Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By PandaBlue
#148258
I have 2 550 motors on a ride - I noticed that one wheel is spinning slower now. Both motors are controlled by separate controllers and i’ve switched the motors and still the same 1 is slower. I’ve changed gearboxes and everything else. Wires are ok. No series/parallel or speed high low switches.

Any idea if:
1. It might be the one motor going bad? Or should a bad motor just not spin at all?
2. Is it going to slow the other motor down or will I just get overall a lower amount of torque but still ok? Just worried that past the no load rpm of the slower motor it will actually drag the other.
User avatar
By wired
#148259
Two questions to start:

What motors do you have (part number and/or specs)?

Did they ever spin the same speed or is this a new problem (timeline)?
User avatar
By PandaBlue
#148261
First Question : These are those 30k RPM motors from China. 550s. They are just labelled RS550S12VDC with 30000RPM at the bottom.

https://ae01.alicdn.com/kf/HTB1UWpbNFXX ... ide-on.jpg

Second Question : I do remember them spinning together before. They are also both identically labelled.

I’m fine with torque being lower as the load is not big just a 38lb child and the motorcycle just weighs 25lbs maybe. I’m just worried that if its dragging the other motor to go slower then im better off switching to my 23k rpm motors in the meantime. When he rides it I still see it going top speed.
User avatar
By wired
#148262
Couple more questions and some thoughts:

Are you basing the motor rpm while free spinning out of the gearbox or gearbox/wheel speed while installed?

Does the rpm change if polarity is reversed at motor?

This will be hard to give a definitive answer based on lack of motor specs. If the motors are timed they will spin faster or slower depending on polarity (one will always be running in reverse polarity in relation to the other due to mounting orientation). Stock motors are not timed and run the same speed no matter what the polarity.
User avatar
By PandaBlue
#148264
Oh I did not know that! So certain motors go faster one direction?

I’m basing it on wheels spinning with the bottom lifted. Both have identical (and I swapped them already) Wheels and gearbox.

But if at one point they were spinning equally then it should not be the case right?

In either case is it ok to run the vehicle with one spinning slower (damaged or polarity thing)? I noticed the vehicle is still fast when my kid rides it i’m just trying to figure out if the effect of the other motor is detremental meaning the ride would be better off with just 1 motor, or the other motor is compensating and it should be fine?
User avatar
By wired
#148265
A couple more questions (yes, I know I'm forming a pattern here but please be patient so we don't overlook anything):

Did you just swap the motor only (from gearbox to gearbox) or did you swap the entire gearbox and motor from one side to the other?

Did you try changing the polarity of both motors and see if the problem shifted from one motor to the other?


Also: How much of a difference are we talking about?
User avatar
By PandaBlue
#148266
I appreciate the help and no issues with questions.

First the gearbox I swapped with a completely new gearbox with same gears and checked lube everything is fine.

Next I just tested it now and reversed polarity it was doing the same speed. Ive also swapped the motor controller wiring as im using 2 controllers.

It is roughly 25% slower than the other motor.
User avatar
By wired
#148268
I'm having trouble following that last response. Let me ask to clarify. Did you swap JUST the motors to the other controller/side leaving the controllers and gearboxes in their original position? Basically did you isolate the motor only to be the constant and the problem follows the motor? I want to make sure the gearbox is out of the equation.

Next question:

If you run the vehicle off the ground and apply slight hand pressure/resistance to the wheels do they spin relatively the same speed?
User avatar
By PandaBlue
#148270
For the isolation, yes i’ve isolated the motor already. Ive first swapped controllers to eliminate it. Ive also replaced the gearbox with a new one. I’ve also actually crossed positive from one controller and negative from the other controller (and vice cersa for the other motor). If bad motors dont get slow im now think MAYBE I got a mislabelled 23k RPM motor.

As for pressure i’m not sure how to do that. What we did notice today is that at 25% throttle, the speed of the motorcycle turning left is faster than when turning right. The right motor is the fast one.

Sorry if i’m not providing the proper answers I just started this modding a month or so ago and am still getting used to the troubleshooting!
User avatar
By wired
#148275
No problem at all. Your answers are great. it's just the internet troubleshooting hurdle. I'm going to assume you have also used different power source/battery when you swapped the motors.

It sounds like you have done all the proper troubleshooting. If one motor was always spinning faster/slower (maybe not noticed at first?), I would say it's defective or mislabeled as you mentioned. Depending on the manufacturer it could be a quality issue.

I have never experienced a damaged DC motor simply slow down without other warning indicators (bearing squealing, dark deposits around cooling fins, obvious burned smell or blue smoke). I'm not saying it doesn't happen, I just never experienced it personally.

25% speed difference and noticeable speed when turning with the faster motor is significant. Have you tried connecting straight 12v from battery to both motors and see if the speed evens out? I would try in both series and parallel just to see what they do. Unfortunately it does sound like you need a new motor at this point.
User avatar
By PandaBlue
#148276
Hold on maybe the squealing could be the motor. I hear some squealing but thought it might be the bearings of the wheels as im on pneumatic tyres. I will try to listen for that.

In any case, if i’m using a 23k rpm motor and a 30k rpm motor together - is it ok to run like this for the next 2 months? Will it hurt the motors or is it significantly slowing down the other assuming just total 65-70 lbs? Because im debating if I should just pop in the 23k rpm motors but I have not because well, he’s zipping around fast and it kinda looks like the one fast motor can pull him up to that speed.

How do you post a video? Maybe there are clues to the sounds I hear. You guys probably know more about what these things should sound like.

P.S. I may try out hat series idea. Parallel has the same effect.
User avatar
By wired
#148277
Probably the easiest way to post video is youtube and provide link. Not my strong point.

If it's the motor squealing, I have found them to be most prominent when decelerating in a no load situation. I.E. Hold the motor in your hand and apply/remove power.

Google "DC motor break in" and see if you would be interested in performing this on the motors and then lubricating the bearings.

If the electrical isn't getting hot or blowing fuses/popping breakers (not sure what parameters you are working with), I don't think you will do anything too serious. You might end up just burning up the other motor due to excess current draw. The decision to swap motors should be based on your setup and how comfortable/confident you are with the functionality as-is.

If the motor ever reached a stall point or simply has a bad bearing it could be your problem. Not a big deal in my opinion. Better that than a bad controller...or two.

Over current protection is mandatory. Electrical system temperatures are a key indicator to high current situations which do tend to lead to failure. Don't be afraid to sniff check the motors. 8-)

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