the 3 electrical connectors up top.
* Undo the top transmission bolts (2 also hold the starter in)
* Undo the pitch stopper
* Undo the stupid little ground cable that bolts next to the pitch stop otherwise you'll have to take it off at the tranny and that sux. (the manual says nothing about this cable)

Noteworthy:

The manual tells you to take off the throttle body and I dunno why, there is no reason at all. The manual wants you to install a tool in place of the pitch stop, I didn't do that either, I used a jack under the engine.

Now put the car in the air!

Underneith:

I had a lift to use, but doing this job on jackstands would scare me. There are not sufficient safe points to position jack stands under the front IMO, but it can be and has been done in the garage on jackstands many times.

EDIT: Here is a DIY for wooden wheel stands that may help people do this job.

DIY: Wooden Wheel Stands

After you have it up in the air.

* Drain the tranny fluid first! Otherwise it will pour out when you take all 3 driveshafts out. My 06 takes a huge T70 torx bit and a 1/2" breaker bar.
* Take the exhaust off and get it out of the way, don't forget to unclip the 02 sensor.
* Pull the rear driveline cover and pull the driveline. You will need to rotate the shaft by hand and then set the ebrake to break the 4 bolts holding the driveshaft to the rear end.
* disconnect the lower sway bar end links on both sides
* undo the lower castle nuts on the a arms and pull the cotter pins
* pull the hub assembly out of the lower a arm
* pull the axles out of the side of the tranny and try your damndest not to damage the axle seals, move them out of the way.
* Put the tranny jack under the front of the tranny ( not on the crossmember cause this needs to come off)
* remove tranny crossmember (6 bolts) drops as one unit. ( great time to change those tranny mounts we talked about)
* put something under the engine to support it, a floor jack with a block of wood under the oil pan works good
* Undo the remaining tranny bolts from the bottom of the bellhousing and remove.
* With a buddy (if you have one, I did) use a pry bar between the bottom of the tranny and the bottom of the frame. 1 quick pry and the whole thing should pop free.
* roll the tranny out of the way.
* with an impact, remove the pressure plate, clutch disc and flywheel.

Putting it all back in:

Here is where being diligent and a little OCD helps....
There are several little grease points that need to be taken care of.
* You need to pop the shifter fork out of the transmission, Take off the old TOB, clean the fork and lubricate the wear surfaces with a little bit of grease not a ton.
* Clean the fork pivot ball next to the input shaft of the trans and use some grease here too.
* Clean all the old clutch fibers off of everything including the trans with a shop vac.
* Clean the input shaft splines and grease lightly.

* Put the new flywheel onto the crank shaft and torque the bolts. You'll either need a friend with a pry bar or the special tool to do this. I believe the spec was 53ish ft-lbs.
* Spray the friction surface of the flywheel with a little bit of brake clean and wipe with a clean paper towel
* Spray the friction surface of the new pressure plate with some brake clean and wipe with a towel too
* using your clutch alignment tool, install the new clutch disc and pressure plate. Torque bolts to procedure and spec.
-----Just an FYI, you really can't put the clutch disc (in this case) in backwards, it will only go one way.

* Putting the trans in;

IMO this was one of the worst parts of the whole job. It wasn't the hardest one I have ever had to deal with but its not fun. Some pointers:
--Grease the bottom two bellhousing studs on the engine
--Grease the two alignment pins on the bellhousing
--Don't shove the trans into place, spend some time getting the angle of the engine and trans to match
--Once the input shaft is in contact with the splines and not quite going in, grab the rear driveline and insert it into the back of the trans. Rotate it until you feel the splines of the trans and clutch line up (It'll stop rotating), then gingerly wiggle it back into place.

* Now reinstall everything in reverse order

Noteworthy:

Reinstalling the front axles is the second hardest part of this job. It requires 2 people, a lot of finesse, grunting and shoving to get them to go. All the while you need to make sure not to damage the axle seals.


The torque spec on the bellhousing bolts is 37ft-lbs.
The torque spec on the 2 large front tranny crossmember bolts is 103 ft-lbs.
The torque spec on the 4 rear crossmember bolts is 50ish (maybe 57?) ft-lbs.
The torque spec on the lower castle nut is 36ft-lbs + lining up the cotter pin hole
The pitch stop mount bolts have 2 different torque values.

I like to put a dab of grease on any steel bolt going into aluminum to help combat electrolysis and corrosion.




If there was ever any doubt, the factory clutch disc is made by exedy, I took a pic ill post.

Some pics of my job:

Car in the air:


Trans jack I made and stabilizer stands:





Trans out:


Tons of clutch fibers:


The little fork pivot ball that needs cleaning and grease:


Flywheel and engine side bellhousing, shows the studs to grease and pins to grease to ease reinstallation:


Old clutch


Factory Disc stamped EXEDY on the center ring, middle of two springs:

[06wrx4me]

40 miles on it, soo far so good. The pedal is firmer than I thought it would be (still a little less than before I replaced the clutch), but then again it is a stage 1 clutch. Engagement is in the middle of pedal stroke, and damn if it isn't nice to have an actual clutch instead of a light switch.

[06wrx4me]

I found this interesting, excuse the crappy pic, but the flywheel side of the clutch disc seems to be more warn and is visibly thinner than the pressure plate side. I wonder if my pressure plate was getting weak and failing me. Kinda what I thought might be happening since there was 0 engagement zone and not a ton of slippage.

[06wrx4me]

Drove it to work this morning, about 65 miles on the new clutch. The pedal and clutch feel is more consistent.

The pedal seems to be settling in and is definitely less effort than with the old clutch to push thus far. The old clutch felt like every time I pushed it in I was trying to crush a very stiff cardboard box, and the pedal squeaked rather annoyingly since new. After new clutch installation and greasing all the contact points, the squeaks seem to have disappeared....for now anyways.

Clutch deceleration noise is definitely less than it was pre-clutch replacement. It is still there, but much more faint. I also think the fact that I replaced all the mounts is helping this out. Before my motor mounts were so shot, that when you let the clutch out on deceleration, the car would almost "bounce" back and forth and the frequency of the clutch noise would change to match.

A note on Group N motor mounts and pitch stop:

I was hesitant to install the group-n motor mounts due to the fact that I hate rattles and squeaks, but my factory mounts were shot and I didn't want to put another set of the stock ones in. The new mounts definitely transmit more NVH, but on the freeway in 5th gear cruising along it isn't noticeable. Only really under acceleration and deceleration.

Even so, I'm freakishly listening for new noises and playing a constant game of "What was that?! Was it my car? Or maybe that Harley over there...?"

One would think the engineer in me would have isolated the variables and only changed one thing at a time...but nooooo. I swapped the exhaust, re-flashed stage 2 protune, installed new mounts and pitch stop. I dunno why i do this to myself.

Hopefully after a few hundred miles, I'll settle down and stop being such a headcase.

[Mikie13]

That's a great writeup. Nice to see pictures of the process as well. One thing is certain however; it further solidifies my thought process that if I have to change my clutch myself, I'd rather push my STI off a bridge.

[Mikie13]

However, let me pick your brain...since you were under there and did all that, how easy do you suppose changing bushings would be? I want to upgrade the transmission crossmember bushings with KB pieces, as well as all the differential bushings. I also want to upgrade the pitch stop as well. I won't be dropping any transmissions in this process, will I?

[06wrx4me]

I changed the tranny bushings with the trans in the car originally. Its not bad. If you replace all the bushings and the tranny mount, it is easiest just to drop the whole transmission crossmember (6 bolts). To do this support the trans with a floor jack and jackstand then remove the crossmember (I'd use an air impact). The change out all the bushings on a bench and reinstall the crossmember.

The Pitch stop requires TMIC removal which can be a PITA to get the hoses back on, but doesn't require any support of anything. It is a bolt on exchange part.

The Diff bushings are a littler tougher since you have to lower the diff and remove some studs. Overall it is not bad, and can be accomplished by backing your car onto ramps, then using a floor jack to drop the diff a little after the studs have been removed.

[Mikie13]

Ahhh good information dude, thank you. I should be able to handle the crossmember bushings easily. I'm well versed in removing the STI TMIC as I've done that a ton. I figured the pitch stop would be easiest. I'll see about the diff bushings then, as I feel they are going to be the biggest pain.

Regardless, I feel a lot of slop in my 115k mile STI driveline now, and want to address it very soon. As mentioned, I wanted to do the pitch stop and those bushings, but anything else you'd recommend?

[06wrx4me]

The motor mounts took the biggest amount of slop out of my drivetrain just now. They took as much as the group n transmission mount did when I did it several years ago.

But the group n engine mounts can be a PITA to get to the bolts. One of heads of mine stripped out and I had to use a nut extractor to get it off.

[Mikie13]

Hmmm...I wonder if engine mounts would be beneficial then with my mileage being so high now...

[06wrx4me]

Hmmm...I wonder if engine mounts would be beneficial then with my mileage being so high now...

I bet they would, made a huge difference on my 06 with 86k miles. The mount is physically a different design than the stockers which helps too.

Group N Impreza Engine Mounts 1998-2007, SubaruGenuineParts.com

[Heide264]

Hmmm...I wonder if engine mounts would be beneficial then with my mileage being so high now...

The GrpN engine mounts made a huge difference in mine... even without the mileage FWIW.

I wouldn't worry about doing any of the transmission bushings. The one piece of my crossmember wouldn't come out (stupid 17mm bolt), but I managed to get everything in there anyhow by just jacking up the engine/tranny and moving the pieces around like a puzzle. The only unusually difficult part for me was getting the bolt out of the linkage for the shifter linkage bushings. I had to basically leg press my transmission to the side. Otherwise, I'd say the whole area is easier than getting my stock heat shield off.

I <3 drive line mods =)

[06wrx4me]

Finally this stage 1 clutch is breaking in.

For the first 350 miles, 1st and 2nd gear were an absolute chore. They were grabby, bitchy, shuddery and hated stop and go traffic. I was not a fan.

For the first 400 miles I stayed at part throttle and below 4000 rpm. After 400 miles I did a couple of higher rev pulls but still not WOT.

Clutch now has 500 miles on it and is beginning to feel a lot better. I spent the whole commute home today in stop and go without a problem. 1st and 2nd gear are a lot tamer.

You can tell this stage 1 clutch has better holding power. The car seems to spool faster and feels much more positive under acceleration.

[Drews]

The Diff bushings are a littler tougher since you have to lower the diff and remove some studs. Overall it is not bad, and can be accomplished by backing your car onto ramps, then using a floor jack to drop the diff a little after the studs have been removed.

You don't have to with a rear diff lock down bar.

[06wrx4me]

So it has 1100 miles on it now. It behaves like the stock clutches slightly bitchy sister. It's definitely more positive, engages harder and holds well. Spool seems faster. I have ran it WOT to redline a few times and I'm impressed. Flywheel/clutch noise is pretty much the same as stock.

I did a launch today and let a tiny little bit of smoke out (of the clutch). Broke the tires loose and pulled very well, better than I can remember.

I am convinced the stock clutch has been slipping at WOT in 3rd-5th for quite some time because I can't remember the last time my car pulled this well.

Hopefully it lasts as long as the stock one did.