This type of clutch is easy to adjust but you either need two people or some way to hold the clutch pedal down to the floor to make the adjustment.
Remove the 4 bolt cover from the bottom of the flywheel housing. Turn the engine over by hand until you find the adjusting window on the pressure plate. Older clutches have a 3/8 bolt (9/16 wrench) that holds a 'tang' about 1.5" long. This tang keeps the adjustment ring from moving on its own. The adjustment ring is make of cast iron and reminds me of a castle. Remove the tang and put a bolt with a nut on it to use as a prying fulcrum to turn the adjuster ring.
With the clutch RELEASED, that is, no one pushing on the pedal, a properly adjusted clutch with a clutch brake will have a gap of 1/2" between the throwout bearing and the clutch brake disc with the brake disc shoved tightly against the transmission input housing. If this gap is too large (usually the case), have your buddy hold the clutch pedal down to the floor while you turn the adjustment ring clockwise as viewed looking forward in the vehicle. The adjustment ring can be stubborn to move, especially if it hasn't been moved in a while--you may have to get things started with a hammer and punch.
After you get the 1/2" gap right, look up on either side of the throwout bearing to see the fingers that pull the throwout bearing away from the clutch. With the clutch completely released, there should be a 1/8" gap between the throwout bearing and the release fingers. If this gap is not correct, make sure the clutch linkage is free and that the pedal is indeed going clear up in the cab. IF these conditions are satisfied, adjust the linkage to provide this gap.
When you are done there should be 1.5" - 2" of free travel at the pedal in the cab. AS the clutch wears this free travel distance will decrease and the clutch will require readjustment. However, it should only require an internal adjustment. If you feel carefully when pressing down on the clutch pedal with the engine off you might be able to feel the clutch brake as increased pedal resistance at the very bottom of the pedal travel.
Newer clutches require the same procedure except that the adjuster ring is turned with a small rack gear in the pressure plate. If memory serves a spring-loaded 9/16 bolt head turns the gear. This is similar to a manual brake slack adjuster. Just remember to get the adjuster ring to turn clockwise you need to turn the gear counter-clockwise.
