Scrap Mechanic Physics / Vehicle building in UE4


I am trying to teach myself a bit more about UE4’s physics through trying to replicate the vehicle construction that is in Scrap Mechanic.

The main think I am stuck on is being able to attach a wheel to an actor and have that drive motion.

The chassis is just a small baseplate at the moment and when i click it it gains physics.
I can also attach wheels to things and make them rotate, however when I let the chasis drop, the wheels rotate and seem to be lifting and moving the plate around, but no real forward motion is given.

To test, I attached 2 chasis together, 1 rotating as if they were like scissors and that drove motion, though of course was messy.

Does anyone have any suggestions as to a way of doing this ? perhaps where I might be going wrong?