Rethink Dirt: Advanced Dirt Track Theory | Hyper Racing Spring Into Action: How To Select Front Springs For Drag Racing - Dragzine The front end will move faster and farther because less force is required to initially extend the spring. These objects would have a tendency to tip or rotate over, and the tendency is greater for taller objects and is greater the harder you pull on the cloth. Suspension Geometry - Balance Motorsport Just as taking Claritin or Benadryl reduces your symptoms without curing your allergies, reducing roll reduces the symptoms but does not appreciably cure weight transfer. The rest of this article explains how inertia and adhesive forces give rise to weight transfer through Newtons laws. Race Car Ride Height 101- With Jerry Bickel And Chassis - Dragzine : a go-kart), the weight transfer should split between F/R axles according to the CG position, just like you instinctively done for the longitudinal acceleration. The following weight transfers apply only to the sprung mass of the race car:-Sprung weight transfer via the roll centres (WTRC): Again, weight transfer is seperate for front and rear. Likewise, accelerating shifts weight to the rear, inducing under-steer, and cornering shifts weight to the opposite side, unloading the inside tires. The major forces that accelerate a vehicle occur at the tires' contact patches. This button displays the currently selected search type. When accelerating, braking or steering, the body of the car rotates in the opposite direction, which compresses the suspension on one side of the car, while releasing the weight on the other side. Conversely, a supercar is built to approximate race geometry with few concessions to prevent spilling the drinks. Before we start this analysis, lets make some important definitions: Load transfer from direct force is one of the two components related to the lateral force acting upon the sprung mass. The amount of weight transfer is detirmined by how wide the track is (wider = less weight transfer) and how high the CG is (lower CG = less weight transfer). The added axle weight will slow the release of the stretch in the tire and help hold traction longer. Scott Bloomquist talks lead weight and weight transfer in dirt racing Now lets analyse what happens when roll centre heights get close to the CG height. Increasing front roll center height increases weight transfer at front axle through suspension links (Term 2), but reduces overall weight transfer through suspension (Term 3). This seems good, as more weight transfer would appear to be the goal, but less resistance is not the best way to make use of this weight transfer. Why? I have heard of many cars running well outside of these parameters and winning. Put the driver weight in the car, preferably the driver. We derived the equations of lateral load transfer in one axle of the car, showing that its composed of three components: Unsprung weight component not useful as a setup tool because of the effect that it has on ride, specifically wheel hop mode. How Does Weight Distribution Affect Race Car Performance? An additional curve might be obtained by plotting the intersections of the lateral accelerations with the lateral load transfer parameter lines, against the reference steer angle. Left Rear Axle Weight for Dirt Racing Take 2 - Hogan Technologies Understanding the physics of driving not only helps one be a better driver, but increases ones enjoyment of driving as well. For example, if our car had a center of gravity 1 foot above the ground and the tires were 4 feet apart, we would divide 1 foot . Weight Transfer for Driving, Racing, and Rally - YouTube Figure 14 can lead us to very interesting conclusions. Then the expansion of the tire will begin to lift the car. When a body rolls, the motion generates rotational torque which must be overcome every time we want to change direction. This can be done in multiple ways. Usually, I'll have 50-80 lbs," Bloomquist told RacingNews.co from Lucas Oil Speedway a few weeks back. Our system is proven to increase traction, and reduce fuel consumption and track maintenance. It must be reminded that changing this term will only change a part of the total lateral weight transfer. Newtons third law requires that these equal and opposite forces exist, but we are only concerned about how the ground and the Earths gravity affect the car. Bear in mind that all the analysis done here was for steady-state lateral load transfer, which is why dampers were not mentioned at all. Taking the moment equilibrium about the point O, of the tyre, we can see that: Dividing the equation by t on both sides, we obtain: But assuming a symmetric weight distribution, , since the left tyre is the outside tyre. As we discussed, we should input consistent units into the equation to obtain meaningful results. Most people remember Newtons laws from school physics. How to find weight load on each car tyre during cornering? Lets analyse the moment involved in roll. The result will be: Now we know that the load transfer caused by a generic moment about a track will be the moment divided by the track width, and we can use that to analyse the effect of each component of load transfer. Transient lateral load transfer is an important aspect of vehicle setup, but lets leave the discussion on that for another day. In that case, changing roll rate distribution or roll centre heights will have little effect in the balance, and other alternatives must be looked at, such as adjusting tyre pressures, tyre size and/or width or moving CG location (so that the inertial forces will be different in each axle). In a single axle, the roll resistance moment will be the roll angle multiplied by the roll stiffness of the axle analysed, . The distribution of dynamic loads can be altered with aerodynamics, with the regulation of wings or the static/dynamic height of the vehicle. Deceleration moves the center of gravity toward the front of the vehicle, taking weight out of the rear tires. This happens because raising the roll centre in any axle will approximate the roll axis to the sprung weight CG. The front wheels must steer, and possibly also drive. Another method of reducing load transfer is by increasing the wheel spacings. However, the pitching and rolling of the body of a non-rigid vehicle adds some (small) weight transfer due to the (small) CoM horizontal displacement with respect to the wheel's axis suspension vertical travel and also due to deformation of the tires i.e. Figure 8 clarifies. That is a lot of force from those four tire contact patches. The tires and chassis will also make a difference in the spring selection. First notice that there are two particular regions in the plot, where any changes to one of the components will produce no sensitive effect on weight transfer. The vehicle mass resists the acceleration with a force acting at its center of gravity. Deceleration. The second option to alter load transfer from direct lateral force component is to change roll centre heights. This will give: Now consider , the vertical load on the outer tyre in a corner, and , the vertical load on the inner tyre. Weight . Bear in mind that these values were obtained for a fairly heavy race car with an unreasonably high CG, and this is only one of three weight transfer components. Keep in mind, the example we used is more typical for a circle track setup; in a road race vehicle, you'll likely be shooting for a more balanced left-weight percentage of 50 percent (although that is not always . MichaelP. weight is transferred in proportion to static weight. {\displaystyle g} In a pair analysis, steady-state lateral force is obtained for the tyres on a track (front or rear pair), through data from a single tyre. The RF tire is. The figure only shows forces on the car, not forces on the ground and the CG of the Earth. So a ride height adjustment to your race car, or a roll centre geometry change is a very valid tuning device. Friction comes from the tires on the ground and the air flowing over the car. Also, the only direct link between the front and rear tracks is the chassis (all-wheel drive cars are an exception), and vehicle behaviour can be evaluated by looking at the relative performance of front and rear tracks. {\displaystyle a} Total lateral weight transfer is a combination of 3 distinct effects: Lateral force generated by the unsprung mass of the suspension and lateral acceleration is reacted directly by the tires, giving rise to a vertical component defined as Fz1. I hope this article was useful to you, and that you have enjoyed reading it. An important attribute of the suspension is the Roll-centre. Learning to do it consistently and automatically is one essential part of becoming a truly good driver. The reason it is relevant is that the amount of weight on a tire directly affects how much grip is available from that tire. This force is then divided by the weight on the axle, This lateral acceleration is plotted against FLT, with reference steer angle as a parameter. First off I would point out don't assume your tires are correct just based on there all but the same as the leaders, take a kart with 59 % left and 70 % cross he will be on a more juiced tire than a kart with a more balanced set-up like 56 % left and 57 % cross, now if you know his chassis and set-up 100 % ya you can feel little better about the Tires. Join a community of over 4000 clever racing enthusiasts that want to improve their knowledge on the technical side of motorsport! Now lets use the knowledge discussed here applied in the example presented at the beginning of this article, with a little more detail in it. Figure 6 shows the CAD design of a similar gearbox, highlighting the different options for installing pickup points. In this paper, that issue is discussed with a focus on ride rates, roll rates and simple tire data analysis for a Formula SAE race car. Conversely, if you increase rear roll centre height, lateral load transfer increases on the rear axle and decreases on the front axle. This moment is called roll moment or roll couple, , because it is responsible for body roll. Moving weight should be used as a fine-tuning tool to get the car working as best it can for the track conditions. The splitting of the roll moment between front and rear axles is useful in analysing lateral load transfer and this is called roll moment distribution between front and rear axles. The car has turned in towards the apex. The lighter 250-lb/in rate benefits a drag car in two ways. In this situation where all the tires are not being utilized load transfer can be advantageous. A quick look at the lateral load transfer equation might lead you to think that lateral load transfer will increase with increasing roll centre heights because of the direct relation in the equation. Bear in mind that the lateral acceleration obtained from a specific fraction load transfer value will not necessarily cause the correspondent load transfer on the axle. Inside percentages are the same front and rear. 1. Lateral load transfer or lateral weight transfer, is the amount of change on the vertical loads of the tyres due to the lateral acceleration imposed on the centre of gravity (CG) of the car. A big tire car with a lot of power is going to transfer weight much . The second term can be changed modifying the suspension geometry, usually difficult or not allowed in some competitions. The "rate of weight transfer" is considered important. The weight of an IndyCar race car should be at least 712 kg, with an average of 1630 lbs or 739.5 kg. On limit conditions, this will translate in one of the axles breaking loose and skidding before the other. Term 2 always leads Term 3. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright . The next topic that comes to mind is the physics of tire adhesion, which explains how weight transfer can lead to understeer and over-steer conditions. FROM LAP TIME SIMULATION TO DRIVER-IN-THE-LOOP: A SIMPLE INTRODUCTION TO SIMULATION IN RACING. With 250-lb/in front springs, the same 1000 pound weight transfer will lift the front end a total of two inches. During cornering a lateral acceleration by the tire contact patch is created. Greyout's guide to spring stiffness & weight transfer | GTPlanet As with most race car parts, you get what you pay for. Here, is the lateral acceleration in G units, is the weight of the car, is the CG height, is the track width and and are the vertical loads on the left and right tyres, respectively. The second law: When a force is applied to a car, the change in motion is proportional to the force divided by the mass of the car. Here they are the real heavyweights! Here the gearbox has a removable carbon fibre structural outer sleeve, allowing changes in the design of the rear suspension without having to re-test the rear of the car for crashworthiness. The only way a suspension adjustment can affect weight transfer is to change the acceleration. As you see, when we increase front roll centre height, the lateral weight transfer decreases on the rear axle while increasing on the front. As a result load transfer is reduced in both the longitudinal and lateral directions. This is given by: Here, is the sprung weight distribution to the axle being analysed and is the roll centre height for the track. Reference:Dr. Brian Beckman The Physics of Racing, Michelin Raceway Road Atlanta is 2.54 miles long, with 12 turns winding their way through the scenic Georgia countryside. The reason is that the magnitude of these forces determines the ability of a tire to stick, and imbalances between the front and rear lift forces account for understeer and over-steer. If that is the case in the front axle, the car will understeer, if it is in the rear axle, it will oversteer. is the change in load borne by the front wheels, If unsprung mass is isolated, its possible to find its own CG. Briefly, the reason is that inertia acts through the center of gravity (CG) of the car, which is above the ground, but adhesive forces act at ground level through the tire contact patches. This law is expressed by the famous equation F = ma, where F is a force, m is the mass of the car, and a is the acceleration, or change in motion, of the car. Your shock absorbers are considered after your ride and roll stiffness have been selected. Figure 7 shows the gearbox from Mercedes W05, 2014 Formula One champion. You have less lead to work with. For the sake of example, ride stiffness controls ride height, which has strong effects on aerodynamics of ground effect cars (almost every race car with relevant aerodynamics design). This leads as to believe that the roll centre height gain is higher than the decrease in the roll moment arm . This curve is called the cornering coefficient curve for the track. 2. The weight distribution on the rear axle was 54 %. This is reacted by the roll stiffness (or roll rate), , of the car. is the total vehicle mass, and Race car suspension Class | Physics Forums Steering. Weight Training: Everything You Need to Know About Race Car Weight Perfect balance would thus be 50/50, and front weight distribution would be 60/40 and so on. How to Set-Up Your Track Car & Become a Driving Legend - MicksGarage.com As long as the tires stay on the car, the ground pushing on them slows the car down. Check stagger at each tire, even if using radials. The moment can be divided by the axle track to yield a lateral load transfer component: Where is the unsprung weight on the track being analysed. In the post about lateral force from the tyres, we discussed tyre load sensitivity, the property that makes lateral force from a tyre to grow at a smaller rate with increasing vertical load. Figure 3 shows the plot. When a car leaves the starting line, acceleration forces create load transfer from the front to the rear. It is always the case that Lf plus Lr equals G, the weight of the car. Front-back weight transfer is proportional to the change in the longitudinal location of the CoM to the vehicle's wheelbase, and side-to-side weight transfer (summed over front and rear) is proportional to the ratio of the change in the CoM's lateral location to the vehicle's track. Balancing a car is controlling weight transfer using throttle, brakes, and steering. If we use , the remaining roll angle component will be: If we keep the roll moment arm constant, then roll angle lateral load transfer component in one track will obviously be a function of the ratio between the roll stiffness on that track and the total roll stiffness of the car. Weight Management for Speed - Playland Speedway For the SI system, the weights should be in N, the angular stiffnesses in Nm/rad, the lengths in m, and the acceleration is nondimensional (because we are dividing lateral acceleration by the acceleration of gravity). Understanding weight transfer is a fundamental skill that racecar drivers need to know. Queens GTO/Viper. For this analysis, only the rear axle was considered. Changing the moment generated by this component requires changes in either the unsprung mass or its CG height. In this figure, the black and white pie plate in the center is the CG. We define the Fraction Load Transfer, FLT, as the ratio between the difference to the weight on the axle: The parameter represents the total moment in the track about a point on the ground. Any time you apply brakes, add or remove steering, and manipulate the. Some large trucks will roll over before skidding, while passenger vehicles and small trucks usually roll over only when they leave the road. Under hard braking it might be clearly visible even from inside the vehicle as the nose dives toward the ground (most of this will be due to load transfer). b The lateral load transfer parameter. Braking causes Lf to be greater than Lr. Location: Orlando, FL. As an example, Interlagos race track, where the Brazilian Grand Prix takes place has a heavy asymmetry, with only four right-hand corners, and ten left-handers. For weight transfer to be useful to the driver in controlling the car, the driver would need to feel the weight transfer, or something related to it. This fact can be explained at deeper levels, but such an explanation would take us too far off the subject of weight transfer. An inexpensive set of shocks (such as the ones advertised as 50/50 or a three-way adjustable) should work on cars with as much as 300 to 350 . Roll is simply the effect of a suspension reacting to weight transfer. Read more Insert your e-mail here to receive free updates from this blog! . Weight Transfer - A Core of Vehicle Dynamics. Suspension Basics and Drag Racing Dynamics - Muscle Car DIY It is what helps us go fast! The weight shift component for a single axle will be: Substituting roll angle on the expression above, we have: The total moment from roll angle on a single axle will then be: The lateral load transfer from this moment is obtained by dividing this by the axle track width, t: The three components of lateral load transfer should be added in order to obtain the total lateral load transfer on an axle: The expression above can be utilized to calculate the load transfer on each axle, which can then be used to improve handling. HOW MUCH IS ENOUGH? - Classic Motor Racing Club NOTE: This information is from an NHRA Rule Book 2019 Addendum. The following information applies to NASCAR-style Stock Cars; it may also be useful to production-based sports car racers with the engine in the front and the drive wheels in the back. 2. draw the ground line ,vehicle center line and center of the left and right tire contact patches. The CG is the middle, then you split 50/50; the CG is more toward one side than the other, then more weight transfer goes on that side and less on the other. Advanced Weight Transfer Techniques for Go Karting Weight Transfer Part 3: It's All About the [ROTATION] If that was the case, you should work on the roll centres heights instead, and then adjust suspension parameters accordingly. You must learn how different maneuvers . Racing Skills In 60 Seconds - Weight Transfer | Blayze Its also called the kinematic load transfer component, because the roll centres are defined by the suspension kinematics. Weight transfer is the result of acceleration, braking or cornering. Weight (or Load) Transfer Explained (Actionable Tutorial) The inertial force acting on the vehicle CG will generate a moment about the roll axis. Naturally, you're more inclined to wheelstand with an increase in acceleration. This will have a net effect of decreasing the lateral force generated by an axle when the load transfer on it increases. If (lateral) load transfer reaches the tire loading on one end of a vehicle, the inside wheel on that end will lift, causing a change in handling characteristic. With those values, the gravity term will be 1662.1 Nm. What happened? . Here, the load transfer is increased by means of the lateral load transfer parameter, instead of the FLT. Explained: Weight transfer vs body roll (part 1) This can be confirmed by adopting the conclusions from the analysis of figure 10, where we agreed that the gravity term is negligible for roll angle lateral weight transfer component. The input data were based on the manuals from the manufacturer of an important formula category. The Physics Of Racing Part 1: Weight Transfer | ABRS What would you do, in order to solve the problem? That rationale comes from simple physics. Weight Transfer - TurnFast! Race Driving Techniques for Heel Toe By simply raising or lowering the couplers, our machines can gain thousands of pounds for traction. Total available grip will drop by around 6% as a result of this load transfer. When it comes to the chassis ride height, that part of the calculation is already baked into the car, and the racer should not look to the 4-link as a way to adjust this. This is a complex measure because it requires changes in suspension geometry, and it has influence on all geometry-related parameters, such as camber and toe gain, anti-pitch features and so on. Since the car does not actually go up on its nose (we hope), some other forces must be counteracting that tendency, by Newtons first law. Another example would be the effect of ride stiffness on wheel hop frequency. The most reasonable option would be changes on antiroll bar stiffness. 21 Shifting. Again, if that doesnt work, then lateral load transfer will not be the right parameter to change. As fuel is consumed, not only does the position of the CoM change, but the total weight of the vehicle is also reduced. The weight transfer setup recognizes the importance of ride height and roll stiffness in determining a good balanced set up for the car. Weight transferis generally of far less practical importance than load transfer, for cars and SUVs at least. When you apply the brakes, you cause the tires to push forward against the ground, and the ground pushes back. An exception is during positive acceleration when the engine power is driving two or fewer wheels. A perfectly rigid vehicle, without suspension that would not exhibit pitching or rolling of the body, still undergoes load transfer. For a more comprehensive analysis, the effects from suspension geometry such as steer and camber variations due to ride, roll, braking, accelerating, lateral force compliance or aligning torque compliance, can be introduced before entering tyre data. The equation for this component can then be expanded: Because the force coupling nature of roll centres is not as widely known as the definition of the term roll centre itself, some people are unaware of this component. One thing we can tell without any deep analysis is that increasing the roll centre height in one axle decreases the lateral weight transfer on the opposite axle, everything else kept constant. Weight transfer is one parameter that is minimized - to aim for even loading on all four tires; resulting in maximum grip during cornering. So, as expected, the car is not wedged. Car Setup Science #3 - Load Transfer - Paradigm Shift Driver Development In figure 3 the effect is repeated, but from a different perspective. A lateral force applied on the roll axis will produce no roll; Front and rear roll rates are measured separately; Tyre stiffnesses are included in the roll rates; Vehicle CG and roll centres are located on the centreline of the car; We used steady-state pair analysis to show once again that lateral load transfer in one end of the car decreases the capability of that end to generate lateral force. https://www.allenbergracingschools.com/expert-advice/road-atlanta-track-guide/ #Sportscar #racing #motorsport #racingschool #F1 #BeARacer #MichelinRaceway #roadatlanta, Michelin Raceway Road Atlantas multi-purpose racing facility has been a fixture in the motorsport community since its opening in 1970. https://www.allenbergracingschools.com/expert-advice/road-atlanta-track-guide/ #Sportscar #racing #motorsport #racingschool #F1 #BeARacer #MichelinRaceway #roadatlanta, Allen Berg Racing Schools 1835A Centre City Parkway #408 Escondido, California 92025, (888) 722-3220 (831) 272-2844 robin@allenbergracingschools.com Hours Mo - Fr: 8:30 am - 4:30 pm, WeatherTech Raceway Laguna Seca 1021 Monterey Salinas Hwy, Salinas, CA 93908, USA, Michelin Raceway Road Atlanta 5300 Winder Highway, Braselton, GA 30517, USA, Virginia International Raceway 1245 Pine Tree Road, Alton, VA 24520, USA.