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Heavy or Lightweight Clutch? The Great Debate

Jul 21, 2020 | Clutches, Flywheels, Racing

There seems to be a common misconception that a lighter weight clutch and/or flywheel is going to make your car faster or perform better.  We even have one manufacturer in our industry that tells you “put in an aluminum flywheel and make more horsepower!”  The fact is it depends on how you use your car or truck that determines whether you can benefit from a lighter weight clutch or flywheel.

Remember the job of the flywheel – to transmit inertia to help you get your car moving.  On the street, this means slipping the clutch less on takeoff to get rolling and make a smooth transition.  At the drag strip, balancing flywheel weight with gearing will allow you to launch most efficiently without excessive tire spin or bogging the engine.  This is especially true in heavier vehicles!

It Depends…

In general, a street car benefits most from a moderate weight flywheel and clutch package that provides the best driveability, both on takeoff and at low speeds driving along.  If you have ever been in a heavily cammed car and driving along at lower engine speeds, you may have noticed a ‘bucking’ or ‘jumping’ that occurs when the RPM drops too low.  Having more flywheel and clutch weight in this case helps to smooth out the lower RPM engine pulses and keep the driveability smooth.

Drag cars of all different power levels can use lighter weight units IF the proper gearing can be used in the transmission and rear end.  If these gearing options for the transmission are not available, some extra flywheel weight may be needed to achieve a proper launch.

When Lighter is Better…

Applications that can really benefit from lighter weight clutch and flywheel combinations are in circle track, road race or autocross vehicles.  These applications require the engine to accelerate and decelerate quickly to make the most of the combination.  A lighter assembly allows you to drive further into the turns and have the engine decelerate quickly, and accelerate quicker out of the turns to get the engine back up in the peak operating RPM range.  This is why circle track clutches are often multiple disc and smaller diameter.

Balance is Key

So for street, balance is the key.  To that end, RAM introduced a line of lighter weight steel flywheels over the last 2 years that help provide the inertia needed for good driveability, yet allow for a crisper throttle response than you would get with a heavier steel flywheel.  Pair these with the Concept 10.5 dual disc for a great combo of holding power and driving experience!

As with most decisions you make about what parts to use in your vehicle, it pays to carefully consider what you expect from it in the situations you encounter daily.  Do I need this system to allow me to comfortably cruise around, or do I have a different performance objective?  Carefully considering these ideas will help you make the best choice for your car or truck.