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MUD MONSTER, Scrub mountain board | vesc 6 mkIII | 1:7.5 two stage chain drive

So a little background to this build and its versions. I built my first esk8 in 2017 on a longboard with a 1.5kw sk3 motor and a x car beast 150a esc, it was a little champion on hills, but the roads in the UK are shite so i looked into pneumatic tyres, sadly i couldn’t afford a trampa board so instead i looked on ebay and found an old scrub furnace creek for sale at £60.

A couple of months later i had the parts to make a diy electric mountain board, (literally made it in the back of a car on the way up to Scotland for a holiday)



it was using 149kv sk8 motors
x car beast 150a esc
6S lipo
(also using the hobbyking esk8 motor mount)
then the fist time i rode the board i couldn’t find my knee pads and ended up ripping a hole in my knee to the bone
ended up finding another scrub furnace creek for £60 on eBay and thought it was time for a rebuild






i added motorcyle dampas a box for the escs and a carbon fibre vinyl wrap on the deck
replaced the 149kv sk8 motors with 192kv sk3 motors and added hall sensors to the motors so i could run them in sensored mode. i replaced the small hobbyking motor mounts with the trampa carbon fibre ones and added bracing bars across them.
after a pretty brutal session at a skate park i killed a motor, esc and broke one of the motorcycle dampas, so the board was out of action for 6 months

In the 6 months i set up a small blacksmithing business to pay for the repairs on the board
and managed to save up for a complete trampa board, two vesc 6 mkiii, 9" megastar wheels and mud plugger tyres.

as etoxx makes the sexiest spur gear drives for mtbs i decided to make one as he didn’t have a 1:7.5 gear ratio to run 12s 192kv motors and 9" tyre while having crap loads of torque.
so i designed my own spur gear drive.
it uses mod 1.5 12 tooth and a 90 tooth spur gears (https://www.technobotsonline.com)


the drive is made up similar to an etoxx drive tho i couldn’t machine the pom out shell so instead it uses spacers, a strip of aluminium, electrical tape, tie wraps and a v seal to seal the drive from debris.






to house the batteries i am using a a Milwaukee packout tool box and for the vescs i have bolted them to a piece of aluminium and that is glued to a Milwaukee shockwave bit box

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I admire the journey and the work that has gone into this. What part of the UK do you hail from?

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Preston

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Got some good routes nearby up there then!

I was worried my 190kv motors would be too high with 1:5 ratio :rofl: good to see real data. Beautiful build and hell of an effort. I love those scrub decks.

They’re not overheating on you?

I’ve got some 3d printed fans on them (not sure if they actually do that much) the highest temperature i have seen is just over 50°C, i was really ripping the board to see if anything would break

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Built some exxxtra wide trucks from steel, really nice ride feel and extra stability


The new aps 6384 v2 170kv motors have got a nice amount of punch in them

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A real DIY mountainboard great work dude :call_me_hand:

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Great build! also never heard of these scrub decks before but I gotta have one now. Looks sweet :ok_hand:

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Nice diy work

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so a bunch of stuff happened since the last update, first i broke my wrist (that was fun) and i finish a two stage chain drive, But then i bent the motor mount and the truck is now a slight banana shape and one of the sections of chain yeeted itself out of existence. Probably gonna switch to some mefo ice sliders like @NoWind and @Duffman or some 10 inch tyres. need to sort out the chain skipping when braking, replace the mounts with steel/ thicc aluminium and try to reinforce the trucks.

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Stay with 9“ or go 11“ if you can. The quality of 10“ tires are just not worth it.
11“ gokart tires are definitely a level up and you do not need to worry about flat tires as well :sweat_smile:
Unfortunately 11“ will add up quite a bit on weight.
Not the mefo tires, but I guess they are around the same weight.

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you got a link for them tyres? weight isn’t an issue this is my shred through the boggiest mud i can find board (was thinking of the trampa 10" but they look not too grippy)

Sure I have a link, but I guess they do not ship internationally. It’s a local shop in Russia in my city.

http://dako-karting.ru/cat.php?id=6

For comparison the 10“ trampa style tires (I bought them from China before trampa had them for sale)

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How do these trucks ride?

The width on them allows you to really lean into the turn and they give a smoother ride over rough surfaces, they can be abit unweildy and for jumps the extra width can throw you off. They feel very different from channel trucks they give the same ‘resistance’ no matter how far into the turn you are. Imo these ones are abit too wide.

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Why 1:7.5? How high can you go, e.g. can you also make 1:10 and still reach say 30 km/h?

Just depends on the motor kV, voltage and wheel diameter. Possible is everything :smile:

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Will dig the calculator again then …

However, 1:7.5 is the highest ratio I’ve heard of so far? Anybody?

using a two stage gear box etoxx made a 1:20 ratio. i was originally gonna do a 1:8.3 for 11" wheels but decided on 1:7.5 and made it modular so a later up grade would be easier then redesigning a new drive system. using multiple smaller sprockets you can get A LOT more ground clearance then a single larger one.

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