What Causes Clutch Failure to Disengage?
2 Answers
The reasons for clutch failure to disengage are as follows: 1. Excessive pedal free travel: When the clutch pedal's free travel is too large, the separation bearing's push on the release lever reduces, shortening the pressure plate's backward movement, thus preventing complete disengagement. 2. Insufficient clutch clearance: In double-disc clutches, if the adjustment screw's distance from the intermediate drive plate is too small, the intermediate drive plate cannot move back sufficiently, leading to incomplete separation from the front friction disc. Conversely, if this distance is too large, the intermediate drive plate moves back excessively and contacts the rear friction disc, also causing incomplete disengagement. 3. Issues with the front pressure plate springs: Significant differences in length or stiffness, damage, uneven spring hole depths, warping of the inner/outer clutch disc assemblies, or loose rivets can cause the clutch assembly's radial and axial runout to exceed specifications, resulting in intermittent contact.
I've been driving for over twenty years and have experienced multiple clutch disengagement issues. The most common causes are clutch disc wear or deformation. After tens of thousands of kilometers, severe wear on the disc prevents the pressure plate from properly engaging the release bearing, resulting in no response when the pedal is pressed and difficulty shifting gears. Other potential issues include hydraulic system failures, such as leaks in the clutch master or slave cylinders, or air bubbles blocking the hydraulic fluid flow in the lines. Sometimes, an aged or seized clutch cable can also cause this, especially in older car models. It's essential to address these issues promptly to avoid further damage to the transmission. During every maintenance check, I always have the mechanic inspect the clutch wear condition, and I try to avoid prolonged semi-engaged driving.
