Gear Mesh Considerations

[Solus]

Hi,

I recently made a post about how I want to upgrade my Traxxas bandit from brushed to brushless. I got some really good advice from the people who responded to me there, and I went ahead an bought a hobbywing ESC and motor. Unfortunately when I bought the thing I chose an option that had a 5mm diameter shaft instead of a 3.175mm shaft by accident. Fortunately I found pinion gears that would work with this diameter, and have the same pitch as the spur gear. However I realized that with a non Traxxas motor and pinion, the gear adapter (Traxxas part 3790) may not create a good mesh. I have a couple questions related to this:

1. Will the stock gear adapter work with a new pinion gear and motor?
2. If the answer to 1. is no, can I mount the motor without the gear adapter or find an alternative gear adapter?

If the answer to both of these questions is no I may have to send a motor back to hobby wing :/

Thanks in advance for the help

 

[CreepyQuarryCrawler]

Hey hey!
Can you include a picture or two of the transmission?

I am not familiar with those gear adapters, I had to look them up.

If the transmission has standard slots I don't see why you couldn't just mesh it using a small strip of paper.

Over the years I have noticed most spurs are not completely round. Once you think you have it, rotate the spur and pinion and watch for binding.
If there's an area that is really tight or causing binding I would re-mesh in that area.

Again, I don't have a Rustler so toss up some pic so we can take a look.

Thanks,

CQC

 

[81exige]

1. Will the stock gear adapter work with a new pinion gear and motor? -> if the pinion gear you bought has the same tooth count as the stock one, then you shouldn't need to
2. if you're worried about the gear adapter, then at least in my opinion you should go with a different motor mount that allows you to slide in and out to adjust gear mesh - now I can't say for sure *what* motor mount you'll need as i do not own a 2wd traxxas platform, but RPM parts are generally well liked, so I'd recommend this one: RPM gearbox housing + motor mount

 

[CertifiedMike]

If you buy the correct pitch gear, tooth count to match those plates as Traxxas intends, they WILL be the same diameter, doesn't matter 5mm or 3.175mm.

So there is the question. Do you know which pitch, tooth count for those plates? Are they numbered by chance?

The depth of the pinion may present a different issue but deal with that after you test fit with a single pinion.

I also have one of those 3652 motors with 5mm shaft.

My buggy can use 48 pitch spurs.

I bought Robinson Racing Products 2023 and 2025 gears to test on.
Thats 5mm, 48p, 23 and 25 tooth.

I would def check RRP for your set up.

 

[Chubaka]

A reducer will run a 5mm pinion on smaller shaft motors. I also would like pics. That easy set mesh is a dumb idea from traxxas. Id try and find a way around it if possible. I run 32p gears on my trx 2wd and it upped the durability.

https://www.ebay.com/itm/3326631159...euqV7DdRY4dQpWC0DVL8j5SSU=|tkp:Bk9SR66Rw5C9Zw

 

[Solus]

Thanks for the responses so far.

I attached some images of the transmission for you guys. One image is with the adapter and one without.

A reducer will run a 5mm pinion on smaller shaft motors. I also would like pics. That easy set mesh is a dumb idea from traxxas. Id try and find a way around it if possible. I run 32p gears on my trx 2wd and it upped the durability.

https://www.ebay.com/itm/332663115910?_skw=rc+pinion+reducer&itmmeta=01KQMGGS2GD15V0FXJ0DK0MG3B&hash=item4d74445086:g:n90AAOSwSUBgEuRc&itmprp=enc:AQALAAAA0GfYFPkwiKCW4ZNSs2u11xBBRJ3AQmdmcY28Kd5bHd0sjthpUb9DHcxAUieC/jPskpzzdbrbL8U/J42SO+L24x5h6cYmMno5Xl6ZBneGwBUEVnvdomRg7hqllefENfGgwah+HBCaAzWPHJMLdo1LwETJjpVDugJJSpzB/eYeUM3BYUD/UYJIdSxuESNz/LcRQWJi0uyE+4wFg29Nd0CCxE9AQC72nme/Xk7g9po+9dneg/a3MzvKGLpGIxunefeuqV7DdRY4dQpWC0DVL8j5SSU=|tkp:Bk9SR66Rw5C9Zw

My problem isn't that the pinion I have is too large for my shaft. I bought a motor that has a shaft diameter that is too large for my stock pinion gear. Because of this I need to buy a new pinion. I agree that the easy set mesh thing feels pretty dumb rn.

If you buy the correct pitch gear, tooth count to match those plates as Traxxas intends, they WILL be the same diameter, doesn't matter 5mm or 3.175mm.

So there is the question. Do you know which pitch, tooth count for those plates? Are they numbered by chance?

The depth of the pinion may present a different issue but deal with that after you test fit with a single pinion.

I also have one of those 3652 motors with 5mm shaft.

My buggy can use 48 pitch spurs.

I bought Robinson Racing Products 2023 and 2025 gears to test on.
Thats 5mm, 48p, 23 and 25 tooth.

I would def check RRP for your set up.

Traxxas actually has a little chart for determining what position to use with different spur and pinion setups: https://d3if9wubzr0anm.cloudfront.net/manuals/TRX3790-1.pdf. The positions on the gear adapter are lettered as positions A and B which can be seen in the photos I attached. The pitch for my spur gear is 48P which can also be seen in the photos.

If you take a look at that link, it actually shows that you can use a motor screw position of "none" for certain gear ratios, which sort of answers my second question. I can't find the link now, but I did find a page on the Traxxas website that states that the gear ratio adapter is sort of like a nice to have instead of a necessary part. The only thing i'm concerned about now is if I smash this buggy into a wall or something, will the motor shift without that adapter?

It is good to know that if I have the same tooth count as the stock gear, I can keep on using the adapter, so obviously getting a pinion gear that is the same in pitch and tooth number as stock is a good idea. I will also be taking a look at RRP and RPM.

I appreciate the help so far!

 

[81exige]

The only thing i'm concerned about now is if I smash this buggy into a wall or something, will the motor shift without that adapter?

tl;dr use threadlock on the screw fixing the motor to the motor mount, as well as the set screw that affixes the pinion gear to the motor shaft and you should be fine

i have an 8th scale vehicle that's cartwheeled and landed on its roof more than a handful of times. it has a sliding motor mount and i don't think it's unintentionally slid back out or further in, although i do always use blue threadlock on both the motor mount cam (the part that you mount the motor to) and the sliding mechanism (which fixes the cam to the motor mount itself)

a general rule of thumb is if there's metal-to-metal contact, you'd want to use blue threadlock (i don't even think red's an option) with the exception of maybe the wheel nut; for those i just try to tighten the wheel nut as much as possible without going overboard

 

[CreepyQuarryCrawler]

Thanks for posting those.

So it looks like a traditional transmission/motor mount so you'll be able to set the mesh manually without those plates in there. At least from the photos you posted.

I would have to guess those are there to stabilize the motor and try to help from eating spurs.

I converted my stadium truck over to 32 pitch as someone else mentioned which is a more durable gearing set (larger teeth).

I would use washers on your motor screws to help spread the load across the plastic.

Please let us know if you have any further questions.

 

[RustyUs]

The reason for traxxas making the fixed gear mesh adapter inserts...

... is because too many people had motors/pinion gears get crammed into the spur gear during a good hard tumble/mishap. That's my understanding. The raised area on the adapters locks in motor's position rather than traditionally relying on just two mounting screws.

I know there is a chart for stock gearings on different models (stock Bandit 21T pinion gearing uses "C" adapter), but is there a chart that says what AB_DEFG holes are used for what pinion gear tooth count?