Gearing?

I have searched and searched... Don't really come up with much though.
Now that my revo conversion is finished I would like to find the best gearing.
Looking for about 40mph and BL torque (aka flip on lid).
I have a MMM esc, going to have a CC 2200kv motor on 4s lipo.
What do you guys think I should gear it?

[shaunjohnson]

gear it to 40mph
find the user BrianG on this forum, he made a gearing calculator for doing exactly this!

make sure it is a good quality lipo too (at least a zippy or better)

should keep you very happy.
but on my revo (same final drive as you have, just different setup)
i am geared 17/56. since you run a lower voltage try 18-20 / 56.

but using the gearing calculator you will be fine.

[Patrick]

This is Brian's gearing calculator http://scriptasylum.com/rc_speed/_top_speed.html

Thanks guys, I knew about Brians calculator and it is awesome, I was thinking of going with 17/38. I know that will get me over 40mph but how will it do with acceleration?
Shaun I have 4s 25c 5000mah turnigies giving me 125amps continuous. How the heck do you fit a 56t spur on there?! Im pretty sure a 40t almost touches the chassis. Would 17/38 be overgearing? I am running bowtie lprs and badlands lprs too btw.
Thanks for the help.

[BrianG]

56T is for 32p gears, a conversion will use mod1, which gives you 36, 38, and 40t options. If you specifically want 32p gears, you may be able to fit a 54t on there since 54T @32p is roughly the same diameter as a 40T @ mod1.

What gearing you choose depends on what you did to the tranny. Are you keeping the two speed? If so, you can gear higher on the pinion since first gear is quite low. If going the single speed route, which ratio you chose to install inside the tranny (close, normal, wide) can make a difference. In my conversion, I used the tranny locked in second gear with the wide ratio gearset, 40T spur and 14T pinion. Can't remember the top speed but it was perfectly fine for track use.

Hint: when using the calculator, enter in all your values, and when you calculate the speed, an icon will appear (looks like a set of gears). Clicking that will bring up a table showing theoretical speeds at various pinion tooth counts. The bold one will denote a 1:1 ratio value, which is a decent starting point for a combination of decent speed and cool temps. From there, you can play around and see what works best for you.

Thanks Brian! Your motor mount is amazing, great piece of work. My conversion is in the "Quick conversion question" thread. It is locked in second using Oomps single speed plate with a wide ratio second gear. I plan on using the mod 1 gears. Right now I am using a KD36 11L 2200kv motor from hobbycity, it is to small for the truck and gets hot. I plan on getting a 2200kv CC/neu motor soon. I have a 14t pinion on there right now with a 38t spur, i might have to pick up a 40t to play around with, I also have a 17t pinion on the way as well. I will see what I can do to get me close to a 1:1 roll out.
Thanks
Braden

EDIT: After playing with the calculator a little bit more, it seems all 1:1 rollouts get me about 30mph which is about 10mph to slow for my taste.
What do you think?
Thanks

[BrianG]

Actually, that's Mike's mount (the site owner), I'm just a guy out here in Iowa.

The 1:1 rollout is just a starting point and is generally conservative. It generally ensures a cool running setup, but there is almost always room to gear up. It's just gets you in the ballpark and you go from there.

Oh yeah... I got you two confused! You did the calculator, Mike has the mount, right. Alright! Thanks Brian. I will probably try out 17/38 to get around 40mph. Hopefully it will still have good acceleration.

[shaunjohnson]

your acceleration wont change like it does with nitro.
but it will draw more amps to do it and possibly more heat.
but at 40mph top speed it should be ok

Oh? So all I do is gear for speed?? The acceleration stays the same no matter how I gear?
Thanks!

This little hobby city motor is AMAZING! I was doing speed runs and the motor got up to 280f TWICE!!! It still goes like a champ too! The esc and battery were cool, for $30 this is a motor that is impossible to blow up!

Do you think 14/36 would do me good? I just ordered a CC 2200kv motor too. 41mph with a fully charged pack and 33mph when I hit cutoff. Or would I be over gearing? How do you think acceleration/torque would be?

[shaunjohnson]

Originally Posted by Braden

Oh? So all I do is gear for speed?? The acceleration stays the same no matter how I gear?
Thanks!

This little hobby city motor is AMAZING! I was doing speed runs and the motor got up to 280f TWICE!!! It still goes like a champ too! The esc and battery were cool, for $30 this is a motor that is impossible to blow up!

yep, your acceleration wont change...BUT YOUR AMP DRAW WILL BE MASSIVE!!!!!
amps = heat + voltage drop, heat = bad, voltage drop = dead ESC

make sure you have tope shelf lipo's and top shelf ESC/motor before attempting to do speed runs. never use your speed run gearing for bashing as bashing uses more acceleration and braking, doing this with high gearing is murder on even the most expensive systems.

i would stop using that motor if you value your ESC!!!
280f!! holy crap!!
we are talking de-magged rotors, that'll increase your amp draw hugely.
that'll kill the motor and ESC really quickly!!

electric motors have loads of torque, no matter what your gearing.
simple way to understand it.

you want to do a standing backflip and have it highly geared (very bad btw)

motor goes "oh crap i need a lot of watts of power NOW"
esc goes "ok, i'll get you that amount of power"
battery will go "i CANT give you that much power!!"

that is when things start catching fire.

so gear to 40mph, make sure you have a high quality battery and not an underpowered/underrated ESC/motor combo and you should be fine.

NEVER EVER LET YOUR TEMPS HIT 200*F!!!!!!!!!!!!

I know, I am not using the motor any more. I got the esc for very cheap (it was a possible faulty esc) and I never had another motor to test it with sooo.. I wanted to put it through its paces to see if it works and it does!
But yea, a CC/Neu 2200kv motor is on order.
I don't want standing backflips, just enough power to lift the front end up for a couple seconds when I want to.
Braden

[shaunjohnson]

well your power comes from the batteries.

for what you are wanting to do...

get batteries that at least 4s and are rated for 100-120A continuous (eg, 20-30c 5000mah 4-6s lipo)
get a MMM/2200 combo when you kill your old setup.

my setup only draws 70A when i mash the throttle, but my batts are capable of 150A continuous and i'm running a MMM/2200 combo.

that will give you plenty of power to do wheelies, go 40mph with ease and have nice cool temps.

Im keeping this esc, its the MMM v3 esc, works great. I am getting a CC/neu 2200kv motor. My batteries can supply 125A continuous (5000mah 4s 25c). All I need is a motor and I will be up and running again. Other than that I am REALLY liking the brushless side of things.
Thanks for all the help.
Braden