4WD Turning Difficulties

[Mr_I]

Purely anecdotal, but tonight we put our bot on regolith, and managed to steer without too much difficulty. It is a 4WD in standard ("portrait") orientation, with the difference being we incorporate a shorter wheelbase (to increase the space for the gullet). To use the now-standard way of drawing:

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While I can't say I've read every word of this thread (and especially not all the links off of it), I have to wonder what we did "wrong" to get it to steer. Could it be the shortened wheelbase?
(Yes, pictures coming)