ACT Clutch Technical Bulletins

TB #1: Racing with ACT Pressure Plates
Advanced Clutch Technology clutches are made to replace the stock units in order to increase the torque capacity of the clutch. For many applications they can also be safely used for racing. Your safest route is to follow the recommended RPM limits set by the automobile manufacturer, do not allow the clutch to overheat, and conform to all rules set by the sanctioning organization. For high RPM applications you may want to consider using a belhousing scatter shield to eliminate chances of personal injury. Many of our clutches have ductile iron facings which can handle high RPM, however ACT accepts no liability for clutches used for racing. If you have any questions about an application please call.

TB #2: Release Point Adjustment - Hydraulic System
On some applications when a heavy duty ACT pressure plate is installed the engage/release point may become closer to the floor. This change may be due to flex caused from the added forces placed on the pressure plate and linkage from the increased pressure. Another cause of this change in release/engagement point may be caused by a disc with excessive marcel. The marcel is the wavy metal between the linings which allow the disc to gradually engage. If the marcel is too wavy it takes extra travel to release and engage. In most cases a small adjustment of the master cylinder pushrod reducing pedal free-play will cure the problem. This adjustment is made by screwing the pushrod farther into the master cylinder to allow it to actuate the cylinder sooner. You may also desire to increase pedal travel by adjusting the pedal stop (when equipped). You should never preload the master cylinder. Good repair manuals include instructions and adjustment specifications which are a great starting point. Adjustments are not usually needed if you are using sintered metallic linings because the lack of a marcel allows for quicker release/engagement.

TB#3: Flywheel Resurfacing, Balancing and Special Mods.
A smooth and flat flywheel surface is critical to proper clutch operation and longevity. It is extremely important to maintain the proper step in the flywheel when applicable. A good rebuilder will also be able to rebalance the flywheel to insure that the engine will stay smooth and can reach higher RPM without damage to the engine. For racing applications the flywheel may be altered for better performance. For example, a race car with a slow wearing sintered metallic clutch disc may change the flywheel step to put the pressure plate closer to peak pressure because they are not worried about shortening the longevity of the clutch. Some people choose to have the flywheel lightened for quicker throttle response. These jobs should be left to an expert performance clutch rebuilder who can properly analyze the characteristics of the flywheel, pressure plate and disc used. Flywheel resurfacing, balancing and special modifications are available at ACT.


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