Why Install an ACT Performance Flywheel?

Upgrading to an ACT Performance Flywheel is one of the most effective drivetrain modifications you can make for improving throttle response, acceleration, and overall driving smoothness. Unlike a heavy factory flywheel that acts as a rotational damper at the expense of performance, an ACT flywheel reduces rotating mass, allowing the engine to rev more freely and reach operating RPM quicker. This translates to faster gear changes, improved power delivery, and a more connected driving experience. Whether you're building a track car, upgrading a daily driver, or simply looking to rejuvenate an aging clutch system, installing an ACT Performance Flywheel delivers measurable gains.

This comprehensive guide walks you through the complete installation process from start to finish, covering tools, preparation, removal, installation, reassembly, and post-installation best practices. Follow each step carefully to ensure a successful upgrade that boosts both power and smoothness.

Understanding Performance Flywheels

What a Flywheel Does

The flywheel is mounted to the engine's crankshaft and serves as the interface between the engine and the clutch. Its primary functions include storing rotational energy to smooth out power pulses from the combustion cycle, providing a friction surface for the clutch disc, and carrying the ring gear for the starter motor. A stock flywheel is typically made from heavy cast iron, prioritizing smoothness and noise reduction over performance.

Benefits of an ACT Lightweight Flywheel

ACT Performance Flywheels are precision-machined from billet steel or chromoly steel, significantly reducing rotating mass compared to OEM units. The key benefits include:

  • Faster Revving – Less rotating inertia allows the engine to accelerate RPM more quickly in response to throttle input.
  • Improved Throttle Response – The engine feels more eager and responsive, especially when blipping the throttle for downshifts.
  • Quicker Acceleration – Reduced parasitic loss from rotating mass means more power reaches the wheels.
  • Smoother Gear Engagement – The lighter assembly helps the transmission sync up faster, reducing notchiness during shifts.
  • Better Heat Dissipation – Advanced materials and design help manage heat under aggressive driving conditions.

For a deeper dive into how lightweight flywheels affect drivetrain dynamics, refer to the technical resources available on the ACT Performance official website.

Tools and Materials Needed

Having all the correct tools and materials on hand before you begin will save time and prevent frustration. Here is a complete list:

  • ACT Performance Flywheel (specific to your vehicle make and model)
  • Torque wrench (capable of measuring in ft-lb and in-lb as required)
  • Socket set with deep and shallow sockets (metric and SAE as needed)
  • Ratchet and breaker bar
  • Flywheel alignment tool (often included with the flywheel or purchased separately)
  • Thread locker (medium-strength, such as Loctite 242)
  • Engine oil or assembly lubricant for bolt threads
  • Brake cleaner and lint-free rags for cleaning surfaces
  • Jack and jack stands (or a vehicle lift)
  • Transmission jack (highly recommended for safety and ease)
  • Safety goggles and mechanic's gloves
  • Shop manual or torque specifications for your specific vehicle

Do not attempt shortcuts with tools. Using an improper alignment tool or skipping a torque wrench can lead to clutch chatter, vibration, or component failure.

Preparation Steps

Proper preparation is critical for a smooth installation. Follow these steps in order:

  1. Park on a flat, level surface and engage the parking brake. Chock the rear wheels for added safety.
  2. Disconnect the negative battery terminal to prevent any electrical shorts or accidental starter engagement.
  3. Lift the vehicle using a hydraulic jack at the manufacturer-recommended lift points. Place jack stands securely under the frame or subframe. Never rely on the jack alone.
  4. Drain the transmission fluid if required by your vehicle design. This prevents spillage during removal.
  5. Remove the starter motor to gain access to the bellhousing bolts and free up space.
  6. Support the transmission with a transmission jack. Remove the crossmember and any driveshaft components as needed.
  7. Disconnect all electrical connections, sensors, and hydraulic lines attached to the transmission case. Label connectors to simplify reassembly.
  8. Lower and remove the transmission carefully, taking care not to damage the input shaft or clutch components.

Once the transmission is out of the way, you'll have clear access to the clutch assembly and flywheel. Clean the area with brake cleaner before proceeding.

Removing the Old Flywheel

With the clutch assembly removed, you can now focus on the flywheel. Follow these steps precisely:

  1. Lock the flywheel in place. Use a flywheel holding tool or a bolt and strap system to prevent the crankshaft from rotating. If you don't have a holding tool, you can wedge a large screwdriver into the ring gear teeth, but be careful not to damage the teeth.
  2. Remove the flywheel bolts using a socket and breaker bar. OEM bolts are typically torqued to high specifications and may require significant force to break loose. A crisscross removal pattern is not necessary for removal, but it helps prevent warping.
  3. Carefully detach the old flywheel from the crankshaft flange. If it sticks, tap it gently with a rubber mallet. Do not pry against the crankshaft surface.
  4. Inspect the old flywheel for signs of hot spots, cracks, glazing, or uneven wear. This can reveal underlying issues with the clutch or engine.
  5. Clean the crankshaft mounting surface thoroughly using brake cleaner and a lint-free rag. Remove any old gasket material, grease, or debris. A clean surface is essential for proper flywheel seating and bolt torque retention.

Important: Always replace flywheel bolts with new ones. OEM bolts are often torque-to-yield and should not be reused. Many ACT flywheel kits include new bolts, but verify this before installation.

Installing the ACT Performance Flywheel

Now for the core of the installation. Take your time here to ensure everything is aligned and torqued correctly.

  1. Position the new ACT flywheel onto the crankshaft flange. The flywheel should slide onto the locating dowel or pilot bearing without force. If it doesn't seat easily, check for debris or burrs on the flange.
  2. Apply a small amount of engine oil or assembly lubricant to the threads and under the heads of the new flywheel bolts. Do not over-lubricate, as this can affect torque readings.
  3. Install the bolts and hand-tighten them in a crisscross pattern to draw the flywheel evenly onto the flange.
  4. Use the flywheel alignment tool if provided. This tool centers the flywheel on the crankshaft and ensures concentricity. Not all aftermarket flywheels require this, but it never hurts to verify.
  5. Tighten the bolts in stages using a torque wrench. Follow the manufacturer's torque specification for your specific vehicle. A typical specification for flywheel bolts ranges from 50 to 80 ft-lb, but always consult your vehicle service manual for exact numbers.
  6. Apply the final torque using the specified angle (if torque-to-yield) or the final torque value. Tighten in a crisscross pattern to ensure even clamping force.
  7. Check for any interference. Rotate the crankshaft by hand (using a socket on the crankshaft bolt) to verify the flywheel spins freely without rubbing against the block or bellhousing.

Pro tip: Some ACT flywheels come with a separate pilot bearing or bushing. Install this into the crankshaft before mounting the flywheel if required. Pack the bearing with a small amount of grease.

Reassembling the Clutch and Transmission

With the new flywheel securely installed, it's time to reassemble the drivetrain components. This stage requires as much care as the removal.

  1. Install the clutch disc and pressure plate using a clutch alignment tool to center the disc on the flywheel. The alignment tool mimics the transmission input shaft and ensures the disc is centered for smooth engagement.
  2. Torque the pressure plate bolts in a crisscross pattern to the manufacturer's specification. ACT provides specific torque values with their clutch kits. Typically, this ranges from 15 to 25 ft-lb.
  3. Inspect the throwout bearing and pilot bearing for wear. Replace them if there is any roughness or play. A worn throwout bearing will cause noise and premature clutch wear.
  4. Reinstall the transmission using a transmission jack. Align the input shaft with the clutch disc splines carefully. Do not force the transmission; if it resists, rotate the output shaft slightly to align the splines.
  5. Reattach the transmission crossmember, driveshaft, starter motor, and all electrical connections. Refill the transmission fluid to the correct level and type.
  6. Double-check all bolts and connections. Torque the bellhousing bolts, starter bolts, and crossmember bolts to specification.

For a detailed reference on clutch alignment and transmission installation, consult the installation guide available from ACT Performance installation guides.

Final Steps and Test Drive

Before starting the engine, run through this final checklist:

  1. Reconnect the negative battery terminal.
  2. Check all fluid levels including engine oil, transmission fluid, and coolant if disturbed during removal.
  3. Start the engine with the transmission in neutral and the clutch pedal fully depressed. Listen for any unusual sounds from the bellhousing area, such as scraping or rattling.
  4. Allow the engine to idle for a few minutes to ensure the clutch and flywheel are seated properly. Rev the engine gently and observe the tachometer response. You should notice quicker rev changes compared to the stock flywheel.
  5. Test the clutch engagement by shifting through all gears with the engine off and then with the engine running. Ensure smooth engagement and disengagement.
  6. Take a short test drive in a safe area. Start with gentle acceleration and braking to feel the new flywheel characteristics. Listen for any vibrations, chatter, or abnormal noises.
  7. Re-torque the flywheel bolts after the first heat cycle if recommended by the manufacturer. Some high-performance applications require a re-torque after 500 miles.

After installation, you'll immediately notice the engine revving more freely and the car feeling more responsive. Keep in mind that a lightweight flywheel may change the driving character slightly — the engine may decelerate faster when you lift off the throttle, and you may need to adjust your shifting technique for the smoothest transitions.

Common Mistakes to Avoid

  • Reusing old flywheel bolts – Always use new bolts to ensure proper clamping force and prevent bolt fatigue failure.
  • Skipping the alignment tool – Installing the flywheel off-center can cause vibration and premature wear of the crankshaft bearings.
  • Over-torquing or under-torquing bolts – Both can lead to failure. Use a calibrated torque wrench and follow specifications.
  • Forgetting to clean the crankshaft surface – Any debris or oil between the flywheel and crankshaft will cause wobble and vibration.
  • Neglecting to replace the pilot bearing – A worn pilot bearing will cause clutch drag and difficult shifting.
  • Not supporting the transmission properly – Dropping or misaligning the transmission can damage the clutch disc or input shaft.

Break-In Procedure and Long-Term Care

After installing an ACT Performance Flywheel, proper break-in is essential for maximizing its lifespan and performance. Follow these guidelines:

  • Avoid aggressive launches and hard shifts for the first 500 miles. Allow the friction surfaces to mate evenly.
  • Vary engine speed during the break-in period. Avoid sustained highway driving at a single RPM.
  • Perform regular inspections of the flywheel surface and clutch components during routine maintenance. Look for glazing, hot spots, or uneven wear.
  • Use high-quality transmission fluid that meets manufacturer specifications. This reduces wear on synchros and bearings.

For ongoing maintenance, keep the clutch hydraulic system properly bled and adjusted. A spongy pedal can lead to incomplete clutch disengagement, which puts unnecessary stress on the flywheel and pressure plate.

Conclusion

Installing an ACT Performance Flywheel is a rewarding upgrade that delivers noticeable improvements in throttle response, acceleration, and driving smoothness. By following this comprehensive guide, you can complete the installation with confidence and avoid common pitfalls that plague less prepared enthusiasts. The combination of reduced rotating mass and precision engineering transforms the way your vehicle delivers power, making every shift feel more connected and every corner exit more responsive.

Whether you're a seasoned DIY mechanic or a first-time modifier, take your time with each step, use the right tools, and always refer to your vehicle's specific torque specifications. With proper installation and break-in, your ACT Performance Flywheel will provide years of reliable performance and driving enjoyment.

For additional technical information and product support, visit the ACT Performance official website or consult your vehicle manufacturer's service documentation for model-specific torque values and procedures.