Outer Limits 4x4 Board

I have a problem with my 60 series it seems like the chassis rails are moving together and causing the shackles to push all one way like the width between the springs is wider than the width between the chassis rails.Anyone had this problem and found a fix?.

What brand of springs are you running?

My old Ultimates have always 'walked' (splayed leaves), I just give them a spray with lanolin and a tap with a BFH once a month. And replace the bushes once a year