Clutch and Flywheel Change Review

• Preparation part 1: Get the parts There are quite a few options out there for miata clutches, ranging from the 2 OEM units, beefier units from Mazda Competition, MAX-5, FM/ACT, and so forth.
• Prepartation part 2: Get the tools I have done two jobs so far: the first without air tools, the second (Tatjana) with air tools. Air tools rock. Nuff said. In either case, the most important tools are several 1/2" extensions between 3 and 12 inches, as well as a universal joint. To get all of the tranny bolts, you require to play extension games. Having air here really makes live easy. A clutch alignment tool should come with any aftermarket kit. For OEM, just pick one up or borrow one.

  Additionally, if you decide to remove the PPF (which is how I like to do the job), a SST is required to easily get the PPF out of the rear. This is *NOT* covered in the Miata Enthusiast guide. Its possible to tap the slider out of the top of the rear end, but having the SST or equivelant makes it much easier. Basically, the SST is just a special threaded bolt that helps pull the slider down out of the rear PPF mount. This is much easier to see in the Mazda shop manual. For my 92, that is page J10 and in more detail, J12. This SST can either be ordered, or if you are smart, you just go and by an M14x1.5 bolt that is pretty long, and thread it up. This will pull the sleeve down. Then, a short M6x1 is used to lock the sleeve while the M14 is removed.

  If you are going to remove the rear main seal, a simple seal puller tool is handy. I got one for $6 from Harbor Freight. The other seals are easy to get with a screw driver

  If your tranny is as oily as mine was from 10 years of a slow leaky CAS (I changed it....previous owner did not :), some rags and a bottle of Gunk cleaner is a good idea. I worked on the tranny and PPF for 30 minutes to make it a bit cleaner.

• Preparation part 3: Read up If you are reading this before the job, you are off to a good start. Miata.net has some good tips, as well as both manuals. The Enthusiast manual is a good read for a step by step (with the exception of them not mentioning the rear slider on the PPF mount, as noted above). The shop manual just has a few pictures, and as usual, is not that handy but a good reference for torques, etc.

• C-Day: Time to get dirty
  • Do a part check. Do you have the tools? 2 quarts of tranny fluid? (I used Redline MT-90 from Finishline) Rags and towels? Band Aids?
  • Jack the up as high as you can. The more room under the car, the less cramping you will have. I used larger 6 ton jack stands to get the car very high rather then smaller jack stands extended in full. This requires a two step jacking process. A few hockey pucks are a good tool to put on the jack and get the car a few inches higher when jacking the car up the second time (after its on the stands with their low setting)
  • You probably will want to take the exhaust and downpipe out. This is one place that may cause issues as there is a bracket on the stock downpipe that attaches to the tranny. Often, the bracket bolt is rusty. For me, I have the FM downpipe that does not use this bracket, so I did not need to do this (though I did have to unbolt the downpipe from the turbo housing).
  • I chose to remove the PPF as the manuals both suggest. Just more working room, and not that big of a deal IMHO.
  • Put all nuts and fasteners aside and LABEL the bags. In some cases, you can just re-attach the nuts into the assemblies for safe keeping, such as one of the PPF brackets to the frame, or the rear drive shaft bolts and washers
  • When you loosen the clutch slave cylinder, you can see some of the starter bolts from that angle.
    
  • When you are ready to attack the tranny bell housing, have a sharpie on hand to label bolts, and get ready to remember how things look. Here are a few pictures of the starter bolts and how they are arranged.
    
    
  • Label all bolts that come off, especially the longer 17mm tranny bolts, in the order they came out. Not all the 17mm bolts are the same size. This picture shows an example of an ordering. Note the small spot where the downpipe bracket goes into the bell housing: it does not support the tranny at all, which is how turbo folks can do away with it.
    
  • Use some rope to help support the tail of the tranny once the PPF is out of the way via some object (like a breaker bar) in the cockpit. Don't use rope that is too thick: 1/2" is fine, as you will have a tricky time with clearance into the cockpit from the shifter opening.
  • Once the Tranny is out, an air gun makes quick work of the pressure plate and flywheel to gain access to the rear main seal. Careful when taking off the pressure plate so that the clutch disc does not drop on you. Additionally, the OEM flywheel is 17lbs for the 1.6, 19 for the 1.8. Have a helper support it while you remove the final bolts.
  • I used the seal puller from Harbor Freight to hook the rear main seal and pop it out. Mine was dry after 100K, but its an easy $15 preventative part. Apply a thin amount of oil to the sides and slide the new seal on. Gently tap it down with a rubber mallet/wooden handle to seat the seal.
  • With the tranny out, now is a good time to clean the area by the clutch release fork. It was a mess on my car, probably residue from that 10 year leaky CAS. The front tranny seal can be changed as well, although you need to gain access to it being the plate identified in this picture. You may want to order a replacement paper gasket for this, as the gasket is very thin and easy to rip (and mine was pretty dirty). This seal pops out rather easily with a small sharp object. Replace the throwout bearing on re-assembly with a bit of grease as well.
    
  • Clean the outside of the tranny as needed. You can also drain the shifter turret oil with that nifty drain bolt, rather then turning the tranny upside down. That train bolt is not accessible normally due to the PPF. The wiring clips in red were a PITA to get loose from above before removing the tranny. At least polarity does not matter when re-installing. Remember the shift turrent takes 90cc of fluid, give or take.
    
  • While you are at it, replace the rear tranny seal. It should pop off without much fuss. Do you like the close up pic? You can really see the sand grains in the oil sludge from the previous owner's driving (New Jersey area).
    
  • When installing the flywheel and pressure plate, use star patterns when torquing the bolts down. For the pressure plate, a large tipped screwdriver pinned between flywheel teeth will hold the flywheel in place well enough to torque the pressure plate bolts. The BFS is a tool everyone should have to complement the BFH.
  • After re-installing everything, and double checking things like the wiring harness, speedometer cable, rear ground cable on the power plant frame (you did clean the ground area while you were there, right :), go out for a spin. If you used an aftermarket clutch, its probably that you will need to adjust the pedal rod length so you can fully release the new clutch from the flywheel since the pressure plate is likely stiffer. This is not that hard, and covered in the manuals. Two nuts are locked together. Break one free, and extend the rod lenght a bit. I needed 4-5 full turns of the rod for my Max-5, which was having trouble fully engaging on the inital test drive. Now she works like a charm, and grabs a bit off the floor, but not in the middle of the cluch range. Adjust to your liking.
• Lightweight Flywheel: I took advantage of the clutch change time to also replace the flywheel. Instead of $400-$500 for a nice aluminum or chromoly unit, I simply picked up a used 1.6 OEM, and had a local machine shop trim the back ring off and balance the unit. This cost $100-$150 from typical shops, depending on rates and who you know. You end up loosing 3-4 lbs. Its noticable on my car, but only slightly. I would need to drive a 8-9 lb car back to back to tell the difference in greater detail. Here are a few pics of the flywheels, with a 1.8 OEM unit thrown in for good measure.