LIGHTWEIGHT FLYWHEEL AND HEAVY DUTY CLUTCH INSTALLATION

BACKGROUND

After owning my car for 7 years now and having increased the power output and it's use on the track I thought it in my best interest to upgrade the clutch. Many have looked at me askance when I tell them I'm still on the original OE clutch. It's never let me down so why change it? A deal too good to refuse arose and I did like the idea of installing a lighter flywheel. A lighter flywheel has lower rotational inertia and thus spins up faster. In essence allowing more of the engine power output to be transmitted to the wheels - energy to spin up the rear wheels vs. the flywheel. As for the clutch, added clamping force for more reliable power transmission, 'nuff said. I had always had my eye on the SR Motorsports lightweight flywheel and ACT clutch combination. At 9.5 lbs for the flywheel (vs the 22lb OE flywheel) it is considerably lighter yet still remains drivable on the street. The ACT clutch is a HD clutch with 30% more clamping force. The package came with the street/strip disc, which I preferred. Puck clutches are essentially undrivable on the street and are only really intended for 100% racing/drag racing use. Their binary off/on engagement makes them tricky to use smoothly on the street. I had looked into other flywheels, many of which are quite good, Racing beat for example. ACT was the only real choice for a clutch. I did not have a very good experience with the Centerforce clutch(es) used in my 2nd Gen. RX-7. Two clutches in 30,000 miles with only street use. So ACT it was. And now on to the installation. A fairly big job but not one that cannot be done fairly easily with time and the right tools. With a friend/neighbor and a lift it took us about 4 hours start to finish with me taking about an hour to clean things as we worked. If done in a hurry I have no doubt we could have finished in about 2 hours. So on to the details.


INSTALLATION


All the parts for the installation.

What parts I had ready: Flywheel and counterweight with new grade 10 bolts, pressure plate and clutch disc with new grade 8 bolts, new rear main seal, new pilot bearing and seal, new throw out bearing, 3 quarts of redline MT-90 tranny oil, a stainless steel braided clutch line, and some ATE Super Blue brake fluid. The SS clutch line was done at the same time for simplicity. Much easier to change when the tranny is out!

Some simple things to do to the night before to prepare for the work, 1) spray down all the exhaust bolts with PB Blaster or Liquid Wrench, 2) put the car in neutral and do not engage the parking brake 3) I removed the shifter knob, center console, and shifter so everything "topside" was ready to go, 4) disconnect the battery, and 5) leave the car overnight to allow it to cool.

Removing the center console is pretty easy, simply pry up on the rear and it should pop out. The shifter knob is screwed onto the top of the shifter itself. The shifter has a funky three stage rubber boot, the bottom most boot held in place by 4 10 mm nuts. The shifter is held into the top of the tranny with three 10 mm bolts. Piece of cake. Disassembly is easy just remember the order the stuff came out! (sorry no picture)

I won't get too detailed because most is detailed in the TSM but first up, remove the mid pipe/main cat and associated air pipe. Remove the undertrays down the drivers side (1 by the tranny - AL, and 1 in front of the differential - plastic). Disconnect the starter - one plug and the positive cable.


Where to start? High flow cat and air pipe removed.


The only thing to say here really is to be sure to mark (I used whiteout) the drive shaft alignment to the differential input flange. The rear bolts on the PPF do NOT have to be loosened or removed. Basically it's just the removal of the 4 bolts on the drive shaft, the drivers side plastic undertray, and the aluminum X-member.


Stuff to remove from the rear end area.


With the starter disconnected just remove the 2 bolts and nuts and set it aside. Unbolt the front 4 bolts holding the PPF to the tranny. There is also a small heat shield to be removed from the PPF. Before removing the drive shaft drain all the tranny oil or have a plug ready to put in the tranny output. Be sure to drain both the front and rear sections of the tranny - there are TWO plugs. With the drive shaft disconnected at the back and the PPF hanging down maneuver the drive shaft out. I also remove the clutch inspection cover at this point. You can see some oil drips on the PPF. This because I had failed to put thread locker on the three shifter bolts "topside" when I had installed the short shifter and the bolts had worked themselves very loose and thus the oil leak around the shifter seal. Lesson learned.


Starter and Drive shaft removed


Shown below rear differential with drive shaft disconnected and X-member removed.


Parts removal from rear complete.


On a more humorous note, a year or so ago I had a legendary off-track excursion at VIR in a torrential downpour after week of off and-on rain. Traveling at about 70 mph I skated through the mud doing 2 complete 360's coming to rest calf deep in the glop. In any case it took me the better part of a day to clean the mud and grass out of every thing including *inside* the car. However, the detrius will always remain a part of my car. And so the evidence shows as seen below.


Grass from my boating trip at VIR.


Disconnect the wiring bundle on the tranny. Be sure they are all disconnected - I believe there are 4, and be sure they are tucked away well. The last thing you want is to have the entire weight of the tranny hung up by a single wire. Bad for the wire and bad for you if it breaks.


Are you sure you unplugged all the connectors?


The Power Plant Frame (PPF) can simply be angled down under it's own weight with enough room to maneuver the tranny out. I took a good look see at my PPF for any signs of weld cracking also. Many drag racing types have reported these kinds of failures. As expected mine looked fine.


Angle of the PPF angle when disconnected from the tranny.


And now for the good schtuff. (but first remove the clutch slave cylinder from the bell housing - two bolts) Time to pull the transmission. 4 bell housing bolts and disengage the tranny input shaft/throw out bearing from the pressure plate and it comes right out. RIIIIIIIIIGGHT!?! Separating the throw out bearing from the pressure plate is very tricky indeed. With the tranny forward a big flat tip screwdriver must be inserted between the ring clip on the pressure plate and the throw out bearing. The ring clip must remain compressed - it is two pieces that slid apart perhaps a 1/4 inch. If the ring uncompresses it cannot be separated from the throw out bearing. And all this must be done through the inspection port. It helps to have two people. When you know what you are doing it takes a couple of seconds but if you don't you could spend hours trying to separate the tranny from the clutch. Use the new throw out bearing and pressure plate to practice with. With that said, yes, the tranny comes out very easily.


And there you have it - the original clutch


Have you ever had that sinking feeling when working on your car and you drop a nut or bolt and it disappears into oblivion never to be see of or heard again? I had such an experience awhile back removing the intake elbow. Dropped one of the chrome acorn nuts. I listened for it to hit the floor only to be greeted with......SILENCE! Ah nuts. I must have hunted for that nut for at least an hour. Never found it. And the icing on the cake...Mazda no longer makes the chrome nuts, only some generic looking "green" things. So after dropping the tranny wouldn't you know it there it was...the chrome acorn nut that I lost over a year ago nestled into a cranny on top of the tranny!


Missing in action but found at last!


Next simply remove the pressure plate. My flywheel looked pretty good with minimal heat/chatter marks. Might also be a good time to look over the motor mounts while you are up close and personal to the rear of the engine. I also looked over the turbo rear oil line as well.


The OE flywheel with the infamous flywheel nut with a gazzillion lb-ft of torque applied to it.


With fingers crossed and a powerful air tool attack the flywheel nut. I did this with hand tools on my 2nd Gen. RX7 and it took a 3 foot cheater on the end of a breaker bar and two people to break the nut loose. This time around it was a piece of cake. Once the nut has been broken free do not remove it all the way. The flywheel is a press fit onto the eccentric shaft and requires a couple of heavy hits with a big hammer. Cover your eyes as that flywheel rings like Big Ben when hit. When the flywheel lets loose it will literally pop off, and hence the reason to leave the nut still on the eccentric shaft... to make sure it doesn't pop of and drop on your foot! When removing the fly wheel be sure not to loose or damage the keyway also.


Only three hits with the air tool and it was off!


Almost to the halfway point next is to remove the rear main seal (dirty orange seal around the eccentric shaft) and the pilot bearing and pilot bearing seal. The rear main seal is easy but the pilot bearing can be neigh on impossible without the factory SST pilot bearing removal tool. We had such a tool and the pilot bearing came out with ease.


With flywheel removed time to install the new seals and pilot bearing


With the seals out it's time to do a good cleanup and install the new seals and bearing.


THIS is the halfway point.


Look around as it's rare to have such easy access to PIA to change parts. Pictured below the oil temperature/pressure manifold (that nut pictured on the underside is one of those 1/32 of a turn per wrench application type nuts with the car assembled - see how accessible it is with the tranny OUT!), the clutch line to be replaced with the SS line, and the infamous crappy OE oil pressure sending unit. I wish I'd bought a replacement had I known how accessible it would be with the tranny out...live and learn.


Some items of interest.


Time to put it all back together. Yippee! When comparing the new vs the old clutch pulled from the car it was amazing in how good a condition my OE clutch disk was in. Lots of wear left as can be seen by the radial wear lines still clearly visible. In short my clutch could easily have lasted another 30,000 miles.


New hardware vs. the OE hardware.


New seals carefully installed with an SST. It should look like the picture below. Lubricate the pilot bearing with some good high temp silicone grease and place it to the proper depth. Install the pilot bearing seal carefully also...it is very small and fragile.


Nice and clean.


Install the flywheel/counterweight assembly. I torqued the counterweight bolts to 80 ft lbs. Install flywheel nut using the same air tool we took it off with. The torque spec for this nut is ludicrous. When installing the flywheel we had a bit of trouble with the keyway which had a tendency to want to rotate out of it's groove when the flywheel was being mounted. Just a bit of work with the emery cloth and the flywheel slid into place without upsetting the position of the keyway.


SR 9.5 lb light weight flywheel in all it's glory.


Install the pressure plate and clutch disc. Make sure the alignment tool is in place before tightening the mounting bolts. From here on out it's simply a case of putting everything back in the order you removed it. You did remember where everything came from right? Before installing the tranny clean out the bell housing and remove the clutch fork. Check the fork for signs of cracking - they break easily with the use of heavy duty pressure plates. When removing the clutch fork slide the old throw out bearing out with it. Clean the tranny input shaft and regrease and install the new throw out bearing and rebolt the fork back into place. Reinstalling the tranny can be a bit tricky as trying the align the input shaft splines with the clutch is difficult simply because the tranny is kinda heavy but it will go on fairly easily when aligned properly. Then just refill with tranny fluid, 2.6 quarts to be exact (I used Redline MT-90 synthetic gear lube) and start reassembling. As the good books says reassemble in reverse order.


ACT Street/Strip pressure plate and clutch disc...INSTALLED.


And last but not least while I had all this stuff apart I took the opportunity to replace the clutch line with a braided stainless steel variant. I had it...it was easy to install...so I installed it. It is actually an old front brake line. It is a bit longer than the stock line but the ends are the same and it works well.


Braided SS clutch line.


POST LOGUE
After Reassembling all the parts - nothing leftover thank goodness except a pile of snapped exhaust bolts, I started up the car. No grinding noises...a good sign. Ease out the clutch and BAM the car jumps 5 feet and stalls. "Ummm....errrr...it's a bit tight!" A quick adjustment and everything felt great. Short test drive and all is still well. Now it's time to take it to the track after a short break in of course ;-)

After all is said and done I have a couple observations, 1) the right tools make things SO much easier. 2) you MUST have air tools to do this job else you will never get the flywheel nut off. 3) having a lift makes things SOOO much easier. I've helped with this job done on jack stands, do-able but definitely much more tricky. 4) Unless you drag race IMO the stock clutch looks to be perfectly adequate unless you just HAVE to have a lightweight flywheel and have it all apart anyway.



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This page last updated October 3, 2005

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