Installing new PTO clutch armature after previous one broke apart. The u-notch on the armature's inner collar broke.
I'm wondering (1) how snug the key should fit in the shaft slot, and (2) how much of the key should be visible/available beyond the rotor to fit into the u-notch on the armature. It nearly disappears into the slot on the rotor.
Got a used pulley, and everything fits together nicely, but I'm worried the key doesn't have enough "bite" on the armature. The key doesn't fit cleanly or too deep into the u-notch on my replacement armature. I have a clutch from a 318 (single-pulley) and the key slides right in. And the old 420 key has small slot in one end - I'm not sure if is supposed to be there to allow the key to slide into the u-notch, or it was damaged when the clutch broke. The key on the 318 has no slot.
The key should slide in by hand. The rear ramp will stop it, but the armature should fit just as easily as the key, so it doesn’t press hard into the ramp on the crank. You can also use the armature to slide it into the friction plate.