HorizonHobby.com How-To: Understanding RC Gearing
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- เผยแพร่เมื่อ 12 มี.ค. 2012
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One of the most common questions we hear about RC cars and trucks is, "how fast does it go?" While this seems like a common, ordinary and easy question to answer, the truth is that there are a number of different factors that contribute to a vehicle's speed, torque and acceleration. One of the big determining factors is the gear ratio and transmission of your vehicle. While things like installing a faster motor or higher voltage battery are easy things to understand, wrapping your head around gear ratios can be like taking an advanced course in physics, geometry, algebra and trigonometry. While there's a lot going on, there's some simple ways to get a basic understanding of what the gears in your transmission do, what changing them means and how things work. We've also put a list of commonly used terms together for you below for quick reference to help you as you progress.
External Gear Ratio -- The gear ratio of the gears that are visible or outside of a transmission case. This is the ratio of the pinion and spur gear.
Final Drive Ratio -- The gear ratio of the entire drive system in a car or truck. This includes the internal gear ratio of the transmission and the external gear ratio of the pinion and spur gears. You can calculate this ratio by dividing the spur gear tooth count by the pinion gear tooth count and multiplying that total by the internal transmission ratio.
Gear Ratio -- A gear ratio is the relationship between the number of teeth on two meshed gears. This relationship is expressed mathematically. For example, if one gear with 50 teeth is driven by a gear with 20 teeth, the gear ratio is 2.5:1. You would calculate this by diving 50/20 for a total of 2.5.In an RC Car, you have 2 different ratios you'll need to work with to achieve the proper gearing for a specific application and goal. The first is the external ratio and the other is the internal ratio.
Internal Gear Ratio -- The gear ratio of a vehicle's transmission gears separate from the pinion and spur gear ratios. The internal ratio is a fixed number determined by the manufacturer of your vehicle.
Module -- For countries that use the metric system, Module is the equivalent of pitch. It typically refers to the pitch diameter, in millimeters, divided by the number of teeth. The higher the number on the pitch, the finer the tooth profile is. The common module types are 1.0 module and 0.6 module.
Pinion Gear -- A small gear that directly attaches to the output shaft of an electric motor.
Pitch (AKA Pitch Diameter) -- In countries that do not use the metric system, pitch refers to the number of teeth on a gear with a 1-inch pitch diameter. The higher the number on the pitch, the finer the tooth profile is. The finer the pitch, the more efficient the gear; however, since they have less material, they are often more prone to stripping if the mesh is not set properly. The more coarse the pitch, the less efficient the gear will be; however, they are also more durable and less susceptible to damage. 48 pitch is the most common pitch in RC, however, 64 pitch and 32 pitch can also be used.
Spur Gear -- The large gear mounted to the top shaft of your transmission in an off-road vehicle, the center differential in an 1/8-scale or 4WD Short Course Truck or the main lay shaft in an on-road vehicle. The spur gear is driven by the pinion gear or clutch bell.
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I appreciate this type of refresher knowledge. Helps when you can “build and UN-build it in your head and logically”
Referring to the math classes I thought I would never use, my very first thought when you said that was going to be using it here today was "I bet you're not". Because for me, that was Algebra lol. I worked for 25 years as a CNC programmer and machinist, and I never used Algebra one time after high school.
But this was a great video that really breaks things down. Good job, and thanks for sharing!
I know this is an old video but this helped so much! Thank you horizon hobby
To determine the pitch of any spur gear use the following formula:
P = (T+2)/D
P = Pitch, T = number of teeth in gear and D = the measured outside diameter of the gear.
The resulting calculation will give you a whole number with a decimal. Disregard the decimal value on the end. The whole number is the pitch of the gear.
Example:
I have a pinion gear with 18 teeth. The measured diameter with a pair of calipers yields 0.415 inch. Using the above formula, P = (T+2)/D = (18+2)/.415 = 48.193, the pitch of the gear is 48
I hope that helps.
Joe
great video!! i finally feel like i have the basics of gearing down pat.
Cool video, it can't get any better than this.
Great information. This helped me out.
Thanks for the info I'm new to RC and bought a Losi Muggy and for now it's a little to fast for me so I'm trying to slow it down a little bit until I get use to it not to mention I'm hoping to get more torque for wheelies
Generally speaking 48P gives you the best combination of durability and efficiency. What sort of car are you running?
This is awesome for a new person to hobby, now because of you I now know what type of pinion I'll ever need just by looking, and also taking into account the application I'll be using💎💎💎💎❤️👊🏿
Very simplified thanks
outstanding video!!! thank you
wow thanks this really helps i understand more how this works than before great video!!!
brilliant video love it
7:20 is what I came here for
thanks
Same
Cheers, should be at start of video as introduction into gearing then all the more complicated stuff later in the video.
Yeah same here. I just need to get a new gearing to make it faster, and now I know how. I was ready to look for this timestamp myself.
I put like before ending see the video cause I already know how he's good explaining things, helped me once though... :)
It all depends on where you're running, the size of the straight away, the battery configuration and more. It's really unique to each track.
Thanks for sharing Sir👍👍👍
Great video! makes me think, i'm updating my maverick strada xb evo to brushless, its a 1/10 scale 4wd, so if I am aiming to get speeds at around 45mph, i just need to look at a higher KV motor esc combo and thats it? Or playing with gears is a must? Seems like leaving the stock gears is the safest option to prevent motor and ESC from overheating?
On the RC8B2 yes, that would be good. On the Rascal are you converting that to brushless? If so I believe the spur gear is also Mod 1 so a 14-17T pinion should get you in the range there.
Great video! I'm going to brushless with an RS4mt and I'm thinking about my gearing and heat. Does too high a gearing cause more heat? And what's the best way to start working down the gear if heat is an issue?
It was like a math lesson, but very informative thanks :)
thank you. nice presentation and good information
Nice job explaining gearing. Can you recommend a short read that reinforces what you just demoed. I find it sinks in better. Thanx
Thank you for the info!
Really helpful guide, thanks! :D I'm only still trying to figure out what to do with my Tamiya M-05M Pro chassis, I want to run it with a brushless system, and the standard gearing options it comes with are 5.8:1, 6.44:1 and 7.25:1. Now I could just look up recommended gear ratio specs of some motors, but since this car is a front wheel drive mini 1:10 scale, won't that also affect what ratio is needed?
@fieryguns Absolutely! Many people have learned on the Super Cub! And it's gotten even better in recent years with a battery upgrade to LiPo and a transmitter/receiver upgrade to Spektrum DSM2 radio gear. You may also want to check out the new HobbyZone Stratos as well.
@fieryguns Well this is more for the surface crowd than the airplane or heli fans. What can we help you out with on planes?
Super information about the gears!! Peace racers
This is a great video for us newbies!
Q: If I'm using a 13T double motor, should I be using a specific size/ tooth number pinion?
Or does the pinion have anything to do with motor turns?
Sounds like your setscrew on the pinion gear backed off is all. Check and see if you can move the gear on the output shaft of the motor. If it moves you just need to tighten the little screw down. If that isn't it I would check to make sure the slipper clutch is tight.
Define "Really Hot". 150-170 is about where you should expect things. Also what motor are you using, how much timing in the endbell and is there any timing or boost in the ESC?
Verry instructive video. I still have a question. If I want to go "in between", so more top speed and more acceleration. Is it possible using a spur gear with more teeth and a clutch bell with less teeth...??
I want to upgrade my Stock Serpent S411 for pure parking lot top speed short to mid run time application. What Spur/Pinion combo would you recommend include pitch also please consider the belt drive gearing when responding. Would love to know your take on Motor, ESC, and battery recommendation to achieve all of this. Money no object. Looking forward to your reply. Thanks in advance !!!
Very informative 👍
There is only one spur gear for ECX, 87T. I would drop a few teeth on the pinion from stock, 2-3 would be a good starting place. If your gear mesh and slipper are properly set there should be no reason the gears get stripped just by changing motors.
Hi , i love the video ! Nice job , but i got a question . If i wanna make my car go faster what should i do ?
@fieryguns It's pretty robust. Plus it's made out of Z-Foam which can be re-glued with any sort of CA, it doesn't need to be the foam-safe variety. If you happen to brake something there's also a full line of replacement parts for both planes.
Do u know anything about the hpi jumpshot sc v2
Thanks a lot!
I have a new 12turn motor cominng for my vaterra awd mustang it cones with a 77 tooth spur should i use the 19tooth or 22 tooth i just want it to have a decent too speed and acceleration all together but mainly focusing on just hauling around sliding and drifting
Great video learned plenty do you cover direct drive?
That is the overall desire, to have the best balance between top speed, acceleration and runtime.
I have an ECX Torment 2wd and I just put a 9T brushed motor in it but I want to achieve more speed, so am I able to go up a gear for tooth or keep my stock ones? I use my ECX as like a Short course truck so I run it on grass and sand.
hi mate thnks for video bt i would like to hv ur own advise abt my gearing..am converting a 1/5 scale harm to electric..am a bite out of fund due to expenses on esc,lipo n motor..i have the 730 kv and the 200 esc both trunigy trackstar..as my harm was petrol i was thinkin to keep my stock gearing which is 23 teeth pinion gear and 40 t spur gear.pinion gear r not so cheap and was thinking if these two pinion will be ok to use with this esc n motor,,what should i expect??top speed or acceleration?will it be safe aswell to use without overheating anythng or any other issue?if nt suitable what pinion gear do u reccomend?thnks
The FDR (Final Drive Ratio) of the Rustler transmission is 2.72:1. So for that transmission you would divide your spur gear tooth count by the pinion gear tooth count and multiply that by 2.72 to get your overall gear ratio. So for wha you have now, 32 / 32 x 2.72= 2.72 for your gear ratio.
With the M05 you have an interesting challenge due to the fixed nature of the motor mounting system. For a brushless I am assuming you're running a 17.5? I think most people are running the largest pinion you can fit in there, so a 5.8:1. The fact that it is front vs rear wheel drive won't affect anything.
i have an sakura d4 awd 1/10
i have a 4400 kv motor and i need to but a pinion gear to put onto the motor drife shaft but i dont know which one to buy. also the big gear is a 92t do i need a better one than that also?
Thank you!
Hi, I have a pretty old Losi XXX-t and I have mot seen any videos or pitures about the truck. I have only seen one other person who has had this particular truck. It is the XXX-T 1/10 scale competition rc truck kit. Now for the problem, I have net been able to find a good gearing guide besides this one but I am still confused. I have a castle sidewinder 3 5700kv setup. My friend built the truck for me way back when and I have just recently done a diff rebuild. That is besides the point though. My spur gear seems to be eating off my gear box! I have the original gear box and the original spur gear. The gear was brand new when I ran it. After 10 minutes of play the gear was basically gone! The gear mesh was correct. I know that the issue is either the gear or the motor plate but I don't know which and I don't want to go out spending money right and left. Any suggestions? If you need more information, just let me know :)
ive got a axial scx10 with a supershafty bomb proof transmission and a tekin roc412 500kv motor what is the best choice for a pinion gear ? 32 or 48 p
Very indepth vid great job...
I'm running a 1 to 1 ratio on my 1/10 scale traxxas rustler and I have a 1/8 castle creations mamba monster 2200kv on 6s I use mod 1..
steel 32 spur and 32 pinon it goes 114mph and gets faster every time I put a larger pinon or a smaller spur and I love it I have about $1300.xx wrapped up in it please check it out ...
My question is what's the final ratio of the traxxas rustler and what's the final ratio of the gears with that ratio please help and keep da gr8 job
They are all relations. For the larger gear to turn once, for example, how many times will the smaller gear have to turn. So for your first example, 7.35... The pinion gear will turn 7 full rotations and .35 of an 8th rotation. In this same time the spur gear will turn a total of one time. Hence 7.35(rotations):1(rotation)
That's exactly what it was!!! The slipper clutch I set to factory specs, but I may e too right because I just snapped the left driveshaft to the wheel now. It's not the part that goes to the motor but to the wheel, the whole thing slides off in 2 pieces. The little pin snapped on the end where the metal piece holds the wheel. I have no local hobby shop near me. Do you sell these? Thank you very much for your help sir!
What is a good spur gear and pinion for a 1/8 scale for 132 ft drag racing
So I am new to the hobby and I'm building different vehicles. How do I find out the maximum gear ratio for any particular motor? How do I find out how low and how high I can go on pinion and spur gears?
@fieryguns What don't you get? What can we help you out with?
As a general rule of thumb when you increase the RPMs of the motor you decrease the size of the pinion. So if you have a 13T motor you would gear it with a smaller pinion than say a 17T motor.
hi. im running a 14t pinion / 48t spur gear right now. if i want more torque or power on my low end i can change my spur gear to 46 or 47? im running a truggy on a very short course or small scale track. thanks. cheers!
Horizon Hobbies I have the Kyosho Inferno Gt 2 Demon. I’m running stock 4s 100c 9000 man battery. It comes with a 17T pinion but I bought a 20T pinion. Is that good? Will it put too much torque on the motor?
Also with the 3500 velineon system if I were to use two 8.4v 3000mah nimh batterys would I need a bigger capacitor or would it not be possible.
@charles1matt Yes, if you're overgeared (too large of a pinion or too small of a spur gear) the motor will overheat. If that's the case just start taking teeth off of the pinion 1-2 at a time until you hit an acceptable temperature.
what spur and pinion size should I run on the 22 sct for indoor dirt track I'm running a 86 and a 18 and it seems kinda slow I have the losi 13.5t motor?
what's a gd pinion to run with a 47t spur, I'm currently running a 21t pinion but the motor&esc gets very hot then the truggy will shut dwn do to overheating
motor-1950kv 6 pole
tire-3.8
This was a really great video! Thanks so much for doing this. One question I have is how do you decide whether to change the spur gear or the pinion gear. So if putting in a smaller pinion or a higher spur gear will give you more acceleration, what decides which one you switch? Or is it just trial and error to fine tune it?
It really is trial and error. I try to run the largest spur gear that leaves the motor as close to the centerline as possible. If I need to change up or down more than 3-4 teeth on the pinion I'll generally change the spur too.
what would u suggest on kraton 6s with max 6 1650kv and a lrager than the stock tire? what gearing should i use so it wont hurt the motor or wont over heat? ...use it for bashing also...thanks
I've actually waited with buying an engine yet as I know this model, and it seems most Tamiya models, don't seem to like Brushless and LiPo's very much. So I'm picking the engine based on what is possible with the gear ratio, I just want it to be rather swift, don't have to break speed records but neither do I want to get anywhere near toy-grade speeds. (Which in my book is 25 MPH/40 KPH.) So hoped to put something in that'll make it go around 30-40 MPH/48-64 KPH. Question is, how many Turns/kV?
I have an ECX Torment and I want to change out the drive shafts. My question is there any metal driveshafts out their I can use to swap out the plastic drive shafts on the Torment.
My b4.2 came with a 75 and 81 spur, I tried a 23 pinion with the 75 and the 17.5 turn motor got hot really fast. So I would rather run the 81..what would be a good pinion# that will keep temps down? I don't need a lot of top speed so, mostly low and mid would be better at my track.
Omg your a genius.
this was almost 10 years ago but with steel spur gears do they also get ate up as fast
It really all depends on the size of the track, along with how technical it is.
I want to make my traxxas slash go faster what gearing should I use for speed runs?
nice intro lesson
Hey, I've got an ecx circuit and I put a Titan 12 turn 550 motor on it. Well the motor kept getting too hot so I loosened up the gears. Next thing I know the spur gear gets stripped so I was wondering what pinion and spur gears should I use to get the fastest result (without striping the gears)
Can someone help me? I have an ECX 1/10 4WD torment short course truck and it won’t move even though the battery is charged. If I lift the wheels off the ground and accelerate, the wheels will spin for a bit and then they will randomly lock up and make a jamming noise. I don’t know what it is that is causing the problem.
I have a Traxxas Slash 2wd with stock tires and transmission and right now I have an 86 tooth spur and a 23 tooth pinion which equals a ratio of 3.74 and my transmission ratio is 2.72 which equals a final ratio of 10.17. Now if I were to keep the same spur and use a 32 tooth pinion I would get a final ratio of 7.32. With that ratio would I have higher speed or faster acceleration? I am also using a Traxxas velineon system with an 8.4v 3000mah nimh battery, so would that gearing cause cogging?
My Arrma infraction came with a 46 tooth gear. I ordered a replacement that said it was for my car came 50 tooth, is that ok?
The plates should be but you'll need to get different slipper pads for what ever brand of spur you go with.
Thanks.
how do you change a motor on an ECX roost without permanently screwing it up but make it faster at the same time?
Good video
The lower the ratio will yield the faster top-speed but lower acceleration. The 32T pinion will give you more top speed. Cogging is caused by a number of reasons but the biggest is the motor/ESC themselves. The more you load a sensorless motor, however, can magnify that problem.
i have a ecx amp mt electric car and whn i push the throttle foward or back it sound like it going fast but bearly moving
What is a good spur gear and pinion gear for drag racing my 1:8th scale ...2900 tp motor
Should I go with a metal diff gear if going brushless? I own a Duratrax Evader ST
I swear these videos are gold for rc wannabe kidz like me.
What is a good gear ratio for 1/10th offroad buggy stock racing?
If im running a rc on dirt concrete and grass what pionion is best 19t?
Thank u
Which ratio is beat for short course parking lot racing of a traxxas slash.
@horizon hobby what would you gear a rustler with an sv3 4600 for offroad??..was given to me with no spur or pinion and i am new to the hobby
good video
I did the adjustment and my car still slips, goes nowhere in forward but moves out in reverse. would the teeth on my gears be buggered?
The problem is that you can get that size spur gear in a variety of pitches. Pitch and tooth count are completely independent from each other.
👍👍👊👊📹📹 good info
i hv a question. do they pinion n spur gear size contribute to the cogging problem on rc? tq
If I current have a 83 spur & 18 pinion on my Slash 2WD, what combination/change would be in my best interest to gain more speed on a small asphalt oval track? Thank you! 🤘🏻
D.P.T. Bump up the pinion to 23 you should be happy with that
20-24t it's really in your best interest to but a 5 piece set starting with 20 and up and test to see what you like best, the Drag Slash comes with a 22t and 29t, I would say 20-22t to avoid heat problems.
I can't post links on TH-cam but I believe that TRA1951 is the part number you're looking for. If you check on our website you can see a photo to compare.
@fieryguns Either the Stratos or Super Cub would be ideal for you. They are designed for the first-time pilot.
i have a arctic hobby land rider 305 on road car. i converted to a brushless but the grub screw was rounded so i bought a new motor mount and i have bought 2 different pinions 48 pitch and 32 pitch the 32 is too big and the 48 is a little bit too small.. im confused
So how do I know the final drive of a b44.2? No transmission just front rear diffs. Pinion and spur ??