Carisma GT24/GT24B/GT24TR: What's Under the Hood, Installing a Slower Motor

Today, we will open up the Carisma GT24 and put in a slower brushless motor, from 8000kv to 6000kv. Whoa, slower? Am I insane? Why? Outside of winter months, I've been experiencing ESC cut off after driving the truck hard for a couple of minutes. The stock motor is 8000kv, which is more than a handful when running with 2s lipo power. Either the motor draws too much amp or the motor/ESC is hitting thermal cutoff. The overheating may be due to insufficient airflow. I'm not sure, but let's try a slower motor and also see if I can simplify wiring a little bit here.

Under the hood, we see a GL 18A ESC, Radiolink R4FGM receiver, and a WLtoys 5g metal gear servo. I'm too lazy to shorten the cable from the servo and ESC. Those can be tucked away neatly just behind the servo mount. This blue motor is the stock 8000kv brushless motor (16mm). For its power output, it's actually a fantastic little motor. It's secured onto to the motor mount via 2 screws from the front. Unfortunately, the pinion gear pitch is neither 0.5 mod or 64p.

With the motor disengaged from the drivetrain, let's test the smoothness of the drivetrain. This is not bad for a shaft driven AWD drivetrain, especially as this is a pretty low cost platform.

The slower motor going in is this 6000kv (16mm) brushless motor that came with the Mini-Q Q7. It's an extremely "notchy" motor that feels more like a brushed motor with strong magnets. It gets the job done though. I will unsolder the JR connector and replace with 2mm bullet connecters off camera. This pinion remover has made multiple appearances in other videos. It was only $9 and well worth it.

Okay, the motor went back in. The pinion didn't feel very tight on the motor shaft. Not sure if it will be a problem later. I tried to tidy up the cables. There's not a whole of space if I want to keep the chassis cover on. However, I do want to keep as much of the cover on to resist dirt and small debris. In retrospect, the 2mm bullet connecters are too bulky for this application here. I should've soldered wires from the ESC directly onto the motor. I cut off part of the central support brace on the backside of the cover to create more space. The cover goes back on more easily now. I hope more interior space also means more airflow to cool the ESC and motor. The slower motor should also run cooler. If I still run into cutoff issue, I will have to suspect something wrong with the ESC.

On this modded GT24, the lipo battery still goes into the old battery compartment. I use a GL battery with a JST-PH plug. Let's power everything on and see how it does. Steering works. That's good. The inexpensive Wltoys 5g metal gear servo, running without a saver, is still functioning well. Throttle also looks good. Throttle control is all there, and even with the slower motor, power seems sufficient. I didn't record the footage, but to test I pinned the throttle for quite a while. The ESC felt warm but all the power was there.

Please excuse the video quality of the running footage. I haven't had a chance to take it outdoor. Despite downgrading the motor, the GT24 running 2s was still more than fast enough to be fun. Power-wise, it's actually quite similar to the Mini-Z Buggy running 8500kv with 4xAAA NiMH voltage level. GT24 is lighter than the Mini-Z, and so it wants to dart and fly around even more. While this is not representative of a hard outdoor run, I was looking out for ESC cutoff, but I didn't encounter one. That's good news. However, as the mini run went on, an issue came up. The pinion on the motor was getting loose. Acceleration became noticeably softer. I will either use a bit of CA glue, or I will need to buy a fresh pinion. Or I Will need to revert back to the stock 8000kv motor.

This is Sammy and thanks for watching!

Music: "Instructions for Living a Life", Savfk (   • Instructions for Living a Life by Savfk [C...  )