could be a problem with the collision box that causes some incredibly huge forces.
downsize the collision box (for testing purposes make it really small) and double check that all critical values (collision box, coupler points, pivot points, boogie and wheel settings) are set to the correct values, including the correct prefixes (+/-) and no mix ups between commas or full stops in values.
furhter regarding the collision box: my impression is that the size you enter in the blueprint gets for some unknwon reason enlarged when you export it. when i set the collision length to the correct position, e.g. the buffer length, then the resulting collision box in game can be a little larger which makes coupling impossible and causes consists to explode when you uncouple.
db schenker rail driver in training