Flywheels

Do the revs drop slowly between gear changes, or does the clutch need replacing anyway? A new flywheel can change how quickly the engine picks up revs and how the car pulls away from a standstill. This category is for you if you are replacing your clutch or building a project focused on response.

What does the flywheel do?

The flywheel is mounted on the crankshaft and gives the clutch a friction surface to work against. It also stores rotational energy, which smooths out the engine's running and makes pulling away easier. A lighter flywheel can make the engine gain and lose revs faster, while a heavier one typically gives a smoother idle and softer take-off. If your car has an automatic gearbox, you need a flexplate instead, which you will find under clutches and flywheels.

How to choose a flywheel

Weight alone does not decide whether a flywheel suits your project. Look at several factors:

• Driving: On a track day a light flywheel can give quicker response, while traffic queues and everyday driving often benefit from a little more mass.
• Clutch: The flywheel must match your clutch disc and pressure plate in diameter and bolt pattern.
• Car and engine: Fitment depends on model, model year and engine variant, e.g. ACT XACT Flywheel Prolite for Mazda Miata 90-05, where 90-93 requires a 1.8L clutch.
• Noise and vibration: A lighter flywheel can cause more gear rattle at idle, depending on the gearbox.

We stock flywheels from brands such as ACT, Exedy, SPEC, Clutch Masters and Action Clutch, and ACT is available in both Prolite and Streetlite versions.

Fitting and compatibility

The flywheel is replaced when the gearbox is removed, so it makes sense to do it together with the clutch. A clutch kit or a kit with clutch and flywheel makes it easier to get parts that match. Use new bolts if the manufacturer specifies it, tighten to the specified torque, and check the release bearing at the same time.

Frequently asked questions

Can I reuse my old flywheel when replacing the clutch?

It depends on the wear. A flywheel with cracks, blue heat spots or deep grooves should be replaced. Some can be resurfaced, but not all types are designed for it, e.g. dual-mass flywheels. Follow the manufacturer's instructions.

Will I notice a difference with a light flywheel in everyday driving?

Often, yes. The engine can gain and lose revs faster, so pulling away typically requires a little more throttle and precise clutch control. How big the difference is depends on the weight reduction, the engine and the car's total weight.

Why does the flywheel need to be balanced?

Imbalance can cause vibrations and put strain on the crankshaft bearings. New flywheels are typically balanced at the factory. If you have your old flywheel resurfaced, it may be necessary to check the balance afterwards.