TRX4 Axles with Axial Transmission - Gearing Calculations

Update to the TRX4 VS4-10 build and how-to tackle the math of calculating overall gearing so I could finish installing the Axial style 3-gear transmission into this build.
Full Build Breakdown can be found here: www.HarleyDesigns.com
Vanquish VS4-10 Chassis: bit.ly/2EdOGeN
Transmission Build:
Motor Plate: bit.ly/2EAHzgB
Transmission Housing: bit.ly/2wmjKoj
Gear Set: bit.ly/30OscL4
Dig System: bit.ly/2QnW0cz
Idler Gear Shaft: bit.ly/2MbTYxM
Slipper Eliminator: bit.ly/2Mb9aeg50t
50t Spur Gear: bit.ly/2kyZOfD
20t Pinion Gear: bit.ly/2lPunOq
Suspension:
SCX10-II Links used: bit.ly/2HRwWYN
TRX4 on VS4-10 Links: bit.ly/2lQ5mTe
Driveshafts: bit.ly/30I6vfq
Incision 90mm Scale Shocks
Rolling Stock:
Method 310 Wheels: bit.ly/2W68sDY
Proline Hyrax Tires: bit.ly/2VOPKeN
Crawler Innovations Foams: bit.ly/2QnZjjZ
Crawler Innovations Tuning Discs: bit.ly/2VR6sui
Electronics:
Castle Mamba X: bit.ly/2HDVncb
Holmes 3500 Puller Pro: bit.ly/2Eyyyo6
Futaba S9177SV Servo: bit.ly/30jjtQD
Futaba 2106GF Receiver: bit.ly/2W1w1wS
Futaba 4PV Radio: bit.ly/2HsOUz8
Gens Ace 3s battery: bit.ly/2Mb7Xns
Gens Ace 4s battery: bit.ly/2HEqeVT
Vanquish Products 2" Rigid Light Bar: bit.ly/30UQsLw
Details:
Proline Power Wagon: bit.ly/30O2LJh
Origin radiator: bit.ly/2I1MDeV
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[@tomandrews5392]

Understanding the math is awesome...This makes building a custom rig much easer...

[@moe282]

Great summary! I had a ton of people asking me about gearing on my SCX based beetles when using TRX axles and so I just added a link to this video in my build FAQ 👌

[@Stickies72]

Thank you Josh, as much as this is a very technical explanation, it is also very important information to know so you can really fine tune your rig for optimum performance. 👍👍👍👍👍👍I did check out the website and holy moly man, you have made a bunch of really sweet builds.

[@MikelangeloPhoto]

Oh man... that’s helpful! I had no idea how most of this worked. Well done!

[@AkagiPro1]

Want to see this rig running!! And that dig function 🙏🏼

[@kevingoodrich3050]

One of my favorite builds you have done

[@acrandroid]

You have a talent for explaining things, even to me that I'm from another country. Thanks!

[@gripking131313]

I just gave up on the ar44's on my vs410/scx10 ii hybrid. This video just pointed me in the right direction. Thank you.

[@michaelburton831]

Excellent vid Josh! Super cool and informative.

[@fredwaldrop3810]

I have the same set up, I didn't know how to solve the problem. Now I do, thank you sir!

[@toddgall5260]

Loved this video. Info I've been trying to find and explained well.

[@dwaynekaye2000]

Very good info.im a newb to crawling and totally understand strait away what your saying. Very detailed and easy to follow.👍. Imagination is only ones limitation and totally inspired to have a crack at a build like this I'm very mechanicly minded and love the engineering side of things. Looks amazing as well.👍👍

[@Nickwillfixit]

Will be keeping this video on hand as new to crawling and although I know gearing calculation's more for 1-1 and my 5th scale where I dont use under or overdriven gearing although it is giving me some idea's for my Kraken's, LOSI's and HPI's for sand and mud running on tight track's.

[@CarminesRCTipsandTricks]

THANK YOU Josh for a tutorial that was extremely informative and NOT dumbed down for the junior RTR crowd!!! 😎👋👋👋👋👋 *NOT PUTTING THEM DOWN,* it's just that those of us who are more experienced, value information like this! This was extremely informative and valuable. Thanks again!! Carmine ✈🚂🚙

[@RevolutionX]

Very informative video! Very well explained.

[@mocrawlerrc1731]

Mad paint skillz! Nice video, great info!

[@derekhell666]

Super helpful because I’m thinking about putting trx4 sport portals on my Axial UMG10

[@rcbloke1766]

I’m loving theses videos keep them coming 👍👍👍

[@odomandr]

Share that gearing spreadsheet....

[@nuge74]

Great vid, very informative thanks!

[@michaelhoyle2665]

Good to know you can always get a job as a math teacher if this RC thing doesn’t work out. Lol.

[@renobob7781]

Class was good, apple for the teacher 🍎🇺🇸☝️

[@Rare_Brad]

Holy crap. That was a lot of math. Never do that on a Monday again.

[@jameskilburn3230]

Awesome info! I’m a nerd like that I guess. Thanks man it was great

[@blakepurdum]

Good info 🤘

[@belair64]

I just completed a similar rig. But I mated a Element Stealth X tranny to Sport axles. In stock form it has 99.8:1 to the front tires, over 100:1 to the rear.

[@HarleyDesignsInc]

Yeah that sounds like a really low ratio, definitely need to look into the gearing options. The Element uses an pan drive slipper also I believe so gearing choices may be limited.

[@josbarhorst6574]

I love another matt lesson...

[@billcox87]

another very helpful video brother, loved it!! question on the servo thou, having over 1000oz of torque would be killer but at $250, it is a little butt hurty, how is the durability gearwise, and is it waterproof?? how does it hold up against Josh abuse;)

[@davidbanaszak562]

Great Video can you do a math video on TRX-4 overdrive and underdrive gearing? specifically on how it affects torque output from various motors like a Holmes Hobbies revolver or a puller pro in addition to a stock trx-4 motor. it would make understanding why this is beneficial easier and help identify the best mods for the crawler market.

[@HarleyDesignsInc]

The benefits to OD/UD aren’t always about the math. The values just need to fall into reasonable ranges for them to be effective at their designed tasks. I go over the overdrive percentages at the end of this video for a TRX4, as for the motors, that’s not something that this math is really for. You’d have to start comparing dyno graphs from each which is something better suited for Holmes Hobbies to do.

[@rcdabbler]

Would a higher KV brushless motor also be an option? For instance, if you just happened to have a 3300kv sensored motor lying around, the default gearing from this setup would essentially gear down that motor for more trailing speed, wouldn’t it?

[@johngrant1337]

That cool info. How is that truck compared to the VS4-10 pro (the $750.00 truck) ?

[@Ziggy8750]

I really like how the rear bed looks but I see no mounts for the rear. Does the rear bed fenders just flap all over the place?

[@ddavidson0404]

Can u talk about what u did with the tires? Cutting slicing..

[@xxrfmxx]

pro body job love it

[@pcx4545]

I understand you're using a dig but if somebody is not interested in one what's your opinion on using SSD's high ratio Wraith transmission with this axle conversion? I already have that axle setup with a stock ratio Axial 3 gear transmission and went to a 44t spur and 22t pinion and the speed is pretty much what i want with a 3S battery but i'm considering going to the SSD's trans

[@quintonkarlik2148]

Can you use the vfd twin transmission and these axles?

[@dslfrk59]

Does the sport and defender/bronco have different gear reduction in the portals? Everyone keeps saying 2.3:1 in portal but mine measures 2.55:1....... 9 input and 23 output. That's 7.89 axles ratio not 7.11

[@user-ho5vm9rv1e]

Does that have two different size tires front to back

[@bobbyjoemacdonald5081]

What’s the benefit of using trx4 axles as opposed to vanquish?

[@00godlovesus]

Good morning:)

[@Cobbaru2008]

What bumper is that?

[@mitchh3399]

Hey just a few questions, would you be able to share the gear spreadsheet for us and why did you ditch the locking differentials?

[@HarleyDesignsInc]

I would need to redo the spreadsheet as it was just something I threw together quickly to do the math. I got rid of the lockers as they just aren’t an item I like to run. I prefer to keep everything locked.

[@tangosierra1]

Got my Trx4 running at 42.66:1

[@jamestowne1481]

If I wore to add the trx 4 axle to my 10.2 in the rear with ar 44 in front would I use the same method to find the right gearing ?

[@HarleyDesignsInc]

Gearing would calculate the same way. But you have to make sure you can reverse the rotation of the rear axle or that it spins opposite of how the AR44 does, which I don’t recall.

[@frankkrivitz3323]

Will the TRX4 on VS4-10 Links p#IRC00202 be available through your distributors? I like to support local hobby shops as much as possible. Thanks...

[@HarleyDesignsInc]

They have been available for awhile, but may not be an item thats popular for distributors to commonly buy.

[@mastermindrc4404]

Hey man i have a chassis vs410 phenix and vfd trans can i do the same with the vfd trans and skid or do i need to make custom links ?

[@HarleyDesignsInc]

I have made TRX4 axle work with a VFD before. You will need a couple new links though, I created a custom set that you can buy for that though. It's on the Vanquishproducts site. IRC00202 is the part number. I used that in combo with the SCX10-2 link set but the Phoenix set will work as well I believe.

[@JuvsTagabanRC]

can I use trx4 sport stock transmission gears and spur/pinion paired with scx10ii ar44 axles? is that possible?

[@HarleyDesignsInc]

That would not be an ideal combo. Going to the largest spur and smallest pinion would get you the closest but still not perfect.

[@JuvsTagabanRC]

@@HarleyDesignsInc thanks for your guide bro. How about using the scx10 portal axles, will that make the cut?

[@TheLowjack27]

What would you recommend gearing wise with the vfd trans and trx4 sport axles? Would you still run a 50 spur and 20 pinion? TIA

[@HarleyDesignsInc]

Yes that’s still where I’d start.

[@TheLowjack27]

@@HarleyDesignsInc I actually left the stock 56t on it and did a 15t pinion and its not that bad still has a little pep but would not call it fast lol

[@thereviewguy5598]

Also what would happen if you over drive both front and rear axle ?

[@HarleyDesignsInc]

Then you are just matching the gear ratio and you have no overdrive but a higher gear ratio.

[@josh_rit8045]

This reminds me of school. I hate school. I hate this video

[@blakedenley3792]

Have you put trx4 axles under a vs4-10 with vfd transmission???

[@HarleyDesignsInc]

I have but it requires some less than ideal spacers on the axle side to be used to make the upper link clear the trans. I prefer to stay with the 3 gear for this setup.

[@clyde19770]

What did you use for the panhard and drag link, stock 10.2 parts?

[@clyde19770]

Never mind, I just ordered one. Great video, I was about to cut links and figure gearing on Wednesday. Thanks for putting in all the leg work!

[@mikebultema2536]

Anyone else end up with smoke rolling out your ears? 🤣🤯

[@PhoenixRCCrawler]

👍🏽🐒

[@thereviewguy5598]

Can we get some run footage of this truck?

[@HarleyDesignsInc]

There is a running video of it on the channel.

[@thereviewguy5598]

@@HarleyDesignsInc ok I’ll try to find it.

[@skirmich]

Changing the TRX4 spur and pinion is not easier? 45/15 = 47.4:1 final gear ratio.

[@HarleyDesignsInc]

The point was to get away from the TRX chassis and trans.

[@skirmich]

@@HarleyDesignsInc Oh ok..

[@richardscofield668]

Awesome info on the math but it’s a 9t not a 10 for the Portals. 2.55

[@richardscofield668]

TheCLA8N 75 like I said he did an awesome job explaining the math. I’m letting him know he’s off a tooth which actually makes a big difference. He thinks he will have 46.2:1 but will actually have a 51.22:1 ratio which is out of the range he was hoping for. So I’m not calling him out just trying to help. I just put trx axles under a wraith and also put those SCX10ii axles under the trx, it can get frustrating quickly.

[@jammyhires4598]

Use a Capra transmission

[@kts8806]

Sorry my dog ate my homework!!

[@drtmi8789]

Looking kind of pasty there Josh.

[@stanandstansfriend6019]

I always knew you were part robot and computer how else do you explain your gear ratio teachings. Lol

[@SpsTamiya]

im getting nose bleeds from the math