Trying to understand bunt motor s demise..

[04zrx]

Hey all, I've been in a bad spot lately with my Ridgecrest and I've read several posts on the forum about burning up motors. I still don't understand what exactly causes a motor to burn up, other than heat.... caused by resistance (I guess..)

Last night I was running my Summit and crawling on the rocks. I got thinking about what I've put that motor through and it is amazing to me that it hasn't gone up in flames. It's a stock motor no mods to the drivetrain at all.
How is it that I can bash the hell out of that big heavy rig with no problems but my little Ridgecrest I burnt up a Quality motor. When I had the stock motor in my Ridge I didn't have problems either. Is it the 3s in the Ridge that is doing it?
I just was hoping to discuss the reasons that cause motors to smoke....

all replies welcome

[k7zpj]

A smoked motor is usually the result of over gearing, binding or too tight of mesh between the spur and the pinion. The common theme here is that something is causing the motor to work harder than it is capable of doing. A over loaded motor is going to draw more power which means more current which means more heat. At some point the insulation of the windings starts to melt and burn. That is why the magic smoke comes out.

When you run a loaded motor full speed at a higher voltage without gearing down it is going to run hotter than it would when at full speed at a lower voltage and same load. Higher speed at same load is more work which requires more power and causes more heat. This means you need to gear down when you go to a higher voltage battery to keep from over heating he motor. Which is the long way of saying: Volt Up and Gear Down

I use a combination of finger tips and temp gun to check after about 5 minutes of running to make sure the temperatures are so that I can hold my finger on the motor for about 5 seconds or around 130 degrees.

[EddieO]

Well, to be frank....the Summitt is produced by Traxxas, who KNOW how to gear a motor and released it with such. You are running the stock setup, so everything is how it should be. The Ridgecrest however, you have overgeared, plain and simple.

There are multiple points on a motor that can fail with heat. Typically the windings first, but the comm tabs or the comm itself are also two places we see failures.

It's not the 3s,its not the motor....its the gearing and typically the driving too, they are not race trucks. If you want to go fast, buy an RC10T.

Later EddieO

[04zrx]

gear down, so you are saying "GEAR DOWN"? I think I'll gear down.........

[Charlie-III]

Originally Posted by 04zrx

gear down, so you are saying "GEAR DOWN"? I think I'll gear down.........

Gear down as in....larger spur (more teeth) or smaller pinion (less teeth).

All this is assuming the pinion/spur mesh is set correctly & there is no binding in the drivetrain.

Running a higher voltage pack will make the motor want to spin faster, keeping the original gearing now means you are overgeared, thus heat & smoking motors.

[04zrx]

good things are on the horizon, my new pinion gears came in , waiting on my spur gears now.... I suppose I also need to compensate for the larger diameter tires and the extra weight of the wheels? I'm running 2.2 Mayham wheels and irok tires.