A Note -
The clutch from the old 240zx's fits it it and is the price as the stock one. Plus it grabs harder because the springs are stiffer. I had one in my car and 60k later am going on my second one. (I beat on my car so... ) But it chirps em in thrid when it's new so you might wanna recommend it to people. Both times I have had 'Pierre Z' of Hawthorne do my clutches and they know their shit and do a great job.
The Clutch Install
I have a 91. The process is quite easy. But set aside a lot of time, and have a strong guy who knows something about cars. It took me a total of 6 hours of labor to do the job. Find a shop that will resurface your flywheel ahead of time, and make sure they will be open when you plan to have your flywheel out. I recommend pulling the tranny and flywheel in the afternoon of one day, or at night, as long as lighting is sufficient. This way, even if you run into problems, you can work all night to get the flywheel off. Drop the flywheel off in the morning so you can be sure you can get back to it that day.
Parts you will need:
Lithium based grease
The biggest bottle of GOJO/handcleaner you can buy(LOL)
Tools you will need:
Open-end wrenches (metric)
Socket wrenches (metric)
Clutch alignment tool
Pilot bushing removal tool (w/ Slide hammer)
Needle nose pliers
1/2-inch drive socket wrench or breaker bar.
Tranny lift, or Floor jack
First off lift your car and be sure to use jack stands to secure the car. Disconnect the negative terminal of the battery. Drain the tranny fluid. This is done by inserting the end of a half in drive socket wrench into the drain plug underneath the tranny, and unscrewing it. Remove the entire shift lever assembly. Youll have to remove parts of your dash until you can get to it. Inside the tranny, you'll see a retainer ring holding it in. You'll have to use some needle nose pliers to squeeze the ends together, and pull it out. There is a tool made to do this, but I don't know what it is called, and most people do not have access to one. It may be kind of hard to remove it. Next, remove the driveshaft. To do this you have to remove the bolts that hold it together with the 3rd member (differential) and the crossmember holding the center of it up. The end attached to the tranny will slide right out. Be prepared to catch some oil. Disconnect all the wiring harnesses that go into the tranny. You'll need to remove the speedometer cable as well. Remove the starter. Remove all of the bolts that attach the bell housing to the motor. Some are hard to see. Take you're time and make sure you get all of them out. Support the transmission with a jack. Remove the crossmember under the tranny. Slide out the transmission 1-2 inches. You may need to pry with a screwdriver. You shouldn't have to force it. If it does not come out make sure you got all the bolts off. Once you have it out slightly, rotate the transmission about 180 degrees. If you don't, the tranny will not clear as you slid it out. Make sure you keep the jack supporting the weight as you do this. You don't want to put a heavy load on the input shaft. Once it's upside down, you should be able to slide it out. Again, keep the weight of the tranny on the jack. It helps to have a friend help you with this. You may need to maneuver the tranny a bit as you slide it out. Once it clears, lower the jack and you should be able to wheel the tranny out on the jack. Now you should be able to access the clutch. Put the clutch alignment tool in the disc. Using a socket wrench, slowly loosen the bolts holding the pressure plate to the flywheel. Do each one in sequence a little at a time to release pressure slowly and evenly until it comes off. Take off the disc. Remove the flywheel. This is a lot easier with an impact wrench. Take the flywheel in to be resurfaced. This is a good time to clean the tranny. Be careful not to get any water in it if you spray it with a hose. Next you need to remove the throwout bearing. Just slide the unit off. The arm seems to be attached, but pull and it will come off. Hold the arm in place though. The bearing itself will have to be removed from the carrier (I'm not sure what the technical word for this part is, but you'll know what I mean when you see it) that it is attached to. I removed it by sticking the bearing in a vise, and finding a socket that matches closely to the inside of the bearing, and knocking the carrier out by hitting the socket with the hammer. Make sure to note which way the bearing faced before you remove it. To get the new one in place, place the carrier on the new bearing, on a block of wood, and gently tap it in using a hammer and the same socket used before. Pack some lithium-based grease into the inside of the T.O bearing assembly's shaft. Also put grease onto the shaft itself, and take the old clutch disc and slide it back and forth on the splines of the input shaft to remove excess grease. You will need to put grease on the contact points of the clutch fork arm, and behind it on the fulcrum. Reinstall the T.O bearing assembly, and make sure the clips are in the correct place. Now, to replace the pilot bearing, you need a slide hammer with a pilot bearing attachment. Pep Boys rents tools for free, so I just borrowed it from them. Once removed, place the new on in using a socket of similar size, and a hammer, and gently tap it in until it stops. Put the flywheel back on. I also used the impact wrench to do this but I believe you are supposed to torque it down. I was not able to, so I guessed. Place the new clutch disc on by using the alignment tool to hold it in place. Install the pressure plate. You will have to do this slowly, as there is pressure, and you want it to go evenly on the studs. The hardest part now is to get the tranny back in. It is essentially the reverse of removal. But it will take some heavy-duty feeling around and pushing, pulling, and turning to get it in. Make sure you don't rest the weight of the tranny on the diaphragm of the pressure plate. You definitely do not want to damage it. Use the jack to support the weight of the tranny, and only use you hands and arms to position the tranny. It will take some time to get it to line up just right. Everything else should be reverse of removal. Just try to remember where all the nuts and bolts are supposed to go. As a suggestion, especially if this is the first time you will be replacing a clutch, READ THE MANUAL! READ IT MANY TIMES. READ IT UNTIL YOU MEMORIZE THE PROCEDURE. It's hard to keep getting out from under the car and flipping through the pages with dirty hands. Make sure to use loctite on the driveshaft to differential bolts, so that they don't come loose while you are driving. Also when loosening and tightening the driveshaft bolts, set the parking brake so that the shaft does not turn while you are trying to wrench on it. It helps to have a friend help you with this, as you'll need him to set and release the parking brake as you are doing this. There are 4 bolts and you'll need to be able to turn the shaft as you go along.
Simon Kim had recommended the ACT pressure plate and their street disc. They ran out on me, and I desperately needed one, so I chose the JWT unit. I still have to break it in, so I won't know the results until then. 450 miles to go. =)
ACT has the T.O Bearing and pilot bushing, but you may want to check
the Nissan dealer
for these parts. I found it cheaper there, and I didn't have to pay for freight charges on them.
I had used a Centerforce unit before, on my 83 Celica. I liked the clamping force, as it was strong enough to break my differential gear, and a tranny gear. This was only the 30% increase clutch. As far as the dual friction, I wouldn't because of my experience with the Stillen unit. I'm not sure if it was because of the Kevlar material, or poor quality, but I have decided to stay away from fancy materials until I absolutely need it. My Centerforce unit was quite stiff though. I had to use a pretty good amount of force to push down the pedal.
Hope this is of some help.