TRX-4 Magnetic Body Mounts

thingiverse

I was unsatisfied with the commercially available magnetic body mounts for the TRX-4 because the magnets were weak. So, I designed my own. They use 3/4" x 1/8" countersunk N52 round magnets with 10.5 pounds of pulling force per magnet. There are two magnets per mount and two mounts for the vehicle, for a total of 42 pounds of pulling force. I can literally lift the whole vehicle by just the body, and that's with brass upgrades on the front axle plus a brass differential cover on the rear axle. With my Defender body, grabbing the front fender flares and yanking up hard will release the mounts. There are two different lengths of mounts: one for a chassis post spacing of 72mm and one for 82mm spacing. The magnets I used: https://www.kjmagnetics.com/proddetail.asp?prod=RC22CS-P-N52. I put the north-facing magnets on the chassis and the south-facing ones on the body, but just to make it easy to remember (north is always up). You can orient them however you want as long as oppositely-magnetized poles are facing each other. This design requires M4 x 5mm flat head screws, preferably with 8mm head diameters to prevent the screw exiting the bottom a significant amount. These are the screws I used: https://www.mcmaster.com/catalog/129/3427/93395A249. If you use smaller-headed screws (many are 7.5mm or less), you can grind off the extra length if necessary. The body side mounts also require M3 lock nuts and M3 x 10mm (thin through-body holes) or M3 x 16mm (thick through-body holes) button head screws. The chassis side mounts use the chassis body posts and clips to attach.