Clutch University - Chapter 9

SMALL DIAMETER CLUTCHES FOR OVAL TRACK RACING


RAM ASSAULT WEAPON CLUTCH

In oval track racing, the ability to quickly accelerate and decelerate the engine will lead to improved lap times.  The engine should be able to help slow the car into the turn, and accelerate quickly coming out of the turn in order keep the engine in its optimum power band.  The further you are able to drive into the turn and have the car slow sufficiently, and the faster you are able to have the engine accelerate into the optimum RPM range coming out of the turn, the lower the lap time will be.

Oval track cars use small diameter lightweight clutch assemblies.  The lighter the overall weight of the clutch, and the closer the weight of the clutch is to the center line of the crankshaft, the faster the engine will be able to accelerate and decelerate.

Oval track multiple disc clutches use diaphragm covers to provide the clamping pressure.  Due to the reduced diameters of these clutches, multiple clutch discs are required to prevent clutch slippage.  The number of discs needed will be determined by the load on the clutch, and the diameter of the assembly.  Normally, an oval track clutch uses two to three discs.

Because oval track diaphragms are smaller in diameter, the pedal effort to disengage the clutch will be higher.  Oval track clutches are frequently used in conjunction with hydraulic release systems in order to relieve the pedal effort and simplify the release mechanism.  Rounded or angular contact release bearing faces will also reduce the pedal effort required.

Because of the very low flywheel mass, oval track clutches have poor street drivability from a standing start and are not recommended for use in street vehicles.  

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