JM8 M4A1 "GEARBOX" MOD" TUTORIAL" FULL ASSEMBLE

After Quality Hard gels tried & tested https://ausgel.com.au/ Blue plunger metal rail , "zhenduo" seller ebay https://www.ebay.com.au/itm/Toys-Gel-... High ROF High tourqe motor https://chainsawproducts.com.au/produ... Metal gear kit installed with factory JM gearbox brass bearing sleave, do not rub at all, no distortion. Only when you install aftermarket ball bearings as the length of the ball bearings full under the margin for tolerance/clearance.Only when they rub requires shimming :) Ball bearings that aren't shimmed will cause distortion and a horrible winding noise. NOTE: There are three different brands that make "Metal Alloy gear kit", hence why I made it clear in the video footage at the start as to the stamped markings on the gears which are distinctive. However the other no name branded gear requires shimming as they have been machined slightly different especially the spur gear, they do happen to full under the required tolerance. Not the set in this video.