I just replaced my release bearing (the engine and box are out of the car) and I noticed that the clutch arm (the little rod that sticks out of the bell housing) is very stiff. Did I over-tighten it? How easy should it be to move it forwards and back? Should it be stiffer after the gearbox is mated to the engine?
You should be able to move it along the "free play" back and forth easily untill you feel the release bearing touch the pressure plate, then it will become very hard to move any further by hand.
If it's fitted to the engine then Drvewasher is spot on;
You should be able to move it along the "free play" back and forth easily untill you feel the release bearing touch the pressure plate, then it will become very hard to move any further by hand.
"Once you break something you will see how it was put together"
There is/should be, a lockwasher on the bolt assembly so the bolt need only be tightened until it just nips the fork, the lockwasher under the nut prevents the bolt loosening any more.