Xinlehong 9115, GPTOYS Foxx S911 brushless upgrade

Recently I bought this 1/12th scale RC truck. I am actually new on Remote controlled trucks but not actually a newbie on this. I have RC from the past but they are actually toy grade. I been reading and viewing this mid toy class RC, that is why I bought it for my son. Very affordable too, not so cheap, not expensive like of those hobby grade line up.

This is an electric RC truck that uses 390 brushed motor. 4 independent suspension and 2.4G transmitter receiver for non interference functionality.


Almost all parts of this mid scale hobby grade RC truck are replaceable, Tires uses the standard 12mm hex adaptor, shocks can also be replaced with an oil filled RC shocks used by high end models, and most of all. Brushed system of this model can be upgraded to Brushless system just like what I did and to give it a little more twist. The stock steering servo can be used instead of replacing it to another servo. (Excited to know how then you are in the right place).

Description of this Xinlehong 9115 RC toy truck:

Features:
Made of high quality ABS material
Ready to run and no need to assembly
With large capacity rechargeable battery
1/12 scale suitable for indoor and outdoor control
2.4GHz supporting a range of remote control about 80 meters
Shock absorption and collision avoidance design provided longer service life
The controller can be switched between 2 modes

Specifications:
Brand name: XINLEHONG TOYS
Item NO.: 9115
Item name: High Speed RC Monster Truck
Material: ABS
Color: Blue and red for option
Scale: 1/12  
Drive System: 2 wheel drive
Remote control frequency: 2.4GHz 
Max. speed: 40km/h
Transmitter battery: 2 * 1.5V AA battery (not included)
Car battery: 9.6V 800mAh Li-ion-Fe battery (included)
Remote control distance: About 80m
Charging time: About 100mins
Working time: About 10mins
Suitable age: Above 8 years old
Wheelbase: 210mm
Wheel diameter: 100mm
Wheel width: 50mm
Ground clearance: 55mm
Battery size: 55 * 48 * 15mm
Car size: 310 * 270 * 150mm (artificial measurements error allowed)
Car weight: 1097g (battery included)

Package Information:
Package size: 33.5 * 28 * 17.5cm / 13.2 * 11 * 6.9in
Package weight: 1773g / 3.9lb

Why I chose this model from the many available in the market like GoolRC, Wltoys, etc etc of the mid range RC truck?

Youtube videos of this model made me purchase it via online. It has a good review from all sources of RC fanatics video blogger out there.This model cannot be bought locally here in my country  As I write it before, It was very affordable with many rooms for improvement and fun doing it. I made my decision. I bought the two color version of 9115 or with other name as Gptoys Foxx S911. But of course one will be used by my son so we can play together. I have the intentions of Upgrading mine to a Brushless system which it will be discussed here at the later part of this post.

Both was bought at 60 USD, and I tell you, this is not a bad mid range RC truck, it has some speed, fun to drive, although 2WD only, I have no problems steering it to where i wanted it go. The lacking side of it was the playing time and will only take me 8-10 minutes on a fully charge battery.

Stock battery is already a 3S LiFePo type..not Li-ion. but only 800mah. 

Again there are still room for improving this playing time by converting to another system rather than trying to put a larger battery, that will just shorten the life of the 390 brushed motor of it. We all brushed have carbons that tear and wear. The only solution is to upgrade it to brushless system. There is no other way around it. Did tried using other source to power it (talking about battery). It just didn't work out well with motor heating up too much.

Gathering ALL parts for the UPGRADE to Brushless system.

Actual 390 brushed motor of 9115 with pinion gear

What we need to make this happen on a Xinlehong 9115 or Gptoys Foxx S911, there are many brushless motor to choose from, I will not reiterate all of them here, there is just too many out there, but we are looking for a Brushless motor that will fit the gearbox of this model without having to tear a portion of it. I want to remain it as it is..

So the dimension of the Brushed 390 motor must be considered in picking the right size of the Brushless motor.

390 motor dimension

The length of the motor is 44.5mm or 45mm with the solder pin

The diameter of the motor is 28mm

This two dimension will be the exact motor to look for thus we end up with 2845 xxxxKV

 xxxxKV is all about how fast the motor can spin per volt. To know more about KV, kindly search some info about it.

The mounting hole on some 2845 are quite the same as the brushed so don't worry, there are lots of way to mount it. The original pinion gear for the motor was fixed on the 390 brushed motor, so need to purchased one with the right number of teeth and shaft size mounting for the upgraded motor..And I came up with this BRUSHLESS MOTOR since it was cheap for me as I am just starting to learn the world of brushless at this time, (not actually new to motors)

I picked the

Surpass 2845 3100KV with 35A ESC..( more on this later) as my starting point, I am just so worried with the upgrade and not upgrading those Nylon plastic gears of the gearbox may snap with the additional rotation it may produce with this brushless motor.

You can do buy other KV rating of this motor but you have to take the risk, well I don't.

The shaft diameter is 3.175mm.

Installing it on the stock gearbox was not that hard enough. The mounting screw hole though needs to be widened a little for the 390 brushed motor and this brushless motor differ on bolt size. Go figure it out.

So i end up like this.

Perfect fit on the gearbox without removing any portion of it. Using the 2838 will just be shorter in length.

Putting it back on the chassis will look like this.

The wire fits and snap perfectly. The position of the ESC and the new receiver for this upgrade fits well on the original battery location of the unit...

Wondering anything about the set-up?..Was that the stock steering servo?

Yes indeed it was, and not replacing it, just modded the wires coming out to 3 wires with the help of a circuit.

Normally the stock steering servo has 5 wires..but the ESC needs 3 wires to make it work. Those 5 wires coming out from the OEM steer servo are as follows.

2 wires for the motor and 3 wires for the feedback trimmer. The trimmer has a value of the standard 5 kilohms..almost all servo feedback tripot uses that value, and it is do fortunate to know this that the STOCK sterring servo indeed using 5kohms, that makes it easier for meto perform the modification.

Again the solution was that 5 wires and make it 3 wires with the help of a circuit.

Donor circuit comes into place,

taken out from my OLD walkera dragonfly pitch servo controller. The circuit will be added to the 5 wires of the stock steering servo. I put a 5 pin connector onto it as shown so that the stock connector can just be plugged it in

as shown.and so i end of with 3 wire for the receiver. so no need to replace the steering servo and re think of how to mount the steering linkage to a new servo.

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