Hey guys,
I threw a Reedy brushless system from a TA SC10 in my Traxxas Monster Jam truck running 2s lipo.

90t spur and 16 pinion.

I was checking temps and they got to about 165 F.

But after about 20-25 mins of running and jumping the truck slowed to barely anything and I noticed a tiny bit of smoke from the motor. Again it was about 165F.

I let it cool and then tried again (for about 15 seconds) and it ran again.

Any ideas on what happened?

Should I look at my gearing?

165 is a normal operating temp. Neodymium magnets start to demagnetize over 200. You might have brought your ESC to thermal shut down but I've never heard of it still working, they usually shut down completely.

Yeah I knew the temps were fine. It doesn't make sense. The smoke was definitely from the motor.

Was it new or used when you put it in? Was it yours originally if it was used?

Both were used.

It ran beautifully for 25 minutes or so.

Here's the possible problem (and this might not be your problem) I see and IMO your gearing is fine.... "Sometimes" once a BL motor has been heated up beyond 200 degrees, they loose mass amounts of efficiency meaning they require more power to be pulled to achieve the same results; speed/torque and HP. For the laymen's, ultimately what ends up happening is they heat up quicker. Not to mention, when you temp a motor you get the outside heat, not the internal heat where it's most important.

165 is not something to worry about if your constantly on the throttle for a packs entirety. Unfortunately one can not tell if a BL motor was ran in those temp ranges before one purchases it used.

Thanks for the insight mate. I was assured by a very good 'trader rating' seller than the esc and motor were kept in A1 condition and always at good temps. Hopefully he was telling the truth. Lol.

Any other suggestions? Would a 19/86 gearing be better?

There is such a thing as under geared overheating too. You find yourself constantly pulling all the throttle to get the speeds your used to. Gearing up would/could eliminate full throttle all the time. Try it out. When you were at 165 on the motor can, what was the ESC temp?

I honestly can't remember. No where near that of the motor though. Because I remember thinking it wasn't high at all.

Forgot to mention I was running on tar road and grass (mainly road), with a bit of short, sharp accelerating (jumping, wheelies etc) and a couple of longer speed runs (dragging my neighbours nitro buggy).

I ordered a 19/86 gearing combo. I'll see how that goes with temps.