I'm replacing my timing belt. The new belt is slightly short with the amount of slack needed to fit back on. Is this due to it's a new belt? It has the same amount of teeth as the old belt.

 

what you might have to is go from right to left or conterclock wise when you are putting on the belt that way there is no play in the belt on the side that is opposite the tensioner. also you have to make sure the timing belt tensioner is retracted where the belt will be easy to go on.