links then disconnect them for the corner balance. If we are running twice as stiff a RR spring as the LR, we would need to change the height of the LR spring twice as much as the RR spring so that we don't affect the ride height as we hunt for the correct or desired weight distribution. The cosine of 18 degrees is 0.95106, and that into 1.0 is 1.05146. Always Now that the car has the correct ride heights and weight distribution for your setup, you need to make sure those don't change at the track. Put the car on ride height blocks without the shocks in the car and then measure the shock length from center of bolt to center of bolt. Do youhave recommendations for such corner weight percentages? Make sure the tires are centered on the scales. We run a fixed chassis meaning no suspension and the Briggs lo206 so we aren't sliding it around the corner but tracking almost like an asphalt Kart. If the car feels loose throughout the corner, lower both track bars evenly. The CG height 6. You should read the spring preload amount. Check your tire pressure and bump it up to the hot pressure I was booked for 100 laps split across four or five sessions. Many electronic scales will perform the calculations for you. A. For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. Measuring from the center of the tires I got It changed the wheel weights by 10 pounds at each wheel: I finally went too far when I took two turns off the Right Front (went This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. Positive front toe (tires pointing in) generally is desirable on lightweight cars that don't have a lot of shifting weight, such as go-karts. These weights are in ready to race form (including driver on board). Corner weighting is huge. If we remember, or record this number, then we can easily make changes in the future to get to our intended crossweight percent fast and easy. stiff springs on your coil overs. I recommend adding an eighth or slightly more to the lowest corner just to make sure you pass tech. Jacking weight will not alter the left side or the rear percentages. The left side changes, of course, will be 4.75 times the multiplier for front or rear. After these items are completed, it is necessary to corner weight the car. Do this at every wheel. In our example we will be using the same method with corrections for different rate springs. Less fuel equals faster speeds. It's better to make many small changes than to try The same thing happens with a race car. Compressing the spring of a left-rear wheel or adding wedge puts more of the car's weight on that corner. Right Front tires. Those will tend to reduce friction and bind at the expense of NVH and added wear. The front will show close to 60%. Then if it's for a particular road course, you will find several seconds optimizing for select turns and throwing any of the above methods out the window A friend's Chump Car found 2 sec at VIR making it turn right better than left. Are they adjustable? And I cannot really move any weight around. In April 2013 I corner balanced the S for the first time in Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. springs to put more weight on the left rear (and right front) tires and Also double check that the Check your tire pressure and bump it up to the hot pressure turns. Wedge Delta can also be thought of But in a right turn, the opposite occurs and the handling is worse. lot of force to the suspension. racers add "wedge" by adjusting the right rear spring perch--they Jun 7, 2018 #8 . 12. want balanced turning in both directions. That is equal to 7/8 turn of the adjuster. To make sure your spring changes don't upset your ride heights or crossweight percent, you need to mark your wheel spacing to the fenders. At the rear, your rear control link angles are critical to maintaining rear alignment and determining rear steer angles and/or reducing rear steer altogether. If you want more turn in one direction put extra weight into the inside rear or outside front. Wedge Delta and what values work best for certain tracks and conditions In this example, we will adjust the crossweight percentage on a sample car with different rate springs. traction or bite in left turns. Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe Here's how we find the multipliers. I used a laser level to project a horizontal Youre always going to have some friction, especially depending on the type of suspension used. The Track (FATT) event and it handled superbly. When working with static weight distribution, we use two percentages to analyze the car's corner weights: Left weight percentage and rear weight percentage. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. Mudboss Setup #3 - Traxxas Slash transmission setup and diff oil for oval racing Oval RC 216K subscribers Subscribe 812 Share 51K views 2 years ago #diff #setup #mudboss Traxxas Slash. as Left Rear Bite + Right Front Bite. McMaster-Carr adjustable end links Lowering the cross weight does the opposite of raising the cross weight. I dont get this. want balanced turning in both directions. Only after I spent a lot of time bouncing on the door sills did it settle down and stabilize. This will pitch the vehicle's. It is important that you complete the corner weighting process before doing an alignment. You can see in the "Target Corner Weights" section that the Left We will deal with preload on the bar later on. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. If the driver lifts early but still has a fairly good amount of roll speed into the corner, there probably isn't much brake being used. I was surprised to find, contrary to my experience, that the Vette came is very close to itsexpected weight as soon as it was let down on the scales, without having to take bind out of the suspension. Speaking of springs, it's a good idea turns. them for the corner balance. You will have to repeat this every time you lower the car onto To find LF weight: Some engines are used in two different classes with the only change being exhaust system. , = change needed to get to target weight, Cross Weight = My car is a 1987 Honda CRX, set up according toITC class rules. 1) Tweak: Tweak is the amount of weight on the LR as opposed to the RR. over I guess I should work on losing weight personally (i am 220~). the front ramps then jack up the rear and lower it onto the rear scales. Right Front = Basically - after you finish the set up routine, the car goes in the hauler. You can drop the front end slightly or raise the rear end for more aggressive turn-in. < Enter your corner weights in pounds or kilos and click 'Calculate'. used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales . Hot Rod. not to push it off the scales, to unbind the suspension (as the car is 7. % 50% is optimal, Wedge = This approach is commonly used in oval track racing. Then the car will move more easily from one setting to another. important for oval racers, especially on dirt ovals. Timely refresher that leaves me with a question Ive had for the last couple years that I have not found an answer to in hours of searching. For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. but tend too love the 1/2 miles.I just cant figure out a way too get these. Other than that you need to watch the suspensions. Right Front tires. as Left Rear Bite + Right Front Bite. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. However, you can choose to use them. To get good accuracy easily make sure you get the low hanging fruit first like removing the friction between the tires and the scales so there is no bind. All of these factors play a huge part in what each corner of the car will weigh. Rear weight percentage for road racing and autocrossing is less definite. retract the right rear tire which puts more weight on the Left Rear and The LF needs to go up 0.3125 and the RF needs to go down the same amount. Or maybe I read the post wrong. Once you have installed your coil-over suspension, mount the rims with the tires you will be racing with, and complete all other items that could impact the vehicles weight and placement of that weight. positive Bite and positive Wedge Delta. 5 diameter stainless ball bearing on top of a 1" shortwell socket on the center of a floor Jack and jack the car up in the center of the rearend housing. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. You can estimate your car's center of gravity "weight jacking," or "scaling," involves adjusting the spring perches of a car It's one reason why racing pushrod suspensions tend to employ geometry with minimal shock/spring movement,requiring ultra-high spring rates and very high damping force shocks. balancing see my corner balance how-to and I plugged in a bunch of numbers into my calculator and it all checks out. I noticed that the spreadsheet I'm using on the left of the picturesets my "target corner weights" to less than 50% (49.6%),why is that? Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. I primarily just making sure it meets class mininum weight, but I may mess with the balance if its off by much, but I dont think it is. and stock rear sway bars connected. Of course you can add too You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. When I first lowered it onto the scales, its total weight wasin the low 2600 lb range, which is way too light, considering the car's stock curb weight is 3086, and I took less than 250 lb out of it. Corner_Balance.zip, Excel Corner Balance Spreadsheet Screen Capture. We don't ever move weight around to get crossweight, but we do move weight to change our front-to-rear percent or the side percent of total weight. Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. I didn't hunt for that missing 1 %. This is but one method and I encourage everyone to ask around and find a method that works for your type of car, this one may not be the most efficient. CG Height Calculator, Cross Weight % = You can change ride heights later on, but remember that your front moment center geometry will change and your rear geometry will also change, including link angles and pinion and third link angles, as well as rear alignment in some cases. A common example of caster is a shopping cart. I borrowed some scales to weigh my Terceltomorrow. is especially true if you don't have adjustable spring perches. right swapped). the scales. line above each scale and placed a ruler on the top We used to run about 1/8 of toe-in at the local tracks, and this helps the kart to cut through a corner easier in the center, where the steering is the greatest. Since the front and rear shocks are of different lengths you Shock Angle-measure the angle of the shock installed and at ride height. Strive for repeatable and take the measurement as a data point, instead of an absolute. Can do to just left sidesor right sides, or to all 4. 2023 Motorsport Marketing. racers only turn left we can balance the car for better grip in left Bite and Wedge Delta are The other two corners will gain weight. Make sure all of the weights are in the car including fuel, oil, battery, cooling water, hood, and so on, or weights that will simulate those. Understanding corner weights. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. For pure race cars this isnt a consideration. 2 coils cut off springs 4 corners. Kart racing chassis are designed in a manner to allow it to turn the only way it can, without having a read differential - with the inside rear tire lifting off the track on corner entry. in the driver's seat to load the suspension. If you think you need to make crossweight changes, remember the amount of change per adjuster number, in our case it was 7/8 turns per percent of crossweight at the right sides (left sides again are times the multiplier), and make even percent changes, such as a half percent or whole percent. anti-roll bars then leave them connected. But stagger is not a good idea on a road course or autocross either, where the ideal is 50-percent cross-weight and no stagger. That is why a stiffer right rear spring makes the car looser. ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. Now that's pretty cool! Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. I'm anxious to see what Proform says about my experience. I 1. (TVW LSP) - LF = 769D. The third thing I look for to make at the track dirt race car handling decisions is where the driver lifts the gas going into the corner, and the overall entry speed. "There's a lot of freedom when it comes to setups using various styles of springs" in dirt late model racing, said a source. 2 When you make a spring change, bring that corner back to the measured distance from the wheel rim to the fender mark by adjusting the spring height. So, ride heights in the front are more critical for maintaining camber angles. So we turn the RF adjuster up (to lower that corner) 2.5 turns and the LF down (to raise that corner) 2.5 turns. Move ballast first, since it's easier. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. weights and percentages and generates target wheel weights to achieve a 50% springs settled over the first 3 months. You could also raise the left front or right rear ride heights to do the same thing. The tiles & salt seemed to help because the weight never If your car's diagonal corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). . The salt acts as tiny ball bearings and will allow the tires to oval racing world and is simply another word for Cross Weight. Some racers like to take matters into their own hands-and that's OK. February 2017 -Suspension design process. racers discovered they could insert an actual wedge into the left rear My big stumbling block on this subject is how to get accurate readings by removing all the friction/bind from the tires, sway bars, bushings, etc.