The effects of Undergearing?

[KTRTS]

My motor (TO core stock) is getting too hot after a 5 minute race; I'm runnign a FDR of 9.12 (in a schey mi2) on a very tight, twisty track, so I don't think I'm undergeared, but it made me wonder about what the effects of undergearing are? :)

[Prelude14WRX]

the only affects of undergearing i know of is a lot of torque and a really slow boring car lol. Id try differnet gear ratios at practice time to see whats up.

[AlexV2024]

no if you gear way low the motor will get just as hot as if you over geared and have the same bad effects except theres also the chance of throwing a wind when its at the upper rpm ranges and you hit stuff or stuff like that. (ive thrown a wind once in a 12x2 that was under geared, and just hitting high jumps in my 4wd buggy) might not be a problem in stock but under gearing is just as bad as over. just use less trigger insted of gearing down.

~Alex

[highroller]

Severe undergearing has the same effect as overgearing. Since motor is being restricted from reaching it's full power range it starts to build up heat leading to the same problems as you would if overgeared. Cars beings to slow, stall, burn the brushes even throw a wind - you may confuse it with dumping or a interference problem. You generally have a 3-4 tooth range with motors where on the lower side it makes the ideal torque and the higher range makes the most rpm but going 1 or 2 teeth above that is where you develop problems.
First way to tell gearing isn't right is motor gets hot, how vehicle accelerates thorugh different areas (should start out quickly and be at speed 3/4 of the way - if it seems to get a burst of speed right at the end it's not geared properly), vehicle may run very good for 1-2 minutes and start slowing (once motor starts building up heat, the brushes cannot conduct current- car may hesitate, buck, stall ). I use two methods to determine the right gearing - watch how vehicle develops speed from a start to end of a given point or how it accelerates, then check motor temp, brushes (turn bluish black, silver in very extreme cases), look at winding for changes in color (the wire will change color from copper, to a tarnish, to almost blackish blue). Motor temperature in itself is not a 100% accurate method of checking gearing as some motors get extreme warm but are made to operate as that temperature.

[monyet fangkeh]

what do you mean by throw a wind? sorry for the noob Q.

[KTRTS]

It's when the copper coils wrapped around the armature come off I think.

Thanks for al the help guys, really appreciate it :)

[AlexV2024]

yea thats what it is, and since the gap between the arm and magnets is smaller then the wind it flattens it out and rips it off the rest of the wire. then the motor locks up and you get the joy of rebuilding the motor.

~Alex

[highroller]

The wire you see wrapped around each armature stack is referred to as windings. Winding generally referrs to the number of strands of wire used, but in english we use one meaning for several in this case we mean one of the wires snapped.

A motor may continue to run once a wire snaps - and other will slow or stop suddenly it depends where it breaks off at and which direction the ends go.

[mark123]

yea thats what it is, and since the gap between the arm and magnets is smaller then the wind it flattens it out and rips it off the rest of the wire. then the motor locks up and you get the joy of rebuilding the motor.

~Alex

that happened to me. i was driving my car with a 23turn in it and then it just stopped very quickly.i took the motor out and relised that the wire was riped off so then i ddi have the JOY og rebuilding my motor ;)