Brushless Question . . .

[traxxas-dude]

I was thinking about getting a brushless system for my stampede (considering the hacker c40 7T with the competition speed control, 12 cells)

My question is, why do people gear DOWN when they get a brushless system? They have 300% of the torque of a brushed motor has, so why gear down? if anything, wouldnt you gear up?

[TheLaxPlayer]

Brushless motors usually have about 70,000 RPM's. With those RPM's you must gear down or risk frying your motor. Motors are expensive. Also, I have heard many times that people melt gears on stampedes with brushless systems.

[traxxas-dude]

still, cant the bl handle the load that the stampede would give it? Or would, like i think your suggesting, be overloaded by stock gearing? what tooth pinion should i run on my stampede? I was thinking about a 15 tooth or so?

[crono man]

a c40 7t on 12cells will most likely destroy your stampede tranny

[traxxas-dude]

well, i upgraded the tranny with all aluminum/steel gears, and has MIP CVD's

[DualBL]

with brushless motors, you have to gear down, because of Cogging, and the fact that brushless motors run best at higher rpm's.

[BobNovak]

Originally Posted by DualBL

with brushless motors, you have to gear down, because of Cogging, and the fact that brushless motors run best at higher rpm's.

This is only true (cogging) with sensorless brushless motors not sensored. Even though brushless motors have more torque than brushed motors you still have to gear them correctly or they will overheat just like a brushed motor. All motors, brushed or brushless, have that sweat spot for gearing where you get the best acceleration and top speed for a specific track, and this varies from track to track.
Bob Novak

[chilledoutuk]

the gearing does not really effect the cogging of my sensoreless brushless systems but as bob said you have to gear your setup to the application.
For example theres no point gearing your car on a tight track so high that you never max out your speeds as your not taking advantage of the full rpm range of your system.

[tcolesen]

I find that gearing does affect the cogging on my Warrior 9918. The higher I gear, the more cogging.

[Rtsbasic]

Gearing doesn't really affect cogging on my system much, although doing a really slow speed turn it cogs more the higher its geared. I still gear to the track and not to prevent cogging, same in my 1/18 mamba as well.

[starluckrc]

Lower gearing keeps current draw down as well (which keeps voltage up). All that torque comes at the expense of current draw as torque is a function of current (kt).

[Brushless Pede]

I geared up my pede because I needed it to go faster for racing. I still pull better wheelies by far geared up than I ever did with my brushed motor. Its geared at 17/90 and its the Novak SS on 7 cells. It goes about 35 with this gearing. Maybe a tad less.