Which parts should not be washed in cleaning solvent?

The friction disc and throwout bearing are components in a manual transmission system that can be adversely affected by the cleaning solvent. The friction disc, designed to generate friction for engaging and disengaging gears, may absorb moisture or chemicals from the solvent, which could interfere with its performance or cause premature wear. The throwout bearing, which plays a critical role in the clutch operation by helping disengage the clutch, can also be damaged by solvents that remove lubrication, leading to potential failure.

While the clutch cover can usually handle cleaning solvents without negative impact, it is typically best to avoid washing any parts that are critical for friction and lubrication. Cleaning solvents may introduce residues that impair the performance or longevity of the friction disc and throwout bearing. Thus, it is important to treat these components with care and avoid exposing them to such harsh cleaning methods.