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Need new motors? Grind a gearbox? Adding teeth to a pinion?
By mcjunkified
#64249
Lot's of information! I want to replace the motors on my son's MT F-150, but before I can cross reference everything and figure out what to buy, my ADD kicks in and I've spent 2 hours on a completely different topic.

Here's the scoop:

It has 16T motor pinions and it's a 15-16-17 GB. Will a 700 series motor fit it, or do I need to go with a 500 series? I have figured out that I need a 32p pinion gear, which should work with this GB right?

TAZ11, you put these in a vehicle with what you said was a #7 motor. What kind did you use? would it be an upgrade from stock? I'm past the point of personal preference and to the point of "someone tell me what to buy to make this thing go faster". So, what motor did you use in yours or what motor would you buy?

Thanks a bunch. When I get time, I will take pics of the gears and such and post on here. Then maybe someone who knows what they're doing can provide some reference for us?
User avatar
By taz11
#64253
I used a stock motor just to test the pinion options. A 32p 16t pinion will work in a 15,16,17 7R. 15t and 17t will not work.

I usually just over volt the stock ones to get more speed. I have used the 775s linked in my sig. These are awesome...but probably not what you are looking for They have monster torque but actually have slightly less top speed.

HPI 550s seem to be a popular choice...but I haven't tryed them.
User avatar
By taz11
#64254
BTW...... Almost a year later....16T 7R still going strong with a 32p 16T pinion :D


.....and they said it couldnt be done :evil:
User avatar
By bruces_eviltwin
#66736
I recieved some 7r 23 tooth boxes just need to order some pinions, gonna give the 22 tooth a trial as soon as the budget says I can get motors
User avatar
By bruces_eviltwin
#69597
I have 23t 7rs that im going to try 22t pinions in as soon as I get the truck back together
User avatar
By daveweber34
#69728
I'm confused as to why all these other pinion gears don't work. From reading this thread, the pin for the first gear is moved depending on what pinion gear it is labeled for. So, if is labeled as 18-19-20 the first gear is located slightly farther away from the motor to account for a larger pinion gear. Correct?

If it is designed to fit 32p gears, then why the heck label the gearbox "18-19-20t" if only a 19t, 32p pinion gear will work? Why doesn't a 32p, 18t or 20t work? Is the diameter of those pinion gears causing problems?
User avatar
By taz11
#69784
Because the stock 18t and 20t pinions are not 32pitch. A 32p 18t is too small and will strip the first gear. The 32p 20t is too big and will bind causing the 1st gear and pin to fail and excessive motor temps do to increased drag.
User avatar
By daveweber34
#69792
taz11 wrote:Because the stock 18t and 20t pinions are not 32pitch. A 32p 18t is too small and will strip the first gear. The 32p 20t is too big and will bind causing the 1st gear and pin to fail and excessive motor temps do to increased drag.



Ok, I'll buy that. But, that makes me ask another question unrelated to the 7R. In my regular 19t #7 GBs, I replaced the stock motors with the Banebot 775. I upped the aftermarket pinion to a 32p, 21t after reading it worked for you Taz. Why the heck does that set up work? I would think that it shouldn't because the pinions are different. That is what is confusing. That some stuff works on the regular #7s but not the #7Rs. I thought the only change was sturdier gears for the 7R. Otherwise everything else (i.e. parts placement and motor mount holes) were the same.
User avatar
By taz11
#69802
Well.....It shouldn't work. I guess you've been lucky so far. In order to move up to a 21t pinion you need to change the gearbox too. The case and pinion should always match.

How long has yours been that way?

I'm thinking since you have a motor without that little locator ring.....the play in the bolt holes may be helping you out.
Last edited by taz11 on Thu Jul 12, 2012 2:48 pm, edited 1 time in total.
User avatar
By daveweber34
#69806
Wait a minute....let me look up something....ok, yes, I did get the idea from you ( http://forum.modifiedpowerwheels.com/viewtopic.php?f=30&t=1201 )

First post by you, Taz, 2nd paragraph just below the shim picture....

Due to the slightly lower rpm of this motor, I swapped out the 19ts for some 21ts.


You don't mean swapping out the 19t pinion for a 21t pinion do you? What you meant is that you swapped out an entire 19t, #7 gearbox for a 21t, #7 gearbox? Am I reading that statement by you correctly now? That's not how it came across as a noob to PW modding. It sounded like you were only swapping the pinion gears, not the whole gearbox.

Drive time so far for the whole set up has only been one hour of really light driving. If I'm understanding your statement correctly now, I better order some new 19t pinions for this or get whole new 21t GBs.
Last edited by daveweber34 on Thu Jul 12, 2012 3:21 pm, edited 2 times in total.
User avatar
By taz11
#69809
To summarize ....

#7 gearbox..... you must use a 32p pinion with the tooth count indicated on the GB case. ( that is why your 19t made awful noises in a 21t GB)

#7R gear boxes MUST use the stock pinion OR a 32 pitch pinion with the same tooth count as the middle number on the GB
( IE.. 18-19-20GB takes a 32p 19t, 15-16-17GB takes a 32p 16t)


There is no 23t gearbox with out a motor..... there is a 21-22-23 gearbox. It is only specifically a 23t when a motor is installed with a 23t gear. The stock 23t gear is not a 32p so you cant use a standard 23t aftermarket pinion.


Hopefully that clears up some of the discussion above.
Last edited by taz11 on Sat Jul 14, 2012 3:34 pm, edited 1 time in total.
User avatar
By taz11
#69811
Dave... Yes that is correct.

Read the FAQs and it will reduce "newbee whoopsies" :P :P :P :P :lol: :lol: :lol: :lol:

Anyway, you will need 19t pinions or 21t gearbox cases.....You can swap the gears over, just need to keep the case and pinion the same. Its usually easier to swap the hole thing....but cheaper if you can find some broken 21ts and steal the cases.
User avatar
By daveweber34
#69842
taz11 wrote:Dave... Yes that is correct.

Read the FAQs and it will reduce "newbee whoopsies" :P :P :P :P :lol: :lol: :lol: :lol:

Anyway, you will need 19t pinions or 21t gearbox cases.....You can swap the gears over, just need to keep the case and pinion the same. Its usually easier to swap the hole thing....but cheaper if you can find some broken 21ts and steal the cases.



Thanks. I remember reading the FAQ at the time but I think I came across your post after I read the FAQ and to me it read like you could just do a straight pinion swap. Once I saw that, I just ran with it and never went back to the FAQ. My mistake. Lesson learned. I'm sure it won't be the last one. :mrgreen:
User avatar
By daveweber34
#70019
Ok, I've been doing some homework on figuring out what the pitch of the different gears are for the various 7R gearboxes. I've gone to this site: http://www.engineersedge.com/gear_formula.htm. It list various formulas for determining a gears pitch. The relevant formula for us is this:

Pitch = (Number of teeth + 2)/Outside Diameter or more simply P = (N+2)/OD

I had my stock 19t motors out of a unibody Jeep so I measure the diameter with my micrometer and it was ~.672". So that would an equation of:

P = (19t +2)/.672 or P= 31.25
Now that is not exactly 32p, but pretty darn close.



To verify some more I checked the stock 16t motors on the Extreme Machine I just picked up. The pinion gear diameter was ~.577"

P = (16t + 2)/.577 or P = 31.2
Again, this is darn close to 32p and virtually matches the pitch on the Jeeps 19t pinion gear.


So with this information, let's do some math on what the pitch should be for the various gears.

13-14 7R GB.
Don't know. If someone has a vehicle with those pinion gear tooth counts, could you throw a micrometer on them?


15-16-17 7R GB.
It is known that the 16t pinion IS 32p, correct? If that is the case than the ideal equation would be:
32p = (16t +2)/.5625"

So, the diameter of the pinion gear would have to be the same for the 15t, 16t, and 17t pinion gear, correct? As such, that would mean the equation for the 15t pinion gear pitch is:
P = (15t + 2)/.5625" or P= 30.22 or P = 30..... 15tooth, 30 pitch pinion gear. (Maybe 31 pitch actually? In the real life micrometer reading I did on my 32p, 16t and 19t pinions, they both had to be rounded up about 3/4 pitch to get to 32p)

Now, 17t pinion gear.
P = (17t + 2)/.5625" or P = 33.78 or P = 34.....17 tooth, 34 pitch pinion gear


18-19-20 7R GB
We KNOW that the 19t pinion gear is 32 pitch for this GB, right? As such, the ideal equation would be:
32p = (19t + 2)/.65625"

So, for the 18t pinion gear:
P = (18t + 2)/.65625" or P = 30.47 or P = 30......18 tooth, 30 pitch pinion (Again, 31 pitch maybe? Does this need to be rounded up like my real life pinion gears?)

20t pinion gear:
P = (20 + 2)/.65625" or P = 33.52 or P = 34......20 tooth, 34 pitch pinion




21-22-23 7R GB
We KNOW the 22t pinion gear is 32 pitch, right? So, the ideal equation would be:
32p = (22t + 2)/.75"

So, for the 21t pinion gear:
P = (21t + 2)/.75" or P = 30.67 or P = 31 pitch? .....21 tooth, 31 pitch gear (is this supposed to be 30 pitch maybe?)

23t pinion gear:
P = (23t + 2)/.75" or P = 33.33 or P = 33........23 tooth, 33 pitch gear (is this supposed to be rounded up to 34 pitch maybe?)




What does this mean?????
If the middle gear number (16t, 19t, and 22t pinions) are all 32 pitch, then it looks like the lower pinion number, 15t, 18, and 21t pinion gears would be either 30p or 31p. The higher pinion number, 17t, 20t, and 23t would be either 33p or 34p.

EDIT:
After some more research this morning I have found that for applications like these brushed motors we use, you are only really dealing with 24p, 32p, and 48p gears. Outside of those pitches, good luck trying to find oddball pitches like the the "off gears" would require to fit those same gearboxes. Power Wheels may be able to get those pitches close to 32 made, but they are not made for the aftermarket like we would be looking for.

Like Taz and Hootie have been saying all along, just stick with the middle gear number at 32 pitch for the gearboxes.
Last edited by daveweber34 on Sat Jul 14, 2012 10:37 am, edited 2 times in total.
User avatar
By daveweber34
#70020
Yeah, I did a bit more reading and I see that the common pitch size for motors/gearboxes like this is 24, 32, and 48. It makes me wonder why the heck PW is labeling the gearboxes like they are if the pinion gear would need such an
oddball pitch size to make the different pinions work? It also makes me wonder how imprecise those plastic gears in the cases are?
User avatar
By hootienchyna
#70046
Plenty has been answered about this topic since the first post in it.

Now just formy own satisfaction here is some info
The diameter of the 7r pinions are as follows
15t .574
16t .574
17t .574

Now for regulal #7 32 pitch
15t .540
16t .573
17t .605

Now for all YOUR knowledge please explain how the 32 pitch 15 and 17t can mate up with the first gear in the 7r gearbox.
The 7r was designed to accept 3 size pinions without having to move the first gear or motor mount screws. They simplified it by changing the diameters of the pinions which is why only the center pinion size mates up PROPERLY.

PLEASE DONT CHALLENGE MY EXPERIENCE WITH THE GEARBOXES WHICH IS WHAT MY BUSINESS DEALS WITH THE MOST.
User avatar
By bruces_eviltwin
#70048
Im pretty sure it was suggested that some of the 7r gearboxes haver never been released on a vehicle however it was not said that they dont exist. In fact they are available from hootienchyna on his site http://WWW.MLTOYS.COM" onclick="window.open(this.href);return false;

also I find it very disrepectful to tell a moderator as well as 1 of the most respected people on this forum to leave this topic! Between hootienchyna and Taz im sure they have forgotten more about power wheels than some of us will ever know.

daveweber34 your math on pinion pitchs does a good job of showing how thepinion system seems to work, we just need to physically measure all the pinions so we can make a definate chart!

thanks to all for your efforts on this subject
Last edited by bruces_eviltwin on Sat Jul 14, 2012 11:52 am, edited 1 time in total.
User avatar
By daveweber34
#70054
hootienchyna wrote:Plenty has been answered about this topic since the first post in it.

Now just for my own satisfaction here is some info
The diameter of the 7r pinions are as follows
15t .574
16t .574
17t .574

Now for regulal #7 32 pitch
15t .540
16t .573
17t .605


The 7r was designed to accept 3 size pinions without having to move the first gear or motor mount screws. They simplified it by changing the diameters of the pinions which is why only the center pinion size mates up PROPERLY.



Good info again Hootie. As I've learned from this thread, only the middle gear will have 32p threads. The other gears will have a different thread pitch. Since only 32p gears are sold in the aftermarket, we are limited to the middle gear number on the cases.


Just to let everyone know, here are the thread pitches based on hootie's 7R pinion diameters
15t = 29.6p
16t = 31.4p (32p aftermarket pinions work)
17t = 33.1p

Thank you for your work hootie.
User avatar
By daveweber34
#70055
Kriss,

All hootie and Taz have been trying to say the whole time is that the logic that applies to the 15t-16t-17t #7R gearbox also applies to the 18t-19t-20t, and 21t-22t-23t #7R gearboxes. Meaning that for those who are trying to use an aftermarket pinion or the old #7 gearbox pinions, one can only use the middle numbered pinion gear (16t, 19t, and 22t respectfully). That is the only 32p pinion gear that will mate properly with the #7R gearboxes. Any other 32p pinion gear tooth count and its diameter will be either too large or small. It may work for a time, but it will lead to premature failure of either the gear box or motor. Since 32p pinions are all that is sold aftermarket (no one makes a 33p or 30p gear), you have to go with the middle numbered gear.

I hope this helps
User avatar
By hootienchyna
#70057
I must clarify 1 thing, never did i say the pinions were a different pitch in the 7r.
I stated that the pinion size is the same which means that a 7r pinion that is 16t or ANY MIDDLE NUMBER ON THE GEARBOX
Is the same diameter as a standard pinion. The other 2 pinions above and below will not MATE properly and chew the first gear in the box.
User avatar
By hootienchyna
#70058
daveweber34 wrote:Kriss,

All hootie and Taz have been trying to say the whole time is that the logic that applies to the 15t-16t-17t #7R gearbox also applies to the 18t-19t-20t, and 21t-22t-23t #7R gearboxes. Meaning that for those who are trying to use an aftermarket pinion or the old #7 gearbox pinions, one can only use the middle numbered pinion gear (16t, 19t, and 22t respectfully). That is the only 32p pinion gear that will mate properly with the #7R gearboxes. Any other 32p pinion gear tooth count and its diameter will be either too large or small. It may work for a time, but it will lead to premature failure of either the gear box or motor. Since 32p pinions are all that is sold aftermarket (no one makes a 33p or 30p gear), you have to go with the middle numbered gear.

I hope this helps


Someone who reads and understands, thank you
User avatar
By taz11
#70066
Sorry guys..... Those that have been following this topic may notice that there are some posts that are missing.

After some unpleasant behind the scenes PMs, It was decided that some of this discussion had to go away.

It was in the best interest of this site and its members. I will be editing more posts in an effort to remove the balance of the crying and disrespect that was presented here.


Thanks to those members that jumped in and supported me and the other members of this site.
Last edited by taz11 on Sat Jul 14, 2012 3:35 pm, edited 1 time in total.
User avatar
By taz11
#73570
Disturbing.......

Not sure if it is just coincedence but.......

I got my hands on (dont ask) a lot of 7Rs....bits and pieces. Some good, some bad....the failure point in almost all the bad ones was the teeth on the first gear......as far as I can tell they all had stock motors and pinions. Also seemed to be more 17ts in the broken pile...... not sure what that means.

Just passing it along.
User avatar
By sea_stork
#73706
They fixed the weakest link (final gear). First gear must be the next weakest link.

Found this. Maybe it will mean something to someone who understands these a little more. http://www.ebay.com/itm/2-CUSTOM-Power- ... 2ec008706b

How would you custom build these?
User avatar
By taz11
#73707
sea_stork wrote:They fixed the weakest link (final gear). First gear must be the next weakest link.

Found this. Maybe it will mean something to someone who understands these a little more. http://www.ebay.com/itm/2-CUSTOM-Power- ... 2ec008706b

How would you custom build these?



SCAM
User avatar
By wired
#73719
I don't mind seeing ads like this for the comic relief but seeing that they actually sold some just makes me shake my head.
User avatar
By sea_stork
#73735
SCAM



Not surprised, seeing who the seller is...


wired wrote:I don't mind seeing ads like this for the comic relief but seeing that they actually sold some just makes me shake my head.



Yep.
Last edited by sea_stork on Wed Aug 15, 2012 1:31 pm, edited 1 time in total.
By insomniac42
#74128
Ok so let's see if I understood all of that. Please forgive me my computer is down and all I have is my cell phone for internet so I might have missed a lot. Lets say I found a #7r 21t with matching motor. I wanted to upgrade to a 775 motor I would need a 32p 22t pinion? If that is correct I will continue with my 2 projects.
Last edited by insomniac42 on Sun Aug 19, 2012 3:25 pm, edited 1 time in total.
User avatar
By bruces_eviltwin
#74129
that is the general theory although it hasnt been proven yet with the 21 22 23t gearbox yet. I have the boxes but just havent gotten things put together to test it yet
By jimk
#74131
I have an Kawasaki Ninja (like the Arctic Cat) with Monster Traction Brute Force. My right rear drive hub and drive gear are stripped. I want to replace both motor/gearbox assemblies. I want to go with a 7R (unless someone convinces me otherwise). I have 2 questions,
1. which 7R should I get and what will the different numbered 7R boxes give me in terms of torque & speed?
2. Do the different numbers effect the orange plastic final drive in a way that the wheel hub will have to be changed?

Any advice will be appreciated. I have a fleet of these for my 2 boys, 3 & 5 yrs old. They drive the crap out of them. 2 Stingers are 18v. I installed extra wiring when assembling a new Hurricane. Otherwise is in stock..because it runs incredibly smooth on our blacktop as well as grass. I have the Yamaha which needs voltage upgrade but I need advice on battery options.

Bottom line-they like to go fast. I have time for maintenance and average upgrades...NOT major modifications. Any advice is welcome.

You can email me at jimk75@hotmail.com
Attachments
fleet.jpg
Last edited by jimk on Sun Aug 19, 2012 7:37 pm, edited 1 time in total.
User avatar
By bruces_eviltwin
#74144
the drive hubs are identical to the #7box and it seems the final drive ratio is the same when you have identical drive pinion numbers, the 7r is definately a little tougher. mine are running 18volts and the kids love it!
By wspec
#78231
bruces was you able to get the 23t 7r gearboxs going with the 22t pinion? I am about to buy gearboxes and would like to know if this setup is working well...
User avatar
By bruces_eviltwin
#80591
wspec wrote:bruces was you able to get the 23t 7r gearboxs going with the 22t pinion? I am about to buy gearboxes and would like to know if this setup is working well...

jury is still out, I have less than an hour run time on it and we got 8 inches of snow today
User avatar
By taz11
#84749
I might have killed one :? :? .

I have not had time to look into it yet. I have it set up with a Banebots 700 on 24 volts in my 4x4 Jeep. Something locked up near the end of the PW meet a few weeks back. I will let you guys know when I get a minute to tear it apart.
User avatar
By bruces_eviltwin
#84789
taz11 wrote:I might have killed one :? :? .

I have not had time to look into it yet. I have it set up with a Banebots 700 on 24 volts in my 4x4 Jeep. Something locked up near the end of the PW meet a few weeks back. I will let you guys know when I get a minute to tear it apart.

I assume thats with a esc?
User avatar
By taz11
#84792
bruces_eviltwin wrote:
taz11 wrote:I might have killed one :? :? .

I have not had time to look into it yet. I have it set up with a Banebots 700 on 24 volts in my 4x4 Jeep. Something locked up near the end of the PW meet a few weeks back. I will let you guys know when I get a minute to tear it apart.

I assume thats with a esc?



Yes
By insomniac42
#84818
so im getting 2 #7r 19t gearboxes. im going to pair them with Revolver 700-HO Motor from kershaw designs. also throwing heatsinks and fans on the motors. anyone use these motor/gearbox combo yet?
User avatar
By bruces_eviltwin
#84857
i believe taz may have those, you would have to stay with 19 teeth
By rman
#84972
great thread!


I'm planning a rebuild of my boys super6 f150s... would really like to go with the 7Rs. where is the best place to get them? I have seen them on ebay and ML Toys fro $45/ea... at that price I may have to go with with regular 7s and just replace them as they break/wear
User avatar
By bruces_eviltwin
#84978
7's are far more available, i bought new ones for the sake of research i havent seen any used ones on here
By jtlee2012
#85729
Hello weve got a jeep hurricane the gearbox you have post is what we need one of the gears thats in the one we have has 2 teeth mising if you can point me in the right direction to get one that would be awesome
By insomniac42
#85820
I ordered some 19t gears for my new motors. But they seem to be too large in diameter. (don't fit thru the hole going in to the gearbox) is there a place you guys get these gears from? I should need a 19t 32p gear correct?(I have a 19,19,20 #7r gearbox) with a 700 series motor
User avatar
By taz11
#85830
insomniac42 wrote:I ordered some 19t gears for my new motors. But they seem to be too large in diameter. (don't fit thru the hole going in to the gearbox) is there a place you guys get these gears from? I should need a 19t 32p gear correct?(I have a 19,19,20 #7r gearbox) with a 700 series motor



19t 32 pitch will work. Make sure you have the correct pitch gear. I different pitch will change the outside diameter of the gear.
By Woodfield1
#99894
Used HPI 550's motors on with 15t pinion on the 15/16/17, 7R Gearbox. It held up for about two weeks and then broke one of the middle gears.

Not sure if I'm going to try the 16t with an ESC or keep the 15t pinion as it didn't chew up the first gear on in the gearbox.
User avatar
By bruces_eviltwin
#99896
Woodfield1 wrote:Used HPI 550's motors on with 15t pinion on the 15/16/17, 7R Gearbox. It held up for about two weeks and then broke one of the middle gears.

Not sure if I'm going to try the 16t with an ESC or keep the 15t pinion as it didn't chew up the first gear on in the gearbox.

in a 15 16 17 gearbox you must use a 16t 32 pitch
By Woodfield1
#99897
Yes, that is what I read all through this post. But I was surprised that the 15t pinion didn't chew up the mating small gear. The gear that broke was one of the middle ones. I went ahead and ordered the 16t but again when I opened up the gearbox I fully expected to see the mating pinion gear broke but it was good. Just seemed odd.
Why wont anyone help me??

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