There are basically three types of teams. Those who win on a fairly consistent basis, those who are close to the front, but almost never win, and those who wonder what the first two are doing to go so fast. There is a fourth group that doesn’t relate to our discussion. Those are the teams that are just happy to show up, have equipment that will never be able to compete, and are completely satisfied with the situation. And I am happy for them.
But this presentation is for those who really want to improve their setups and be more competitive. As we enter the last few races of the season, the second group needs to tweak their setups to gain that couple of tenths that will put them at the top of the heap.
The third group has nothing to lose and needs to make major changes in order to move up the lap chart. And now is the very best time to do it. Experimenting during the late part of the season when you are fifth to tenth in points or higher could help you find that speed to make the start of next season more fun. So, let’s see how we can improve our setups.
The most basic rule of handling and speed for a race car lies in increasing the speed we can go through the middle of the turn. It has been said before, and rightly so, speed gained in the turns will be carried throughout the lap. This is true for both circle-track racing and road racing. The Mercedes F1 cars are faster in the turns and slower on the straights. They win a lot.
Mid-Turn
We start out by solving our mid-turn handling problems. We do this because our mid-turn handling affects both entry and exit to a large extent. A car that is tight in the middle will most likely be tight into the turn and tight off. If excessively tight in the middle, the car could be loose off as a result of the tight-loose syndrome.
To change mid-turn balance, we can do one of the following:
1. Raise or lower the rear Moment Center (MC) by moving the panhard bar or J-bar up or down. For leaf spring cars, we can raise or lower the actual spring, but that is not an easy thing to do. Metric four-link cars also have a tough time changing the rear MC height and must rely on other methods to change the balance.
2. You can change the rear spring rates. Softening the right rear spring, and/or stiffening the left rear spring will increase the rear roll and will tighten the car, as will softening both rear springs. The inverse is true, stiffening the RR spring and/or softening the LR spring will loosen the car.
3. Softening the front springs will help the car turn, but to a lesser degree than making rear-spring changes. Spring split at the front also has less affect and has more influence on entry characteristics than on mid-turn.
4. Installing larger or smaller sway bars will have an effect on handling. The stiffer the bar, the less the front will want to turn. So, to help cure a tight car, we can go to a softer sway bar.
5. Increase or decrease the crossweight percentage. As we make changes to the crossweight, we affect the handling of the car, and we can easily make the car neutral in handling by making crossweight changes. But this is not the ideal method by any means, just the easiest.
6. We can increase or decrease the stagger. This is never an acceptable way to tune the handling of your race car. For a defined radius of turn, there is an ideal stagger that will allow the car’s rear wheels to roll around that radius and not influence the direction the car travels from following that radius. Learn what stagger your track needs and use that.
The telltale way to know if your car’s setup is balanced is to read the average temperatures of the left side tires. Doing this tells us how much work those tires are doing. If the LF tire is cooler, then it is not doing enough work and we need to make the front more compliant, or softer, and possibly make the rear less compliant, or stiffer, until the left side tire temperatures match up.
Entry Problems
Once we have setup the car to be neutral in both handling and dynamical balance through the middle, we need to evaluate the entry handling. If our entry is without issues, meaning it is straight ahead, neither tight nor loose, and it needs no excess steering input beyond the normal transition from straight to left turn, then we are good to go.
If all of the alignment issues have been sorted out, there should never be entry problems, but there are influences that could affect entry stability and balance. Here are the top ones to consider.
1. Rear alignment is the number one cause of entry problems. The cause relates to either the misalignment of the rear tires or by the rear steering of the rear end. A car can become tight or loose on entry and that can translate to mid-turn problems. The truth is, you should have checked and corrected any rear-alignment problems long before you came to the track. Rear alignment and rear steer are not mid-turn tuning tools.
2. Shocks affect entry. Shock rates that restrict movement of one or more corners of the car can negatively affect entry. An LR tie-down shock, or one with excessive rebound control will help cure a tight-in condition by loosening the rear, but this is only a crutch.
The two corners most affected by the dynamics of corner entry are the LR corner and the RF corner. A RF shock that is stiff on compression can cause a tight condition on entry and a LR shock that is stiff in rebound can cause a loose condition on entry.
3. Brake bias changes affect corner entry. There is an ideal brake bias that will allow maximum braking of the front and rear set of tires based on the loads those tires carry. Different cars with different centers of gravity will require different brake bias.
Tune your brakes so that wheel lockup occurs simultaneously at the two ends of the car under heavy braking. We do not want the brake bias to influence entry handling characteristics. Never try to correct a tight car by increasing the rear brake bias or fix a loose-in car by increasing front brake bias.
4. Setup Changes to solve corner entry problems? We never want to make changes to our spring rates, sway bars, weight distribution, or MCs to try to solve entry problems. When we do that, we will certainly change our mid-turn handling in a negative way. We should have already tuned the car so the mid-turn handling was balanced correctly.
There is an exception to the above rule. We can initially plan out our spring selection so that our entry transition is best for the type of track we will be running. For flatter tracks, running even spring rates across the front or a softer RF spring rate as opposed to the LF spring rate will help the transition into the corner. It is best to make that choice before you go to the track so you won’t need to make changes after you tune the mid-turn.
Stiffer RF spring rates over the LF spring rate can help the transition into a high-banked track where the outside of the track rises up to form the high banking. In this case, the vertical forces are high at the RF on entry, and we need more spring rate at that corner to control those forces to limit excessive RF wheel travel.
Throttle modulation on entry can help solve problems associated with abrupt release of the throttle. If we quickly jump off the throttle and into the brakes, we can upset the car to the point where it affects our entry speed and stability. It can also cause us to slow too quickly and attain a slower speed than is necessary for the radius of the turn at that point.
Corner Exit Handling
Most of the time, solving the mid-turn handling will solve corner exit problems. If we were tight in the middle, we would most likely be tight off or tight-loose off. If we were loose through the middle, then we would be loose off.
The process of increasing mid-turn speeds means we have also increased our exit speeds, or the speed at which we begin to accelerate. This is a big deal, and the reason we spend so much time perfecting the mid-turn balances and trying to increase speed through that portion of the turns.
The way that some tracks are laid out contributes to corner exit problems. A flat track offers less grip than a banked track because we have less of the dynamic downforce created by the banking to help provide more overall grip. So, we need to enhance bite in other ways. The transitions in the track banking angle on higher-banked tracks may also contribute to exit woes.
Loose Off Condition
We can use Rear Steer to solve loose off problems. If we know we are good through the middle, then a loose off condition can be solved with the application of rear steer that happens only upon the application of power.
The most common way to create rear steer in cars equipped with the three link suspension is to increase the angle of the left trailing link, the front being higher than the rear. If we also decrease the anti-squat by decreasing the angle of the third link, when the car sits down on turn exit under acceleration, the LR wheel will be moved back creating rear steer.
We can tune the amount of rear steer by changing the angle of the LR link. This works very well and compensates for the rear tire drift caused by adding power. The rear tires will attain a new angle of attack to gain traction and if we cause rear steer, we immediately give the rear tires that angle of attack it needs without needing to step out.
Shock rates can temporarily increase the crossweight percentage on exit to tighten your car off the corners. If you run shocks with a stiffer compression rating on the LR corner than on the RR corner, then when the shocks move as the car squats coming off the corner under acceleration and while the loads transfer to the rear, then the LR corner will momentarily carry more load and the LR and RF will share that increased load.
Throttle Control
This is a learned art and will allow the rear tires to maintain their grip on the track surface and help to provide better acceleration. Once we lose grip in the rear, we must back off the throttle until we regain grip before we can continue to accelerate. By exercising throttle control, we may feel as if we are giving up performance, but in reality, we are providing the most acceleration possible.
Throttle control is defined as the modulation of the gas pedal through a range of motion, never moving quickly from one position to another, in order to keep the tires in contact with the track surface. The rate of change in throttle position must be altered depending on your position on the track and through the corner, so the driver must develop an educated foot.
Many dirt drivers report they never got past half-throttle over the course of an entire race in which they won. This means they were working from off-throttle to half and many points in between. The development of efficient throttle modulation is one of the most effective tools you can use to promote bite off the corners.
Final Words
The above suggestions are based on our belief that you have already solved the most critical issues facing your race car. Back at the shop, you have aligned it, checked, and corrected the MC design, checked for binding in the suspension, rebuilt the shocks, and done all of the other maintenance things we know we should.
The last thing to do is run the car. Teams that are conscious of the effects of all of the various changes and know basically how much affect each change has on the handling of the car will go through the process fairly quickly. If you’re just now learning these things, take good notes and concentrate on what is happening. Ask lots of questions of your driver, so you know exactly what changes to do and how much. And when you do get the car all dialed in, be sure to maintain that good setup.
Sources:
Afco Racing
(800) 632-2320
www.afcoracing.com
Allstar Performance
(269) 463-8000
www.allstarperformance.com
Capital Motorsports Warehouse
(800) 278-2692
www.cmwraceparts.com
Coleman Racing
(800) 221-1851
www.colemanracng.com
Day Motorsports
(800) 543-6238
www.daymotorsports.com
DRP Performance Products
(888) 399-6074
www.drpperformance.com
Integra Shocks and Springs
(800) 472-3464
www.integrashocksandsprings.com
Longacre Racing Products
(800) 423-3110
www.longacreracing.com
Mittler Brothers Machine
(800) 467-2464
www.mittlerbros.com
PitStopUSA
(866) 722-3432
www.pitstopusa.com
QA1
(800) 721-7761
www.qa1.net
Smileys Racing Products
(866) 959-7223
www.smileysracing.com
Speedway Motors
(855) 313-9175
www.speedwaymotors.com/
The post Tune Your Handling to Win appeared first on Hot Rod Network.