I've been looking at the page with the wheel sets with contacts, Great stuff, thank you, looks like the thing to do if the friction is minimal and the contact good. If I understand correctly to have the ball bearing system I would have to change at least 1 set of wheels on the Stock car that already has metal wheels. Alternatively if I install article LGB 63193 ELECTRICAL CONTACT it would be easy and a little cheaper , but are these the ones you say make the car immovable like a brick? You must think I'm really slow but all this is very new to me and I want to be sure I understand.