I have the Bronco Hotchkiss H39 tank kit and noticed there are no rubber components on any of the wheels or on the tracks. Was this the case on the actual tank or are the directions incorrect? And if there were no rubber components, what about the problems with metal-on-metal causing harmonic vibrations (a problem on Soviet T-34's when they had to use all-steel wheels for a time)?

From memory, some Hotchkiss tanks had rubber wheels, some did not. I think it switched from the H38 and the H39 (but don't quote me). Maybe check out the Chars-Francais webpage.

Dunno about the vibrations. I don't really recall if the H38/39 was even very fast or not...

The tracks were all-steel. The H-35 series used rubber-tired road wheels, which suffered from a short road life. The H-39 (including the short gunned H-38) used steel rimmed wheels. The low road speed apparently caused no vibrational problems (and lots of other tanks used steel rimmed wheels, including all Soviet KV and IS heavy tanks and most late war German tanks).
Trackstory has an excellent reference in English and French on the Hotchkiss series. Available direct from the publisher Editions Barbatins at http://perso.orange.fr/minitracks/index.htm