Gruber
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M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
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#149394
Pre project note: I reused some of the original metal frame. It is galvanized. You MUST remove the coating with acid before welding. Use appropriate gauge wire, USE FUSES, solder connections and seal from elements.

This started out a few weeks ago as a $25 Craigslist dune racer. I have a 3 and 4 yo and they needed an upgrade from their old 6v ride on.

After taking apart and cleaning all the switch internals, cleaning and greasing, it ran perfectly. The only problem was the run time. 2 kids+ hills and 3 acres, meant unhappy campers when it ran out of juice. Added as many batteries that I could, but it wasn't doing what I needed it too.
I wanted to retain the auto braking, speed control and reverse (for now) that the power wheels had.

Version 1: 25cc
Not about to spend a bunch of money on batteries, forever, I started searching. I found, essentially, a string trimmer engine mated to an alternator.i decided this is how I would fight the battery.
Found a new (closeout/overstock) alternator locally for $25. I had a 25cc trimmer engine laying around, and slapped it together.
Did some welding and wiring, and the first version was done. The engine was running flat out, and was charging the car, and providing power. Except it only worked on slow. Going into fast would bog the engine and stall it.
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Attachments
2013-01-12-099.jpg
Home brew (not mine) inspiration
charger.jpg
Commercial model 80-100amps 35cc 4-stroke
charger.jpg (26.94 KiB) Viewed 143 times
Last edited by MyOtherRideIsUrMom on Sat Jul 14, 2018 11:34 am, edited 5 times in total.
#149395
Version 2: 79cc 4-stroke
Since my proof of concept worked, the only thing left to do is what I do best: go overboard.

IF I could find one, people wanted insane prices for 35cc, 4-strokes. Screw it. Harbor freight has a 79cc (3hp) 4 stroke for $99.
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Using my observation skills, I noticed this engine was much larger and heavier (22lbs), and wouldn't "hang off the back". Only one thing to do: strip it and do the frame. 16ga x 48" was perfect, and the drill press took care of the holes.
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Made a rear extension and some cross braces for the engine and strength. Engine is contained within the outer frame providing: a bumper, buffer from parts, and wheelie protection. Wheelie bars will be added if needed, I don't think they will though. All of the spinning mating adapters will be hidden in the rear "engine" cover.
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My son wanted a hitch, so I took some of the tube, squished the end in a 20 ton press, grind it round, drill hole, weld end shut and done. Perfect hitch. Added a hook too, for general stuff.

Early mockups
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Finished the frame. During a different project, I needed a big oven. So I build a big (6'x6'x6') walk in oven in my basement. Making use of the oven, I coated the whole thing, plus front axle and door bars with Prismatic Powders "blood red" that I had from a different project. After baking, I did a hot coat of clear and re baked.
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Putting it back together ( for the hundredth time)
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Along the way, I also did:
New back tires
Fix steering linkage slop, toe and camber
Shim out front panels to fit a motorcycle battery in front
A bunch of other stuff I'll update as I remember

My son wanted some lights like my tractor. So Amazon has 2 led "light bar" for $8 and I had a water proof switch. Wired, tucked and fused. They are the same ones I have and they've been great for me.
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Tomorrow I will put in engine and finish up (hopefully) then test drive. If all goes well, I'll get a mouldable remote fuel cell, ESC and do a big electric motor/tranny upgrade. Ill also fab up a quiet, double insulated "blast" pipe style exhaust once it is running correctly. Probably electric start at some point too.
To make use of the hitch, I have a lawn mower (3'x4'?) Dump trailer that I'll put some wide tires on and make a quick hook up.
He, and sometimes his sister, want to drive around while I mow (2 hrs), pick up sticks, give sister rides to wild flower patch, etc. This should hopefully yield a great yard car for them.
Last edited by MyOtherRideIsUrMom on Thu Jul 12, 2018 2:20 am, edited 8 times in total.
#149396
ITS ALIVE (and works)

Just finished the build (so far) for my new proof of concept with the 79cc engine. I feel kind of bad, my son had just gone to sleep, but I promised him he could ride it today. So, I woke him up. In a foggy state, he was able to drive around the yard so I can see any adjustments. Ill get a better video of him driving tomorrow.

Not sure yet, being how it was used and I never checked the condition, I may have stripped the gears. Don't really care, was planning on upgrading anyway. Could also have been a operator error.

Im not even sure how many times I took this apart and put back together to test fit; it was a lot. Motor and alternator are mounted on rubber vibration isolators, alternator exciter switch on back cover, back "engine" cover fits perfectly to conceal the alternator. Dynamat was added to back of seat for a "firewall"/heat shield, mostly because I had it laying around and I was waiting on my oven. Air intake for cooling alternator was added, ill be adding dc fans. Ordering the new gears and motors tonight and will install asap. Ill also order a new header pipe and building a kid safe, quite exhaust.

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Last edited by MyOtherRideIsUrMom on Wed Jul 18, 2018 8:43 am, edited 1 time in total.
#149434
The next thing to take care of was the exhaust. It is super loud, and exits right behind the driver. I'd rather build it than buy it. Especially when it was around $20-$25 to build.
Started with an arnold lawn mower muffler from Wal-Mart for $5. It was sealed, so it opened it. I re did the inside and made it so I could unscrew to open it (to change the packing) $10 in pipe, a vibration mount for an engine, paint etc. It's all in the oven now, when it's done I'll wrap it with some DEI exhaust wrap and install. Muffler detaches quickly now, and I'll be trying different ceramic and glass packing.


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I just noticed that the hook on the hitch was making a bunch of sound. I'll have to redo video.



No hook
Last edited by MyOtherRideIsUrMom on Wed Jul 18, 2018 3:37 pm, edited 5 times in total.
#149436
Very cool/interesting build, cant wait to see how well it works.
#149438
Got the kids in it after messing with the exhaust. Still trying different packing.
Worked well, but with 2 kids/ or 1 kid and big hill, it needs more torque. Time for electric motor upgrade.

I would also like the throttle on the engine to be variable, not just 100% all the time.
Havent decided yet
1. ESC with a stepper motor that controls throttle and is triggered before electric motors
2. ESC with a lawn mower type control where the shifter went.

anyways, they rode around for an hour or so. I had my son doing hills as I was making adjustments. the gas usage after this was maybe 1/5th tank or so. That will all change after the new electric motors and other adjustments


1 Kid

2 Kids

In high you should have 12v to each motor (paralle[…]

Got the kids in it after messing with the exhaust.[…]

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