Guys, relax!
We have not tested EVERY gearbox out there (and will not).
We tested a lot of them, and none of the ones we tested lasted in the MF.
I will not name them, since some mfg may take offence. (The products are not bad products, they are just products that were developed before this level of power was common, or they were designed for less power) Many of them do work on the PK370.
We can only report what we have tested extensively, and does work.
The gearbox housing is not the main issue. The housings rarely fail in normal use. E-Flite's gearbox is made of virgin polycarbonate, which is among the strongest, toughest, and heat resistent plastics. Properly installed, you will NOT need to retighten screws!
The gear/shaft is the issue. Many of the exisiting designs are not able to handle the torque, and gear mesh loads generated by a pk400 (at temperature). A lot of work was done to the design to make this possible. (There are several failure modes of various gear shaft assemblies. Shaft movement relative to gear, tooth failure, etc.)
We are not naming products that do not work, and I am NOTquestioning any specific product. Please take my words as they are, there is no need to read between the lines.
We are only making clear that our product was extensively tested and works well, and that several existing products (Including our V1 gear/shaft) will not work at these power levels.
Modelers are always free to run what they like, and are welcome to do so. We would rather avoid our customers having headaches.
We are happy to see you post your experiences with the Himax gearbox.
Best Regards,
David