Bingo. All that complication was because you had to do that to get the most out of a brushed motor. It sucked, brushless improved things greatly.

Im not sure what is meant by brushless being more efficient. It is better in most every way except torque density. Look up torque constants of same frame brushed versus brushless. You get more torque per amp out of brushed.

a magnetic field takes time to collapse and expand and its not the same in both directions. as the rotor moves faster it gets more important that the field collapses fast enough to avoid repelling the next permanent magnet. at higher rpms the field changes angle which creates more complication. dynamic timing is something a brushless motor can be setup to do. im not aware of a way to do that with fixed commutation in a brushed motor.

since continuous power is peak power limited by the motors ability to convect heat away... a rotor that is energized (brushed) absorbs heat rather than the case on a brushless. so heat is transferred to the air moving around in the air gap but the surface area is a little less than the case. So heat will build on the rotor shaft and be transferred to the bearings and then in turn transferred to the case. you usually have hot spots at the bearings. Peak power is greater in a brushed power but continuous is less because convection and conduction arent working as well as brushless.

Brushed motors have almost completely died in robots for primarily 1 reason. most people arent aware of the previous points. they died because of maintenance.

high end motion control is dominated by 2 motor types. variants of a brushless dc motor (synchronous) and variants of an AC motor (asynchronous). The ESC or drive that is providing power is synched to the rotor or not but the waveform is the same fundamentally. if you have an asynch motor eddy currents are created to move a non PM rotor. if you have a PM motor eddy currents are not created to move the rotor the attraction and repel forces come from an electro magnet and a permanent magnet.

is aluminum magnetic? look up some youtube videos and you will see some pretty interesting stuff that look like magic. an eddy current is created that puts the brakes on a magnet moving over aluminum. it doesnt repel or attract. I always wondered why people paid money for aluminum bolts for aluminum bolts in the motor can.

There's friction between the brush and commutator and the parts wear out fast. There's a big loss in efficiency right there.

You think?????
The startup of racing with Brushless had the ESC of the month, continious new ESC's performing better, it took a while that the hardware stayed the same and firmware updates become possible.
Even in stockracing with all the same motor and a blinky ESC there are a lot of perfomance differences on the track, for sure if you use a box stock motor it will have the worst performance.
Again, shimming is most important. Using a motor analizer to read the sensor positions and with the solder iron to outline sensors to be equal and even with morte timing is also done to gain more performance. Rewinding stators to get a shorter wire is still possible on races where the resistance limit is not meassured. The new trend is to replace the 3 scres of the housing for titanium or another non magnetic material.
Not to mention cheating tricks like mounting a blinking LED in the ESC that it stays blinking no matter what program is used.

And the list goes on......

Most of the tricks are based to gain extra sensor timing so get rid of the sensor timing and stockracing will become even more simple and more equal.

I said it's better. I didn't say it's perfect. And seriously, that part that I bolded? You basically just said it's possible to cheat when they're not looking. That's not unique to brushless. People got caught cranking the timing or rewinding the armature on brushed motors back in the day.

True, but rewinding the stator and re-soldering sensors is something the avarage racer will not think of, or can not do.But shimming and creating extra play on the mounting of the sensor board is one of the things most racers do to get an extra timing but is unknown to the starting racer. Get rid of the sensor and there is a better reason the motor endbell can be locked/welded/soldered to stay closed.

Rev limit controlled by the ESC would solve nearly all the stock issues. The 2018/2019 European Touring Car Series(ETS) is running a brand new 17.5t class using a MuchMore ESC, I believe they have set the limit at 19,000rpm via special software and a fixed gear ratio, I don't think a controlled gear ratio is practical for club racing though.

I really appreciate posts like this as they entice my curiosity. I work at a tech company in a non-technical role which is perfect for my lack of attention span. My ADD sym/asym research tells me that symmetrical motors work well at low rpm and disadvantage in cost. Both of these are barriers to entry in rc. For a given voltage and current, rpm increasing as load decreases is a desirable quality which aids driveability.

Eddy currents and "magnetic" aluminum. Our equipment uses this principle to enhance accuracy. A really cool experiment to see how it works is to drop a magnet down an aluminum tube. Since aluminum is NOT magnetic, it won't stick to the side. It IS however conductive. Just like passing a magnet past a copper coil which creates electricity, the magnet falling through the tube acts like a coil creating a current and therefore, a magnetic field. The field attempts to hold the magnet in place which slows the falling magnet to a speed limited by the efficiency of the tube's conductivity. It's a bit trippy.

And on AL screws... The benefit is that they do not have a static effect on the magnetic field like steel. Since steel is also conductive they have both a static and dynamic effect on the field, albiet less dynamic since it's less conductive than AL. The truth is in the numbers though. Motors turn more rpm with non-magnetic hardware. The hall sensor accuracy (which we measure in asymmetry) also increases with non-magnetic hardware. Stainless or TI would be better than AL. Find me a non-magnetic and non-conductive screw and I'll pay big dollars for them.

ceramic bearings

before them.. we used dentist drill bearings... super high speed.. stainless steel..

on the 27 turn Stock motors.. it was possible to alter the brush hood for the brushes to change timing....
cut the commutator down small.. more rpms... and power..
as there was more brush to commutator contact.. but cut the brush face to reduce friction. and the comm drops.
then drill a very small hole into face of brush.. insert cotton.. so you have more comm drops on the brush longer.

not about motors... but the 1/10 scale carpet pan car

1/2 inch thick by 6 inches by 6 inches.. machined True flat steel plate
1000 and 2000 grit wet/dry sand paper.
to flat polish the diff rings..
then get from US bearing..... 1/8 inch ball bearings..... grade 8 steel, ground to 0.00001... true.. 100 in a box.
for a super smooth diff... a smoother diff has more speed.

I could spend 10 hours per week.. just to get ready for the STOCK class pan car Saturday night Race.. for years...
I started RC racing in 1991...

Yes and no.... when working with an handout motor indeed the differences will be minimized. If people can bring in their own motors then the war on torque will start....

Hand out motors just aren't feasible for most club racing, I agree it's the best way for bigger meets. But for club racing I can see no better way than an ESC which has a rev controlled limit to go with the matching turn motor. The ETS decided on a 17.5t motor set at 19,000rpm by the software on the ESC, I think it blinks a certain colour the same way blinky works now. There would be small differences between motors but I feel it would be a lot less. I race mod so I don't have #stockproblems.