Gears and pinions

[Gameover]

Prolly a stupid question but I'm looking at buying some spare pinions and gears. My questions are what do the smaller amount of teeth compared to the larger amount do? All small spin real fast right so more get up and go? All large have more high end? What about big and small together? So many options any help would be great thanks!

[HomeRacingWorld]

Lower Gear Ratios: When the numerical value of the gear ratio gets larger, the gear ratio is said to decrease. For example, a gearing of 8-38 (4.75) is lower than 9-36 (4.0). Lowering the gear ratio will typically increase brakes and acceleration while decreasing top speed.

Higher Gear Ratios: When the numerical value of the gear ratio gets smaller, the gear ratio is said to increase. This is also referred to as using a taller gear. For example, a gearing of 11-38 (3.45) is higher (taller) than 10-36 (3.6). Higher gear ratios will typically increase top speed while decreasing brakes and acceleration.

For better acceleration and braking, reduce the ratio: fewer teeth on the pinion gear, more on the crown, spur, or anglewinder. This type of configuration is ideal for tracks with a lot of tight curves.

For more top speed, increase the ratio: more teeth on the pinion, and fewer on the crown, spur, or anglewinder gear. This type of configuration is ideal for tracks with long straightaways.

Not my words, but it's an easy to understand explanation.

[Gameover]

Perfect thank you!

[Florida_Slotter]

Gameover,

That was straight out of Harry-Pedia.

[Mayberryman]

[Dangermouse]

There is a thread on here that has been considering that very question mayberryman

viewtopic.php?f=5&t=6977&p=81546#p81546

[HomeRacingWorld]

Well sir, in all honesty I do not know and never had any reason to find out. I don't race in any group that the difference would be beneficial.

We mostly stay with stock ratios and tune the model around it.

If you ever test the theory, please post your findings. Free Slotburger for your efforts :)

[Florida_Slotter]

[chappy]

Hi Mayberryman, , boy what a loaded question that is, I bet you could get 6 people with 6 differing answers to, that one. People would be talking about variable factors in testing etc etc.
But if you promise not to bite I will give you the results of a test I conducted yesterday.
I ran a slot it inline chassis only with the orange endbell 21.5 k.
only thing I did was change the gearing .
10.5 volts on a mdf track, tires cleaned with water. Everything remained constant except the gears.
8/24,,,, and 10/30,,, both 3 to 1 ratio.
I'll cut to, the chase . Lap times virtually the same , acceleration better by a touch on the 8/24.
Handling better on the 10/30.
Braking distance measured on 10 times per gear set, result 1.5 cm shorter stop on the 10/30 gears
1.5 is not enough to say the 10/30 stops shorter as any driveing difference when brakes were applied could have been the difference.
10/30 fast lap 6.254,,,8/24 fast lap 6.244, 1/100th of a second, again could hve been my driving.
all gears were brass slot it, pinions and crowns.
Now if. I were to, have run 8/24 or 10/30 3 to1 against say 9/30 or 3.33 to 1 then I would have better brakes on the 9/30 just like Harry explained.
Remember that no matter what diameter spur you use , it is compensated by the appropriate pinion since the distance on a sidewinder between the motor shaft centre and the axle centre remains constant.
clear as mud right.
Bob

[Foamy]

If we are talking about not changing ratios, bigger pinions will give you more top speed.
In 1/24th Drag Racing, a couple MPH gain can be found. Examples are 20/60 is a couple MPH faster that 16/48, and that is a couple MPH faster than 9/27.

When I did 1/12 R/C racing back in 1980, the cars came with 32 pitch gears. When I and my friends went and got 64 pitch gears from a gear supplier, the cars were faster and lasted longer on the batteries at the same ratio.

[chappy]

On a car with the same ratios, say 3 to 1 for example.
The motor must revolve 3 complete turns in order for the wheel, to revolve once
at 30k rpm motor the wheels would turn at 10k
10/30. 9/27. 8/24.
What would make a difference is the tire diameter.
A 21.5 mm tire travels approx 1.5 cm in a complete revolution.
a 43 mm tire should travel a lot further because at one revolution it covers more distance, also known as roll out. I dont know what scale the op or Mayberryman is talking about, but if 1/32 , using slot it sidewinders,
the spur gear choices are 18mm for a slot it chassis and 19mm for a fly or scalextric.
Both of these are dependent upon the distance between the drive shaft centre and the driven shaft centre.
in this case armature shaft and axle.
If you were using an 18mm 30 tooth spur and a 6.5 mm 10 tooth pinion , that would indicate a distance of
12 .25mm , less the depth of gear engagement. Say a total of .5 mm is used in the mesh, or lash.
at .25mm per gear.
so the distance between the straight line armature shaft centre and the axle centre would be the noted 12.25 mm. This dimension can not be exceeded , in effect limiting your gear combinations to 12.25mm.
Also the spur could not exceed the size of the tire
So in reality the size of the tire , which is the final driven will determine the top speed, with all ratios being constant and the rpm being constant.
What you may find however are small differences in acceleration and braking, but at these sizes they are almost negligible.
So even with a larger dia. Pinion you would have to, use a smaller diameter spur to fit the space.
Acceleration may be better, or, time through a drag trap.
But top speed would be the same if the ratio is the same., At least thats the science to it.
Bob