ARRMA ARA709069 Shim 12.1x19.5x0.3mm

The ARRMA ARA709069 Shim measures 12.1x19.5x0.3mm and is a genuine factory replacement shim for ARRMA vehicles.

Shims are the thin precision washers that set endplay and spacing on shafts, bearings, and gear assemblies through the drivetrain. At 0.3mm this is a fine adjustment shim, used where clearance needs to be dialled in accurately rather than taken up in large steps. Combined with thicker shims it lets you land on exactly the right spacing during a rebuild.

Why that matters: correct shimming keeps gears meshing at the intended depth and bearings running square. Excess endplay lets components shuffle under load, which shows up first as drivetrain noise and later as uneven gear wear and stripped teeth. Insufficient clearance preloads the assembly, creating drag, heat, and premature bearing failure. The difference between the two states is often a single thin shim like this one.

Being thin also makes these shims the most easily lost hardware in a gearbox. They cling to grease, fall away unnoticed on disassembly, and are easily forgotten during reassembly.

This is a direct factory replacement that installs in the stock locations with no modification required.