LEGO 5600 Radio Control Racer - Steering Knuckle

The LEGO 5600 Radio Control Racer was one of my favourite toys as a kid. It sat in a box for a few years. When it was rediscovered, the steering knuckles had cracked where the axles pressed in from the 26 years of associated stress.

In an attempt to relive my childhood and share those memories with my son, I sought a printable replacement. Originally, I discovered the model by @asphastratus_71069 (here). I didn't like the design with the nut and bolt to clamp the axle in place, and the caster angle seemed a little off, so I created this part from scratch to replicate the failed ones. It's nearly an exact copy of the original LEGO part, except for the shape of the “pins”, which print better as cylinders. Print with the "wheel side" of the axle holes facing up; supports are required (bed only); I printed with 60% Gyroid infill for a little more strength. PLA or PETG should suffice.

After printing, file any rough edges on the pegs. Use a bench vise and an appropriately sized punch or other cylindrical metal object to press the axle into the centre hole of the knuckle. One vise jaw presses the rear of the printed knuckle, the other jaw presses on the rounded face of the axle pin through the front of the wheel. Be sure to leave enough space while pressing the axle in for the wheel to spin freely (0.25 - 0.5mm gap).