Motor questions from a new r/c basher

[trphyhntr]

Hello all. As a newbie I have some basic questions about motor selection, particularly for bashing. I haven't taken an interest in racing yet, so track rules don't matter to me - but I wan't all the speed I can get! (I have a Rustler with XL-1 esc)
If fewer turns means more rpm, why does my local hobby shop recommend I buy a 27-turn Trinity motor from them? I don't understand why that would be faster than my 20 turn, and it is expensive.
What is cutting the comm?
How to break in, and how important is breaking in a motor?
How long does an average mild modified motor last?
'Rebuild' just means new brushes, right?
Any and all information is appreciated.

[murphy3688]

If fewer turns means more rpm, why does my local hobby shop recommend I buy a 27-turn Trinity motor from them? I don't understand why that would be faster than my 20 turn, and it is expensive.
if your truck comes with a closed endbell motor like a stinger or something of the sort, an open endbell motor would generally be faster. brushes are better, comm is better. wee!

What is cutting the comm?
that means you use one of these beasts: http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNB54&P=ML to smooth the commutator. a perfectly rounded surface has more contact area to the brushes, which means more power to the motor (the brushes sit against the comm)

How to break in, and how important is breaking in a motor?
take a four cell battery pack with alligator clips and clip it on each motor tab. let the battery run out. as its running, submerge the motor in a cup of water (you arent getting shocked) for five or ten seconds (some do this until the battery runs out). this seats the brushes better against the comm... its a really good idea to break in a motor. there are plenty of places online on this method, and youll hear many different ways.

How long does an average mild modified motor last?
what are you doing with it? lol. motors can last a long time, even if uncared for.

'Rebuild' just means new brushes, right?
im not sure...


if someone catches somethin i said incorrectly, please let me know. i dont want somethin messed up.

good luck!

[murphy3688]

sry, double post

[racer234]

Breaking in a motor is basically running it at low voltage so the brushes can seat. I wouldn't recommend dipping it in water though; that technique was used when the brushes weren't as soft as today, and they weren't serrated. Today's brushes dont need to be dipped in water. As for a 'rebuld', generally this means you cut the comm, and replace the brushes.

[Hachi_Roku]

'Rebuild' just means new brushes, right?

Rebuild could mean different things to different people. To some people rebuilding a motor could be just a simple brush change, but to some racers, rebuild could mean replacing brushes, align brush hoods, clean and relube bearings, cut the comm, cleaning all the grit inside the motor than top it off with a dyno run than break in the motor.