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KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By Scooterseg
#148959
First post so don’t eat me alive...

Have stock dune racer and upped it to two 12V 14 amp hour knowing stuff was going to break as my kids beat the crap out it. Yes it is wied with 12G with two 30 amp fuses.

First problem/upgrade needed... popped a 30 amp fuse and something smelled burnt. Reduced back down to one battery. Left wheel spins fine right wheel does not. Took off some plastics and little motor only works in fast mode. Doesn’t really spin in the other two modes.

Did I burn a motor up or something else?
Recommendations for other upgrades for 24V to be dependable? Kids love the speed!
User avatar
By Hammer-fm
#148969
Most likely burned up the motor (brush failure since it sounds like it's blown open). At 24V the stock motors (as you say, "little") don't last long. Either tone it down to 18V or get 775-series motors. Either way you'll need to replace what you have.
User avatar
By Scooterseg
#148970
Ok thanks. Does it matter who their made by? I see traxxes and other brands make the 775. I will get two ordered, just wondering if their is a better brand.

Also is it necessary to install the ESC kit? Eventually I want to put rubber wheels and possibly some sort of suspension to make the ride not so rough. My kids ride it on road and off road terrain.
User avatar
By Hammer-fm
#148976
As far as brand goes, there is certainly some amount of quality across the range, but there is only so much power output you can get reliably out of this type of (brushed, 7-size can) motor. I've burned out "nominal" 18V motors (eg. Banebots 18V) at 22V with a heavy load. If you go with an RC car motor, you'll want one on the higher end of the turn count. You can't run a 14.4V motor of any size and expect it to last long at 24V.

If you want something cheap, you could try the Nichibo 775 motors from Jameco, discussed here. These probably won't last a long time at 24V, but they should outlive the stockers by a substantial amount and they're cheap. At 18V they'd probably hold up for a very long time.

An ESC will help improve the longevity of both the gearbox and the motor (the current limit means substantially lower power dissipation at startup, though you also sacrifice some starting torque), and the variable-speed control is more fun to drive, if my kids are any indication. My opinion would be to get at least a 35A ESC, and 55+ would be better. My homebuilt ones don't have a current limiter but probably should :lol:.
User avatar
By Scooterseg
#148992
Does someone make a 24v motor that will drop right in? Maybe Peg Perego motor? My kids really like how much torque and speed it has gained. I don’t want to buy a motor just to get it going again. I’d prefer to buy a set of motors that are going to last and keep the new speed and torque.
User avatar
By Hammer-fm
#148993
There's no 7- or 5-series motor that will have that kind of power as a standard rating.

At 24V the stock motor would have a theoretical peak output of 820W, along a very high power dissipation. That's just not supportable within the power dissipation capabilities of a motor that size (or even the 7-series case) Only scooter motors could do that. My workaround was to have two 7-series motors in each gearbox, but that's a very custom solution.

If you look at standard 24V motors, they're all much lower power (eg. the Banebots 24V, Peg Perego motors, etc.) than your stock one is at 2x the voltage, and none of them are going to run 30k RPM -- which is where the stock one is at 24V.
User avatar
By Scooterseg
#148997
Thank you so much for this info! I understand I should lower it to 18V, but my kids still want it to go faster. how long do you think the 775 motors will last? My kids ride it almost everyday. I will go ahead and buy the 775 series for now. Is there anything else besides the esc and heat sink I can do to try and make the motors last longer and keep them from burning up at 24V? Sounds more like I need to invest in a different toy as the Powerwheels even with upgrades is almost already topped out...
User avatar
By SlideRule
#149004
When re-ordering motors, be mindful that the old pinion gear is likely not going to work with the new motors; it doesn't have a set screw. Also, the 15T (32P) gear (https://amzn.to/2IGYnpw) does not fit properly. I ordered them and total diameter is too small. I considered trying a 16T (32P) as it looked like it was almost the exact diameter, but I ended up just ordering motors/gears combo from MLToys (still waiting on the shipment). I sent them images of my pinion gears to confirm, but we'll see.

I also have the Dune Racer fwiw. This is what I ordered (http://www.mltoys.com/product-p/matched-550s.htm).

EDIT: These are the pinion gears in mine.




I see others are saying the 16T (32P) is the correct gear. I don't have my gearbox handy to confirm. I wish I had known all this because it's been quite a headache just to replace 2 motors all because of the original, non-standard, gears that came in the Dune Racer.

If this is all useless to you, hopefully it will help someone else browsing the forums.
User avatar
By Scooterseg
#149006
I am mechanically advanced but just a novice with electric. Aren’t the 775 series better than these 550 series?
I assumed I was buying Traxxas or banebot 775 series with gears and heat sink for best results running 24V.
User avatar
By Hammer-fm
#149007
When using standard 32P (or mod0.8) pinions, you have to use specific sizes, and it's not necessarily the same as what came with the vehicle.

The "15-16-17" gearboxes used in Dune Racers, Hurricanes, F-150s, Escalades, etc. -- take 16T pinions in the standard pitch. For a 775-class motor the key words are "5mm pinion 32dp" or "5mm pinion 32p". You can keep it simple and get something like this cheap e-bay pinion:
https://www.ebay.com/itm/HobbyStar-32DP-Pinion-Gear-16T-Hardened-Steel-5-0mm-Bore-5mm-32-Pitch-16-32P/171955600929?epid=525168309&hash=item28095a3e21:g:-0cAAOSw8GhZhNDf

For more information about why 15/17T aftermarket pinions don't work well, see this thread. It is possible to use 15/17T but you have to hog out the screw holes in the gearbox and build an offset sleeve for the motor.

Some more reading:
http://forum.modifiedpowerwheels.com/viewtopic.php?f=9&t=21628&p=148387#p148400

And yes, you'll need to file a flat on the motor shaft so that the set screw can work correctly. If you just tighten it up on a round shaft it will slip.

As for the last question: The 775 motors are heavier and larger. This means more thermal mass (slower to heat up) and more area to dissipate heat. MHO, heat sinks are of little use since the windings don't touch the case at all. Cooling down the case will have little effect on the winding temperature. (they make a ton of sense on brushless motors, but not brushed ones).

As for longevity options that don't involve scooter motors and crazy gearbox mods, here are a few other options:
(A) Go down to 18V but move up to a 19T gearbox (eg. from a Mustang) and 19T gear. You'll have to use a step-drill bit or similar method to expand the axle hole. Combining this with the Nichibo (cheapo) 775 motor that I pointed you to should yield a 90% speed improvement over the stock 12V / 15tooth combination, and about 50% more torque than stock motor/gearbox @ 12V.
-> Note that you can also get a Corvette gearbox and use a 22T pinion for more speed at the expense of some torque. This would give you a theoretical 120% increase in speed and 35% torque improvement over the stock Dune Racer @ 12V

(B) Stay at 24V, go to a Banebots 18V motor and add relays for the throttle. This motor doesn't spin as fast as the Nichibo and will probably last longer at 24V. However, it has a much lower wiring resistance and the stall current rating is ~180A each at 24V, vs 133 for the Nichibo (at 24V; it's 66A @ 12V, nearly the same as the stock motors). Running with the stock foot pedal is likely to not last very long, but the 80A SPDT car relays should hold up ok.
Note that 24V the Banebots is running 26000 RPM, and it's going to have a huge amount of torque (>3x stock). I predict immediate stripped gearboxes with this setup and 16T gears, though if you run with a 22T gearbox at least that will reduce the torque to something "more reasonable" (2x stock).

An ESC combined with either of these will reduce the starting torque and peak heat dissipation. It will improve longevity, but if you really enjoy the additional torque you have now, an ESC will almost certainly be a step backward. The standard "500/1000W" ESCs on ebay have current limits of 30-40A. The stock motors @ 12V pull >80A (as a pair of motors) at startup...

Good luck, whatever you decide. Cost-wise it's fairly economical to buy two empty Mustang or Corvette gearboxes and you just swap the guts over and purchase the appropriate (19 / 22T) 32DP 5mm pinion gear. Going to 18V is a bit of a bummer because you have to mess with 12V and 6V mixed batteries... which is part of why I came up with my 4x 775 motor solution.
User avatar
By Scooterseg
#149010
Ok, so since you know a lot about the effects of different combinations what if I did the 7R 23T gearboxes with banebot 775 18V motors and dropped it down to 18V? Would it be reliable and pick up speed and torque still to keep the kids happy? I’m all about moding, but I can’t have this down for weeks at a time as stuff breaks... seems like these are the best options you said with the “safe” 18v Setup.

Eventually I would assume steel gears with rubber tires

Side note, lot of free time this week, I realize it’s prob cheaper to piece all this together, but is m.l.toys stage 4 speed worth it? Seems like everything we’re already talking about together for my 24v setup...
User avatar
By Hammer-fm
#149018
I quickly mocked up 4 setups in my modeling spreadsheet (https://drive.google.com/open?id=1oECCWbLNtmnL6m08cD9ctb90gJwhgL7q). It's got too much data on it (I'm an electrical engineer, so... what do you expect? :lol: ) -- but let's just concentrate on the summary statistics: Peak torque @ takeoff , Maximum Speed, and Per-motor heat production @ 75% peak speed (which is usually a medium load -- eg. medium grass or a fairly steep uphill on pavement).

First - stock w/15T gear
Second - 24V w/15T gear
Third - Banebots 18V @ 18V w/22T gear
Fourth - 7013F @ 18V w/19T gear

The latter two options are pretty close; the 7013F won't pull as much current (easier on the foot-pedal switch) than the Banebot, but it has correspondingly-lower starting torque. Top speed is roughly the same, as is the heat production. They'd both be run in a "fairly comfortable" range as long as you're not climbing steep hills in tall grass (very high load). On the other hand, the stock motor @ 24V theoretically is both slightly faster and has slightly higher torque, but is pulling a lot more current and the heat production is very high, plus it can't dissipate the heat it does create as quickly as it is a smaller motor. Even on flat pavement, it will likely run hot and if it doesn't directly overheat (short out the wiring insulation), it will wear out the brushes very quickly.

Moving to either of the 775 options shown here will be a big improvement over your current situation. I wish I could point you to a more "drop-in" 24V option -- they're probably out there, but I don't have specs for anything that is a great fit and meets your other goals.
motor_comparo.png
User avatar
By Scooterseg
#149021
So I was all ready to buy the stage IV speed kit for the corvette from mltoys so I can have 24V with 23T for the fastest set up I can get and drop it in the dune racer I have and they said you cannot put that gearbox on the dune racer because the axle size and wheels size is different on the corvette... please help with this last question so I can get my kids power wheels back up and running. MLtoys said 17T is the highest I can go for speed...
User avatar
By Hammer-fm
#149022
The wheel hole is different but I had no problem using a step-bit to "Fix" that. I DID use a drill press, though with a step-bit it may be fine even without that. I didn't even bother taking any of it apart just flip it over (teeth down on the drill press table), support the case, center the step-bit and go.

Small case has a hole diameter of 0.490". The large case is 0.800". It's been awhile but I believe I used my 4-20mm metric step bit (20mm cuts a ~0.790" hole). US step bits will probably get you 3/4" -- 0.750" which is going to be a tight fit on the axle -- if you have a way to ream it out just a bit more that should do it. It's supposed to be a slightly loose fit, but going to something like 7/8" is going to be too large.

The metric bit I used is from this exact cheap set.

I'm running those modded 19T on one of my Hurricanes. There's no structural difference that I can see, so I don't expect any issues down the road.

The only concern is that you may void your Stage IV's warranty...
User avatar
By Scooterseg
#149023
What’s the speed difference between 17T and 23T? theoretically I guess? Just want to see if it’s worth it or just go with banebots for much cheaper.
User avatar
By Hammer-fm
#149024
You can go with the Banebots with either tooth option, and you will use the same gearbox case in either case (but if you are putting it together yourself you'd buy 22T pinions, NOT 23T -- that's the standard size that fits ).

As for speed, it will basically be linear with the # of teeth, so 22T vs. 17T will be (22/17) faster (30%), and will have 17/22 as much torque (which will be plenty -- those motors have plenty of torque).
User avatar
By Scooterseg
#149028
Since I have the dune racer already with no problems in the gearboxes. If I buy the stage IV kit for the corvette from ML toys can I just change out the bottom gear instead of drilling it out? Not worried about the warranty since I’m doing pneumatic tires also. I read that only the placement of the first gear is the only difference in gearboxes...

Edit: I just realized the gears are the same... it’s the black housing that is smaller for the axle?
User avatar
By Hammer-fm
#149030
It's only the housings that are different: small axle vs. large axle, and the 4 tooth options (13-14, 15-16-17, 18-19-20, 21-22-23). That was why I was saying your cheapest route is to just buy a pair of 21-23T EMPTY gearbox -- since you can just drop your existing gears in. The only other parts you'd have to buy are the new motor pinions and the motors themselves.

MLTOYs made their steel gears with the same # of teeth as the stock plastic gear, so the main thing you're getting there is a more durable 1st gear -- there's no "ratio" advantages.
User avatar
By Scooterseg
#149047
Ok. So I went with new gear boxes. Titan 775s with 23T on them. Will buy 22T if they don’t work properly. Rubber pneumatic wheels. Last upgrade I would like to do is the variable speed pedal. I keep reading that Ryobi makes a 24V drill switch that I can use with the stock pedal. Is there a thread somewhere with that switch and how to install it. When I look it up the 18V switch keeps coming up and I’m already running 24V.
User avatar
By Hammer-fm
#149058
I haven't tried any of the drill switches, but most of them are not likely set up to handle the type of current draw you're going to have with two fairly high-power motors. It's possible that one has current limiting built in -- there's no way I can tell from the picture.

The Titan is a 10-turn motor, which means it's likely going to be spec'd at a 150+A stall (per motor, @ 16.8V - so 200-250A @ 24V, disregarding wiring/battery losses) vs. 120A with the stock motor (@ 24V). Unless the controller has current limiting, it's almost certain to fail with that kind of load.

A real motor controller may be a better investment -- perhaps something like this: Kelly KDS 200 amp controller. I haven't personally used one, but a few people on the board have.

Unfortunately a brushless controller won't work on brushed motors -- the use inherently different control methods.
By Rob222
#149061
I agree on using an ESC instead of the drill trigger switch.

Cheaper 24v controllers :
http://www.electricscooterparts.com/spe ... 4volt.html

Also, check out their "Premium Foot Pedal Throttle" Item # THR-89.
This foot pedal is easy to install and works great. Stock it is a little hard to press but is very easily modified to make it easy for kids to press down. You can also easily modify the throttle to limit the total movement to control top speed.
http://www.electricscooterparts.com/thr ... ndard.html
User avatar
By Hammer-fm
#149062
If you want to retain similar torque to the "24V stock", you'll need a hefty motor controller. The primary figure of merit is going to be "Maximum current". Do NOT look at the "power #" -- it's useless for this purpose. Most of the 500W controllers are 30-35A, vs. 200A for the Kelly controller I listed below.

200A is overkill anyway (your batteries won't output that much), but I think anything less than 50A is going to be a disappointment if you're looking for hard acceleration or capability in high-drag conditions. There are several controllers on that web page that would be usable there (eg. 24V 1200W - 60A maximum).
User avatar
By Scooterseg
#149066
Ok I got everything together and I am very happy with the results. Just bench testing it the tires are screaming. If I buy the pedal do I still need the esc?

Also starting off in fast mode it pops 30A fuse, only ones I had on hand, had to start in slow mode and then switch it into fast mode. what size amp fuses should I be buying so it won’t trip them starting off in fast mode?
User avatar
By Hammer-fm
#149089
Those Titan motors will pull a lot of current at startup (stall), so I'm not surprised it's blowing the fuse. You could try a slow-blo 40A fuse and it may be ok. You could also replace the fuse with a resettable thermal breaker (they're generally even slower to trip). Starting in low may be better for long-term durability anyway - those will put out quite a bit more torque than stock (even stock @ 24V). An ESC will also cure both problems.
User avatar
By Scooterseg
#149093
Thanks again for all the advice. 24V with 23T gears and rubber tires was so ridiculously fast my daughter let go every time she switched it into fast mode, mainly because the she kept over correcting the steering and it was throwing her around. Had my friends kid go on it who’s about 60-65 lbs and it snapped the large gear and the second largest gear in the slow start instantly. Going to order an esc so I can adjust the top speed and slow down how hard the motors are trying to turn the rubber tires.
User avatar
By Scooterseg
#149114
Not yet. I haven’t bought an esc yet. Waiting on new gears to come in tomorrow. I have 15T that I’m thinking about switching back in for now so the top speed isn’t so high. Looking at eastcoast power up which would mean I don’t really “need” the pedal. As nice as the variable speed pedal sounds that still puts all the power in my daughters foot a football field away from me. With eastcoast it’s almost plug and play and I can just adjust the settings as she gets better with age and I can still put the 23T in later too.
User avatar
By Scooterseg
#149248
So I installed the eastcoast power up and love everything except now the power wheels only last five minutes on my friends three acres. The batteries are brand new. What can be the case that it would run out of power that fast?
User avatar
By MFusick
#149257
Is there a walk thru how to do post for a beginner that wants to upgrade to 24v? I would like to just buy everything I need to do it properly, rather than go step by step learning and replacing parts.
User avatar
By Hammer-fm
#149261
I would expect better runtime than 5 minutes with 2x 14ah batteries. Is it extremely tall grass or other high-drag surface? Do you have any way to measure the power draw (I have one of the digital LCD displays that shows voltage + amperage + power + wH -- they're pretty useful).
User avatar
By Scooterseg
#149290
No tall grass. Pretty flat actually. About 70-80lbs between the two kids and had east coast power up on 3s acceleration and 75% power which is what is recommended for “off road” use. They did a couple of laps and that was it. Going to take everything apart and make sure all connections are good. Might sodder a bunch so they can’t vibrate since there is no suspension, but that kind of stumped me. Also the charger seems to charge the batteries extremely fast compared to the stock power wheels charger. It Says they are charged in just a few hours compared to 18 hours on the stock charger set up for charging in parallel. Kind of suprising and possibly why they are dying so quickly...

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