This will be my build thread for my kids' power wheels electric ride on cars.
My eldest has a 12 V Shelby Cobra and my second has a 6 V Mini Cooper S.
Mod #1: Rubber tires on the Cobra
After about 6 miles in the past 6 years the plastic wheels had come apart.
I taped them back into their correct shape and filled the void with Great Stuff in order to salvage them. I would have ordered new ones and still added rubber but no one has them in stock.
I cannot recommend this as it expressly states that it won't work well in closed spaces and they're correct. There were many hassles with this.
Then I got a few old bike tires from the local shop and cut them to the diameter of the wheel, splayed them out after removing the metal hoops and used some low profile wood screws to attach them to what was left of the wheel surface.
Ideally you're going to do this long before the mounting face of the wheel gets as thin as mine are.
Before going this route I also looked into lawnmower tires and go kart tires but they're just so expensive and would require even more modding to make work. I came across a couple used ones for free and they were too big. The clearance up front is very close at lock so I would have to be even more careful if I tried to put a real tire there.
Mod #2: Make the Cooper faster.
The Cooper was slower than the Cobra's slow mode so after looking into it I put a 12 V battery in the Cooper and now it's medium fast. On some 6 V cars they say it can fry this that or the other thing but it hasn't done anything untoward after over a week.
Mod #3: Cooper battery relocation to reduce "torque steer."
It's a one wheel wonder (back right) and whenever she accelerates it drags the zero traction front wheels laterally about 30 degrees to the left. I've advised her to lean forward on acceleration, which helps. In order to assist with front traction I mounted the battery onto the firewall. It helps, but not enough. The forward lean is still necessary. Before it's almost too late (as with the Cobra) I will add rubber tread to the tires which may help, too.
Mod#4: A real throttle pedal and brakes.
The next step is to use these donor scooters in order to provide variable throttle acceleration. I'm working through some questions since I have no idea how electronics work and I'm not sure if it's cool to use the twist throttles from these 24 V scooters with 12 V systems. Ideally they will "just work" and I can rig something up with cables to replicate the UX of using a pedal. My eldest can probably learn to use a brake but I'll have to see about using the resistance of the motor itself to stop the Cooper. This is not yet the right time to add any complexity to the driving experience on that one.
I got this pair for $50. One works fine but has a cracked frame. The other acts as if it turns on and has power but doesn't respond to throttle input-- although one time I was sure it did for just a moment. I haven't dug into them yet but I'm hopeful that since one was used hard enough to snap at a weld then the other one is just shaken loose somehow. In any event, the batteries in them when wired in parallel will keep me from having to buy a new riding mower battery, I hope, thus justifying the cost to Mrs. P3PPY.
After that gets to working I'll see about adding the motors to the cars. I expect I'll need to keep at least some of the power wheels OE motorwork in place since these scooters require a 3mph kickstart to get going. I also do not want them running these at the full 24 V yet because it's so silly fast. The cracked one keeps trying to launch out from under me. So then I'll also need to know if I can run 24 V motors at 12 V indefinitely without causing issues of some kind. For all I know the throttle control does just that by limiting the volts to the motor, but ???
