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TurboTimmy

Brushless Grasshopper

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I currently have a Grasshopper with a 27t Axial brushed motor. I have also run a Sport Tuned motor in it as well.

The ESC is a Tamiya TBLE-02 brushed/brushless and the battery is a 7.2v 1600 mah Viper Nimh. 

I was wondering what the best brushless motor would be without changing anything else....And would it be worth the time to do it? I am perfectly happy with the 27t motor-but running brushless is something I'm really curious about.

Thanks for any replies.

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Out of all the runners, I don't think I'd put a 13.5t on Grasshopper.  It's a good recipe for shell destruction.  

But if you want to try it, why not?  It will give you an oomph.  

You might want to use it with LiPo.  You could keep your NiMH, but a brushess drains a lot, like 3A.  NiMH tends to drop off at 1.5A or 2A.  Depending on the battery of course, but generally that's how it goes.  Which also means, you'll need to solder a new connector, like Deans or XT60.  I would go through all that trouble, if it were Konghead, Dynahead, DT02, DT03, DF01, 02, 03.  Something that could get more out of the brushless.  But as I've said, why not? 

There are people who make a boat out of the Grasshopper chassis.  This person didn't take no for an answer.  I'd say try it.  If it's too much, it can give you an excuse to buy another buggy.    

WUmAwY1.jpg

 

 

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A couple of things I’ve learnt with brushless which may help you is, 

If you are using it in dusty conditions try and get one with as few vent holes on as possible as dirt can travel through the motor and into the gearbox. But I have sealed this before by cutting a gasket between the motor & mount (similar to the paper gasket on the Tamiya brushed motor) to stop the dirt getting in. 

There are more wires involved so you will have to solder at some point. 

They are a lot of fun once set up well. 

 

I recently upgraded my NiMH Sport Tuned Blitzer to Lipo 13.5t LRP Brushless and it flies now. But as @Juggularsays, could be detrimental for a hard body. The beauty of the LRP motor if you can find one (and is pricey compared to other brands) is that is plug & play with its pre-soldered wires an attached Tamiya connectors. Although you will also need a sensor wire as they don’t come with one unlike Hobbywing. Here’s a link to the 17.5 version of what I have,

 https://www.lrp.cc/en/product/vector-k7-brushless-motor-175t/

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9 hours ago, TurboTimmy said:

I was wondering what the best brushless motor would be without changing anything else..

I would go for a complete new brushless combo, the tble02s requires a sensored brushless motor, and for the price of those, you can have a Goolrc sensorless brushless motor and esc (with deans connector and low volt Lipo cut off, if you go down the route).

This is one I use in one of mine - 

 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F223615173305 

(If you want a shop about, look for a 3.175mm shaft on the motor -some say 3.2) 

Quick look on YouTube, grasshopper with the above combo - 

 

 

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I am going to politely contradict my learned friend @Wooders28 now 😉 I really didn't get on with those cheap sensorless combos. The lack of fine throttle control just really annoyed me! I know lots of people are down on the tble02s but for light weight 2wd applications its just fine in my opinion, and has nice throttle control. Everyone is right about plugs and soldering though. I use Deans, but XT60 are good too. I bought a cheap soldering iron from BandQ, some liquid flux and good solder feom an online rc shop, watched some youtube videos and had a go. It takes a bit of practice, but it's nit as scary as you think. Or ask around. My mate is well into electronics and i had no idea until i asked on a couple of whatsapp groups if anyone knew anything, so maybe you have a secret soldering friend too?! For a brushless sensored motor i have had really good results from blue can motors you can buy on ebay. Just search ebay for "efficiency brushless motor" and loads of blue can motors pop up for £20 in 17.5, 13.5 or 10.5. For the grasshopper, 17.5 or 13.5 will be a fair step over a silver can. You will need to buy a sensor lead too as the one with the motor will be too short. Can a 180mm long lead and you will be fine. 

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Thanks for the info, gentlemen. How about a Tamiya 16t brushless? That already has the leads attached.

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16t brushless isn't strong.  It's 2400kv.  Multiply that by 7.2v, you'd get 17280 RPM.  That's 1000 rpm slower than Sport Tuned.  

For that price, you might get a brushed Super Stock and a Hobbywing 1060 ESC.  In my opinion, Super Stock would outperform any 16t.  

(About that video though...)

I am surprised that 4300kv isn't faster.  At 7.2v, the motor should give him 30,000 rpm.  That's almost twice as fast as Sport Tuned (18,200 rpm).  But it doesn't seem much faster than Sport Tuned.  

If you think about the reason, 4300kv would use around 4A.  NiMH simply cannot supply 4A.  Also, Tamiya connector cannot let more than 2A through either.  Which means, that blue Grasshopper could be limited to 2A (and the voltage would drop too).  Many mediocre NiMH batteries would go below 5v, if you are using big-drain motors like 4300kv.  That will give that blue Grasshopper, 21500 rpm.  Then, the video seems about right.  

Below chart shows voltages at 9C discharge.  But Lipo batteries are staying above 7v.  NiMH batteries are staying at 6v.  Brushless motors can't give you the advertised rpm if the battery cannot supply the amp (thus voltage dips too).  

If you consider the voltage drop, 16t might not be any faster than a silver can.  You can use 16t, if you can change the gear ratio.  But that's not an option for the Grasshopper unless you get one of those adjustable pinion mounting kits.  If you use a mounting kit, the motor might interfere with the rear suspension.  

KeKr97n.jpg

For sensored/sensorless thing, Sensorless could cog, especially in slow speed.  Sensored has no problem in that department.  But sensorless has tiny bit faster reaction time.  So if you gun your throttle all the time, sensorless would do okay.  Cheap, robust and waterproof.   

If you are racing, however, you might see your Grasshopper jerking and hesitating before entering corners.  In that case, you'd prefer a sensored motor.  Tamiya TBLE-02S can only use sensored, which is why most people just use 13.5t.  And 13.5t is strong enough and inexpensive enough.  Soldering needs some care.  If you are a careful person, you'll do fine.  

 

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On 8/10/2019 at 12:12 AM, Juggular said:

I am surprised that 4300kv isn't faster.  At 7.2v, the motor should give him 30,000 rpm. 

That's unloaded RPM.

I do wonder if companies are, generous with their ratings? 🙄

On 8/10/2019 at 12:12 AM, Juggular said:

If you think about the reason, 4300kv would use around 4A.  NiMH simply cannot supply 4A.

Looking at the official specs, the Goolrc 4300kv has a max of 75A, (must be stall amps). 4A would be the lower end of the scale (gentle throttle/ cruising?), I'm guessing it would be closer to 20+ under hard acceleration.

I swapped from the 4300kv Goolrc to a 3800kv Castle, and the castle is so so much faster. But just the castle motor is almost 3x the price of the full Goolrc system.🤷‍♂️

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10 hours ago, Wooders28 said:

I do wonder if companies are, generous with their ratings? 🙄

With cheap Chinese stuff, you betcha!  

 

For brushed motors, I subtract about 30% of the RPM.  For brushless motors, I subtract only 10% because it's got so much torque (only if LiPo is used).  From above video, I think I'd subtract 30% also, if NiMH is used.  

Brushless has 1100% torque.  Stock 540J motor has 255g/cm.  17.5t has 2794g/cm.  Because of this, brushless doesn't lose much RPM. You can go up a tooth.  

Below was for a 17.5t brushless.  Unloaded benchmark shows 286, 257, 280 = 274 N.mm average. (That converts to 2794 g/cm)  Sport Tuned has 350g/cm.  That's 8 times the torque of the Sport Tuned, 11 times of the silver can.  Max amp shows 88, 72, 76A (which NiMH cannot supply).  Steady draw should be about 3-4A unloaded.   

uEjpr5P.jpg

xi5zHnw.jpg

 

Below is a test for ten 17.5t motors.   

Constant amp draw is generally below 4A. (one of them go up to 5A, but mostly 17.5t motors draw below 3A)  So yes, gentle cruise would draw 4A.  Gunning the throttle would draw even 90A.  XT60 connector is rated for 120A burst and 60A constant?  So, 90A burst should be fine for XT60.  If a 2WD buggy with a 4000mAh battery lasts about 45-50 minutes, that means combined average of burst and steady would be about 5A.  

(The variation among 17.5t was far greater than I thought.  2.1A for one motor, 4.9A for another.  2300kv to 3300kv!  Seeing that, Castle being faster makes sense.  Not all motors are created equal.)  

 

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33 minutes ago, Juggular said:

For brushless motors, I subtract only 10% because it's got so much torque (only if LiPo is used). 

Here's my K1 with a 4.5t on 2s, no load (pretty much) max rpm.

2019-01-04_11-26-31

Here's exact same set up (but with grippy tyres) after a run on astro turf, around 30% less.

2019-08-12_09-51-59

(Might have not got up to full speed in the room I had?)

 

45 minutes ago, Juggular said:

If a 2WD buggy with a 4000mAh battery lasts about 45-50 minutes, that means combined average of burst and steady would be about 5A.  

My Yokomo truck runs a 3800mah /110c with a 6.5t, and gets just under 6mins.....

Full charge to cut out :- 

 

 

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Amazon sells those 60amp "gool Rc" esc's branded as RCharlance. Seem to work well. I have one in my Boomerang with a cheap 3650 (540 sized) Amazon motor and she does 35mph/56kph now on a 7.2 volt NIMH battery :D to see it click Here

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For best bang for buck. I'd keep the tble02 and pick up a 17t BRUSHED motor. The tble02 though not rated for a 17t brushed motor will run this set up all day long. It's what I run in my Lunch Box, same axle and similar motor loading. These can be had for 8-10$$. Plenty of speed and good run times with a decent capacity 2s lipo. Not so fast you're going to destroy the thing either. 

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How about an ARRMA 15t Mega Motor? I already have one of those. Will it work with a TBLE-02? If so, what size pinion gear?

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3 hours ago, TurboTimmy said:

How about an ARRMA 15t Mega Motor? I already have one of those. Will it work with a TBLE-02? If so, what size pinion gear?

What kind of battery are you running? Are you sticking with NIMH or going to Lipo?

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