I think it depends on model.
The early models were certainly on 18:1, You were lucky to push <15rps on a 7.4 lipo with them. But they were sold with the intention of pulling an M130 on the USA market. On 11.1 you were looking at <20rps when set for 350fps.
The newer models I have less idea about. I've actively avoided them.
What's your rounds per second and what batteries do you run?
Less than 15 rps on 7.4v it's 18:1 on an 18K motor.
Less than 20 rps on 11.1 it's 18:1 on a 18K motor.
The safe level of RPS I would use is 25rps. Any more than that requires a gearbox rebuild, with modifications made to stop the gearbox eating itself, Short stroking ect.
25rps on 7.4 and 18:1 is a 35K motor.
25rps on 11.1 and 18:1 is a 25K motor.
The other important question is why do you need to do the teardown in the first place? Is the gearbox non functional?
Because if the gearbox is functional I would almost certainly do the motor rather than the gears. A motor is easier to change, and doesn't require the time or the effort that is involved with a gearbox rebuild. And in pretty much all instances when you do open a gearbox up there is more cost than just the component you originally intended to replace. It's normally prudent to do a full service, Shims, Bushings, Airseal nozzle, Grease at the most basic level, but it adds a layer of cost. You may also run into issues like the COL getting jammed up on the sector cam, loosing parts, inability to get the box closed. It is never a simple job.
