The ACS units consist of two permanently coupled vehicles, one holds the Infra Red receiver and it's battery and the other vehicle is the power car with it's battery so the extra weight of the metal powered chassis is more or less off set by the added weight of a second battery to lug around. There is still room within the body to add extra weight if you have issues with a particular model.
The traction tyres are made of soft rubber and do pick up dust which can reduce their ability to grip the rail. In this scale a piece of dust on the wheels or track can be like rolling over a speed hump.
The traction tyres are made of soft rubber and do pick up dust which can reduce their ability to grip the rail. In this scale a piece of dust on the wheels or track can be like rolling over a speed hump.