hi Joker,
remember that the higher the length to width ratio you make your chassis the worse the bot will turn.
as a thought experiment compare the turning ability of a single axle with a wheel at either end to your current chassis design.
which of these will turn better?
this (single axle with wheel on either end):
|-----|
or this:
|-|
:
:
|-|
i don't know if i'm making this clear but i advise you make your chassis as short and wide as possible.
dunk.