ARRMA ARA721418 Button Head Screw Flanged M4x18mm

The ARRMA ARA721418 is a flanged M4x18mm button head screw in the V2 specification, used as chassis and drivetrain hardware across ARRMA vehicles including the Kraton 6S platform.

The flanged button head design does two jobs at once. The rounded button head sits low and presents no sharp edges to catch on debris, while the integrated flange spreads clamping load over a wider area beneath the head. That wider bearing surface is what stops the screw pulling through or crushing into composite parts under load, and it removes the need for a separate washer, which is one less loose component to lose during a rebuild.

At M4 diameter these are structural fasteners rather than trim hardware, used where real load passes through the joint. Screws in these positions back out under vibration, strip in the hex drive when a worn tool is used, or shear in a heavy impact. A rounded hex socket is the common failure and it turns a two minute job into a drilling exercise, which is why replacing suspect hardware early is worth doing.

These are direct factory replacements manufactured to the correct thread specification, so they install in the stock locations with no modification. Keeping common ARRMA screw sizes on the bench is what keeps a rebuild from stalling.