Traxxas mini rock racer- brushed our sensored brushless?

[miniSummit]

I'm trying to pick a replacement esc to replace my vxl pos that will work with my vineleon motor today and the next motor I'll use when my vinelion dies. What I can't decide is what motor I'll use next...

The rig: Traxxas mini Summit with the wheel base stretched 2.5", axial rear axle, locked differentials.
It's very similar in size to the Vaterra Twin Hammers but it only weighs 3.5 lbs with both batteries!

I only have 2 esc's in mind they differ in that they will either run sensorless brushless and brushed (Castle Creations Sidewinder 3)
or
Will only run brushless, sensored or sensorless (Hobbywing 60a)

Both choices are waterproof and I want to stay all waterproof, motor and esc. I'd like to get smooth low speed torque and acceleration and similar top speed to what I have now. This is not a rock crawler but I'll do a little rock traversing with it.

Let's start by saying I don't generally like the Vineleon 380 motor. It's very fast and punchy but is not good at going slow. It's a little too powerful on 2s for the stock car to be durable. I've tried the tranny gear swap and it makes the whole car too slow. I will be running 2s batteries as that's what I have already. I will probably have to get a 550 sized motor mount, that's ok.

1: If I go sensored brushless it seems the only choices are 550 sized and very powerful, Right? Tell me if I have other options, please.

2: If I go brushed what motor would give me smooth low speed acceleration, smooth torque, and a top speed of around 25mph?

Before you flame realize that this is a unique smaller lighter rig than you are used to and I don't want want drive shaft shedding torque!

Thanks in advance for the suggestions

[Olle P]

Originally Posted by miniSummit

... I want to stay all waterproof, motor and esc.

Brushed motors are generally considered better for running in water.
A brushless inrunner could be made pretty watertight though...

Originally Posted by miniSummit

I'd like to get smooth low speed torque and acceleration and similar top speed to what I have now.

Shouldn't be a problem, somewhat depending on how long you run the truck before giving the motor a chance to cool down.

Originally Posted by miniSummit

Let's start by saying I don't generally like the Vineleon 380 motor. It's very fast and punchy but is not good at going slow.

The typical result of not using a sensored motor.

Originally Posted by miniSummit

1: If I go sensored brushless it seems the only choices are 550 sized and very powerful, Right?

Not at all! There's a bunch of sensored 540 size motors as well.
Realise also that the Velineon motor isn't exactly "low power" either, since it's used as an upgrade from the fairly powerful 550 size 12T Titan motor!

Originally Posted by miniSummit

2: If I go brushed what motor would give me smooth low speed acceleration, smooth torque, and a top speed of around 25mph?

All brushed motors give you smooth handling at low speed.
To reach the desired top speed you need about the same maximum power as the one provided by your current motor.

You could for example try a 21T Titan (part #3975) on 3S LiPo, with a slightly larger pinion than what you're using right now.
You'll get more motor torque but lower revs and thus the same power.

Originally Posted by miniSummit

... I don't want want drive shaft shedding torque!

If it can handle your current motor there should be no difference after adjusting the pinion size.

[miniSummit]

Thanks for the good response. I'm not sure what you mean by this, could you elaborate?

Originally Posted by Olle P

Shouldn't be a problem, somewhat depending on how long you run the truck before giving the motor a chance to cool down.

I hadn't realized I had a 540 sensored motor option for less power than the 550 size. I'm currently thinking of using a 10.5 turn sensored 540 and water-right it myself.
Does that seem like a good choice?
Thanks

[OSRC]

I run a HW sensored 35a ESC and a 17.5 motor in my SCX10's and it's very peppy. Would be very punchy in a lightweight rig. 10.5 might be a bit fast. It's all subjective of course, depends what speeds you are looking for.

[Olle P]

Originally Posted by miniSummit

Thanks for the good response. I'm not sure what you mean by this, could you elaborate?

Bashing heats up the motor.
The longer you run the warmer it gets, up to a point where the added heat is the same as the cooling.
The choice of motor and gearing sets a baseline for if that temperature point is above or below "too hot".
Running for short periods with cooling in-between prevents the motor from reaching the point of "too hot".

Originally Posted by miniSummit

I hadn't realized I had a 540 sensored motor option for less power than the 550 size.

As I pointed out; your current Velineon is supposed to deliver MORE power than a brushed 12T 550 motor.

So how much slower (in per cent) do you want the top speed to be compared to what you have today?

[miniSummit]

Originally Posted by Olle P

As I pointed out; your current Velineon is supposed to deliver MORE power than a brushed 12T 550 motor.

So how much slower (in per cent) do you want the top speed to be compared to what you have today?

I don't want to give up much if any top speed. I want the low end to be smooth and controllable. The 380 in a crawling situation has a tiny bit of power with cogging and then it jumps hard. Not much in between. I just want to smooth that transition out.

I got a Castle Sidewinder anyways so brushed will most likely be in my future.

[Olle P]

If you want that power AND good low speed characteristics you'll definitely need to go up in physical motor size.
Using parts for the 1/16 Revo you should be able to fit a 540/550 size motor.
Run the 21T Titan (#3975) on 3S LiPo with your current ESC. That'll give you more low speed torque and control while keeping the top speed.

[miniSummit]

Great, thanks for the tip. It's there any other brushed motor you know of that would give the same results with 2s?

I got the Castle sidewinder 3, so brushed will be in my future.

[Olle P]

Originally Posted by miniSummit

... It's there any other brushed motor you know of that would give the same results with 2s?

Not unless you go even further up in size, which you don't want to.

The key is to have a motor with more low voltage torque and general efficiency than your current one (which the 21T Titan does) while providing the same top power (which the 21T Titan does not, unless you feed it more voltage).

[miniSummit]

Gotcha. Thanks for the explanation. I've got a couple of runs with the Castle esc and the power delivery is smoother than with the vxl esc but it's clear that the 380 brushless motor it underpowered at slow speeds.