TRX-4 Sport Upgrade Path

[Rockin140]

I did a HH Crawlmaster Sport 15t with 9/45 gearing in my single-speed Sport. Fantastic low-speed control!

 

[slothRC]

I did a HH Crawlmaster Sport 15t with 9/45 gearing in my single-speed Sport. Fantastic low-speed control!

Thanks for the info! I’m very interested. You wrote “9/45 gearing”... which gears specifically did you replace? Sorry, I’m still learning all of this stuff.


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[Stormin2u]

When adding brass keep it as low as possible. Any extra weight above the axle centerline will have a negative effect on performance. It's important on any crawler but especially the high clearance chassis and axles of the TRX4.

 

[Harleyflyer]

basically the weight of a tiny servo and 2 gears.
Gearing works like this, the motor produces power, Power=torque*speed so if your first gear is half as fast as 2nd gear it produces twice as much torque, since the power remains constant.

If you haven't purchased a radio, then I would cross that off the list and get a castle mamba x and a brushless puller pro instead. Nothing wrong with traxxas remotes. Extra buttons for lights...I have them, never use them, a button on the car is just as good IMO. Oh nm you already bought an ESC and the remote.
Well you can run a brushed motor nn 4s for extra speed, but not with the HW1080.
And 2200kv or a 21t 550 3slot or 10t 550 5slot are the only brushed motors I would recommend.

I am thinking about getting a TRX Sport. If I wanted a drop in brushless motor replacement, would the Mamba X and Puller Pro be the best option assuming I was just going with the single gear transmission? I am looking for a very good slow and precise crawler. Still debating if I go stock motor and Hobbywing 1080 esc but I really like the idea of brushless.

Thanks,
Keith

 

[themountain]

If you look for a great servo look no further ...AGFrc.... 834 oz/in of torque "thumbsup"
https://youtu.be/7U-mzBrXML0

 

[Inspector86]

I use the Savox 1230SG specifically because it is rated at 500oz in at 6v. This makes it compatible with the stock TRX4 receiver which also runs at 6v. I run with a HW1080 set to 6v output, HH Crawlmaster Sport 12t w/9t pinion and 45t spur and I can't recommend this combination enough. Smooth, cool running and dependable.

 

[Harleyflyer]

I use the Savox 1230SG specifically because it is rated at 500oz in at 6v. This makes it compatible with the stock TRX4 receiver which also runs at 6v. I run with a HW1080 set to 6v output, HH Crawlmaster Sport 12t w/9t pinion and 45t spur and I can't recommend this combination enough. Smooth, cool running and dependable.

That’s great! I’m very new to RC crawling and with regard to brushed motors, how long will they generally last...or last before they need maintenance like the brushes replaced? I realize this probably varies quite a bit but I’m just asking from an average period of time perspective.

 

[Rockin140]

Thanks for the info! I’m very interested. You wrote “9/45 gearing”... which gears specifically did you replace? Sorry, I’m still learning all of this stuff.

9t/45t refers to the tooth count of the pinion/spur gears (output) of transmission. The stock gearing is 17t/39t - at least in the Sport kit it is.


I installed the 15turn Holmes Hobbies Crawlmaster Sport, where Inspector86 did the HH Crawlmaster Sport w/ 12turns. With brushed motors, lower turns = higher RPM/Speed (for same gearing). Think of it as more turns = more weight to spin around vs lower turns = less weight to spin around. My Sport w/ the HH Crawlmaster 15t and 9t/45t gearing calculates to a 5.22MPH top speed.



One of the members here has a speed calculator available for download. Maybe he will chime in or do a Google search (better than RCC search).


Hope this makes sense and helps! I'm learning too"thumbsup"

 

[mr_alister]

So let me get this straight. A HH crawlmaster 15T will have a higher top speed than a 21T trailmaster but still have better low speed control/torque? How does that work?

 

[Rockin140]

Maybe this will help... https://holmeshobbies.com/motor-recommendations

There are others on this forum that can explain the technical differences better than I can. In the mean time, look at the chart's top bar: Motor Type. Then search for those different types.

I'm sure you'll get better responses than this, but it's a start.

 

[mr_alister]

Looks like the crawlmaster series are not necessarily more torquey but just smoother since they have 5 slots. I bought a 21t trailmaster which is right in the middle of everything in that chart so it should be a good place to start...

 

[themountain]

So let me get this straight. A HH crawlmaster 15T will have a higher top speed than a 21T trailmaster but still have better low speed control/torque? How does that work?

No... a 550 crawlmaster sport 15t 5slot is as fast as a 35T 540 can Trailmaster sport...more or less;-)

 

[Gramps]

This might help explaining the differences in HH brushed motors https://www.youtube.com/watch?v=TOqn5rAoAZs

 

[Inspector86]

The Holmes Hobbies Crawlmaster Sport 550 12t or 15t @ $20 is arguably the best budget brushed crawler motor currently on the market. The Crawlmaster series motors are equipped with a 5 segment armature which is the reason for the much smoother start up and slow speed control as compared to a standard 3 segment armature. Also, you want to run the smallest pinion gear you can which will increase torque delivery at the expense of some top speed and run 3S over 2S. As John Holmes always says, "Gear down and volt up".

The TRX4 with 2 speed transmission comes equipped with 11t pinion and 45t spur where the single speed Sport is equipped with 17t pinion and 39t spur. The 2 speed can run an optional 9t pinion and the 1 speed can run an optional 15t pinion.