PowerWheels Derby Jeep Build

Powerwheels Derbies are all the rage for the ultra young demo crowd. Deep in my heart I am jealous these did not exist when I was a kid. Instead, my brothers and I DESTROYED multiple radio flyer metal wagons bashing them into each other in the driveway. I built this jeep for my nephew to play with initially, while knowing that it should get years of use from him, my baby boy (at the time), and now his baby brother too!

I will say the experience is quite different when you have a rooting interest in the Powerwheel derby than when you don’t know any of the kids. When my nephew would drive, I was captivated watching him. However at most derbies my reaction is typically more…Couldn’t they have started this earlier? Because I know that this Derby is going to run late, I’ll be waiting on a skid steer to help load a mangled car, and then have the drive home after that. I have the same gripes with not enough and/or undersized equipment for clearing the derby arena of dead cars between heats. Perhaps the powerwheels and lawnmower derbies could take place while the arena is being cleared, what an even more efficient use of time that would be! Alas, at this time I have no plans to start my own derby promotion enterprise, so I will be content to pop open a V8 Energy, drive home, and deal with it.

This build started with a Powerwheels jeep that I found on marketplace for $20. It did not come with a battery, but for that price I figured it was a good deal. I spent a lot of time shopping for a battery combo to go with it. To test it out I used a lawnmower battery, but I did not want to leave it like that long term, (kids and battery acid don’t mix). I wanted to supply the 12 volt system to 18v to make it faster, which takes some tinkering. Some obvious choices are one 12 volt and one 6 volt battery, or three 6 volts in series, or even a power tool battery. I opted for the three 6 volt batteries in an attempt to make the charging operation easier and help batteries last longer. One mistake I made was going too small on the amp hour capacity of the batteries. I got three 7ah 6 volt batteries, and they were just too small to last for longer than about 10 minutes before slowing down. Someone correct me if I am wrong, but I believe running them combined to produce 18v in a 12v system also discharges them quicker. My other issue with the batteries is that the F1 terminals did not hold up over time. When I pulled these batteries out to replace them with the 12v 19ah battery from this project, all the batteries were swollen, and the terminals had broken off the batteries that were connected to the Powerwheels leads. The only other wiring mod I did was to add an inline automotive fuse to try and protect the drive motors from burning up if they somehow got stuck. I used a 30 amp fuse, because that is supposed to be the size of the internal breaker on Powerwheels factory batteries. To charge the batteries without disconnecting them, I used a universal laptop charger with selectable voltage, and added alligator clips to it.

One quick tip, as I did not know this initially but found out later. This jeep and many other Powerwheels I’m sure, have two forward speeds. The trick is, that there is a screw in the shifter that locks out the high speed. If you did not know about this, all you have to do is remove the screw and the jeep now has a second, faster speed.

These jeeps are apparently notorious for the front end sag they develop overtime. The fix is to cut the front end support rod that goes between the spindles, take about 3/8″ out of it, weld it back together and grind it smooth. If you really wanted to, you could thread the two ends of the rod and use a coupling nut to make it adjustable. I did not do that, but I did go overkill replacing the retainer caps on the wheels and spindles with 7/16″ nylock nuts. For the spindle tops, there was not enough material to engage the top of the nut, so I used a thin nut, drilled it and the spindle top out, and used a cotter pin to keep it together.

The jeep came with a hood when I got it, but had since been blown away by a Kansas wind storm. To replace it I sacrificed a storage tub lid, and I think it fits pretty good. I also added some wood doors to replace the missing ones, held on with carriage bolts. Other ornamental decoration I did on this ride is the “headers” fashioned out of PVC pipe and reducers. I’ve got 4 pieces of small pvc (1/2″) slid into a larger piece (1.5″) on the bottom and then for the collector it is a bell reducer. The hood bolts are not strictly ornamental, but were super easy to add, as the stock hood clips were missing. To attempt to rigidize the plastic a bit for demo derby use I took some Great Stuff expanding foam and did the underside of the front bumper, the rear underbody, and the battery compartment. I would not do the battery compartment again as it collected water and made a mess. Taking it apart to paint the pieces coordinating colors made it turn out pretty cool in my book.

I will be testing out adding rubberized undercoating to the wheels for more traction. I do not want to add too much traction with cut up bike tires and guarantee burnt up motors, but I would like it to not get stuck on flat grass! I think the undercoating could be a good compromise to increase traction, but still burn off and let the wheels spin if they need to.

If you want to get deep into modding your ride-on toy (Ha!), checkout modifiedpowerwheels.com and mltoys.com. I used both these sites as a resource when building this jeep and I learned a bunch I didn’t know before. As it stands now, I’ve got it back with a 12v 19ah battery, and I think it goes fast enough to entertain my 3 year old. As a bang for the buck kinda guy, I’m happy with the performance of the jeep right now, but maybe another derby dad will challenge me to step it up this year. We shall see!

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