Competition Clutch 2006-2015 Mazda Miata 12.20lb Steel Flywheel

The Competition Clutch 2-10060-ST is a 12.20 lb one-piece steel flywheel for the 2006-2015 Mazda MX-5 Miata, the NC chassis with the 2.0L MZR engine. Most NC owners land on this part one of two ways: the clutch is being replaced and the original flywheel shows hot spots or shudder, or the car sees autocross and back-road duty and the owner wants the engine to pick up and drop revs faster without turning the car into a race-only machine. This ST version is the street-weight option; Competition Clutch also makes a lighter STU version for the same car.

What the flywheel does in an NC Miata

Bolted to the back of the MZR crankshaft, the flywheel is the friction face the clutch disc clamps against, the carrier for the ring gear the starter turns, and a store of rotating energy. Cut that rotating mass and the 2.0L climbs through the rev range faster in the lower gears and falls to the next shift point quicker, which makes heel-toe downshifts land cleaner. Competition Clutch machines the 2-10060-ST from forged 4140 chromoly in one piece, so there is no separate ring gear that can work loose. The maker aims the ST line at naturally aspirated and street-driven cars because keeping a little more mass than the STU preserves low-speed torque, which means fewer stalls and less bogging pulling away on a hill.

Symptoms that point to the flywheel

• Shudder or judder from a stop that stays after the disc is replaced
• Blue or black heat spots, glazing or fine cracks on the friction face once the clutch is out
• Slip that comes back early on a new clutch fitted to an old, unmachined surface
• Starter grinding or skipping teeth when cranking, from worn ring gear teeth
• A burning-clutch smell after repeated launches or hard autocross runs

How to confirm it before you buy

Road-test first to make sure the problem is clutch slip and not something else: in third or fourth at low rpm, go to full throttle and watch whether engine speed rises without the car speeding up. Our slipping diagnosis guide walks through it, and the clutch chatter guide covers shudder causes such as worn mounts and oil on the disc. With the gearbox down, measure the old flywheel for runout and look closely for heat cracks. Our resurface vs replace guide explains when machining is still an option.

Fitment

Competition Clutch lists 2-10060-ST for the 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 and 2015 Mazda Miata / MX-5 in the NC chassis. It does not fit the 1990-2005 NA and NB cars or the 2016-up ND, which use different flywheels; the 1994-2005 cars have their own 2-746-ST flywheel. If your NC has had an engine swap or a gearbox from another model, send us the year and VIN before ordering. More NC Miata parts are in our hard parts collection, and the 2-10060-STU ultra-light version is there if the car is mostly a track build.

Install notes

• Competition Clutch matches the ST flywheel to its Gravity, Stage 1 and Stage 2 clutches. For a six-speed NC, the Stage 2 Steelback Brass Plus kit is a natural partner; for a five-speed, the ACT ZM5-HDSS five-speed street kit is another street-friendly choice.
• Clean the crank flange and bolt threads, and torque the flywheel bolts in a crossing pattern to the Mazda service figure.
• Pull and replace the pilot bearing in the crank while the flywheel is off; an OTC 7318 pilot bearing puller makes that quick.
• Clean the friction face with brake cleaner before the disc goes on, center the disc with an alignment tool and tighten the pressure plate bolts evenly.
• Competition Clutch's break-in advice is to shift as often as you can in the first 500 miles so the disc material beds into the flywheel and pressure plate.

Common NC gearbox and clutch issues are covered in our Miata manual transmission problems guide. The flywheel is new, in stock, ships the same business day from the USA and carries a 1-year warranty.

Does the 2-10060-ST fit both the 5-speed and 6-speed NC Miata?

Competition Clutch lists it for the 2006-2015 Miata NC chassis without splitting the listing by gearbox. If your car has a non-factory engine or transmission, send us the year and VIN so we can confirm before it ships.

What is the difference between the ST and STU flywheels?

The ST weighs 12.20 lb and is aimed at street and naturally aspirated cars because it keeps low-end drivability. The STU is the ultra-lightweight version for cars that see more track time and can live with a touchier launch.

Which clutch should I run with this flywheel?

The maker matches the ST to its Gravity, Stage 1 and Stage 2 clutch kits. Pick the disc by gearbox and power level, and always use a clutch made for the NC 2.0L.

Will a lighter flywheel make the car harder to drive?

There is a small change in feel. Revs rise and fall faster, and pulling away takes slightly more care with the throttle. At 12.2 lb the ST is intended to stay comfortable for daily use.

What should I replace at the same time?

Plan on a clutch kit, a pilot bearing, fresh flywheel bolts if yours are stretched or damaged, and new brake fluid for the clutch hydraulics. Check the rear main seal for leaks while it is exposed.

How do I break in the new flywheel and clutch?

Competition Clutch recommends shifting as often as possible during the first 500 miles so the disc material beds into the flywheel and pressure plate. Avoid hard launches until then.

• Transmission Slipping Diagnosis Guide
• Shift Flare vs. Slip: How to Tell the Difference
• Automatic vs. Manual Transmission Repair Cost