Super high gear ratio transmissions for slow crawling

[Voodoobrew]

I am looking for transmission options the have a lot of reduction to use 3200kv brushless motor in but I still want to crawl slow. Reason being is that the higher rpm and more reduction will give better low end resolution and torque. This is just for technical crawling, I don't intend on driving over 4mph ever. I will have the rear underdriven but I am not using that in calculations because the front will be at this stock ratio. I find that I am always barely touching my throttle and in the bottom 5% of the trigger, simply adding a throttle curve Isn't what I want. This is for pleasure use, not for competitions.

stock axial wraith transmission: total reduction - 35.47:1
12t pinion and 56t spur 4.67:1 ratio, 2.60:1 transmission ratio, 2.92:1 differental. I could fit a 9t pinion and 96t spur on my transmission and increase the reduction to 81.07:1 but thats the max possible I am aware of on this transmission.

What I have found so far:
Hot racing - SCP38X01 Low Cg Transmission Gear Box - Ax10 Scx10: total reduction - 192.53:1
Acording to Hot Racing this has an 11.4:1 reduction in the transmission and a 52t spur. with a 9t pinion (pinion spur ratio: 5.78:1) you end up with 65.78:1 to the drive lines and 192.53:1 at the wheel. This has an optional dig.

RC4WD - AX2 2 Speed Transmission for Axial Wraith & SCX10/Honcho: total reduction - 1st gear- 131.21:1, 2nd gear- 46.25:1
with a 9t pinion and 80t spur you get 8.89:1 before transmission, 5.05:1 for 1st gear or 1.78:1 in 2nd gear in the transmission and 2.92:1 in stock ar60 axles.

what other options for low gearing do you know of, and will any of these handle a 3200kv brushless motor at top speeds?
I dont think a planetary gear reduction on the motor is the way I want to go because they all say they cant handle brushless.

On the Hot racing - SCP38X01 with a 5.5 in tire @ 11.1v on a 3200kv motor I expect to get a maximum speed of 3.02mph that is a fairly normal walking pace if the numbers on ther site are correct.
On the RC4WD - AX2 2 Speed with a 5.5 in tire @ 11.1v on a 1700kv motor I expect to get a maximum speed of 2.35mph in 1st gear and 6.67mph in 2nd gear, which sounds nice too.

I used this for my calculations https://docs.google.com/spreadsheet...EjJFcdtjU4hW5xzKsDp01D0a4/edit#gid=1058564524

 

[Voodoobrew]

I wonder with these low speeds would there be much of a difference between brushed and brush-less? I would really like to see how slow I can get these tires to turn.
Just looking for a buttery smooth slow start up.

 

[Highmark]

What are you putting this in and how much space do you have? Have you considered worm (losi) axles? Likewise, a low KV outrunner paired with a lowish gear ratio will have similar properties.

 

[Voodoobrew]

I haven't considered a worm drive, that's a great idea. Hot racing make 25:1 scx10 worm drive axles.
No to outrunners, I don't like the noise. But I hear those revolvers are an impressive choice for low speed control.
I don't know what I will put it in, maybe a custom 3d printed chassis, or some premade ladder chassis 1.9 with a custom skid.

 

[Voodoobrew]

Looks like the worm drives have their problems. Excessive noise and heat being at the top.

I am thinking I like the idea of an ax10 2 speed transmission with a good crawlmaster motor.

 

[Highmark]

The AX2 is a great deal! The first gear is pretty low, so combined with a big spur it might be a good choice for you.

 

[cartronicshn]

what is the reduction on the older r2?

 

[raw111]

i run the ax2 with a brushless motor out of a yeti so 3250? kv and no complaints also ran it with a 3300 brushless in another truck tons of torque in slow but stupid fast in high

 

[WHITE-TRASH]

A Brood or Holmes 5 slot skewed brushed motor in 13 or 16 turn will do exactly what you're after even if geared correctly so it can move up to about 10 mph. Thinking way too hard about this really. :lol:

 

[Voodoobrew]

Probably. I doo want one of those puller motors. It's just on the stock transmitter and hobbywing 1080 so I don't think there is a throttle curve. So high speeds make it doubly hard to crawl.

 

[WHITE-TRASH]

I have a couple 1080's and I had them hooked to 45 turn 3 slot brushed and they crawled fine on 3s in a high geared berg.

My berg has 13 turn 5 slot skewed Holmes cheapie motors and on 4s it crawls great and has enough punch to jump gaps without issue.

 

[Voodoobrew]

I have a bully 2 with a 9t pinion and goolrc 35turn motors. While it can crawl slow good enough for most people, its not as good as I would like.

What 13 turn 5 slot skewed Holmes cheapie motors? Thats the puller motors and there $120.

 

[dacaur]

Sounds like you really dont need brushless. A 70t brushed motor will give you the low end resolution and torque you need....

 

[Voodoobrew]

Just getting a lower turn motor will sacrifice power.

 

[Smokin' Joe]

I found there was a huge difference in low speed control between a cheapie 35t 3 slot brushed motor and a Crawlmaster 13t. Here is a link to a thread where I tested the differences:

http://www.rccrawler.com/forum/elec...-advantage-more-expensive-brushed-motors.html

I feel like I can basically go as slow as I want even with a HW 1080 ESC and RTR transmitter with a stock transmission on 3s (and I have it geared to go faster than 4mph). If you are not set on going brushless, you may not need a different transmission...just a better brushed motor.

 

[Voodoobrew]

I know holmes talked about the differences between the sqewd vs straight armature. I need too find it. I don't think I need need brushless either. It's hard to quantify the abilities between the different motors because the info people look for often is not rated. No one has ran tests. So it's like food reviews. Looking at the crawlmaster vs the puller line on holmes web sight the differences are not apparent. I do remember there was a trade-off. I believe the crawlmaster had better slow start but less torque. Which might not be a big deal if your geared low enough. But with out trial and error I don't know how any one would know where that point is for them.

 

[calcagno45]

what is the reduction on the older r2?

30:1 so max FDR with OG axles and underdrive gears is 99.23:1.

 

[WHITE-TRASH]

I have a bully 2 with a 9t pinion and goolrc 35turn motors. While it can crawl slow good enough for most people, its not as good as I would like.

What 13 turn 5 slot skewed Holmes cheapie motors? Thats the puller motors and there $120.

$50

https://www.amainhobbies.com/holmes...2fRowrPCjFKo27kzIkZxc0DSjHcocQ2RoCEhcQAvD_BwE

Good motors for the money. 5 slots slow the motor down so my 13 turn are pretty equal to a 35 turn 3 segment in terms of speed but they boogie when I need it.

 

[Voodoobrew]

I cant seem to find info on the difference between straight and skewed armature. Or more to the point crawlmaster 540 vs puller crawl 500.
I thought he went over it in one of his older bench videos but can't find it.

 

[WHITE-TRASH]

Skewed armature splits the magnetic fields at an angle so the brake isnt as strong but it is buttery smooth on startup.

5 slot just adds more poles so it is smooth with good power.

The puller has stronger magnets and a machined can if memory serves.