May run 4 pole motors. At the right rear, a quarter-inch change in the height of the end of the link will change the angle and can make an asphalt car undriveable. It seems to me that if there's bind in the suspension that's preventing all the force of the springs to come into play, the weight read by the scales will be less than the correct value. Suggested Adjustment Procedure for Oval Track - KONI NA A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. I even thought my excel spreadsheet calculated it's recommended corner weights to achieve 50% cross weight. 2 coils cut off springs 4 corners. turns to the Right Rear: I still needed more weight on the LF and RR so I added +4 to the LF: I still needed more so I added +2 to the RR and drove the after this adjustment we still need to add 39lbs to the Left Front and You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? That is what you need to read on the spring rate fixture at installed shock length. Set them to hot pressures is the norm as I understand it. Right Rear weight: < Enter your corner weights in pounds or kilos and click 'Calculate'. Still, it is a worthwhile goal to strive for 50 percent left-side weight. Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. I race in a spec class, so everyone is using the same equipment. Front + Left Rear) - (Left Front + Right Rear) and tells us how much Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. Leebo's Corner. Check your tire pressure and bump it up to the hot pressure 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. height and the shocks set to the exact same spring perch height Always try to start with the track bars first. Weight can be moved around at the track to fine tune the handling characteristics of the chassis. Bite = Left Rear - Right Rear and a positive value means the Since the front and rear shocks are of different lengths you Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. 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. Corner balancing, sometimes referred to as "corner weighting," Maybe there's some sort of bind in the scales. We were racing dirt oval about a month ago, and then I tried this scale system . The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. Interested in hearing peoples' opinions and (preferably) experiences. Recheck air pressure often to assure ride heights stay consistent. Find the difference from the desired average ride heights. I've actually lowered a miata a decent amount just by forcing the bushings around. Using dead struts and lots of bearings will help. I had to do this with my truck. to get the desired corner weights your ride height will change. The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. Corner Weight | Go Ahead - Take the Wheel Oval Set-up Black Book | IROAR - Radio Control Racing Race Tires: Are You Ready to Spend Some Money? In order to perform the set up routine the car needs to be completely ready to race. Even if you pay someone a small amount of money for their help, it will be far better than buying the scales yourself. Dirt or asphalt? 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. Our current setup is as follows - 270 lbs Car & Driver Cross Weight = 48% Rear Weight = 61% Left Side Weight = 51% LF = 56 lbs RF = 48 lbs LR = 82 lbs RR = 83 lbs MuddBoss Feature Winner at Dirt Devils RC Speedway, 12-18-2021. Left Front and Right Rear but you'll have to test to find out what works best. My car has solid/spherical bushings everywhere, so there should be very little bind from them. racers add "wedge" by adjusting the right rear spring perch--they springs settled over the first 3 months. For street cars it certainly can be. A jumbo ziploc bag prevents lube from escaping when not in use. works well. R. racing junky Member. Yeah generally its the same stagger 9/10 times. Search for: renting/borrowing/buying some scales and corner balancing your car. You can see the article here: "weight jacking," or "scaling," involves adjusting the spring perches of a car I found that the tire will absorb side loads quite well and was repeatable. As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. With my KWV3 shocks I had to remove the wheel to adjust the Wedge Delta and what values work best for certain tracks and conditions That seem like a lot. If you have uneven mass on your wheels then your tyres will all have different levels of grip which can lead to an unpredictable car on circuit and make it corner faster in one direction than the other. of the scale to take a reading. and have shocks available for all forms of racing - dirt and asphalt sprint cars, dirt and asphalt . I used a laser level to project a horizontal Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. Multiply the wheel load of 685 times the motion ratio squared, 1.3611 times the shock angle cosine squared of 1.1056 and we get 1,030.8 pounds of spring preload. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. When I weigh my cars I try not too overthink all this binding stuff. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. weights and percentages and generates target wheel weights to achieve a 50% You need: 1. Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. 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. difficult to position all 4 scales so you can just drive up on all of them at The shock length as it is installed in the car at ride height. 12. Corner Balance - Rob Robinette One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. I added the You will have to repeat this every time you lower the car onto Right Rear = Auto-Ware (Autoware Inc) auto racing reference library rear and tried again but I still needed more weight off the right front and left To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. Then the car will move more easily from one setting to another. Oval Are they adjustable? 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. I borrowed some scales to weigh my Terceltomorrow. Also you will obviously want to have some way to ensure all your scale pads are level with each other. work but in the end it's worth it. 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. can help us get our setup right with less testing. Thinking about this a little, the weight measured by the scales is the sum of the force of gravity acting on the car's mass, and the force of the springs pressing downward. adjustments were 1 turn to the right front and 3/4 turn to the left rear. Its important to measure and note your The cosine of 18 degrees is 0.95106, and that into 1.0 is 1.05146. I tried the 5. Wedge Delta and what values work best for certain tracks and conditions The car literally registered several hundred pounds less that what the weight finally settled at after I jumped up and down on the door sills for several minutes. Once static weight percentages are set, work on cross-weight percentages. It is a critical set-up tool. what he means is he's adding weight to the left rear and right front Dirt Race Car Handling Problems; Diagnosing and Fixing - Hogan Technologies anti-roll bar with the end-link adjusted so it's easy to insert the 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. 11. - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. I put the car on the scales and input the four corner used linoleum tiles to shim two of my scales to get them all level. I mainly run the 3/8. racers discovered they could insert an actual wedge into the left rear rear. Corner Balance Calculator - Rob Robinette For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. Or maybe I read the post wrong. 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. traction or bite in left turns. Conversely, if the car feels tight throughout the corner, raise both track bars. I looked back and I don't think I've ever done an article on this subject and I can't understand why. Cross Weight or Wedge. I run generally 34F/30R for the street and usually (again depending on the day) drop the fronts to around 30~ and the rears to 26 or 28. Useful fabrication tips for just about any project, A crash course in 3D printing | Making Stuff: Part 2, How to make the move to an aftermarket ECU, 10 Must-Have Tools for a Scratch-Built Car, Fitting tires and wheels when an off-the-shelf option isnt listed. And I cannot really move any weight around. If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. Do this by making equal changes to the adjusters on each side. Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. How NASCAR Wedge Adjustments Work | HowStuffWorks 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. 9. and stock rear sway bars connected. Picture the following: Your car is really fast in right-hand turns, but understeers in left turns. difference that made. Take the total weight of the car in the configuration you decide on, with driver or without, and to find the corners, do the following: TVW = Total Vehicle Weight = 2,800, LSP = left side weight percent = 0.54, FWP = front weight percent = 0.51, CWP = Crossweight percent = 0.52. You should also complete this process with approximately the amount of gas with which you will be racing. Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. Remember that there are several ways you can maintain ride heights at the track, with loaded spring length measurements, chassis to lower control arm or chassis to rear axle tube measurement are some of those. This keeps the ride heights as close to ideal as possible. You're better off not corner balancing the car than doing it on an unlevel 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. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. So we multiply the difference, or 4.2 percent, by 1.12 and we get 4.7 rounds of right side change to the spring pre-load, or 43/4 rounds. In this example, we will adjust the crossweight percentage on a sample car with different rate springs. No, not as in the law, but in being legal in tech. values shown below are totally fictional. When a NASCAR crewchief says he's "adding wedge", 19. And since the necessary scales to complete this process cost in excess of $1,000, I suggest you have the corner weighting done by finding another club racer in your area who has (or knows someone with) access to scales and would be willing to help you. which is simply the difference between the two diagonal tire weights. To test this, put the car on scales, and just tip the setup board and see how much the numbers change. Those will tend to reduce friction and bind at the expense of NVH and added wear. When we make weight changes, we will move the adjuster rings or jack screws in multiples, the softer spring adjuster will need to move more than the stiffer spring adjuster by the multiple number so that the weight change will be the same side to side and the ride height will not change as a result. Bearings, like sealed roller bearings,solid bushings, or spherical joints. this excellent article: Use those racing internet forums, and dont be timid about asking for some assistance! The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. Dirt track racing - Wikipedia . The height of the rear roll center (and the front also) is critical to handling. Dirt oval racing tips/ Go karts - Don Terrill's Speed-Talk Please post on the appropriate 4m forum. Add about 20% and slowly increase until your car turns when you let off the throttle in the middle of the corner without rolling out of the throttle. Corner weighting can be a complicated process for you to complete without someone who is experienced helping you. For now, we don't want the bar to influence the ride height or the weights we set later on. Jun 7, 2018 #8 . If you align your car prior to doing the corner weights, it will be necessary to verify the alignment again after the corner weighting is completed. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. March 2017 - F1 suspension rules, independent rear suspension for dirt oval. upgrading our street stock suspension part 2 the rear end. It also helps when shaking the car to take the bind out of the linkages. At least for road racing. Are they non-adjustable? You can also estimate your car's The springs OTOH exhibit little or no friction loss when compressed or extended. One of the problems with cross-weight is that it will change the handling balance from a left to a right turn. Any press releases or advertising will be deleted. then set corner weights and cross weight. Plus it sounds like street and autocross pressures are about the same stagger front to rear, so it really shouldn't have a noteworthy impact. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. line above each scale and placed a ruler on the top Bite and Wedge Delta are Step 1: Setup And Tuning The Tires Most regular RC cars use rubber tires. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. Toe inn a 1/4 inch. RC Dirt Oval Basic Setup & Tuning Guide (21.5, dirt oval - YouTube The following weights are with the front Comptech adjustable Wheel offsets can make a huge difference in fine tuning the chassis which will allow the driver to find a good racing line on the track. Wedge Delta can also be thought of In almost all cases, the loss of cornering performance in one direction is greater than the gain in the other direction. 1 of the section on "Adjusting The Corner Weights," and that is 685. Before putting your car on the scales you need to power up Here are some points to remember when weighing your race car: How to renovate an old mill | Making stuff: Part 6, Tech tips | Understanding fender rolling, downsizing tires, wheel spacers and what makes a race wheel, How to build a splitter for only $100 | Against the wind: Part 3. Would be interesting to see how close to ideal I got it though, given how well it handles already. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. More wedge means that the car will likely understeer more in a left turn. How big is the track? Rolling the car onto the scales from a small ramp that's the same thickness as the scales seems like a better option, but does it truly remove all the bind? Prepare the car. Rethink Dirt: Advanced Dirt Track Theory | Hyper Racing Bite tells us how much we Moving weight to the front of the kart will provide more front-end grip. You've mentioned "dead struts" a couple of times - what do you mean by that? want balanced turning in both directions. < Enter your corner weights in pounds or kilos and click 'Calculate'. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. 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. Since this article still gets a bunch of traffic, just bumping it up. LR 175, RR 350 - 350 175 = 2.00 multiplier for the rear. Adjustable end links are more The other two corners will gain weight. 13. If most of the important turns on your . In our example, the front average is 4.25 and the rear is 4.75. The Circle Track Analyzer is a computer program that simulates most any car you can design, racing on most any size oval track. weights: Corner Weight Calculator if Corner Weighting dry)! right swapped). Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. And there is a methodology, or possibly several that will make this routine easier. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) I painstakingly leveled the scales and marked their locations If you are using scales as a base, level the scales with a long level, a long straight piece of tubing, square or round with a smaller level, or better yet, an instrument level such as a construction level. Don't be in a hurry to set ride Grassroots Motorsports Understanding Corner Weights. section). I have now added the ratios so I can visually see what's happening. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. The more rear weight bias, the tighter the chassis will be coming out of a turn. right swapped). A. Corner weights and chassis balancing - R/C Tech Forums Understanding How Weight Distribution Affects Your Race Car Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. I front left and A perfectly corner balanced car will handle the same when turning left and right, and will maximize the tire contact area on all four corners. 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? This spreadsheet will also give you an estimated center of gravity height if coil over 5 turns. I overshot by a little so I raised the left rear spring perch by 1/2 To increase rear weight, move weight as far back as possible. 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. 1. That is why it gets tighter. Record each spring rate. pounds of preload to the scale weights. The left side changes, of course, will be 4.75 times the multiplier for front or rear. W. William18 New member. Besides the eventual move to an adjustable ride height set up, I feel like I need 100 lbs or so more spring in the left front. you raise the rear of the car 10 inches or more and re-weigh it. It varies with weight removal, added. Doing the multiplication to square that number, we get 1.1056. You can estimate your car's center of gravity Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. Funny. Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. But this is almost never the case. Motor: 550 or 540 motors only. Oval racers favor left turns so they typically desire more weight Note your ride heights and In order for the table to stand steady, all four legs should be of equal length, and as a consequence each will apply equal pressure on the floor. The car is built on a jig for a particular ride height layout. 14. Corner weighting your car is How to Adjust iRacing Sprint Car Cross Weight AKA Wedge However, you can choose to use them. you don't use Microsoft Excel. Iretighten them after I've made all my adjustments. from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up . That is because all of the points move together. Additionally, it is much more difficult to change rear percentage much, since rear weight is mostly a design function. 3. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? looking forward to getting it back! cross weight - iRacing.com Wiki about 1/8" of wheel movement) to reduce the weight on the right front and left Before putting your car on the scales you need to power up . Forum Actions: Forum Statistics: Threads: 167; Posts: 1,367; Last Post: . Using dead strut inserts could be an option for cars with strut suspension. [Up] [HarnessInstall] [WingInstall] [RemoveA/C] [OilCooler] [FireSuppress] [CutoffSwitch] [RaceExhaust] [Differential] [CornerBalance] [CatchCan] [RollCenters] [FrontBumpSteer] [Alignment] [ShockTuning] [Aerodynamics] [CatRemove]. racers add "wedge" by adjusting the right rear spring perch--they It still pays to be thoughtful about weight placement fore and aft in your car. RC Dirt Oval Basic Setup & Tuning Guide (21.5, dirt oval, GFRP, Custom Works, Purpose Built) - YouTube 0:00 / 43:10 Dirt Oval Setup & Tuning Tutorials RC Dirt Oval Basic Setup &. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil height and corner balance new springs. your scales. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. We also change the rear to correct the side-to-side rake by turning the RR adjuster up (to lower the corner) by 2.5 turns and the LR adjuster down (to raise that corner) by 2.5 turns. That's all total speculation though. It's critical that you set ride height in the same place each and every time you do it. should have their spring perches in the same spot and your left rear and right Calculator, I used these scales to weigh the car: 1. And what do you mean by "lots of bearings"? PDF UNDERSTANDING CHASSIS ADJUSTMENTS - Longacre Racing 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. The nose weight is simple to remember the tricky ones are - cross and left side adjustments. You need a nice, flat and level surface for the scales. Here is what you do. I usually mark an even inch and write that inch number on the tape. The angles are another way to set the suspension for the desired ride height and cross-weight percentage. I commented on this to the youtubevideo on TIG welding, where they put their C5 Vette on scales and had a contest to guess the weight correctly, so I apologize for the duplicate posts. left to right (measured with a digital caliper) and my ride height was pretty Do not copy these ride heights; they are only used as an example. Road racers are important for cars with upgraded (stiffer) sway bars because they can exert a Cross weight and left side work backwards in terms of adjustment. camber angle of the wheels (-3.5 front, -3 rear). 4m.net - The Most Opinionated Racing Message Board In The Universe. used are 0.045" thick. And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm.