derricklong38

Are they necessary, what do they do.

gee-dub

iTrader: (1)

i think you mean capacitors, not resistors (though they do act as resistors if not bridging a dc circuit). anyhow, they are meant to absorb/suppress minor voltage fluctuations in a brushed motor caused the brushes rubbing against the comm. they are not required, in the sense the motor will not work without them, but they are a good idea to use, which is why several manufacturers have them built into the endbells.