A motor assembly for a wheelchair and a corresponding method of use are provided for conversion of a manual wheelchair into a powered wheelchair. The motor assembly includes a crossbar, a motor mount bracket, and a motor that is attached to the crossbar by the motor mount bracket. The motor mount bracket includes a front plate and a back plate that is attached to the front plate by a hinge. The back and front plates are capable of clamping on to the crossbar after the crossbar has been attached to the wheelchair. The crossbar further includes collars that center the drive wheels to the wheelchair when the motor is attached to the crossbar.