View Full Version : Loose pinion grub screws

10-19-2011, 06:23 PM
Just a heads up to X5 owners to check out your pinion for loose grub screws. I had loctited (loctite 243 blue) the grub screws in the pinion during the initial build, and after 30 -50 flights (dont really know the true number) I noticed some red dust from the main gear. Further inspection revealed that the pinion grub screws had loosened (most likley from the motor heat - expansion/contraction), causing the pinion to rock back and forawards on the shaft keys. Yyou can tell if you have this problem by holding the motor in one hand and rocking the main gear with the other whilst watching the pinion. The pinion should not move relative to the motor.

solution : applied permatex bearing mount adhesive to the shaft and pinion and then used loctite 243 on the grub screws again. 20-30 flights later, the pinion is still rock solid. :thumbup:

10-19-2011, 06:30 PM
The main gear should not rock back and fourth either.

Mine doesn't, but my original kits was bad, and empire replaced it.

10-19-2011, 06:38 PM
You should have some freeplay in the main gear to pinion (mesh), otherwise the mesh is too tight and your laterally loading the main shaft and motor bearings, which will cause them to become "rough" quickly. You can't eliminate all play as the main gear is not a perfect circle and there will always be tight spots.

OR do you mean the main gear rocking in the one way beaing hub?