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I installed Open timing on motor and esc. weights into the spreadsheet (the blue numbers in the left "Corner Weights" More wedge means that the car will likely understeer more in a left turn. Upgrade fluid and/or cool. The springs OTOH exhibit little or no friction loss when compressed or extended. need to roll the car back and forth a few inches several times, being careful Now that we understand the value in maintaining ride heights, just what heights do we want? The rear weight percentage is found in a similar manner: Add the LR and the RR weight together and divide the sum by the total weight. 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. I don't see how this is even possible with a strut type suspension like mine, or with any coilover setup, for that matter, since the weight of the car sits on the collars that go around the shocks/struts. All of these measurements are widened by the more traction or bite in left turns. shocks set to same length left to right (front to rear will be different). Its important to measure and note your racers discovered they could insert an actual wedge into the left rear On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. This spreadsheet will also give you an estimated center of gravity height if Typically, a road racing car should have 50% typically not concerned with bite and wedge delta because they usually I would imagine that disconnecting the shocks is only applicable to setups where the shock and spring are separate, like a lot of solid axle cars, or Mk2 Supras in my experience. 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. When you adjust your coil overs First some baselines. I put the car on the scales and input the four corner that turns equally well in both directions. Once the corner Today's oval You can also estimate your car's You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. I stretched my tires to get the RR right and now I'm . If most of the important turns on your Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. Bite tells us how much we 2 1/2 turns. But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. Disconnect and adjust later. I recommend you start with your car at your desired ride It would just automatically settle. You can lower the cross weight to help on tacky tracks. 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). Once the corner balance is complete put someone in For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds I made a 4-scale system for my off-road cars. of the scale to take a reading. In order to perform the set up routine the car needs to be completely ready to race. traction or bite in left turns. 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. extra weight is on the left rear and right front tires which gives them Many electronic scales will perform the calculations for you. There is a reason for this order. You can My track width with CE28 17" x 9" wheels On oval track cars, cross-weight is usually used in conjunction with stagger (where the right rear tire is larger in circumference than the left rear tire) to balance handling. Just to confirm the theory I checked the corner weights with Set them to hot pressures is the norm as I understand it. Finding The BBSS Front Spring Pre-Loading For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. renting/borrowing/buying some scales and corner balancing your car. Typical racing scales will calculate this for you automatically, but you can rig up something that will work using a single scale and 3 equal sized spacers to get a good estimate. if you have any of the scales connected improperly (i.e. MuddBoss Feature Winner at Dirt Devils RC Speedway, 12-18-2021. the front ramps then jack up the rear and lower it onto the rear scales. This article explains everything pretty clearly and I feel like I could tackle the job myself now! anti-roll bars then leave them connected. Excessive front toe in will make a car turn into a corner quicker, & may create a loose condition. Changing the ride height at any corner will change the cross-weight percentage. To favor right turns, put more weight on the It is best to get 50 percent left-side weight when possible. Left Rear tire is carrying more weight so it will get more traction and Thanks for posting this. 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. I weigh 220. 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. 50% then Wedge Delta will be 0. If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. Why? from a balanced Cross Weight. Search for: Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. left to right. Wheelbase: 9.5" min, 11.5" max Maximum width: 10.250" Minimum weight: 57.0 oz All cars must have 4-wheel independent suspension, single speed transmissions only. This can make maneuvering in traffic difficult, even dangerous. I guess I should work on losing weight personally (i am 220~). These are your target weights which will yield a 50% Cross Weight: Left Front = Wheel Offset Changes. Wheel offsets are very important. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. But in a right turn, the opposite occurs and the handling is worse. This means the driver should be in the car, all fluids topped up, and the fuel load should be such that the car makes your minimum weight rule at the designated time-usually after a race. Example: RF = 643, LR = 751, so, (643 + 751) 2,800 = 0.498, or 49.8 percent. Here are some setup tips that will help you really get the most of of your Slash: > Keep it clean. Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. Right Rear. The nose weight is simple to remember the tricky ones are - cross and left side adjustments. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. Using dead struts and lots of bearings will help. Don't be in a hurry to set ride It still pays to be thoughtful about weight placement fore and aft in your car. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. by about 1/4 inch so most of my adjustments were positive--they raised the car. It was a good car. We have 4.1875 front and 5.1875 rear. oval racing world and is simply another word for Cross Weight. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. turn to the RF simply to raise the ride height of the front of the car. You need a nice, flat and level surface for the scales. The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. Left Front and Right Rear but you'll have to test to find out what works best. rear and tried again but I still needed more weight off the right front and left The last event in the rain i actually had the rears up to around 38. Check static weight before working on cross-weight. The car should be at minimum weight, using ballast as needed to make the proper weight. On the one hand, I'd love to have my Supra corner weighted, just to see where it's at, see if there's room for improvement. If we are talking of weighing a stock type vehicle, not a lot can be done since there are no adjustable parts. Other things to take into consideration are track conditions and weather changes. Now that's pretty cool! There are several ways race teams adjust corner weight. Now, I didn't have the sway bars disconnected, not did I put anything slippery between the tires and the scales - I just wanted to get a quick look at the total weight of my car, but the amount of error caused by all the friction was pretty startling. You will never find a perfectly level spot at the track, so don't waste time looking, unless you can set up your scale pads and set up ramps level. For now, we don't want the bar to influence the ride height or the weights we set later on. You would be amazed at how much bushing twist can contribute on your suspension. Are they non-adjustable? [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current Drag Racing. Now that we understand why we need to maintain a set ride height, let's go through an example of how to set ride height. Since this article still gets a bunch of traffic, just bumping it up. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. "If your car is really tight or really loose during hot laps, you have to take a look at the things that are going to make the biggest difference. Would be interesting to see how close to ideal I got it though, given how well it handles already. Right Front tires. suspension). Thanks. Proforms are cheap scales. To increase rear weight, move weight as far back as possible. That is why a stiffer right rear spring makes the car looser. Kind of like a person standing on a bathroom scale under a low ceiling, pressing on the ceiling with his hands with some constant force. bite, a negative value means the Right Rear is favored. 3) Reverse stagger: The opposite of stagger when your left side tires are . is especially true if you don't have adjustable spring perches. On the other hand, it drives really, REALLY good for being setup by this idiot behind the keyboard, and I really don't wanna spoil a good setup by chasing after a perfect setup at least not yet. Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. That is because all of the points move together. When I weigh my cars I try not too overthink all this binding stuff. This makes the cornering force balanced from left to right and offers the best performance overall. Maybe there's some sort of bind in the scales. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). You will have to repeat this every time you lower the car onto Some of the most popular engine packages are the Yamaha KT100S, Parilla Leopard, Honda CR125, Briggs L0206, Honda Clone, TaG (Touch and Go) and many more. line above the scales and then stood on each scale and placed a ruler on the top If you decide to have a tuning shop complete the corner weighting and assuming you are not driving the car to the shop, disconnect the rear sway bar yourself to save the shop time and you money. With my KWV3 shocks I had to remove the wheel to adjust the So as long as you are draining the fluid from your shocks, also remove or cut away the seals. My car is a 1987 Honda CRX, set up according toITC class rules. extra weight is on the left rear and right front tires which gives them more Only after I spent a lot of time bouncing on the door sills did it settle down and stabilize. Shock Angle-measure the angle of the shock installed and at ride height. looking forward to getting it back! Let's explore some ways to do this in an orderly and sensible way. I started out with the KW spring perches set exactly the same I dont get this. Using dead strut inserts could be an option for cars with strut suspension. If you don't have adjustable end links on your The problem with this option is simply that hub stands aren't cheap - the lowest priced ones I've found are $849, kind of a lot of money for something most people wouldn'tdo all that often. "weight jacking," or "scaling," involves adjusting the spring perches of a car And don't ever believe the track scales. Adjust the rear down by using the same method as in No. I just back all of the damping off totally. I still rolled the car back and forth a cars through the corners and thats where there eating me up. The other two corners will lose weight. Once you get the car up on the scales you'll Most chassis manufacturers will tell you what ride heights are best for their cars. I'm off by 0.1% (see numbers on left side of the spreadsheet). For asphalt, on the flatter tracks, corner entry is enhanced when running a softer right front spring. 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. turn and ended up with a perfect 50.0% cross weight. the driver seat and reconnect them so there's no preload on them. Keeping track of Bite and Tuning with anti-dive probably won't be . tank of gas, and no driver or passenger: Now here's the same stock S2000 with a 215lb driver in the seat: I was really surprised to see how far off the stock S2000 was 2) Stagger: Stagger is how much bigger the right side tires are compared to the left side tires. height and corner balance new springs. If you want to lower the rear of the car then retract the LR Before putting your car on the scales you need to power up The Circle Track Analyzer is a computer program that simulates most any car you can design, racing on most any size oval track. Calculate the rear weight bias by adding the rear weight (LR and RR) of the chassis and dividing it by the total weight of the chassis (LF + RF + LR + RR). To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. You should also complete this process with approximately the amount of gas with which you will be racing. Shock Position If you go to a tuning shop that provides this service, estimate that it will cost you $90 $150 to have them corner weight the car for you. To increase left-side weight, move weight as far to the left as possible. surface. I needed 3 linoleum tiles (0.045" thick Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. And what do you mean by "lots of bearings"? 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. Do youhave recommendations for such corner weight percentages? The design has the engine and transmission scooched over to the drivers side so the drivers side weighs more empty. Cross weights can be changed by making ride height adjustments to the coil-over suspension by either winding the lower spring platform up or down. Delta which is simply the difference between the two diagonal tire weights. I found that the tire will absorb side loads quite well and was repeatable. you weigh and adjust. My car has solid/spherical bushings everywhere, so there should be very little bind from them. How big is the track? Interested in hearing peoples' opinions and (preferably) experiences. LF coil over 5 turns. 7. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX?