6wd bouncing when turning

[lemiant]

We have a problem. Our robot rocks wildly when turning at high speeds.
This year we designed our robot to have a similar configuration to a kitbot. We are 26" long by 23.5" wide using 6 wheel drive and 4" Andymark white traction wheels driven via belts off a pair of vexpro ball shifters. The center wheels have 1/8 of an inch of drop, enough that our robot can rock slightly when placed on the carpet. Our weight is distributed towards the back of the robot so that the back four wheels are usually touching the ground. Based on everything I know about drivetrains our wheelbase shouldn't have major scrub problems, but obviously it does. Are there any simple fixes we may have overlooked?

Thanks for your help,

- Alex