Transmission, Clutch, and Driveline
Transmission, Clutch, and Driveline
This domain tests clutch operation, manual gearbox lubrication, driveline joints, and final-drive service. The exam expects you to separate clutch slip, release faults, gearbox noise, and joint vibration.
Core rules
- Check clutch pedal free play and hydraulic operation before removing a gearbox. A clutch that slips under load usually indicates a worn friction disc, oil contamination, or no release clearance; a clutch that drags may have air in the hydraulics or a warped disc.
- Use the specified gear oil. Some manual gearboxes require a particular GL rating or a dedicated fluid; the wrong oil can cause hard shifting and synchro wear.
- Inspect CV boots for splits and grease loss, check driveshaft phasing and U-joints, and look for differential leaks at the pinion and output seals.
- Diagnose by symptom and road test: noise in one gear, noise on turns, vibration at a road speed, or a click on full lock.
Worked example
A customer reports that engine speed rises without road speed when climbing a hill. The pedal has almost no free play. The lack of free play can hold the release bearing against the pressure plate and prevent full clamp load. Check the hydraulic system for a blocked return port and adjust the pushrod to specification. If free play is correct and the disc is contaminated or worn, the gearbox must come out. Do not condemn the gearbox before checking clutch release.
Traps
Riding the clutch at traffic lights, using engine oil in a gearbox that requires gear oil, ignoring a split CV boot until the joint fails, and mismatching driveshaft yokes during reassembly.