As noted the AFX can have four to five grams of magnet down force and be pin legal with the current pin. The other style cars do not have this magnet down force. Does the below "legal" AFX car look like a gravity or magnet car?
The liberal pin we use currently for tech allows this, not the magnet type. The pictured results can be achieved with ceramic or polymer magnets. Both types of magnets must be carrifully placed in an AFX or they will fail the pin test. The advantage of the polymer magnet is it can be made one gram lighter.
I created the pin and test procedure we use in November 2010. It has proven to be simple, cheap, and reliable tech standard. I over reach at the time and feel we need to transition to a lighter pin to keep the class truly a gravity only downforce class. Some simple additional shielding corrects the AFX to a non-magnet condition, not requiring a new build.