A reel mower has a double A arm suspension that lowers a reel cutting unit into a cutting position in a tail down orientation and that levels the reel cutting unit out as it lifts the reel cutting unit into a transport position. The reel cutting unit yaws during turns about a substantially vertical axis having a negative caster angle. The suspension has clamps that can be flipped open or closed to quickly attach or detach the reel cutting unit. A drive motor can be quickly attached or detached to the reel cutting unit using a pivotal wire form. An active counterbalance system automatically offsets the increasing weight of a grass basket on the reel cutting unit to maintain quality of cut. The grass basket maintains a constant spacing relative to the reel cutting unit when the reel cutting unit pitches to improve clipping collection.