This article's point of view is that if clutch is too stiff, one situation is that clutch pressure plate push tab is too hard, and other situation is that inner piston of clutch master cylinder or slave-cylinder is rusted (cable drive problem) ).
Firstly, clutch is too stiff, which means that when we press clutch pedal, it feels very heavy. It's not as good as it used to be or in other cars when clutch pedal is lightly pressed all way. , This is mainly due to clutch pressure plate catch spring. This is caused by hardening because release bearing has to press hold down spring against clutch pressure plate and hold down spring separates friction surface of pressure plate. plate from clutch disc on principle of leverage. If pressure grip spring hardens, we need to use more. Only a certain amount of energy can make clutch disengage normally, so at this time it will cause feeling that clutch is too hard.
Second, because power transfer sequence for disengaging clutch is: depressing pedal - actuating clutch master cylinder - actuating clutch slave cylinder - actuating clutch fork - actuating clutch release bearing - actuating action of cam spring of clutch pressure plate. so remove what was said above. Aside from general pressure plate and clutch spring failure, a more common failure is clutch master cylinder or slave cylinder failure due to its own quality issues or brake fluid usage. (both clutches and brakes use brake fluid). If a pump or slave cylinder piston is rusted and stagnant, it will be harder to compress and clutch will be very stiff (cable drive means that a pull-cable replaces master cylinder and slave cylinder, just replace cable).
I hope my answer helps you.
The above is just my personal opinion, feel free to comment/subscribe/like/.