Gearing help

[Ryd1ZZ]

I'm ready to start messing with the gearing in my erbe but I'm not sure where to start. Does anyone know of a guide to gearing? I'm just looking for a basic run down of how it works.

[asheck]

IMO the best way to regear is in small steps, with a temp gun handy. But knowing what batteries, tires and driving you'll be doing will help us help you.

[KingdomRacer]

I have used this chart for 4s but would love to have a chart like this one for 6s. Plus what asheck is saying is true because although this chart is a good reference it is not an absolute. And honestly I'm bolgging on this thread to hopefully learn more myself.
Here is the link for the chart I use for reference ONLY
http://www.traxxas.com/PDF-Library/5608_manual_addm.pdf

[Ryd1ZZ]

I'm using SPC 8000mah 2s batteries x2, badlands on maximizers, backyard off-road track and bashing.

That chart is helpfull but I'm not sure what the overall gear ratio means. Is lower overall ratio giving higher top speed? Is it giving more torque?

[glbobo]

I have been running 18/56 on MA 8k 2s's but with a 2650kv motor and it barely gets warm. I'm going out with 22/56 today and see how that works.

[asheck]

As long as your batteries are capable, the higher it is geared, the more powerful it will seem. Really temps should be your judge on gearing, do you have a temp gun? Do you have any idea what your current temps are? This is a great site to help with gearing http://scriptasylum.com/rc_speed/_top_speed.html

[BBBB]

Keep a temp gun in hand, install a 54 spur gear (because that will give you the most speed) and start with a 18 tooth pinion and work your way up to a pinion in the temp area you want. I have always set mine up by temp guns only and never had a problem, you just have to have about 6-7 pinions to try and I like to keep my truck on the lower side, my esc fan kicks on at 150 degrees, but my temps run around 125-135 with a Castle Fan installed. Don't forget to check your battery temps and never let any Lipo get to 140 degrees on a regular basis, that's the danger zone.

[Double G]

I'm using SPC 8000mah 2s batteries x2, badlands on maximizers, backyard off-road track and bashing.

That chart is helpfull but I'm not sure what the overall gear ratio means. Is lower overall ratio giving higher top speed? Is it giving more torque?

Quick guide to gearing: Take your typical 12-speed bicycle. The front sprockets connected to the pedals are your pinion gear (clutch bell on nitro engines) and the rear sprockets are your transmission. Follow me here: the smaller sprocket up front connected by the chain to a large sprocket on back results in you spinning your legs very fast but have little speed; but boy can you climb hills with ease. Put the chain on the large front and small rear and you get high speed with less revolutions of your legs; but now start from a stop. Very hard, isn't it?
So if you have a bigger pinion and a smaller spur you will get high speed but lower torque and acceleration. Smaller pinion and larger spur will result in higher torque, faster acceleration at the expense of higher speed.
Throw this in: get a more powerful motor and all other variables (gearing) the same, it will result in more power to the tires. That is why you can put in a more powerful powerplant and up the gearing.
As for the numbers: the higher the number the lower the gearing and vise versa. Take for example an overall gear ratio of 16.4:1. It takes 16.4 revolutions of input (front sprocket/pinion) to turn one revolution of output (rear sprocket/spur). A lower gearing of 18.8:1 will give you better acceleration but lower top end. And the reverse is true.
Hope that helps.

[asheck]

Here's the problem with that analogy, with a bicycle the motor is a certain power. With brushless the higher you gear, the more power the motor makes, as long as your batteries are capable. Your torque does not go down as you gear higher, as a matter of fact your motor torque increases as you are geared higher. The reason bigger motors can handle more power, is because they can dissapate the heat generated, by producing that power. The heat is determined by the motors efficiency. So if you have 2 motors of equal efficiency, kv, gearing and batteries, the size of the motor will not matter, unless your running hot, then the bigger motor will run cooler, and can be geared higher.

Torque is determined by the size of the rotor, and the amp draw of the motor. Wheel torque is then determined by taking motor torque, and dividing it by the gearing. Since you are increasing motor torque, and gearing higher the perception of torque will stay the same, however being geared higher will make it seem much more powerful. This is all dependant on using capable batteries.

[Ryd1ZZ]

Very helpful so far guys. I do have a temp gauge and I'm usually at 100-110 on my motor and 100 on the ESC. I'll try the 54 spur gear since I don't have any other pinions yet and see how that works.

I ended up breaking a driveshaft last night so I'll be making a trip to the LHS, maybe I can score some different pinions while I'm there.

[Novarider]

Here's the problem with that analogy, with a bicycle the motor is a certain power. With brushless the higher you gear, the more power the motor makes, as long as your batteries are capable. Your torque does not go down as you gear higher, as a matter of fact your motor torque increases as you are geared higher. The reason bigger motors can handle more power, is because they can dissapate the heat generated, by producing that power. The heat is determined by the motors efficiency. So if you have 2 motors of equal efficiency, kv, gearing and batteries, the size of the motor will not matter, unless your running hot, then the bigger motor will run cooler, and can be geared higher.

Torque is determined by the size of the rotor, and the amp draw of the motor. Wheel torque is then determined by taking motor torque, and dividing it by the gearing. Since you are increasing motor torque, and gearing higher the perception of torque will stay the same, however being geared higher will make it seem much more powerful. This is all dependant on using capable batteries.

So your saying that if a brushless setup is geared 18/64 is actually making less power than if it were geared 18/54? It's not just requiring less power to do the same thing it's actually making less power? If that's true than gearing for more speed should break more driveshafts because it's making more power.

[BBBB]

Very helpful so far guys. I do have a temp gauge and I'm usually at 100-110 on my motor and 100 on the ESC. I'll try the 54 spur gear since I don't have any other pinions yet and see how that works.

I ended up breaking a driveshaft last night so I'll be making a trip to the LHS, maybe I can score some different pinions while I'm there.

If you go look for a Robinson Racing Pinion, the part# will always have a 87 prefix and the last 2 numbers will be how many teeth is on the pinion, example: 8718=18tooth, 8722=22tooth,8724=24tooth, got it. Her is one a t Tower Hobbies: http://www3.towerhobbies.com/cgi-bin...?FVSEARCH=8722

[asheck]

So your saying that if a brushless setup is geared 18/64 is actually making less power than if it were geared 18/54? It's not just requiring less power to do the same thing it's actually making less power? If that's true than gearing for more speed should break more driveshafts because it's making more power.

This is true.
Think about it like this. Amps x volts = watts= hp = torque x rpm's. Your voltage determines how fast your motor spins. So if you are on the same voltage, the only way for the motor to be faster is by producing more torque. So as you are going faster it takes more power from your batteries to push that.

[Novarider]

Using more power and creating more power are different. Using more power is drawing more power from the batteries while creating more power is like adding more volts or running higher octane fuel. Which is true?

[asheck]

You can not create more then you use. The draw of the motor is what determines both. If it takes 250 watts to go 30 mph, doesn't matter if your on 6s, or 4s the motor will only draw what it takes. The only variable is the efficiency of the motor. Which could come into play depending on the speed your geared for.

[RedRaider]

The link provided in post #3 describes an optional 24-T pinion gear.

I am unable to find where you can purchase that pinion gear??