High Performance Clutch
This clutch came from Fly'n Miata. The manufacture of this clutch is Clutchmasters and sold as a "stage 2" clutch. FM no longer carries this clutch, however it is still available from Clutchmasters. Apparently due to some quality control issues w/ this clutch, FM eventually decided to go w/ the ACT clutch in place of this. Fortunately, I was one of customers who received a properly working Clutchmasters unit.
The pressure plate is made of a carbon kevlar material. A couple interesting characteristics about this material: (1) It has low friction characteristics. Huh? Why use a low friction material? Well, that's ok, because of: (2) It has excellent wear characteristics. The pressure plate that comes with the clutch grips the disc a lot harder. Since the disc can withstand the stronger pressure plate stresses, it holds up fine and doesn't (normally) slip under the loads I apply to it. The pressure plate is stronger because the leaf springs are stronger. The heavier spring force is not significantly felt in the clutch pedal because the fulcrum point of the springs is in a slightly different position from stock. The tradeoff is an increased in clutch pedal travel. It's not that much... maybe an inch or so. I got used to it immediately. Pedal effort feels close to stock; very comfortable and great for driving around town.
Engagement of the clutch is pretty smooth. It's a little hard to chirp the tires going from gear to gear, but that's better on the drivetrain anyway.
After about 45k miles of use including several autocross events and my "spirited" driving style that creeps up from time to time, the clutch held up quite well. The picture at the top of this page was at about mile 45k. You can see some wear marks probably from some hard launches. If I do lots of really hard shifts, the clutch can sometimes "heat up" and get a little soft. When this happens it tends to slip a little bit until it cools down. This is a pretty rare problem for me. Actually, when this happens, it's because I've been driving really too hard on the car - I take it as an indicator of drivetrain telling me, "Whoa!! Take it easy!"
Here's my old stock clutch. The disc was worn down to the rivets. Although the flywheel wasn't in bad enough shape for turning/replacing, it would have been had this problem been neglected much longer. Of course, the clutch slippage was so bad at this point that there was no question that it was time to replace it. The picture above shows the pressure plate at the top and the disc at the bottom. The Fly'in Miata kevlar clutch replaced both of these items.
After 65k miles/5 years of fairly hard use (MANY autocrosses, a handful of lapping days, and a few spanked Mustangs), my Clutchmasters kevlar clutch reached end of life. I ordered an ACT clutch from Flyin Miata which includes the disc, pressure plate, new throw out bearing and pilot bearing. At the time of this writing, the order was just placed and the old clutch was removed. My good friend Jim Sawyer offered to let me use his clutch from his wrecked miata which is a 1.8L version. We're not certain who the manufacturer is of his clutch, but pedal effort was similar to the Clutchmasters. Below is a comparison of a 1.6L clutch disc, pressure plate and flywheel to a 1.8L version. 1.6L is on the left. For more info on clutches and drivetrain differences, see Randy Stocker's website: www.solomiata.com.
Notice the differences between the 1.6L and 1.8L parts? The pressure plate for the 1.6L mounts on the same plane as the disc surface of the flywheel. For the 1.8L, the flywheel has standoffs for the clutch to mount to. This looks as if the 1.8L would vent heat from the disc a little better.