5 replies to this topic

[Paul C-S]

A number of 0.530 diam S16D's arms have come into my possesion. Do I shim a rotor setup or just run with a large air gap?

I have noted here that 16D arms like a bit of breathing space, but how much is too much?

Thanks in advance, PC-S

[Bill Seitz]

Standard diameter for 16D arms is .520. Some of the 16D setups with .150 thick magnets have enough room for at least a .540 arm and in some cases a .560. Personally, I don't like running a .520 arm in these setups, and opt for replacing the magnets to drop the "hole" down to .540. S16D's especially seem to like that. Otherwise, I run a larger diameter arm. So, if you have setups with .150 magnets and the larger "hole", running a .530 arm shouldn't be a problem. You'll get a little more torque and brakes.

[Danny Zona]

A number of 0.530 diam S16D's arms have come into my possesion. Do I shim a rotor setup or just run with a large air gap?
I have noted here that 16D arms like a bit of breathing space, but how much is too much?
Thanks in advance, PC-S

You can run them that way.

Back in the day I would use .518 arms with a .585 air gap.

[Bill from NH]

And get gobs of RPMs Danny?

[Danny Zona]

And get gobs of RPMs Danny?

Probably but I can't say for sure except the the lap times were faster.

I'll add most racers used higher timed arms from 45 to 50 degrees and I preferred 38 degree arms.

Also the big air gap motors with small arms used a smaller pinion.

[Paul C-S]

Many thanks for your helpful comments. I measured the airgap in a new PS S16D motor at 32thou, so there you go. These motors should all run cooler if correctly geared I think.

My experience with newer motors is growing thanks to you guys and this forum.

PC-S