I have a hitachi ex120-5 that is leaking gear oil from the back of the final drive. I see on the parts list there is a seal between the hydraulic motor and the final drive. Can I just remove the motor from the back of the final drive to change the seal or does the whole drive need to be removed and taken apart?
Remove the planetary guts from the front side to change seal #2 . You will need to fabricate a socket to fit nut #39. You likely won’t need the socket for disassembly but will need it for sure to torque the nut to spec when going back together.
Can I leave the sprocket and tracks on and just remove the guts from the front and the motor from the back?
You definitely have to split the tracks. The sprocket stays on. To give you have a better idea how it’s all put together , see the pic below, the motor and final drive are all mounted on the outside surface of the frame. You don’t necessarily have to remove the entire assembly from the frame to change the final drive seal.
Thanks for the advice
IIRC, the biggest pain was pulling / cutting / destroying locking pin # 9 .