Well, the lever of the clutch pedal has to press against a button that is positioned up under the dash, so the clutch pedal height itself cannot be lowered too much or the lever won't be able to rest against that button anymore. (The button deactivates cruise control when you press on the clutch)
If you do reduce the swing of the pedal, you're also going to have to adjust the master cylinder to compensate. When you lower the clutch pedal, you will also have to shorten the piston length on the master, otherwise the clutch will not fully engage and it will slip when you really get on it.
If you want to leave the clutch pedal where it is, but try moving the action lower to the floor (so the clutch engages closer to the floor) then you will make the shaft a bit shorter and leave the swing of the pedal where it is. Or, conversely you can bring the clutch engagement closer to the top of the pedal swing by making the shaft longer, which makes the clutch release earlier and engage later.
To lengthen or shorten the shaft, you must loosen the lock nut and then either twist the screw further into or out of the adjustment bracket. Once you've made your adjustment, re-secure the lock nut and take it for a quick test drive. This way you can adjust the pedal to your own feel, but remember that less is more. You can also seriously screw up your clutch if you don't know what you're doing and drive it too much with a bad adjustment, so be careful.
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1985 300ZX n/a
See my Z project