Enthusiasts with manual transmissions might know whether their clutch release mechanism is operated by cable or by a hydraulic bearing. But if it’s the latter, it’s unlikely they could tell whether the bearing operates in constant contact with the clutch fingers or intermittently—that is, operating only when the clutch pedal is depressed. More interestingly, what would lead a manufacturer of high performance hydraulic clutch bearings to adopt one style over the other? Most will tell you the intermittent style offers a greater range of adjustment and quieter operation. It also eliminates the exhausting prospect of a constantly spinning bearing.
In a Columbia, South Carolina, factory, Ram Clutches makes single and dual-disc clutch sets that transmit from 400 to 1,300 horsepower. The company has also cultivated a fine reputation for the production of hydraulic clutch release bearings. These operate on both single- and dual-disc clutches and function only when the clutch pedal is depressed. Tim Matherly, the acclaimed NMRA Real Street Mustang racer says, “The regular hydraulic release bearings that run constantly have a tendency to chirp. But on the higher horsepower cars, if you’re looking for quality, Ram has the best option and they’re quiet.”
High-performance release bearings that operate only when the clutch pedal is depressed have 0.800-inch of potential travel. More importantly they should be positioned with the correct gap when the pedal is not depressed; that is, the gap between the contact face of the release bearing and the clutch fingers. Excessive gap causes improper release; inadequate gap can cause the bearing to over-travel and collide with the snap ring, or cause slippage as the clutch wears and the fingers move back, making contact with the bearing.
Single-disc clutches operate best with a gap of 0.150-inch while dual-disc sets require a gap of around 0.200-inch. Because the clutch fingers automatically travel toward the release bearing as the friction disc/s wear, an additional clearance of 0.050-inch is assigned to the dual-disc arrangement.
That’s all fine and well, but how do you know when they’re operating with the correct gap? As we know, the entire clutch mechanism is concealed within the bell housing and therefore not visible. However, Southern Performance Specialists, located in Sugar Hill, Georgia, just north of Atlanta, regularly performs the operation and show us in the following series of pictures how it’s accomplished.