Motor causing servo to shift off-centre?!

[Fiddybux]

Hi all,

I wonder if anyone has had this problem before?

My setup - XX4, LRP Quantum 2 ESC, Fantom Vortec 9x1, Futaba S9550 Servo.

Whilst I was going round the track recently I noticed I was unable to turn hard left. On a number of occasions this lack of steering ended up putting me on the straight with oncoming cars coming fast. So I bailed out of the race for fear of a big pile up and lots of damage.

When I inspected the car later on I did some tests, and with the motor attached it definitely caused the servo to off-set more to the right, i.e. the centre position of the servo was not in the middle any more!? The servo would move off centre when the motor was active, but was fine when the motor was stood still. If I disconnected the motor completely and turned off/on the ESC the problem went away and was not repeatable.

Later on I noticed that the middle of the brush wire had almost completely split, meaning there was only a few threads holding it together. Now it has completely snapped after I pulled it.

Also with the ESC set to higher punch levels, this seemed to increase the likelihood of the servo going off-centre...at lower punch settings it didn't happen as often.

So my question is, can a brush wire that is almost snapped off / partially disintegrated cause the servo to go nuts like this? The problem only seemed to happen with this particular motor and other motors did not affect the servo in this way.

I suppose if some of the electricity that was supposed to be going to the comm was actually finding its way to the outside of the motor can and then conducting through the graphite chassis to the servo might cause it??

Thanks in advance all.