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KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
#148620
hi,
this is my first time doing modification to my son Yamaha raptor made by Peg Perego.. Im looking to replace these motors . He mostly ride on the slightly graded grassy backyard,. Which motor would you recommend for replacement and 8 pin or can I used the same 8 pin from the original motor. Any help would be appreciated. It is wire for 12v or 18v.
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#148623
You didn't state what your goal was for the modification. Did you want more speed? More torque? More of both?

You can certainly buy motors that will fit and will accept the same gear but they come in a huge variety of configurations. If the printing on the case is to be believed, the stock motors run 12000 RPM @ 12V. Replacing this motor with a stock Power Wheels motor (15700 RPM) would result in more speed but there isn't enough information to know what effect it would have on the torque since I don't have any torque information on the stock Peg motor here. The stock PW motors have the same knurling on the shaft (this is to retain the gear), which is an advantage if you are reusing the gear (most of the aftermarket motors have a smooth shaft -- you can rough those up and add green or red loctite too and they will hold the stock gears also).
#148634
Unfortunately I don't know anything about the PEG gearboxes specifically. If there is a way to put a larger (775) motor on it, I would recommend that for 18V use. If not, you can try something like a stock PW motor but I'm worried that in a "higher drag" situation - tall grass/hills/etc., it is going to overheat (18V = 2x the heat). My kids burned up a brand-new 550-series PW motor/gearbox in about 45 minutes on hilly pavement at 20V.

Is anything wrong with the current motors? If not, I'd start with 18V on those... They should run slightly cooler than the stock PW motors as they're not running as much RPM.
#148649
I have the Dumar version of the raptor but it uses this exact same motor and gear so you must have the Dumar gearbox. After I burned those motors out, I put HPI GT550s in mine and run at 18V. This raptor is very fast on smooth ground, but like yours, it bogs down in the grass and will quickly trip the circuit breaker. The stock motors are actually 650s but I haven't been able to find these anywhere. They are slightly longer at 65mm instead of the normal 57mm of a 550 motor. The stock motors seem to have more torque but can't handle 18V.

If anyone knows where to get a strong 650 motor, please let us know :)

This is the only place I've ever seen a 650 but this guy doesn't respond to emails and I assume he isn't selling stuff anymore, just hasn't taken his site down.
http://kershawdesigns.com/Motors-ESCs-Brushed.htm

Brian
#148658
I use these pretty much exclusively:

https://www.jameco.com/z/775-7013F-R-Nichibo-Taiwan-12VDC-Motor-12-610-RPM_2210845.html

They work great in FP-brand Power Wheels, but after reviewing the picture of the gear you put in, I can guarantee this won't work for you. You can't get a gear that will fit for these (you can find 9T gears from only one or two suppliers, and 8T is impossible given the larger size of the motor shaft). The 7-series motors are a larger diameter can, typically about 50% heavier (with correspondingly better power handling), but come with a 5mm pinion shaft instead of the ~1/8" shaft in the 5-series motors. Thus the gears are different, and that 8T mod0.8 (or 32dp) pinion gear is just too small to fit on that shaft.

You could try something like this:

https://www.ebay.com/itm/Mabuchi-DC-12V-24V-18V-RS-550PF-DC-Electric-Motor-High-Speed-Power-Large-Torque/302383264602?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D44039%26meid%3Deaef83c8c539438da97392b2c75e16a6%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D112312776240%26itm%3D302383264602&_trksid=p2047675.c100005.m1851

It would probably do well at 12V and should be ~25% faster than what you have. However, at 18V, any kind drag situation is going to either trip the breaker (likely saving gtkids' HPI motors) or burn up the windings on these smaller motors. If you had the capability to put in a different pinion gear (which probably means custom-fabricating a mounting plate for the motor), then you could use the larger 7-series motors, which would last better at 18V.
#148663
Exactly right, I put a 40A breaker on there precisely to keep them from burning out when it gets bogged down. I also put heat sinks on the motors. The HPI motors seem to be pretty popular on here but there doesn't seem to be a great 550 solution that has enough torque. I have thought about going to 775 motors but haven't taken the time to experiment with a making a mounting plate and trying different gears. The tricky thing here is finding a longer pinion gear for these gearboxes.

I found a longer 8T pinion for a 550 but I checked and the company doesn't sell them anymore. As already stated, there is no 8T for a 5mm axle. You might find a 10T but it needs to be longer so it doesn't strip the gear. I'm also not sure if the higher ratio would offset the gain from the 775 and leave you in the same boat.

A 650 motor might be an improvement but I can't find any. The stock motors are 650s, just FYI. They worked great before they burned out but I don't know where to find replacements.
#148669
I think that could be done if you had the right equipment -- a lathe with the right tooling would be fine. I'm not quite as certain about using a file, although I suppose the motor can be its own lathe to some extent -- put the motor in a vice and spin it up with 6-9 volts applied and file it down gently while it's spinning and you may be able to get it smooth and even enough to work. Go fairly slow and stop when the gear is a press-fit, and add a tiny bit of red loctite before pressing the gear on. I've only gone the other way (drilled out a 550-sized pinion to fit a mm shaft) -- and that won't work with the 8-tooth one.

You'd probably want a vacuum to help pick up the filings, as otherwise they will be pulled into the motor by the fan draft (and magnet).

BTW, they have an ebay link for a set of 4 here:
https://www.ebay.com/itm/Nichibo-Taiwan-775-7013F-R-12VDC-Motor-12-610-RPM-4-pcs/112230651034?hash=item1a2177d49a:g:i5gAAOSwImRYSaDp

$15.80 shipped.
#148688
That is a great idea, I hadn't thought about filing down the shafts. I think I will try that also. It seems like it should be easy to do simply by running the motor with the shaft against a grind stone. Definitely cover the vent holes and use a powerful vacuum to keep the filings out of the motor. I have no idea when I'll have time to do this as I'll also have to modify the gearbox metal plate to accept the 775 but I'll post back here when I do.
#148724
I was just reading thru some of the post thinking about projects I've done in the past and reading this, was thinking if I ran into this, I'd make me a template out of poster board or similiar that's thin, but still kinda stiff. That way when I marked the shaft where the pinion would need to sit, I could then brace a piece of the board with a hole just large enough for passing the shaft thru to file and still leave as much as possible room for the vent holes to pull airflow. Those look like pretty long pinions, so don't know how much of the 5mm shaft you'd have to take off. Interesting. If I had the time, I'd almost waste a 775 trying this to see what results it would give. I have a metal lathe, but wouldn't you have to take the motor down to the armature to spin it in the lathe to cut down the shaft? Just thinking.
#148728
You would if you wanted to actually do that in a machine lathe. These motors can be put back together with the right tools but I doubt that would be worth the effort.

I think the main difficulty with the "motor as its own lathe" is just in getting a cutting/grinding tool positioned precisely relative to the motor shaft so that you can remove the exact amount of metal you want.

I would take a piece of 1/8" plastic or (better) aluminum and cut three holes (one for the hub and two for screws). Don't worry about the airflow/vent holes as you're not pulling enough power for it to overheat, and the aluminum would act as a heatsink anyway. Plus you don't want metal filings going into the vents anyway...
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