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Size Matters! Selecting the Proper Clutch for your Application

Sep 29, 2020 | Clutches

Often overlooked when comparing clutch systems in single and dual disc is the clutch size, diameter, and mass.  The simple fact is that a larger diameter clutch is going to give you better holding power. As added benefits, the increased surface area of a larger clutch will dissipate heat better to keep the clutch surfaces flatter, and the increased mass of the clutch is going to require less slippage to take off from a stop. All these points are essential to consider in selecting a street clutch system.

Let’s look at 4 clutch sizes – 9.5 inch, 10.5 inch, 11 inch, and 12 inch. If all clamp pressure specifications were equal on these units, the largest unit (12 inch) would have the highest holding capacity, followed by the 11, 10.5, and 9.5 inch units. 

A good example is RAM LS single disc clutch systems. These packages include a steel flywheel and feature a 12 inch pressure plate and disc, which gives you a nice increase in clamp load yet easy pedal effort. The mass of this unit is going to allow a driver to slip the clutch less on takeoff to get the car moving, and the surface area will wick heat away to keep the pressure ring flatter and less susceptible to hot spotting. Without this, the life of the clutch would be reduced over time and also can lead to premature chatter and ultimately, inability of the clutch system to hold.

The same goes for selecting a dual disc clutch system. While some of our competitors tout smaller diameter systems, we have learned that for street use, especially in heavier late model musclecars, there is no substitute for using a 10.5 inch clutch over a 9.5 in terms of both driveability and longevity in the clutch system. Additionally, the larger clutch systems offer increased clamploads, which can only further increase the life of the clutch system. Think about a Dodge Challenger at 4400 pounds weight – is it going to like a larger/heavier or smaller/lighter clutch better for street use?

There are certainly situations where a lighter clutch system is better. These center around applications where you want to have faster acceleration and deceleration of the engine such as autocross, road racing, circle track, or drag racing where gearing can be optimized. In a drag car, smaller can be quicker. The tradeoff here is that the ‘window of adjustment’ on these sophisticated systems becomes smaller, sometimes making it more difficult to hit on the exact setup that will optimize the performance of the car.

Not sure what you really need for your car? Use our E-Tech tool to send us specs on your car and we will be glad to help you select the best system for your application. 

Think carefully about your application before selecting the clutch system that is best. Smaller is definitely not always better, and as they say, size does matter.