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Thread: gearbox options with little room (1.9)

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Old 09-23-2009, 08:19 PM   #1
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Default gearbox options with little room (1.9)

ok i have searched for different gearbox setups and found not
much. i read the gearbox guide and got a bit from it, but i have
used that info and am running an evader gearbox as a transfer
case, and if i cant find anything else i will have to get another
for the actual gearbox.i have a stampede g/box chopped as much as it
can be, but its no were near small enough. i know theres the stealth
and losi tranny's but the evader is just as small, easily to upgrade
and cheaper.

i have several questions: can i run a 380 motor in it? (in my crawler) or two of them?
is something like the losi mini crawler tranny ok for something like
this? i already have a 380 motor, mounts on the g/box dont matter as it will be modded to fit. a motor plate would be good though. i has looking at plane trannys for 380 motors.
anyway i was thinking maybe i should check out the local lhs first?
not sure, thanks.

oh and i know with a couple of options like a plane g/box i will loose my slipper
but meh. cheers

Last edited by thecrusader; 09-23-2009 at 08:22 PM.
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Old 09-23-2009, 08:43 PM   #2
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Fill in some more info:
Is this a scaler, comp or rock racer?
What chassis are you using or considering?
What axles?

Some food for thought:
  • Remote mount the motor on the front of the chassis between the shocks, mounted on a flight gearbox or a planetary gearbox. Drive shaft back to the Pede trans acting as a transfer case. Motor mount chopped off. Run the input shaft where the spur shaft is(no spur), then outdrives the axles.
  • Small, lite and full of torque, get a Holmes Hobbies 454. It is 400 sized but still has monster torque.
  • Will ruin your COG, but turn the Pede trans on end with the motor high and outputs low.


HPI Wheely King Gear Reduction Gearbox
http://www3.towerhobbies.com/cgi-bin...&I=LXVLE9&P=FR

Great Planes GD-600 flight box:
http://www3.towerhobbies.com/cgi-bin...&I=LXSL79&P=ML

$$$ planetary gearbox from RC4WD:
http://www.rc4wdstore.com/2/product_...roducts_id=854

Try one of these or others they have at Banebots, not sure who on here has tried them with planetary gears. Good prices on them.
http://banebots.com/c/MP-24XXX-370
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Old 09-24-2009, 02:57 AM   #3
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thanks for the reply sweli. it is a scale 1.9 rig. that gd-600
looks similar to what i just bought. i just got this


should do good then

heres what im working with, im using tlt axles a duratrax evader
ext tranny as my transfer case and traxxas bandit drive shafts
heres some pics.
the evader transfer case-


and i was also planning on having the motor up under the hood
at the front.
like you said, like this-


so the 380 motor will be ok?
cheers.

Last edited by thecrusader; 09-24-2009 at 03:03 AM.
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Old 09-24-2009, 05:34 AM   #4
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A stock 380 size motor might be on the wimpy size a little. If you already own it, then it cannot hurt to try it.
Sorry, I didn't realize you were in Autralia. The Holmes Hobbies (US) 454 is a cobalt magnet 400 with gobs of power and doesn't mind more volts.

What is the 380 you have? Some stock versions might have set timing that is advanced in one direction for faster fwd then rev, in the vehicle or plane they were in.
What pinions came with your flight gearbox - ie. what ratio does it give you? Looks around 2.5:1?

The Evader transfer is probably 2.3 - 2.6 ratio. TLT axles are 3:1. In a scaler you are shooting for 35:1 up to 65:1 depending on motor/batt options and the wheelspeed you want.
If your flight gearbox is 2.5:1, and the evader at 2.5, then your at 18:1. So a smaller 380 prob will not give you much torque at that ratio, and might get hot trying.

Good online calcuator. It is for calc'ing speed output. But you prob want something under 3 or 4 mph so you have some crawling torque.
http://www.scriptasylum.com/rc_speed/_top_speed.html
You can plug in you motors rating in KV based on what the sales ads online say is its free spinning speed at a known voltage.
Ie. 10,000 RPM at 7.2v is around 1330kv
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Old 09-24-2009, 06:15 PM   #5
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gear ratios are one thing i have had problems with from the
get go. not on the actual trucks but on paper, especcially
going from the gearbox to the transfer i just dont get it.

the motor was from some chinese micro copy. looks like a plane motor.
its an outrunner and is 4300kv im pretty sur wich i know is high but
if it burns it burns. its only collecting dust atm.

if this helps (main gear 30t, motor gears supplied 10t 12t 14t)
gear rate 3:1, 2.5:1, 2.14:1.

so i take it when its got the 10t pinion 3 turns of the pinion
equals 1 of the main gear and so on... i dont know where to
go from there i couldnt find the evader ext internal ratio
but the st is 2.66:1 and the nitro is 2.4 so its between there
somewhere id say 2.6 . do you think it will work?

thanks again ash.
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Old 09-24-2009, 07:27 PM   #6
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So 3:1 X 2.6:1 X 3:1(TLT Axles) = 23.4:1

My 1.9 scaler is 53:1 and I run a 55T motor in it (about 1000kv). I run a 7.2v 2/3A pack. My 1.9s are smaller dia. I'll have to measure them.
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Old 09-24-2009, 09:39 PM   #7
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I plugged my 1.9 scaler info into the calculator I linked above.
It came out 52.65:1 ratio
7200rpm max motor speed while running in the vehicle
1.42 mph max

To be honest, I wouldn't mind if it was a little faster.
I could boost it a single cell to 8.4v to get it.

What gets me to my ratio over yours, is the Pinion and Spur being 81:12 ratio (6.75:1) versus the Flight gearbox being 3:1

BTW, a link to my Mog (first and only scaler I have built)
Unimog X-Trail on double narrowed TLTs
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Old 09-24-2009, 09:41 PM   #8
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When I plug most of your info in (my smaller Losi rock Basher tires), it comes back 13.78mph.

Give it a try for now and see.
Does the flight gearbox have room for a larger size motor on it (ie. a 540 size)?

If so, there are lots of options later to throw a 80T 540 on it to get the RPM down.
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Old 09-25-2009, 06:32 PM   #9
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nice truck mate (would look badass black), and
thanks for helping me understand it, i didnt
know you multiplied the ratios. anyway i wouldnt
mind the wheel speed as shes not really a crawler
more a scale trail rig.

the flight gbox thingo can take up to a 400 size motor
and i found an old thread called "best 380 motor" i think
and you were on there rewinding your own motors? any way
im gonna see whats at the lhs and just use what i already
got sitting here.

at least now i have a rough idea of how fast it will
be going. thanks man
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Old 12-30-2010, 01:11 AM   #10
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kicking to top
rc truck puller use reduction units as well
the GD600 range from 2.5:1 , 3.0:1 and 3.8:1

I making two reduction units bolted back to back and straight to motor, and divorced shaft to my 2.18:1 transfer case for a range of 35:1 to 52:1 with axial axles at 2.92.

I found this post looking for dimensions of the 7:1 HPI wheely king reduction unit.
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