First build! EMTB, 12s10p, Quad drive - APS 6384s, Full Suspension, twin FOCBOX unity’, DieBieMS, 10" tyres, custom fabricated aluminium chassis

Hi EsK8 legends!!!

Long-time skater, first time builder, first time poster!!

Back story: I am a fabricator/welder by trade and have recently fallen in love with EMTBs after seeing one of the Bajaboard G4Xs!! My background is in Ultra4 buggies and comp trucks/rock crawlers so I have decided to fabricate my own aluminium chassis and build a MONSTER EMTB!!!

The basis for my build so far is thus… And PLEASE give guidance, tips, pointers, tell me what you would do different, tell me what I’m doing well!!

Chassis/board: Custom fabricated aluminium, double wishbone independent suspension. (Almost finished)

Suspension: DNM DV22AR with custom spring rate. 60mm travel. (Already have)

Tyres: 4.10-4 pneumatic. 10” Mini quad tyres…. Why so big?.. Why not!!! Also I have had these in the garage for a while and figured they would be something different and would be awesome and surely would give me the unofficial title of biggest tyres?? (Already have)

Motors: 4 x Alien Power Systems 6384s 130 kV sensored 10mm shaft 3mm keyway (Ordered)

Battery: 12s10p Li-po 30Ah Custom made 30q pack. Am considering swapping this to LiFePO4 pack as spaces isn’t an issue at all but would love your thoughts!!

ESC: 2 x FOCBOX Unity (although I am so torn!! I don’t know if there is anything that would be capable of handling the current I will be drawing!!) Please advise!!!

BMS: DieBieMS. (Considering whether to run a BMS for charge only or not. Please give advice!!) (Ordered)

Drive/gears: 2 Options… Looking at running 5MHTD pulleys 15T/72T with a custom made constant velocity shaft but am considering chain drive with CV shaft too…. Please help!! I am thinking ill need to be around the 5:1 mark. I think.

The build will be updated with photos as I progress, I have just finished cutting the aluminium for the suspension upper and lower control arms and will weld that component together today. It has similar looking upper suspension brackets to a Bajaboard G4X however the turning principle and construction are different for a few reasons…. 1st being I didn’t want to just copy a pre-existing design, even though I have no intention to sell these, I am sure there would still be some kind of copywriting concerns if I directly copied!!. 2nd their suspension and turning design is INSANELY complicated!! So far above my engineering level!! Kudos to Bajaboards for that!!

My details:

6’0”

105Kgs

What I want in order of my priority….

1: Reliability (no one wants their board to catch fire long distances from home)

2: Speed!!! (If it’s not fast it’s not worth doing!!)

3: Range!!! (I am hoping to achieve upwards of 40kms range, the more the better!!)

4: Ability to climb hills!! Don’t have a heap of “Steep” hills but have some that are a reasonable grade % and are quite long. Think max 15% grade but would like enough torque to conquer 20% grade!!

5: Ability to drive on soft sand and dirt!!

drawing%20POC cut%20Ally Drawing%20to%20scale tyres welded%20brackets Springs

More Photos to come as the build progresses.

Look forward to your feedback!!!

Woody

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Seeing this just made my day

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Have you thought about a custom spur gear drive ?

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Damn and I thought my 12s8p quad 6374 build was gona be crazy haha

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@Woody1989 Can you share the maker of the tire you are using?

Kevin

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Hey @moon, I have, I just dont know where to start, I figured Id build the chassis first, and then make some foanm mock ups and ensure clearance is there. I was hoping to enquire with @Nowind @Kug3lis or anyone else who makes gear drives about taking one of their off the shelf products and having it made custom to suit. Just nto sure on their availability to make 1:5 or even 1:6 drive systems customized. any advice in this area?

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Hey Kevin, They are “Guang Li” tyres -_- from china I am sure… but I believe you can find these on eBay if you search 4.10-4 Tyres. They are surprisingly well balanced however I will still be adding some ABC beads to assist.

Woody

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Looks amazing! Gonna build a 4wd for the winter too but mainly from stock parts as I don’t have the tools and access to all the machines I would need. I can recommend you to look through this thread

Maybe there some helpful information for you too.

What amps you expect to draw that you think two focbox unity’s will not handle? I mean, do you already have some experience or log files from similar rides? I haven’t seen @Duffman here for a while but I think @rich can give you some ruff numbers, he kind a push everything to it’s limits (or over…most talented destroyer here…)

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Yeah I dont mind helping out - I have designed a couple gear drives now and I can hopefully help someone out

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You can take the gear drive from @Nowind or @Kug3lis and customize your hanger so that it fit. Looks like you have the tools and it will be kind a more easy and cheap I guess

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Hey @Andy87, I have no data at all, I have just been scared by the forums and post of people gear catching fire, I am completely new at Esk8. I am a total noob hahaha. just thought Id give it a crack. I have read a lot that big tyres and hills = huge amps. I just dont know where to start those calculations without trial and error and at $500 a pop for FOCBOX untiy I dont ant to fry anything…

Thanks for the help though!!! Ill have a look through this thread now!!

Woody

@moon once i know the hub dimensions and design Ill shoot you a PM and we can see whats possible? Cheers Woody

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That was my thought too, Just wasnt sure if the 1:5 drive would be ideal.

Yeah sure np

I think @ervinelin has a crazy 5:1 build

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You will not fry anything as long as you setup your unity’s right. You know that you can limit your battery current to a value that will not harm your controllers. Plus you will split the load to 2 unity’s. I can imagine that it will be a heavy board and the tires will draw some extra amps but that shouldn’t be an issue as far as I can say. Please consider that there is a point where the board isn’t rideable anymore. Too much torque will through you off :sweat_smile: For me I can say with a dual set up, and chain drive I can hardly hit 80a yet. With a 4wd i will be more but not double up. I think with 100a per unity you will sit on a rocket that can climb the Mount Everest :wink:

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you had me at rocket climbing mount everest… :wink: I cant wait for that!!! hahahahaha Thanks for the advice!! I will surely be in touch!! I am definitely considering @Duffman double reduction geardrive… I think this will solve my space issue I was having with bigger sprockets and allow me to run more reasonable sized drive sprockets!!! Thanks for the help!!!

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Welcome! Hold us up to date. Will stick to this thread. Wanna know how it will look and perform in the end!

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Something about seeing

and

in the same sentence is like :open_mouth::face_with_raised_eyebrow::smirk:

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@b264 Your almost personally responsible… hahahaha I have read so many thread with your advice with battery set ups and what not!! 12s10p too big? or is there a different recommended size that would give me good eRPM on 130kV motors with plenty of torque and also have decent range? hahaha Woody

This looks like fun! Man I can not wait for this build thread. Fantastic stuff. Hows the budget on it because you could always chuck 4 arc 200’s on it

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