Advancing/Retarding Timing

[Mark Stiles]

I was wondering whether anyone could give a detailed explanation of the effects of advancing/retarding the timing on brushless motors? Perhaps explain advantages/disadvantages of each maybe?

I'm reasonably up to speed with timing advance on brushed motors, but I'm assuming the theory is different for brushless?

Please no one line answers; I'm after detailed comments on the effects of doing each (advancing/retarding), and if possible why this happens.

Thanks.:)

[PDW]

Changing the timing changes the position of the Hall Effect switches relative to the stator. The Hall Effect switches are, in essence, the sensors in the "sensored motor" description. They detect changes in magnetic field strength, and produce a current when this happens that can be detected by the speedo software.

At the 'endbell' end of the motor, they are positioned so that they see the end of the magnet (rotor), and send a signal to the speedo as the magnet rotates. Basically, is says N-S-N-S-N-.... and the speedo uses this information to help the timing of the current switching in the stator.

As they are attached to the timing plate, and this can be moved, it has pretty much the same effect as moving the endbell on a brushed motor. The Hall Effect switches are moved relative to the stator, so that when it sends the signal, the magnet is further round its arc (or further back, if the timing is turned the other way) relative to the stator, and the current is switched in the stator when the magent (rotor) is in a different position.

Quite why this feature has been included, when exactly the same effect could be achieved in the software, is not clear to me. Nonetheless, it is there, and it can be altered. My experience is that the motor I used was a bit lazy all round at 2 deg timing, but was faster, more responsive, and easier to drive at 6 degrees. All those I race with set their timing between 4 deg and 6 deg and leave it alone. Any tuning is usually done with the speedo settings after that. HTH :)

[Mark Stiles]

So would there be any benefit at all from using retarded timing, or is it like a brushed motor whereby you should tend to run a bit of advance and then work on gearing/speedo settings etc...?

[PDW]

The huge benefit of retarded timing would be us seeing your face when notbetterthannobbystiles cruised passed you on the track with his 12T!! :D

The motor works in exactly the same way as a brushed, with the biggest efficiency gain being the lack of a commutator. Retarding it would make it slow and hot(ter).

No, I wouldn't simply set a timing and play with gearing. To get the best performance from any motor needs the right combination of both. I suspect that the combination of speedo, timing and gearing settings will be key brushless tuning parameters for every track - expecially in 12th where driveability is key.

You'll need to experiment extensively to find which parameter does what (make notes every time you change, especially the lap times) and learn which one to alter in what circumstances. Unlike chassis changes, you're looking for consistent improvements of 10ths to see any benefit in these settings. HTH :)

[Mark Christopher]

im sure there is a bit on the lrp site re adjusting timming on them