I installed a centerforce dual friction clutch in my '95 today. A Big Thanks to all of you with tips on the things I would need to make this a successful project!!! Here are a few things I learned along the way. I am assuming you have a workshop manual. I am only mentioning the things that I did different from the manual.
Drain the transmission prior to doing the job. I did this the night before. You don't need to remove the undercover. I left it on with no troubles. You need to remove the exhaust from the header back. Spray the bolts on the header flange with a penetrating oil. You should do this the night before as well to give it plenty of time to do its job. When it comes to the clutch release cylinder,the starter and all the wiring brackets and such that are attached to the tranny. Don't remove them! Just undue all the bolts and swing them out of the way. There is no reason to totally remove these items. The starter can remain in its place. Just remove the bolts that hold it in place.
The Power Plant Frame: This is the large steel structure that supports the rear of the tranny and the differential. Remove the wiring harness from it, remove the bolts that attach it to the tranny and the differential. Move the harness out of harms way. When you are ready to remove the transmission just lift on the rear of the tranny, disengage the PPF from it, and the transmission can be slid out without removal of the structure. I was using a floor jack to support the transmission. After screwing around with this for a while I removed the jack(while supporting the tranny with the PPF. This next part may not be for everyone but it worked great for me. Just remember that there is a certain amount of risk in removing or installing the tranny by hand. If the input shaft is engaged with the clutch and you drop the tranny there is a chance of damaging the clutch and or bending the input shaft. Be Careful!! I removed the PPF and while holding the tranny up with my arms I just slid it out and on to my chest. I don't know what it weighs but I was able the bench press it with no trouble (100lbs??). I then just slid it off my chest and on to the ground.
The car has 2000 miles on it. The flywheel was completely unmarred. I used emery cloth and burnished the flywheel after removing the old clutch. I used an input shaft out of a RX-7 as an alignment tool. It worked perfect, 22 splines.
I re-installed the tranny the same way. Just bench pressed it up into position and it slid right in. You then just install one of the 17mm bolts in the top of the tranny and one into the bottom while holding up the rear of the tranny with your other arm. After those two bolts are seated hand tight, engage the PPF with the rear of the tranny to support it. R
e-assemble all components in opposite order. Follow factory specs. on torquing.
THAT'S IT!!! Since I haven't put the autorotor on yet I really can't tell any difference. The new clutch is Smooooth. Engagement is silky. Clutch pedal force seems about the same. If anything it may be even easier. It's so close that it's hard to say.
Total install time - 6 hours.
I did a clutch change this weekend replacing the stock 1.6 unit with a stock 1.8 unit on my '90. After reading the write-up from Charles Fearneyhough in the Miata.net Garage section I have some other thoughts and suggestions. While his ideas and suggestions are excellent, they may not be for everyone. I did this with (a lot) of help from Ron Serikaku of the power list. Ron has quite a bit of experience with removing his motor (he has had it out 2 (?) times) but has never removed the transmission. Each time he removed the engine he replaced the clutch so dropping the tranny was never an issue.
Our total time from breaking the first bolt to placing the car back into gear for the test drive was 9 hours. Considering that neither of us had dome a Miata specific tranny drop we were learning as we went. If the two of us were to do it together again it would probably be closer to 6 hours. Again this is assuming (as did Charles) that you have a good general knowledge of what really needs to be done. I would recommend the Mazda shop manual as a reference (we used it quite a bit in identifying various bits and pieces).
**Make sure you are familiar with *all* of the necessary steps in changing the clutch before starting.**
The Mazda part numbers for the throwout bearing are the same between the 1.6L and 1.8L but I don't know if the pilot bearing part numbers are the same. Most people already accept this as common knowledge, but there are some out there that don't know for sure (myself included before this weekend).
As Charles mentioned, the complete removal of the Power Plant Frame (PPF) is not necessary. We removed the wiring harness from the PPF but found that it wasn't really necessary at all. After unbolting the tranny from the PPF we also unbolted *one* of the bolts connecting the PPF to the rear differential and loosened the other without removing it. This allowed us to swing it out of the way without having to worry about realigning it when putting it back in. It also let us use the PPF as necessary to support the rear of the tranny.
After removing the shifter assembly from the shift turret we covered the turret with a plastic baggie and wrapped/ sealed it with a rubber band to prevent any fluid loss from the turret. We did the same with the rear of the tranny after removing the drive shaft. We didn't drain the fluid before doing the job, and if we hadn't had a slight mishap, we wouldn't have needed to top it off when we finished. We did have a small spill from the rear but it was caused from operator error more than anything else. Without the spill the total loss of fluid from the tranny would have been limited to a few ounces at most. Have an extra quart of fluid on hand just in case...
Getting to the top bolts of the tranny was difficult. We used all of the available 1/2" socket extensions in Ron's garage (about 18" worth IIRC) with a universal joint on the end and attacked the bolts from under the car. It's a pain in the tuchus to do these two monsters, but this seemed the only way about it.
After unbolting the tranny and associated bits and pieces from the engine and PPF (we had it supported with a jack stand) we started lowering it. We had a hard time finding the center of the tranny so we had someone in the cockpit of the car holding a rope tied to the rear of the tranny running through the shift turret hole. He lowered the rear while we steadied the front on it's way down. We were going to try Charles' bench press method but we were limited on space under the car. Once the floor jack had gone all the way down we lifted the tranny off of it and slid it out of the way. We then pulled the tranny from behind to the rear of the car so that the bell housing was parallel to the sift turret hole. This gave us ample room to work on the flywheel.
After removing the six bolts that hold the pressure plate to the flywheel it was time to remove the flywheel itself. Unbolting the flywheel can be a PITA if you don't have a way to lock the crankshaft from turning. We made a "tool" out of a piece of angle iron scrap that was about 4' long. We drilled corresponding holes to two of the pressure plate bolts and bolted it to the flywheel so that when turning the crankshaft the "tool" would contact the ground and lock the flywheel.
**NOTE**: If you are removing the flywheel and plan on cleaning it, use brake cleaner (opposed to carb/choke clean, WD-40, etc.) as it dries fast and doesn't leave any residue. Also note that you should be *extremely* careful not to spray *any* cleaning solvent directly on the pilot bearing. You will wind up spraying the grease out of the bearing. Trust me on this one. Of course if you have a new pilot bearing you can do anything you want to the old one...
Replacing is the same as removal. We used our flywheel "tool" to lock the flywheel so we could torque the flywheel bolts properly. We used an alignment tool to get the pressure plate and clutch in straight. If you don't have an alignment tool you *may* (no promises) be able to get away with a socket that is the same outer diameter as the inner edge of the pressure plate fingers. Use a long large screwdriver to hold the socket in place and keep everything aligned while you tighten down the pressure plate.
Pretty much reversed as removal including the person in the cockpit "ice fishing" the rear of the tranny while jacking the front. When we removed the tranny it released an decent amount of weight on the engine which allowed the engine to "spring" forward on the engine mounts. Ron pushed down on the back of the engine from above while I slid the tranny into place and finger tightened two of the tranny bolts.
Back to the Garage
After struggling in vain with extensions & a universal, I found that the top two bolts are MUCH easier to get to from up top. I used my 3/8 drive breaker bar and standard short 12 pt socket. The breaker bar must flex past 90 degrees to clear various obstructions on both sides. With the judicious use of a cheater pipe, the top two bolts were the proverbial piece of cake.
I just did the clutch on my 1990 Miata last weekend, and I used (3) sources of information: The factory manual, a Chilton's manual, and print-offs from Miata.net articles. I have done one other clutch before, so I simply used these as a review of the specifics of the Miata clutch replacement. One thing I didn't see in any of these is that the clamp holding the exhaust to the transmission clutch housing has a threaded nut wleded to it which is NOT removable. I spent some time pushing a wrench around on it before I realized that the only way to get that clamp loose (aside from taking the bolts out of the bell-housing) is to remove the bolt going through it. As I realized, the nut doesn't turn. It should also be said that you should wait on installing and torquing those two transmission bolts holding the clamp until you've installed the calmp bolt, as you'll have a very difficult time otherwise.
Another observation I had is that the clamps holding the wire harness and slave cylinder line to the transmission we're a bit confusing to me when trying to reassemble the transmission to the engine. It took me a while to realize what their arrangment was supposed to be, so pay attention when you're taking them off.
This job took me about 12 hours (I did it by myself, with my wife helping me a couple of times by handing me bolts as I put it back together, but no major help). I have only done one other clutch job, on a '95 Toyota 2WD pickup. I would rate the miata clutch job a much easier one, as you can actually get the transmission supports out of the way to remove and install it, vs the Toyota which had a cross member right underneath the tranny welded to the frame, making removal and installation a NIGHTMARE.
My major revallation from Miata.net (and as others have said, many thanks) is finding out I DIDN'T need to remove the PPF, a step which I was dreading as the factory manual says that of you desroy the bushings you're not supposed to remove, you have to replace the PPF as an assembly. Yikes!
For the record, I got my flywheel ground at a Napa store that did machine work for $32. A new flywheel from Mazda was over $300, per the price quoted by a local Jacksonville, FL dealer.
One more thing is that I have an air compressor and air tools, and they DO make the job easier, especially upon disassembly (when re-assembling, nothing's stuck anymore, so it's easier, but the impact did help a great deal on pulling the tranny up to the motor). Beg, borrow, rent air tools and you CAN do this job. Per the article on Miata.net, I did use universal swivels (impossible, I would think, not to), but I had (2) of them, which made it easier. However, (1) is perfectly adequate.
16 October, 2004