brushless 1/10 slash gearing

[drummin89]

I just received my brushless system for my 1/10 slash and was wondering what I should run as far as gearing. I won a castle creations esc and castle creations 7700 brushless motor for $80 on ebay, was going to put it in my tc3 but since the slash was already brushless ready I decided it belonged in the slash. For now I have the stock spur gear (86 tooth, 48 pitch) and a 18 tooth, 48 pitch pinion. Wondering if there is something better I should run.

Thanks

[Big-Bus7]

first off that motor is meant for more of on-road use so i would gear like 15/90 and go from there see where it takes you heaat wise.

[drummin89]

would it be better to install it in my associated tc3. Either way Im not sure if im going to keep that motor in there. From the ebay ad (and the sticker on the end of the motor) its a 7700kvm motor, and the esc is a castle creations 1/10 sidewinder esc. Castle creations only offers the combo with a 4600 or 5700kvm motor. Im going to be using a 7.4v lipo battery.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220484915666&ssPageName=STRK:MEWNX:IT

[Big-Bus7]

yeah i would put it in your tc3.

[rccardude04]

The Sidewinder isn't rated for use with the 7700. It'll likely overheat the whole thing really quick.

I run a Castle 4600 on my Slash geared 16/86 and it still gets a little warmer than I'd like.

You'd have to gear it like 10/90 to make it really work properly, assuming you want the same top speed as the 4600. The smallest pinion I've ever seen is 12, and down below about 15 you'll have trouble getting it to mesh.

I say gear it REALLY short in the TC3 and keep a close eye on the temperature (especially the ESC temperature). :)

-Eric

[drummin89]

Yeah Im keeping a lookout for a good deal on a 4600 or 5700kv motor on ebay, also posted on the wanted forum.

I plan to run the slash tomorrow for a few runs and will bring a temp gun along to keep an eye on the temps.

[drummin89]

If the temps never get to the danger level would there be any reason to change the motor out to a lower kvm. Anything besides heat that would kill the esc. I bought the spur and pinion gear you suggested I start out with, I will see what the difference is when I get them. I more than likely will change the motor out to a lower kvm anyways as its just more than the slash really needs.

[02edge2wd]

As long as temps are not in the 'danger level' there is no NEED to change motors to a lower Kv. I have the 5700 system and it is still way more than you NEED in a slash (though very fun!) unless your just bashing it will work with low gearing to keep temps at a safe level. A 4600 would be best for racing.

**As a side note, you may want to loosen the slipper so you do not eat spur/pinions. I found that running a steel pinnion instead of aluminum will make the spur/pinnion last a bit longer as the teeth of the pinnion will eventually be shapped like a saw blade, steel (stock traxxas gears work fine) prolongs this process.

[drummin89]

Ok thanks

I brought my slash with me today to run in the parking lot after work to see how she flies. Also brought my temp gun along to see what temps I get. At what temps should I let it cool down.

[ducati777]

Yea these high KV motors are more of a marketing gimick. You can make plenty of power on low kv motors.

Couple of reasons to switch is typically low kv motors running on high voltage have better low speed manners. They launch and tool about at low speed better.

Plus like discussed above, you're limiting yourself to gear ratio selections.

See if you can try out, or buy a low kv motor to compare.

[drummin89]

Any place besides ebay for a good deal on a low kv motor. Any recommendations as far as a good bl motor that won't break the bank.

[ducati777]

why not look for a vxl? Those are probably pretty cheap on the ebay market, especially if they're used.


I put a feiago (sp?) in my rc18t, but I have no idea what a motor for the slash would cost.

[02edge2wd]

I race/run my slash with a VXL system and it works great! I think the VXL motor is a good mix of torque and RPM for the slash. I am thinking of running my sidewinder with the VXL as i have heard people are getting good results with that combo.

[drummin89]

Well I ran it for a bit after work and just WOW. This truck flies. It will be at full speed and I can blip the throttle and it would pull a wheelie. Pretty much pulls a wheelie on demand while moving. Roasts the tires when punching it from a stand still.

I was monitoring the temp about every minute or so and the motor and esc never touched 90. Temp outside is around 55 so I expect that has alot to do with it. I was flying around the parking lot for about 20-25 minutes and continuously temp gunned the motor and esc, all stayed cool. I kept the body off for the first run.

Just to play it safe I picked up a small 2"x2" 12 volt fan from radio shack and mounted it to keep air flowing over the esc heat sink.

Because I know it will not stay this cool in the summer, I found a slightly used castle 5700kv motor on ebay for $50.

At some point I will look at getting a esc that can handle the 7700 safely and probably stick it in the tc3.

[rccardude04]

LOL If it's not getting hot, you're good! I assume you mean 90F, not 90C.

The VXL motor runs really well in the Slash, but if your 7700 and sidewinder really doesn't get hot, then you're alright. I REALLY don't understand how it doesn't get crazy hot, but since it's working I say stick with it.

-Eric

[drummin89]

It wasn't getting hot yet, but im pretty sure in the summer when its alot warmer out, it will. Though I could be wrong as the previous owner said it worked great (of course they all usually say that).

And yes I mean 90F

[ducati777]

I suppose there's a small chance its not a 7700 kv.

You could measure the top speed of your truck, do the math to see what sort of RPM you're turning, devide by your battery volts and get a rough estimate of your KV.

It wouldn't come out perfect, but if it comes out at 3000 instead of 7000, you might have a different motor than you think.

[drummin89]

thats certainly possible, I was actually thinking of that yesturday looking at the sticker on the endbell. The sticker says 7700kv but, and im not sure if this is just a factory thing but the stick was far from center.

Anyone know if the there would be a part number engraved somewhere else on these motors.

I will have to see if I can borrow someones radar gun or gps. That or strap my garmin to it as it saves top speed info.

Anyone know what the formula would be to figure this out.

[ducati777]

just measure it out on the ground, then time the car across.

For example, my normal foot step is just about 2.5 feet, so take 20 steps, I'd have 50 feet. If you time the truck across that, I can tell you how fast you'd be going.

Do several runs and take an average of the times.


Some quick math says 50 feet in 1 second is 34 mph.