touringdriver

iTrader: (16)

looking for some input on what to expect by running larger or smaller spur gears of a touring car with a brushless motor mod or stock? i have no issue with gearing a car but i do hear a lot of racers telling others you gear a brushless the opposite of a brushed motor???????????????????

CarbonJoe

No, with brushless you still put the pinion on the motor shaft.

By running larger or smaller spur gears, you decrease or increase the FDR.

Not sure what you're really asking here?

touringdriver

iTrader: (16)

what are the results to low end and top end quickness by going large/small on spur.

Mr RCTech

iTrader: (2)

Need more information.
Is this for blinking mode (zero timing)?

touringdriver

iTrader: (16)

in my t3 12 i run 48 pitch gears with a 69 tooth spur with final drive at 3.7, another racer runs same car except with 64 pitch gears and same final drive. the reason i ask is his car is a lot quicker/snappier than mine so he really works me over on the infield of our tracks. so my point is his spur is larger in dia. that mine so is that the benefit of running a larger dia. spur? we also run the same 17.5 locked endbell motors as well.

touringdriver

iTrader: (16)

yes blinky mode and this class requires all the same trinity spec locked endbell 17.5 motors.

CarbonJoe

If the FDR is the same, there shouldn't be much (if any) of a difference either way. There are manufacturing tolerances for everything, so his motor might be a little better than your motor (better rotor, etc.). You might have a bad bearing somewhere in your drivetrain. Do the motors come off the track about the same temp?

What if you guys switch motors? Is your car now faster? Maybe his setup or driving is a little better, giving him more corner speed, so he loses less? Are the ESCs identical? Batteries could also play a role.

Have him drive your car, and you drive his. Same end result?

Nilks

I don't know if it is actually true or not (but it has been confirmed by several of drivers at my track), but it seems like a bigger spur (while maintaining the same FDR) gives more bottom end power, where as a smaller spur (still same FDR) seems to give more top-end.

touringdriver

iTrader: (16)

Thanks Nilks, I've been hearing that as well. A 69t 48p spur is a lot smaller in dia. Than say a 100t 64p spur. However with the correct pinions equal the same FDR. Which makes we wonder and ask the benifits of larger/smaller spur.

djnsayne

iTrader: (11)

If the FDR stays the same, the size of the gears shouldn't matter at all...... I would bet that the guy smoking you has a much better battery then you do, or he is just much smoother amd carries his speed better..... how about a video?

Mr RCTech

iTrader: (2)

RIGHT!

A free car can carry more forward bite off the turns,to produce faster lap times.

Try running the smallest spur gear you can without sacrificing low-end torque of the corners.

HawaiiBob

Always run the biggest spur gear that you can to get the ratio you want. There is a difference, do your own experimentation with smaller spurs then try the largest spur that gives you the ratio you want. It affects both bottom end and braking.

wwddww34

iTrader: (9)

It also depends on how powerful your brushless motor is. For example if you are running a 25.5T motor (like those in VTA class) you probably have to find the smallest spur gear and biggest pinion gear that you can fit into your car.
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lee

iTrader: (1)

Spur gear size does not matter if the FDR is the same.
A larger spur will gives you bottom end but the large pinion that would be needed to get to the same FDR will give you top end. Balancing the power out. I would go over the car to make sure everything is free and I would also try differant gearing since not all motors like the same geraing.

Evoracer

iTrader: (24)

I agree that spur size makes no difference. It's all about FDR and car setup. Is the drivetrain free ? Is the diff set up with more slip ? Spool or diff up front ? Belt tension ? All these things will have an effect.
That said, If our spur gears had any real weight to them then the argument would be different. A larger,heavier spur would have less torque effect but greater inertia effect therfore it would be better for higher speed and worse for acceleration. A smaller, lighter spur would be the opposite.
So...because we spur gears that have very little mass (weight), the effects are extremely minimal. Look for other factors between the 2 cars.