RC Buggy Bible Toe is the angle (inwards or outwards) that the tires point when the wheel is straight ahead. Toe-in means the front of the tires point inward, and toe-out means they point outward. Zero toe means the tires are parallel to each other. The biggest effect toe has on the handling of the car is on stability. When a car hits a bump or enters a corner, forces on the tires act to steer the car off to one side, making the car unstable and difficult to control. Toe-in counteracts this, improving stability. Toe-in also causes understeer during initial corner entry. Interestingly, toe on the rear wheels has the same effect on handling as toe on the front. Toe on the rear wheels is useful for tuning the handling of the car as it is exiting corners. Front Toe IN Slower steering response More straight-line stability Too much will casuse greater wear at the outboard edges of the tires Front Zero Toe Medium steering response Minimum power loss Minimum tire wear Front Toe OUT Quicker steering response Less straight-line stability Too much will cause greater wear at the inboard edges of the tires Less Rear Toe IN Less straight-line stability Less traction out of the corner More steering Higher top speed Intermediate Rear Toe IN Intermediate straight-line stability Intermediate traction out of the corner Intermediate steering Intermediate top speed More Rear Toe IN More straight-line stability More traction out of the corner Less steering Less top speed **** Caster ------ Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if its vertical to the lower pivot point then the caster is zero. Less Castor (vertical = 0 castor) More OFF POWER steering into the corner Less steering out of the corner Less straight-line stability More Caster (laid back more) Less steering into the corner More ON POWER steering out of the corner More straight-line stability Benefits of castor: (more positive castor/laid back more) Maximizes tire contact patch during roll, braking, and acceleration Improves turn-in response Increase directional stability Improved steering feel and self-center Increases dynamic negative camber during turn in Castor Vs Camber: Camber doesn’t improve turn-in, positive caster does. Camber is not good for tire wear. Camber doesn’t improve directional stability. Camber adversely effects braking and acceleration. **** Shock Absorbers --------------- The purpose of the shock absorbers is to dampen the oscillation of the springs. The dampers not only dampen spring oscillations, but they also affect handling during transient conditions (such as the entry and exit of turns), but not steady-state conditions. More Dampening Slower shock action = could be unstable on bumpy tracks Slower chassis weight transfer Generally less traction Less Dampening Faster shock action = less chance of tire leaving the ground on bumpy tracks Faster chassis weight transfer Generally more traction **** Springs ------- The purpose of the springs is to control wheel movement and keep the tire in contact with the road over bumps and irregularities. Stiffening the springs front and rear will reduce body roll and make handling more responsive, but cause a loss of traction over bumpy surfaces. Likewise, softening all of the springs will give more grip on bumpy tracks, but increase roll and reduce responsiveness. You can also use the springs to affect the car balance. You can reduce oversteer by stiffening the front springs or softening the rear. Likewise, you can reduce understeer by softening the front springs or stiffening the rear. However, be advised that changing just one end also affects fore/aft weight transfer. By softening the front springs, youll also get more dive under braking. Softening the rear will give you more rear weight transfer under acceleration, which can give you more traction on the rear wheels in straight-line acceleration. Read and understand about anti-roll bars before you come to the conclusion that you need to change your springs, springs should be one of the last, if not the last thing you should change to effect how the car handles other than during a bump condition. Using Softer Front Springs More steering Slower steering response Used on bumpy tracks More diving under braking Used more for tight technical tracks Using Harder Front Springs Less steering Faster steering response Used on flat tracks Minimum diving under braking Used more for large fast tracks Using Softer Rear Springs More traction out of the corner Slower steering response Used on bumpy tracks More front lift under acceleration Used more for tight technical tracks Using Harder Rear Springs Less traction out of the corner Faster steering response Used on flat tracks Minimum front lift under acceleration Used more for large fast tracks **** Downforce --------- Downforce is the aerodynamic force pressing the car down on the track and improves cornering grip. This downforce is dependent on forward speed, and increases as you go faster. Increasing the downforce all around increases cornering speed, but also increases drag, which gives you slower straightaway speed, and you may also need to increase ride height and/or spring stiffness to prevent bottoming. Likewise, decreasing downforce gives you lower cornering speeds but higher straightaway speeds, and allows you to run softer springs and/or a lower ride height. Also, you can also use downforce to fine-tune balance at high speeds. To reduce understeer, increase front downforce or reduce rear. To reduce oversteer, decrease front downforce or increase rear. Keep in mind that these adjustments are dependent on forward speeds and has less effect as speeds drop, so you can use this to give the car different handling characteristics for different speed ranges. **** Differential Settings --------------------- Differentials are used to allow the wheels on the same end of the car to rotate at different speeds during cornering. If diffs are set to tight or are locked the tires will fight each other as the car is turning. Front Diff Looser than Rear Diff Steering response increases If rear diff is to tight, the car will understeer into the corner, and will cause loss rear end sliding out of the corner. Could cause oversteer while entering the corner (depending on other settings) Rear Diff Looser than Front Diff Steering response decreases, stability in turns in increased Could cause understeer or push while entering the corner (depending on other settings) **** Front Anti-roll Bar ------------------- The front anti-roll bar affects the amount the car’s front end rolls in a turn. As a car enters a turn, centrifugal cornering forces cause car roll and weight-transfer to the side of the car on the outside of the turn. A very stiff front anti-roll bar increases the load on the outside front tire, and decreases the load on the inside front tire (it can help to note that a stiff bar will tend to raise the inside front tire, thereby lowering that tire’s load). At the same time, this stiff front anti-roll bar increases the load on the inside rear tire, and decreases load on the outside rear tire. In this situation, the balance of side traction between front and rear ends shifts to the rear, and you get a car with a lower amount of steering, but more steering responsiveness. Don’t get confused between amount of steering and steering responsiveness; a car with a soft front anti-roll bar can have a high amount of steering, but it takes more time for the chassis to roll and transfer weight with this soft anti-roll bar and this creates slow steering responsiveness. A stiff front anti-roll bar will create very quick car weight transfer and thus very fast steering responsiveness, but with a lower amount of steering. In other words, amount of steering refers to how much steering ability the car has; steering responsiveness refers to the speed or quickness of the car’s steering ability. Softer Anti-roll bar setting More steering into corner More steering in the corner Slower steering response Harder Anti-roll bar setting Less steering into corner Less steering in the corner Faster steering response **** Rear Anti-roll Bar ------------------ The rear anti-roll bar affects the amount the car’s rear end rolls in a turn. As a car enters a turn, centrifugal cornering forces cause car roll and weight transfer to the side of the car on the outside of the turn. A stiff rear anti-roll bar increases the load on the outside rear tire, and decreases the load on the inside rear tire (it can help to note that a stiff bar will tend to raise the inside rear tire, thereby lowering that tire’s load). At the same time, this stiff rear anti-roll bar increases the load on the inside front tire, and decreases the load on the outside front tire. In this situation, the balance of side traction between front and rear ends shifts to the front, and you get a car with less rear traction, but more steering responsiveness (refer to the Front Anti-Roll bar page for more explanation on steering responsiveness). The opposite happens with a soft rear anti-roll bar: relative to the stiff setting, there is now less load on the outside rear tire and more load on the inside rear tire. The front inside tire also has less load, and the outside front gets more load. Now, the balance of side traction shifts to the rear, creating more rear side traction in the corner, but less steering responsiveness. Softer Anti-roll bar setting More side traction in the corner More traction out of the corner Slower steering response Harder Anti-roll bar setting Less side traction in the corner Less traction out of the corner Faster steering response **** Tires ----- The tires are perhaps the most important part of the car. You can gain the biggest improvements by installing tires with more grip. Tires are available in many different compounds: hard - soft. Soft tires have more grip than hard tires, but wear out faster. You are also able to mix types front and back. You can reduce oversteer by using hard tires in front and soft tires in back. This gives the rear tires more grip than the fronts, making them less likely to slide out. Likewise, you can reduce understeer by putting soft tires up front and hard tires in back. If you car feels like it is loose or unstable you may actually want to try a harder compound, by using a harder compound the tire will have less bounce, less side flex, and will typically offer a much more stable foundation. Tires are to small: Low forward traction Low top speed Car becomes twitchy Tires are to big: Very slow steering response High chance of traction rolling Tire distortion in turns Less stable Softer Front Tires: More Steering More wear Less stable Harder Front Tires: Less steering Less wear More stable Softer Rear Tires: More rear traction Less steering More bounce on bumpy tracks Less stable Harder rear tires: Less rear traction More steering Less bounce on bumpy tracks More stable **** Camber ------ ( PLEASE READ ABOUT CASTOR BEFORE YOU ADJUST YOUR CAMBER ) Camber is the angle the tires make with the road and is measured in degrees. Tire grip varies with the camber angle, and ideally is maximum when the angle is zero. However, the maximum grip is found with a small amount of negative camber because of tire sidewall deflection (when the top of the tire is tilted inward it is called negative camber. Also, as the body rolls in a turn, the suspension movements themselves causes some adverse camber change. These combined effects mean that for maximum cornering power you need to have some amount of negative camber. However, too much camber will cause you to lose grip because the outside edge of the tire is being lifted off of the pavement, reducing the contact patch. So to summarize, as the camber angle increases from zero, cornering grip improves to a point, then falls off. -2 deg. ~ -1 deg. Front Camber Quicker steering response More overall side traction Less chance of traction rolling -1 deg. ~ 0 deg. Front Camber Less quick steering response Less overall side traction More chance of traction rolling -2 deg. ~ -1 deg. Rear Camber More overall side traction More traction under braking Less chance of traction rolling -1 deg. ~ 0 deg. Rear Camber Less overall side traction Less traction under breaking More chance of traction rolling **** Gear Ratios ----------- General: Gear ratio affects the balance between a car’s acceleration and top speed. A small clutch gear with a large spur gear produces a high gear ratio (the figure is a high number, the gear is called short) gear ratio, giving faster acceleration but lower top speed. A large clutch gear with a small spur gear produces a low gear ratio (the figure is a low number, the gear is called long / tall), giving slower acceleration but higher top speed. Measurement: Gear ratio is measured by simply dividing the spur gear (two speed) teeth number by the pinion gear (clutch) teeth. Adjustment: You can change the clutch and two-speed gears independently or together to get different gear ratios. This applies to both first and second gear. Remove a gear and replace it with one of a different tooth number. YOU MUST add the teeth number up between both first and second gears, they must equal the same. For exaple if first gear spur is 47 teeth and first gear pinion is 17, add 47+17=64. Then add your second gear spur and pinion, 20+44=64. This will ensure that you will have the same mesh on both gears as long as you have mounted your engine straight. Lower gear ratio (longer gear) lower acceleration, higher top speed Higher gear ratio (shorter gear) higher acceleration, lower top speed **** Ride Height ----------- A lower ride height lowers the center of gravity, which reduces weight transfer during cornering, acceleration, and braking. The reduced weight transfer improves cornering. A lower ride height also lowers drag at high speed because you are presenting a smaller frontal profile to the airstream. Also, by lowering the front end and raising the rear, you can improve high speed stability and increase downforce by preventing high-pressure air from building up underneath the nose of the car. If the car is too low, it can bottom out, though this can be eliminated by stiffening the springs(which could cause problems elsewhere).
Posted on: Mon, 19 Jan 2015 21:02:52 +0000
Trending Topics
Recently Viewed Topics
© 2015