All the usual disclaimers apply . . in short, do this at your own risk, blah blah blah. Also, people have different methods of doing this job, and I have mine.
Replacing your clutch really isn't that hard; the actual swapout literally takes maybe 10min. It's all the stuff you have to remove to get to it that makes the job a pain, then putting everything back together. Two things to remember: 1) take your time- make peace with the fact that this will not be a quick job, and 2) use the proper tools. For example, don't try and use vice grips to loosen nuts and bolts, or try to loosen a nut from a weird angle- make sure the socket is properly seated onto the fastener. Use a universal joint wherever needed, and use PB Blaster or WD40. If you don't take this advice, you'll be sorry- nothing will grind your progress to halt worse than a stripped fastener.
The three main components that are typically replaced in a clutch job are the clutch disc, pressure plate, and throwout bearing. For this reason the 3 are sold as a "clutch kit" by many vendors. Another part you should consider replacing is the pilot bearing, but beyond that, the other parts that make up the clutch mechanics don't really wear down as hard: the fork, pivot pin, spring clip, and guide tube. As far as specialty tools, you'll need external torx socket set for the transmission bolts, and a clutch disc centering tool. I got both from Pelican Parts. You'll need a flywheel lock tool only if you're removing the flywheel (which I did not). Lastly, you'll need a few different lengths of ratchet extensions, ranging from 6" to 10", as you'll have to join them together to reach the upper tranny bolts. Make sure you can span at least 2ft with them, and have universal joints handy because you may need to make some bends along the length. Get some baggies to organize and label all the nuts and bolts you’ll be removing. I wrote the socket size and torque spec on the bags for easier reinstallation. Torque specs are given at the end of this writeup.
Raise the car whichever way you like, just make sure that what you do is solid and stable. My ghetto method employed cinder blocks for $1.40 each. What you see in the photo is 9.5" from the tires to the ground, which gives ample clearance to work underneath. If you follow my method, you'll have to raise the rear a little more when you disassemble the guibo; the rear wheels will need to free spin. More on this later . .
First step: remove all this crap. The exhaust is best dealt with by dropping it in one whole piece from front to back. The connection points are easy enough to find, so I won't go into that. Careful with the nuts on the exhaust manifold- hit them with PB Blaster first, let it soak in for a half hour or so, and then attack them. A breaker bar works well here- leverage is your friend. Disconnect the O2 sensor harness(es) before you drop the exhaust!!
Leave the sensor(s) attached to the exhaust pipe. Once the assembly is off, remove the large heat shield- 6 bolts hold it to the chassis.
Remove the clutch slave cylinder (2 nuts) and unclip the wiring harness for the backup light switch. Release the O2 sensor harness(es) from their brackets on the transmission crossmember, if applicable. Tie everything up and out of the way.
Support the tranny with a floor jack and remove the tranny support bracket (crossmember). Leave the tranny bushings intact; just loosen its top nuts to slide the assembly off. Note the dirt circles in the photo left by the 4 bolts on the crossmember. This is how you'll line the crossmember back up when reinstalling. If your crossmember doesn't show this, then outline the bolt positions with a Sharpie before removing.
Before you disassemble the guibo (flex disc), mark the parts of the assembly to make sure you put them back in the same orientation- one mark on the tranny output flange, one on the guibo, and one on the driveshaft flange. White Out or white electric tape works well. If you screw this up or your marks come off, here's how to figure it out: note the alternating arrows molded onto the edge of the guibo. Each arrow points to the side where a corner of each triangular flange should go. And if you wanna be anal about it, the nuts should go on the flange side and the bolt heads should go on the guibo side. The theory is that the nuts have less surface area than the bolt heads, so the flange acts to increase it. But that last part isn't overly critical; neither end sees much stress because the guibo flexes. Mine were all faced in the same direction, so I left them that way.
You'll need to turn the driveshaft by hand to access each nut and bolt assembly, so make sure the rear wheels can spin freely. Use an open end box wrench on the nuts, as a socket will not fit in there. If your bolts are as hard as mine were to loosen, your hand/arm strength won't be enough to keep the whole thing from moving . . that is, if your driveshaft has some play and your parking brake isn't strong, as was the case with mine. You can position the driveshaft such that you can wedge the wrench against the tranny's bushing mounts as it holds the nut, while cranking on the bolt on the other end with a ratchet and socket. These self-locking nuts aren't supposed to be reusable, but if you do use them again, apply a threadlocker such as Loctite 262.
Use a Sharpie to outline the bolts and bracket of the center bearing before removing it. It should be put back in the same orientation to keep the driveshaft aligned. Ultimately, this means it should be centered and pulled forward- there should be no slack at the rear section of the driveline. So if you mark it before removing, there should be no worries.
Now remove the rear cross brace. Arrows in photo point to the 4 bolts. Support the driveshaft with jackstands, and loosen up the guibo coupling to release and lower the entire driveline. Never let it hang unsupported- you can damage the u-joints or the rear flange.
If you're changing the tranny fluid, now is a good time to drain it. It’s easier to turn these plugs while the tranny is still attached to the motor.
You'll now have enough room to take the shifter assembly apart. All you need to detach from the tranny is the shifter arm and selector rod. The clip/pin that holds the shifter arm to the tranny is kinda hard to figure out since you can't see from underneath how it works. All you'll see is the clip, as shown in FIG. 1. In FIG. 2, you can see how it comes off- this shot was taken after the tranny was dropped. FIG. 3 shows the two circlips that have to be removed in order to pull the selector rod off. Use a screwdriver to pop them off in the direction of the arrow shown in FIG. 3a. Don't lose the yellow washers. Then slide the selector rod out as shown in FIG. 4.
Finally, you’re on to the transmission itself, which should still be supported with a floor jack. DISCONNECT THE BATTERY (-) CABLE BEFORE THIS STEP
or you will get the shock of your life when you mess with the starter! Some bellhousings have 11, but mine only had 10 bolts. Except for one on the passenger side (which was a standard hex head), they’re all external Torx bolts. Which is a good thing, because the sockets tend to stay on them better. This means you can reach in through the engine bay, place the socket onto the bolt head without it falling off, then come back underneath the car and attach the extensions and ratchet onto it- you’ll end up doing this for the upper bolts on the driver’s side. Unless of course you have a helper (I didn’t). In the photo above you can see how the ratchet extensions come from the back of the tranny all the way up front to reach one of the starter bolts. To get more room in the engine bay, remove the MAF sensor, intake bellows, and throttle position sensor harness. You’ll be able to get your hand down in there to reach. The very top bolt will be difficult, and some of you with large hands may have to remove the intake manifold altogether. I didn’t, so I’m not gonna get into that.
And speaking of starters, there are two ways BMW mounted them. Some have threaded flange holes on the starter (easy), and some have thru bolts with a nut on the starter side (bastards!). If you have the latter, you may have to have someone hold the nut on the engine side while you unscrew the bolt on the tranny side. I was able to just loosen the nut and bolt, then come around to the engine bay and undo the nut by hand while keeping a finger on the bolt head. To prevent this nightmare when reinstalling, get a lock washer (tooth washer or split ring washer) and slide it onto the bolt end before threading on the nut. This way, once the nut is on finger tight, it won’t spin while you torque the bolt head. Note the starter guide pin in the photo below. This lines up the starter when you reinstall the tranny, more on this later . .
Now that you have all the bolts disconnected, you should be able to just slide the tranny out towards the rear and away from the engine. It may take a little wiggling, but it’ll move. The Bentley mentions using an engine support to stabilize the motor- don’t worry, you don’t need it. The engine will just shift backwards slightly and come to rest on the firewall. Drop the tranny nice and easy, but keep it upright because there’s a pressure vent on the side that will leak fluid out if you don’t. It only weighs about 75-80lbs, so don’t be afraid of it. The photo above shows the spring clip, fork, and throwout bearing inside the bellhousing. The clip is attached to a plastic pivot pin hidden behind the fork. Coat the new throwout bearing and the guide tube it rides on with lithium grease before putting it on (inset photo).
On the engine side of things, you’ll see the pressure plate. Remove the 6mm socket cap screws highlighted in green, and pull the pressure plate off the guide pins. The clutch disc just sits in between, and will fall out once you do this.
Here you see the pilot bearing sitting inside the center bore of the flywheel. You don’t need a puller to remove it; just stick your pinky in there and pull it out. If it gives you trouble, that means it’s a little crooked coming out. Just tap it back with the handle end of a screwdriver to straighten it, and try again with your finger. As long as it’s straight in the hole it’ll come right out. This is a sealed bearing, so no lubrication is needed- just install the new one and push it back as far as it will go. Here’s a pop quiz for you more experienced members: what other unrelated problem do you spot in the photo??
Clean the mating surface of the flywheel; I used rubbing alcohol for this. Place the clutch centering tool through the center bore of the new clutch disc, and hold it in place, centered over the flywheel’s center bore, while you slide the new pressure plate onto the guide pins. As you replace and tighten down on the pressure plate screws, it will sandwich the clutch in between. Cross-tighten the screws the way you would tighten the lug nuts on your wheels, alternating opposite sides. Once they’re all torqued down, you can remove the clutch centering tool.
That’s it, time to put everything back together in reverse order. Ease the transmission back on to mate with the engine. Remember that starter guide pin I mentioned? Keep an eye on it and make sure it goes into the starter flange correctly, or you’ll end up pushing the starter forward and the bolt holes won’t line up. While you’re reinstalling the driveline, sight it from front to back to see that it runs straight along the whole length, and centered in the chassis tunnel. If you marked the bolt positions as mentioned earlier, you should have no trouble. When installing the exhaust, get all the fasteners loosely in place first, then check to see that there is at least Ĺ” clearance everywhere there’s close contact with the chassis. Then tighten everything down. Once you’re all done, reconnect the battery cable and start her up!
Quick note: when universal joints are used with torque wrenches, they change the torque value as the drive angle increases. In such cases, I added 3-4 ft-lb to the specified value (this increase is not reflected in the list below). I didn't use science for this, and I don't know exactly how this is calculated, but you may want to do the same. "M" numbers below refer to the thread diameter of the fastener in mm.
-manifold nuts: 22 ft-lb
-support bracket to transmission: 17 ft-lb
-center hanger brackets: 17 ft-lb
-rear muffler clamps: 11 ft-lb
-heat shield: 11 ft-lb
-guibo nuts & bolts (grade is stamped on the nuts):
M10 (8.8 grade): 35 ft-lb
M10 (10.9 grade): 47 ft-lb
M12 (8.8 grade): 60 ft-lb
M12 (10.9 grade): 74 ft-lb
M12 (10.9 grade, M3 models): 85 ft-lb
-center bearing mounts: 16 ft-lb
-rear cross brace: 17 ft-lb
M8: 17 ft-lb
M10: 31 ft-lb
-bushing mounts: 16 ft-lb
-drain/fill plugs: 37 ft-lb
-clutch slave cylinder: 17 ft-lb
-transmission to engine bolts (external Torx):
M8: 16 ft-lb
M10: 32 ft-lb
M12: 53 ft-lb
-pressure plate screws (grade stamped on bolt head):
M8 (8.8 grade): 18 ft-lb
M8 (10.9 grade): 25 ft-lb