Steel or Aluminum? Why Flywheel Selection is Important

May 30, 2024 | Flywheels

We covered this topic a few years back, and we think it’s time for us to review and expand on it a bit.

To better help you during the flywheel selection process, you must first understand what role the flywheel plays in overall clutch performance. 

The Flywheel’s Purpose 

The job of the flywheel is to store and transmit inertia to help get the vehicle moving. A heavy steel flywheel can store and transmit more inertia, while an aluminum flywheel will store and transmit less.  

How this applies to your specific vehicle depends fully on its weight, power level, gearing, and intended use. 

In general, a street-driven vehicle will benefit from a RAM steel flywheel. The inertia it creates helps you move the vehicle without excessively slipping the clutch. Excessive slippage leads to faster wear of the clutch and reduced life.  

Heavier flywheels are also significantly better for low-speed driveability. This can be especially important in vehicles with aggressive camshaft profiles, which tend to make the car ‘surge’ as the RPM gets lower. The heavier flywheel will help smooth out those engine pulses and avoid this surging.

The rear-end gear ratio and the transmission low gear ratio can also have a big effect on this drivability. A car with an aggressive rear gear ratio (3.73 or higher) and/or transmission low gear ratio (2.90 or higher) can often take advantage of a lighter steel flywheel such as RAM’s LW series units. The RAM LW series steel flywheels gain you a bit of engine acceleration without sacrificing drivability.

How RAM Flywheels Help 

When is it beneficial to use a lightweight flywheel like our RAM aluminum flywheels? Drag racing vehicles are excellent candidates for taking advantage of an aluminum flywheel.  

In these applications, low-speed drivability is not a concern, and your engine typically operates in a high and narrow RPM window. Using an aluminum flywheel will allow your engine to accelerate quickly off the starting line and after each gear change. 

Units like our RAM single-disc sintered iron clutch systems and multi-disc clutch systems are offered with an aluminum flywheel.

Another ideal place for lightweight flywheels is in circle track, autocross, and road racing applications.  

These vehicles maximize acceleration by keeping the rotating weight down. This allows the user to drive further into the turn and have the motor decelerate quickly. And you’ll get back onto the throttle sooner coming out of the turn, which helps get the engine back into its peak operating RPM range faster. 

This is why many cars in high-level circle track applications use a smaller diameter multidisc clutch system. The entire weight of these lightweight, small-diameter clutch and flywheel systems can be as little as 12 pounds!

We are always happy to help you select the correct flywheel for your application.  Please use the RAM E-Tech form to give us the specs on your vehicle and how you intend to use it and we will give you our best recommendation!