This tech tip describes how to modify the old 4mm chassis for use with the new wider spur gear.
The new wider 2nd speed spur gear can touch the old 4mm chassis, so it is necessary to relieve part of the chassis where the spur gear touches. First check to see if you have the newer (V2) or old chassis; this modification is NOT necessary for the newer V2 chassis.
(click to enlarge)
(click to enlarge)
On the old chassis, mark the place where the spur gear touches the chassis. Using a file, remove material from the chassis until there is a small space between the spur gear and the chassis. Make sure that the spur gear is not touching the chassis; if it still touches you must remove more chassis material until the gear does not touch the chassis at all.
