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Advice on building my first LCG rig

P

ParrotSandwich

Newbie
Joined
Apr 18, 2021
Messages
21
Location
Budaors
Hi,

After 2 RTR-s, I am looking for advice on building my first LCG rig.

Goals:
  • End up with a crawler that outperforms my near stock Capra (RTR + Proline tyres + brass portal caps in the front + 1080 ESC)
  • End up with something flexible that is easy to change / improve later; avoid lock-in
  • Do not break the bank
  • 2S, if possible
I have no plans to compete, not interested in adhering to any rules, just want to have fun.

I plan to start with the following parts:
  • Capra axles. KYX axles from Aliexpress, but I replace the housing with Axial plastic housing - I don’t want any aluminium on the underside of the car. I was considering straight AR44, it is even cheaper, but my local terrain begs for portals.
  • Fimonda Frame Rails (link)
  • Element skid to start with (until I can get my hands on a delrin one)
  • Element Stealth X transmission. I want to try out just a bit of overdrive, but not much
  • Desert Lizard shocks in full droop configuration
  • HobbyWing Fusion SE 1800Kv

What do you think about this? Does it make sense?

My biggest concern is the “extra” 1.92 gear ratio in the portals, combined with the 3 gear transmission. Final Drive Ratio is 90 (huge difference to stock Capra FDR of 25). Is the FDR 90 OK? Will it work with the selected motor? On 2S?
The second concern (that I’ll just have to try and see, I guess), is this frame too flat for the portals? Would I be better off with this one instead?
The motor and the axles are the most expensive parts, these are the ones I least want to replace.

Thanks for any advice. Don’t hold it back!

PS. I am in Europe, some parts (e.g. a delrin skid) are not as easy to come by as in the US.
 
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I can say for sure that Stealth X + Capra Axles + SE 1800 on 2S = almost unbelievably slow. Like... sub 2mph wide open. Even with tiny spur and huge pinion I think you'd struggle to get to mid-3s.
You're building yourself a 4S rig, IMO. Change out that SE for some flavor of AM32 and a low to mid 2000s outrunner and you've got a weapon. I just recommend against 2S no matter what avenue you choose.
 
I am not ready to give up on the SE 1800 yet (great value, no whining, available where I live). Nor on the portals, yet. I am also convinced of 3s, but want to stop there.
I can fix the portal reduction from 1.92 to 1.50 with overdrive gears.
With 3s, this will get me to ~4mph which I think I can live with - if not, there comes 4s.
 
... or I can just pinion up like you said, e.g. go from the stock 18/87 to 33/72, and leave the portals alone. This cancels out the portal.

I am learning...
 
The fusion models are only rated for a 3s battery. so if your backup plan is going to 4s your going to need a whole new power system.

Or this, I did something similar. Made a custom tube buggy from some scx10.3 axles I had laying around paired it with a Axial 3 gear transmission not realizing that the portal gears really gear it down. I'm running a fusion pro 2300kv so my motor is faster. I used a traxxas trx4 45 tooth spur gear and drilled out the center to fit the 3 gear and tighten down the nut so it doesn't slip. Put a 22 tooth pinion on the motor and now speeds are ok for trailing. I'm not sure how the stealth transmission works so your results may differ.
 
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Opps forgot pics
 

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Druxus said:
The fusion models are only rated for a 3s battery. so if your backup plan is going to 4s your going to need a whole new power system.

Or this, I did something similar. Made a custom tube buggy from some scx10.3 axles I had laying around paired it with a Axial 3 gear transmission not realizing that the portal gears really gear it down. I'm running a fusion pro 2300kv so my motor is faster. I used a traxxas trx4 45 tooth spur gear and drilled out the center to fit the 3 gear and tighten down the nut so it doesn't slip. Put a 22 tooth pinion on the motor and now speeds are ok for trailing. I'm not sure how the stealth transmission works so your results may differ.
Click to expand...

Thanks Druxus, I missed that limitation. But I still plan to go with the Fusion 1800 on 3S. It is just an amazing value: motor, ESC and BEC for a very reasonable price.
So, change of backup plan. I have two options to gear up, pinion/spur and the portals. With the 33/72 pinion/spur alone, I can bring down the Final Drive Ratio to 40. This should be enough. If not, I do the portal overdrive too.

I think you went from from 13/56 to 22/45 -> you geared up 2.10x, this cancels the portal geardown of 1.92. I plan to do the exact same: go from 18/87 to 33/72 -> gear up 2.21x.
 
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ParrotSandwich said:
I have just found this 9imod outrunner and this RhinoESC on AliExpress. Cheaper than the Fusion.

Do I need the longer 3542, or I can get away the shorter 3532?
Click to expand...
i run the 3542s in large heavy 1/8 scale rigs and they work fine

i also run alot more reduction than a 3 gear on portals in my opinion the heavy gear reduction is really nice and also kinda needed with a outrunner and the top end is fine for a crawler

with a ultra light lcg i would say go with the smaller 3532 it will have slightly better start up and wont make as much noise
 
Thanks ferp420! I will go for the smaller 3532. Having a separate ESC, changing the motor became a lot cheaper.

And I decided to go 4s too. I spent the last two days educating myself on this and now I see that this is the way to go. (Thanks again DrIsotope.)

I have ordered the parts and I am sitting on pins and needles now. I am pretty confident that I will meet my original goal of flexibility. If something is not right (which I expect to happen), I will be able to fix it cheap and easy.

Wish me luck!
 
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