Re: Robbobs bored and building a shafty
 

A: Love that truck
B: thread subscribed .... "thumbsup"




True, small footprint and more current engineering. "thumbsup"

Re: Robbobs bored and building a shafty
 

Ok let me hammer this out here and see if it makes sense to anyone .......


So using the T-case gears from an SCX2 .... 20T and 26T plus add in a 36T XR gear ...

Working backwards from outdrive ....

26T gear is on the outputs .... then you go to the 36T gear giving you 1.80:1

Then 36T gear gos to the 20T SCX2 gear ..... (1.30:1)

That 20T would run off the motor pinion of lets say a 22T giving 22/20=1.18:1

If I take the 1.80 * 1.18 that would give me a trans ratio of 2.12:1

A: Am I correct?

Ideally my goal would be to double the amount of output rotations to motor input rotations ..... or even more if possible.

Re: Robbobs bored and building a shafty
 

driven / drive gear

20/22=.91
36/20=1.8
26/36=.72

.91*1.8*.72=1.183

so 1.183:1 is what i come up with.

also, since the idlers cancel each other out, just do final/ pinion. 26/22=1.18.
that only works when its gear on gear contact, not when it gears besides gears(compound gears) if that makes sense.

Re: Robbobs bored and building a shafty
 

So I would basically need a 52t pinion to come out with a 2:1?

Gearing blows my mind lol.

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Re: Robbobs bored and building a shafty
 

Pretty much, unless you use compound gears like what the lnc trans uses.

you could try direct drive into a 2:1 t-case, input onto the bigger gear.

i usually try to figure out what i want for a final ratio first, then go backwards from there.

losi axles are either 25:1 or 21:1.

so if you wawnt a final drive of 50:1, you would need 2:1 in the trans if using the stock worms. 2.4:1 trans if using 21t worms.

Re: Robbobs bored and building a shafty
 

Compound gears have me lost even more. Any ideas?



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Re: Robbobs bored and building a shafty
 

What if (just using these numbers for examples) the 36 and 20 were compound gears ...... would I go bigger gear between the 20 and pinion? And how much bigger?

Re: Robbobs bored and building a shafty
 

Why compound gears? I have been planning to build my own tranny for Losi axles using 32P pinions. 12T on motor -> 22T -> 25T on output shaft (2,06:1). Should give enough play room for the output shaft placement.

Re: Robbobs bored and building a shafty
 

32 pitch could do it but I was hoping to stay more with a 48p style. Less noise with better gear mesh and wear.


Plus I would like to find a combo of gears that could be bought easily by the driver then we could produce the trans.

Re: Robbobs bored and building a shafty
 

somewhere in the equation, if you want 2:1, you'll have to have a drive gear 2x bigger than the driven gear.

Re: Robbobs bored and building a shafty
 

You're not helping :ror:

But I like learning and challenges. :mrgreen: "thumbsup"

Re: Robbobs bored and building a shafty
 

just so im clear....do you want the output of the trans to turn 2x for every one revolution of the pinion(motor) 1:2 ratio
or do you want the pinion(motor) to turn 2x for one revolution of the output 2:1 ratio?

Re: Robbobs bored and building a shafty
 

Robinson has load of 48P pinions, easy to get and good quality. Let's say 16-18T on motor, 32-36T idler, 34-40T on output shaft. Worth of try maybe :)

Re: Robbobs bored and building a shafty
 

I'd like the output/driveshafts to spin 2 rotations for every 1 pinion rotation.

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Re: Robbobs bored and building a shafty
 

got it!

so you want 1:2 ratio.

yup, the pinion will need to be huge.
i have an idea using a lnc trans, when i get home this evening ill check and see if it'll work.

Re: Robbobs bored and building a shafty
 

what about trying to reverse the gear size on a gru from great planes? they are like 10 bucks. or you could use it in conjunction with the lnc trans maybe.. hmmm...

Re: Robbobs bored and building a shafty
 

scratch what I said. make it belt drive.

Re: Robbobs bored and building a shafty
 

Bob, you guys are putting my poor old brain into over load try to follow what you're trying to do.:lmao::lmao:
Ernie

Re: Robbobs bored and building a shafty
 

Mine too.

Re: Robbobs bored and building a shafty
 

Are you sure? You want to reduce revs not to increase them, I'm I correct? In that case you want right the opposite