PRO SECRETS

PRO SECRETS 

If you are going to race on-road rc touring cars with rubber tires,

you will need to budget some money for tires in order to be

competitive.

For example, a set of tires might be good for only 4 - 5 runs

(20 minutes of run-time) before they start losing grip. Although

the tire may look good on the outside and look far from being

worn out, their grip level is gone.

When racing, ask the fast racers how often they change tires.

You'll be surprised to learn that they probably use new tires

every race day.

If you're on a tight budget, you can try applying oil of wintergreen

to your old tires. Oil of Wintergreen can be bought in drugstores

and will help soften and increase the grip of old rc rubber tires.

SUSPENSION TUNING TIPS

SUSPENSION TUNING TIPS

Increasing front track-width will result in more understeer, while

decreasing it will result in less understeer and faster steering

response.

In general, more suspension travel (less downstop) makes the

car more responsive but less stable. It is also better on a bumpy

track.

Decreasing the ride-height (lowering the car) gives you more

grip. However, because of changes in suspension geometry and

decreasing ground clearance, there are also negative consequences

to doing this.

In general, more negative camber means increased grip.

Nevertheless, it should always be adjusted such that the front

tires wear flat, while the rear tires should wear slightly conical

to the inside.

Toe-in is used to stabilize the car. In the case of oversteer (the

rear end losing traction before the front), adding extra rear toe-

in may help, but this makes on-power cornering a little more

difficult. If the car is too stable and pushing (understeering),

removing some front toe-in will remedy this. 

Anti-roll bars are used to adjust the car's side- raction. In general,

increasing the hardness of an anti-roll bar on one particular axle

decreases the side-traction of that axle and increases the side-

traction of the other axle. For example, if you make the front

anti-roll bar harder, you decrease the side-traction of the front

and increase the side-traction of the rear. This will result in less

steering (more understeer).

Changing the front anti-roll bar has more effect on turning-in

(entering a turn, decelerating, off-power).

Changing the rear anti-roll bar has more effect on powering-out

(exiting a turn, accelerating, on-power).

TIPs TUNING RC CARS

TIPS FOR TUNING TOURING CARS

Shock Oil

Use heavier oil in hot weather and lighter oil in warm weather. If

your rc touring car is understeering, try lighter oil at the front.

If car is rolling excessively, try using heavier oil at the rear.

Coil Springs

If understeering, use softer springs at the front. If oversteering,

use harder springs at the front.

Shock Position

For high speed tracks, place shock absorbers to a more horizontal

position. For technical tracks, place shock absorber in a more

vertical or upright position.

Front Stabilizer or Anti Roll Bar

This will reduce the side grip of the front end. It will reduce

chassis roll and may result in understeer.

Rear Stabilizer or Anti Roll Bar

This will reduce the side grip of the rear end and reduce chassis

role.

Gear RC

Gears: Pinions and Spurs

This article is going to mainly pertain to ground vehicles, nitro or electric. We’re going to go through the gearing of these drive trains and figure out what all the numbers mean. You’ll learn the difference between a pinion and a spur gear, the important characteristics of gears you’ll need to know, and you’ll learn how to choose the right gears to get more speed or more torque out of your car or truck. Most of the concepts are easy to get on this subject, especially if you’ve ever ridden a 10-speed bike before. The same gear principles apply to your R/C vehicle.

It doesn’t matter if you’ve got a nitro vehicle or an electric one, the principles of gearing apply to both in the same way, the gears are just different sizes, that’s all. The biggest difference between the two is that sometimes nitro vehicles have two speed transmissions. In either case, however, the gear that’s mounted on the end of the motor or engine is called the pinion gear. It’s the smaller one that drives the bigger gear called the spur gear. Most cars or trucks are sold with gear sets that will give you average speed and average amounts of torque. Options are usually available up or down with both the pinion and the spur gear to give you a number of variations of gearing.

Two of the characteristics of every gear that you need to be aware of if you are going to make changes to your vehicle are the number of teeth, and the pitch of the teeth on the gear. The number of teeth is easy to figure out – you simply count them. Sometimes this number is stamped on the side of the gear: for example 52T for fifty-two teeth. The more teeth a gear has, the bigger the gear. The pitch of a gear in layman’s terms refers to the size and distance between any two adjacent teeth of the gear. This is important to know before you go changing one of the gears, because one will have to mesh properly with the other. Be aware that you cannot mix gears of different pitch sizes. If you do, you will end up stripping the teeth from one or both of the gears and your vehicle will immediately go nowhere. Standard pitch sizes in R/C are 32P, 48P and 64P.

Before you go and start playing with gears to find more speed, you should know what gear ratio is and how to calculate it. It’s really a simple concept actually. Gear ratio is the ratio of teeth between the pinion and the spur gears. Say for instance you have a 24T pinion and a 72T spur. Your gear ratio would then be 24:72 which is reduced to 1:3. That means that your pinion gear is going to rotate three times for every revolution of the spur gear. In other words, you will get one third the rotations out of the spur gear as you will the pinion. So if your motor is running at 24,000 RPM, your spur gear will move the transmission at 8,000 RPM. This process of reducing speed through gears is known as gear reduction. This is necessary because motors and engines operate at speeds that are too high to work efficiently in any drive train. There simply is too much speed and not enough torque.

OK, now you’re ready to get some more speed out of your car or truck, but how do you change the gears to do it? Let’s go back to our example. We want to change the spur gear to get more top end speed, so the spur gear will have to rotate faster. A larger gear with more teeth will make the gear ratio larger, causing the spur to move slower, so that won’t work. We have to go the other way. You want a smaller spur gear with less teeth for more speed. Take a spur gear with 70T to our 24T pinion and you get a gear ratio of 24:70 which reduces to 1:2.92. If the same motor runs at 24,000 RPM you will get the spur moving now at 8219 RPM. Amazing, with only two less teeth, we got an additional 219 RPM, or 3.65 revolutions per second. That’s cool, but can’t we do better? Sure we can. Let’s now change the pinion gear. To get more speed, we do the opposite of what we did with the spur gear. You want a bigger pinion with more teeth to get that gear ratio where we want it. Let’s go with 26T pinion and the 70T spur. Now our gear ratio is 26:70 which is reduced to 1:2.692. At 24,000 RPM on the motor, you get 8915 RPM on the spur gear. Just by changing each gear by two teeth, we get an additional 915 RPM or 15.25 revolutions per second.

Remember that it doesn’t matter whether you’re running electric or nitro powered vehicles, these calculations are the same for both. If you ever get stuck in figuring out if you need a larger or smaller gear size, just think of riding a 10-speed bike. (In this case though, your “pinion” is actually on the rear wheel, not the pedals.) You shift gears to get more speed and when you do, the two gears approach the same size. When the two gears are the most opposite, large and small, you get slower speeds but more torque, meaning you can take off easier from a stand still. This same principle applies to any gear system, including R/C. So now you’re ready to leave the competition in the dust, right? Installing gears on cars or trucks is not always easy to do, but you will notice a difference in performance as we have mentioned above. Next time, we’ll look at the differences between the radio control systems available on the market. Until then, go out, have fun and please support your local hobby shop.

How should I adjust the gearing?

How should I adjust the gearing?

First of all, don't overheat the motor.

Secondly, make small changes when gearing up. If you make a big change you are likely to cook your motor. Add one tooth to the pinion, two only if the motor was *really* cool the last time. Don't change the spur gear unless you have maxed out the pinion (e.g. 26 teeth for 48 pitch gears).

Thirdly, get somebody to time your laps with a stopwatch. Change the gearing and do it again. Compare the typical laps from each run -- not the fastest laps. Choose the gearing that makes your typical lap the fastest, while not overheating.

What does gear up mean?

When somebody tells you to "gear up" they mean to use a smaller gear ratio, i.e. a larger pinion. 

On an electric car, there are 2 Gears on your car that you need to worry about changing: the Spur Gear and the Pinion Gear. The Pinion Gear is the one attached to the motor, the Spur Gear being the gear the pinion comes in contact with. On a Nitro vehicle, you might have 4 gears...2 for the 2-speed on the motor and 2 for the 2-speed on the 'drive train'.

Changing the Pinion or Spur Gears will result in much different results.

On the Pinion Gear, the higher the number of teeth, the faster (top end) your car will have, but you will lose acceleration. The lower the number of teeth, the faster your car will accelerate, but you will lose top end. More top end usually results in less run time, also.

On the Spur Gear, the higher the number of teeth, the more acceleration the car will have, but the less top end. The lower the number of teeth the more top end you will have, but you will lose acceleration.

Changing the Gearing

On an electric car, the Pinion is changed by loosening the screws to the motor (or, in some cases, removing it from the car) and then removing the Pinion. Slide the new Pinion on, re-install in car (if applicable), and adjust the Gear mesh.

To change the Spur requires a little more work. Depending on the vehicle you own, it could be as easy as removing 2 screws or disassembling a whole portion of the car. See your instruction manual for the procedure as it applies to your vehicle.

On a Nitro vehicle, changing the Pinion gears requires the removal of the motor from the car (in most cases). You will then need to remove the gears from the clutch bell and replace with the appropriate gears.

Changing the Spur Gears on a Nitro vehicle requires the disassembly of a portion of the car (in most cases) to remove the gears and replace with the appropriate ones. See your instruction manual for the procedure as it applies to your vehicle.

R/C Car Gear Ratios

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R/C Car Gear Ratios 

The gears of a car follow a simple concept but can have an enormous effect on the performance of the vehicle. The diameter of the gears should be adjusted to match the specific application in which the vehicle will be used for. This means that a different gearing will be used for a large track with sweeping turns than for a small track with tight turns. A simple explanation of gearing is necessary. Basically, a large pinion gear (the little gear attached to the motor) will offer increased top speed and decreased acceleration and a smaller pinion gear will offer decreased top speed and increased acceleration. The opposite is true for spur gears (the large gear attached to the tranny that the pinion gears runs against), a smaller spur gear will increase top speed and decrease acceleration while a larger spur gear will decrease top speed and increase acceleration. A standard way of comparing gear sizes between cars is to use Gear Ratios. 

There are 2 basic types of gear ratios for your RC car, the pinion to spur ratio and the overall drive train ratio. To equate the pinion to spur ratio, a simple formula is used: 

Pinion to Spur gear ratio = # of teeth on spur gear / # of teeth on pinion gear 

To give an example, assume you have a 25 tooth pinion gear and a 100 tooth spur gear installed on your car. The pinion to spur ratio is 100/25 = 4. Therefore; your pinion to spur gear ratio is 4 to1. This means that the motor must rotate 4 times to rotate the spur gear once. 

The other basic gear ratio is the overall drive train ratio. To equate this, the following formula is used: 

Overall Drive Train Ratio = (# teeth on spur gear / # teeth on pinion gear) x Tranny Gear Ratio 

Here is an example. Assume you have a 25 tooth pinion gear and a 100 tooth spur gear installed on your car. Your transmission gear ratio is 2.25 to 1 (the transmission gear ratio is complicated to equate but it is usually given to you in the transmission instructions). The overall drive train ratio is (100 / 25) x 2.25 = 9. Therefore; your overall drive train ratio is 9 to 1. This means that the motor must turn 9 times to fully rotate the wheels of the car once. 

Sometimes people refer to the gear ratio of the car instead of the number of teeth on the pinion and spur gears. A low gear ratio number will offer increased speed and decreased acceleration and a high gear ratio number will offer decreased top speed and increased acceleration. For example, a 3 to 1 ratio will give your car more speed and less acceleration than a 5 to 1 ratio. 

It is important to understand that there are limitations to what an electric motor can handle when it comes to gearing your car. This means that a larger pinion and a smaller spur will increase your vehicles top speed up to the point in which the motor is overloaded. When the gear ratio is too low, the motor will not have enough output to benefit, and reduced performance can be expected. The key here is that a proper gear ratio is very important. Don't just put on the largest pinion gear and smallest spur gear that you can find and expect to go fast. 

Another issue regarding gear ratios is tire size. The size of the cars tire will have an effect on the speed a vehicle reaches. A larger tire is like running a lower gear ratio and a smaller tire is like running a higher gear ratio. The formula used to calculate gear ratios that take tire size into consideration are very complex and aren't necessary for most applications. Just remember that a larger tire will increase top speed and decrease acceleration and a smaller tire will decrease top speed but increase acceleration. 

There is no strict rule for setting up gear ratios in your vehicle. Different cars, tracks, motors, batteries, driving style and many more variables all affect the size of the gears to be used. The best method of setting up your own ratios is to start with manufacturer recommendations and then experiment on your own. Use a stop watch to see if changes you make are for the better. The proper gear ratio selection can make the difference between an A main finish and no finish at all. 

 

Myths About Brushless Motors

Myths About Brushless Motors  

 

  Myth #1 - You Only Need One Motor

False, you will still need several motors for each application ou decide to use them in. No tuning options to allow you to maxiumize performance. Its easier to replace the whole setup.

Myth #2 - Motors Are Indestructible

False, brushless motors can still be susceptible to shorts due to faulty winding, debris entering the motor and heat. Magnets used on the rotor will demagnetize from use.

Myth #3 - Torque and RPM Are The Same As Brushed

False, you will need to give up one for the other. That is another reason why you need more than one brushless motor.

Myth #4 - No Maintenance

False, cleaning, bearing replacement and magnet zapping will still be needed for top performance. Also, any damage to the motor can may cause the motor to fail.

Myth #5 - Batteries Do Not Matter

False, batteries will play a bigger part since brushless systems depend on high voltage, amps and super low internal resistance to operate as a race motor. Bottom line is that you will need to have quality batteries.

Myth #6 - All Speedos Can Be Programmed For A Level Playing Field

False, again at this point batteries will make a huge difference. Good quality packs will be essential. In the end, a Team Driver will still have the advantage due to speed controller programming knowledge, access to unpublished technology and the ability to jump the regulator that restricts the amp flow, undetectable traction control, drivers will need a laptop to have their own secret profiles set, special developed FET's etc. This leaves the average racer out in the cold. It is much easier to just tech a "spec" brushed motor.

Myth #7 - Brushless Performance

There will still be better motors than others due to manufacturing tolerances. No two speed controls for standard motors work the same and they have been making these for 25 years longer. Remember the price on a brushless motor when you have to replace it because it does not perform as claimed. There is no way to increase performance other than the speed control, out of abilities of the normal racer. Tweaking and tuning your motor and race car will be a thing of the past. Race winners will now be decided by who's motor is the fastest out of the package. If its not yours, you may as well stay home and run by yourself in your driveway, since there is zero you can do to improve the performance. 

SEVEN WAYS TO IMPROVE YOUR CAR'S PERFORMANCE

SEVEN WAYS TO IMPROVE YOUR CAR'S PERFORMANCE

For those who have already bought rc cars, hope

your are having lots of fun. If you need more speed, here are

seven ways to make your car go faster.

1. Ball bearings - these will reduce a lot of friction in the axles

and transmission. Expect 10 - 20% increase in speed.

2. Using lightweight parts - graphite chassis, aluminum screws,

titanium drive shafts will make a car lighter. This results in faster

acceleration, top speed, reduced motor wear, and longer battery

life. Expect a 5 - 10% increase in speed.

3. Improve suspension and car handling - oil filled shock

absorbers, tuned springs, and sway bars will help your car go

faster around corners, and handle a lot better, especially on

rough tracks.

4. Faster steering - a high-speed steering servo will help your

car react faster to steering inputs. 

5. Faster electric motors - modified motor provide a great

speed and power boost over the stock Mabuchi 540 motor. A

mild 24 degree motor may push your touring car to 30 mph,

while the highly modified 10 turn motors push electric touring

cars near 40 mph.

6. High capacity batteries - racing quality NiMH battery packs

are made of individual cells that have been matched, so that

each cell provides the same power and discharge curve as all

the other cells in the battery pack. This ensures maximum power.

7. Electronic speed control - replacing the stock mechanical

speed controller with a budget electronic speed control (esc) is

already a big plus. ESC provides smooth throttle control and

precise braking capability. Budget ESC can handle 19 turn

motors, while high capacity ESC can handle the hotter 10 turn

modified motors.