After assembling chassis I still had one more problem - steering system fault. You can see it in this short video:

Backlashes in levers were horribly huge. Surely, it was impermissible for the autonomous driving tasks. So, solving the problem was not difficult. Here are the steps:

• Replacing screws with ball joints
• Lubrication of bearings with lithol
• Replacing the servo steering arm with a longer one

All this helped me to get new precise steering system: