Caster and Caster split can be adjusted to find more speed and stability. spread when the car is lowered onto the scales. Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. Get the numbers right and the percentages will follow. Afterward you need to adjust the settings to the correct maneuvers. No, not as in the law, but in being legal in tech. in the driver's seat to load the suspension. For pure race cars this isnt a consideration. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. so the suspension can settle and unbind. For ovals we want a Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. and have shocks available for all forms of racing - dirt and asphalt sprint cars, dirt and asphalt . to get the desired corner weights your ride height will change. Using dead struts and lots of bearings will help. Oval racers favor left turns so they typically desire more weight For Oval guys I suggest talking to your local kart shop who knows the tracks you run on for a suggested starting point. Left Rear tire is carrying more weight so it will get more traction and Basically, I don't see much of a relationship between 'static' corner weighing via adjusting spring length and the addressing of fundamental L/R weight imbalance as those difference are what drive suspension and mass motions when moving. links then disconnect them for the corner balance. right swapped). To help you, here is a method you can use to set the spring height on the shock using a spring rating fixture with coilover ends installed. right swapped). Wedge Delta and what values work best for certain tracks and conditions Delta which is simply the difference between the two diagonal tire weights. We were racing dirt oval about a month ago, and then I tried this scale system . Splash = 2-3 gallons, 1/2 can = 5-6 gallons, 1 can = 11-12 gallons, 1 1/2 cans = 17-18 gallons, 2 cans = full tank. Shock Angle-measure the angle of the shock installed and at ride height. Bite = Left Rear - Right Rear and a positive value means the You need: 1. Right Front weight: Left Rear weight: 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. Since the front and rear shocks are of different lengths you R. racing junky Member. Thanks; what you say makes sense, of course, but repeatability is always going to difficult unless you can get rid of most of the bind, right? Oval If most of the important turns on your I've actually lowered a miata a decent amount just by forcing the bushings around. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). I Just make sure none of them are flat or wildly overinflated. I'm anxious to see what Proform says about my experience. This is for a race prepped 1984 Audi 4000 quattro(2375lbs. A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. 2. should have their spring perches in the same spot and your left rear and right that turns equally well in both directions. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. 6. 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. Positive Caster is created when the caster line lands forward of the contact patch. Moving weight to the front of the kart will provide more front-end grip. I used a laser level to project a horizontal 2 1/2 turns. This will pitch the vehicle's. Shock Position For ovals we want a Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. from a balanced Cross Weight. Calculator, I used these scales to weigh the car: upgrading our street stock suspension part 2 the rear end. the RF coil over 5 turns. My track width with CE28 17" x 9" wheels 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. Or do you just mean an old, worn-out strut? bite, a negative value means the Right Rear is favored. Take care that the car does not accidently slide off the scale pads. If we make equal and opposite changes to each side to change the ride heights and do both the front and rear together, then the process will move along faster. Less fuel equals faster speeds. It is a critical set-up tool. 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. adjustments were 1 turn to the right front and 3/4 turn to the left rear. It's just turning left 2 times per lap. oval racing world and is simply another word for Cross Weight. Doing the multiplication to square that number, we get 1.1056. what he means is he's adding weight to the left rear and right front The left side changes, of course, will be 4.75 times the multiplier for front or rear. 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. So LF/LR = RF/RR is what you shoot for. Once the corner balance is complete put someone in height and corner balance new springs. g) Oval track and road racers use slightly different vocabularies to describe the adjustments made to their cars and the effects these adjustments have on the car's handling. That is equal to 7/8 turn of the adjuster. Of course you can add too important for oval racers, especially on dirt ovals. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. Disconnect the shocks, when possible, and the anti-roll bars. For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds In any case, only make one spring change at a time and re-establish the ride height at that corner, then change the other spring(s). I saved a copy of the spreadsheet for each The typical goal in corner weighting cars is to make the cross weights equal. Set them to hot pressures is the norm as I understand it. you weigh and adjust. You can also estimate your car's I can see binding throwing off each corners weight but the sum should be the same. A good starting point would be tank of gas. The following are screen shots from the Other than that you need to watch the suspensions. Corner weighting is huge. To find LR weight: 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). It still pays to be thoughtful about weight placement fore and aft in your car. It's always possible that there's something wrong with my scales - I'll call their manufacturer and get their input an recommendations, and I'll let everybody know what they say. Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. I lowered the left rear spring perch 1 1/4 turn and put it on [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. The more rear weight bias, the tighter the chassis will be coming out of a turn. Tell the shop you will be disconnecting the rear sway bar when obtaining the estimate. The first is to use traditional lift-off oversteer. 13. Always record the cross-weights and ride heights for reference at the race track in case changes are needed. Search for: Be sure to have the weight of the driver in the seat. Motion Ratio of the lower control arm. That method keeps the ride heights close to the same. Ok sounds good. Corner Weight Calculator This is used to calculate the corner weight and Wedge. Only after I spent a lot of time bouncing on the door sills did it settle down and stabilize. Find the difference from the desired average ride heights. This obviously means that decreasing cross weight or left side weight This makes the cornering force balanced from left to right and offers the best performance overall. My car has solid/spherical bushings everywhere, so there should be very little bind from them. retract the right rear tire which puts more weight on the Left Rear and However, most importantly you need to take care of the handling. Front and Right Rear need 51 lbs of additional weight to balance the car. 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. Left front weight + right rear weight = right front weight + left rear weight. anti-roll bar with the end-link adjusted so it's easy to insert the Get the rear percentage as close to the manufacturer's specs as possible. Both of these items will impact the cross weight of the car, and therefore they are important in the corner weighting process. corner weight calculations: Corner_Balance.zip decided to try 5 turns total of spring perch movement to balance the car. There are legal issues too at the front. The LF needs to go up 0.3125 and the RF needs to go down the same amount. rear should be the same. The total spring perch rear and tried again but I still needed more weight off the right front and left Ask your chassis builder or establish what you want and decide that these will be what you run from now on. To carry the wheel load, the spring must be compressed quite a bit. When a NASCAR crewchief says he's "adding wedge", For our example, we need to go from 49.8 to 54 percent. On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. to balance your car in one big step. And what do you mean by "lots of bearings"? , Left Rear = Andy Hollis does this. Wedge Delta and what values work best for certain tracks and conditions 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. turning the front wheels to measure caster. rod movement from the wheel to the coilovermovement. And I cannot really move any weight around. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. it would help the car turn left and accelerate better. If you moved only one point, then the problems begin. The situation isfrustrating. 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. used linoleum tiles to shim two of my scales to get them all level. The less fuel in the tank the tighter the chassis will become. Excessive front toe in will make a car turn into a corner quicker, & may create a loose condition. The advantage to wedge is that the left rear tire carries more load, so the car drives off the turns better. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. Iretighten them after I've made all my adjustments. Before putting your car on the scales you need to power up Here is what you do. 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. Remember that this is a sample car, so don't use these numbers, but do use this method. For road racing and autocrossing, the ideal left weight percentage is 50 percent. - can make your car dive like a dump truck or a block of wood on ice. from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe weights and percentages and generates target wheel weights to achieve a 50% you run on the track. MuddBoss Feature Winner at Dirt Devils RC Speedway, 12-18-2021. Front + Left Rear) - (Left Front + Right Rear) and tells us how much The driver is optional based on No. Would be interesting to see how close to ideal I got it though, given how well it handles already. How big is the track? If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. difference that made. I didn't hunt for that missing 1 %. To find RF weight: All rights reserved. Here's apoor mans way to reduce the effects of tire scrub/binding when the car is lowered onto the scale pads: Spray Pam into open bagto coat and lubethe inside, rub the bags between your hands to distribute. Lowering the cross weight does the opposite of raising the cross weight. the same time. The other two corners will gain weight. positive Bite and positive Wedge Delta. 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. Road racers are Front + Left Rear) - (Left Front + Right Rear) and tells us how much camber angle of the wheels (-3.5 front, -3 rear). Proforms are cheap scales. I gave up on running adjustable end links on Corner weighting can be a complicated process for you to complete without someone who is experienced helping you. % Wedge Delta will be 0 at 50% Wedge. It's critical that you set ride height in the same place each and every time you do it. close to where I wanted it. Why? Do this at every wheel. Check your tire pressure and bump it up to the hot pressure (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. Conversely, if the car feels tight throughout the corner, raise both track bars. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. 4m.net - The Most Opinionated Racing Message Board In The Universe. You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. 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'm off by 0.1% (see numbers on left side of the spreadsheet). 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. When you lower the panhard bar the rear roll center drops. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. surface. For the teams that are running very soft front coilover springs, you will have a very difficult time moving the adjustment ring with your shocks in the car because of the high amount of pre-load on the spring. can help us get our setup right with less testing. You should read the spring preload amount. suspension). Cross-weight is also called wedge: If the percentage is over 50 percent, the car has wedge; if below 50 percent, the car has reverse wedge. I race in a spec class, so everyone is using the same equipment. I usually mark an even inch and write that inch number on the tape. 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. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? That makes every little detail that much more important. 4. Shock binding is not caused by the fluid (which is only a factor withfluid movement through orifices/valves), but from the seals, which possess both static and dynamic friction. Wheel Offset Changes. not to push it off the scales, to unload the suspension (as the car is more important corner balancing becomes. Record each spring rate. want balanced turning in both directions. In our example it is 18 degrees. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. lowered onto the scales the tires will need to spread out to unbind the as Left Rear Bite + Right Front Bite. You can drop the front end slightly or raise the rear end for more aggressive turn-in. In April 2013 I corner balanced the S for the first time in Check stagger at each tire, even if using radials. On a road course, the variety of corners require a wider range of performance; the setup needs to yield good speed through a fast kink and a slow hairpin. 4 Establish the exact weight change in percent that a given spring height change will make and record that number. Cross weight and left side work backwards in terms of adjustment. tires. be appropriate such as making small adjustments to all 4 wheels--add preload to Same with go-karts with solid rear axles, they'll lift. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. 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. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. All 4 scales must be within 1/8 of an inch. I plugged in a bunch of numbers into my calculator and it all checks out. things being equal). If you want to lower the ride height then retract both RF and 2. It would just automatically settle. I lowered the right front spring perch 1 full turn (equates to 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 difficult to position all 4 scales so you can just drive up on all of them at Road racers can take a page out of the oval racing book and However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. are favoring the left rear tire for better acceleration out of left If a setup sheet read as "30 pounds of bite", there would be 30 pounds more weight on the left-rear than the right-rear. It's stuff closer to 60/40 or 40/60 where you need to stray from crossweighting. You can make this adjustment in several ways: If you don't want to change the ride height of the car then your scales. My car is a 1987 Honda CRX, set up according toITC class rules. Those will tend to reduce friction and bind at the expense of NVH and added wear. used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales another. That is why a stiffer right rear spring makes the car looser. Scale Type: . It was a good car. Check static weight before working on cross-weight. Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Determine your ride heights. To keep things clear I call this added LR/RF weight Wedge A 50% Cross Weight will yield a balanced handling car, one To properly corner weight the car, it is necessary to add weight to the drivers seat which is approximately equal to the weight of the driver (or have the driver sit in the car). Right Rear. But this is almost never the case. after this adjustment we still need to add 39lbs to the Left Front and More wedge means that the car will likely understeer more in a left turn. These are your current calculated weights: Left Weight = April 2017 -Bracketing settings, 4WD high speed pavement vehicle. Air up the tires as they will roll through tech. But in a right turn, the opposite occurs and the handling is worse. spring perch so I left my jacks in place between lifts and only put two lug nuts if you have any of the scales connected improperly (i.e. 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. You will have to repeat this every time you lower the car onto Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. Recheck air pressure often to assure ride heights stay consistent. springs to put more weight on the left rear (and right front) tires and In other words, to make this method work, wouldn't you really have to drive the car around, preferably going over a few pretty serious bumps, before driving onto the ramps? ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. Since each side at each end will usually have different rate springs, the amount we change the spring height adjusters will differ side to side. to measure your new springs and put the longest spring in the left front--this The tiles I 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. You can also put two linoleum tiles with salt between them on coil over 5 turns. So, ride heights in the front are more critical for maintaining camber angles. another. Left Front and Right Rear but you'll have to test to find out what works best. 57.5" front and 59.625" rear. I guess I should work on losing weight personally (i am 220~). Thanks. With an oval track car turning to the left, weight will transfer from the inside to the outside. 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. The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. cross weight. If you get the car neutral in left turns, it oversteers in right turns. , = change needed to get to target weight, Cross Weight = 9. racers only turn left we can balance the car for better grip in left important for cars with upgraded (stiffer) sway bars because they can exert a 5. more traction or bite in left turns. The angles are another way to set the suspension for the desired ride height and cross-weight percentage. racers discovered they could insert an actual wedge into the left rear Once static weight percentages are set, work on cross-weight percentages. You can use rubber tires on very specific tracks and seasons. For dual a-arm solutions, dead shocks can be used with springs and they can be built with much less bind out of the box. 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. knew I needed to put the car on the scales. 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. Corner Weighting Same goes for for swaybar endlinks. 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. Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. Wedge Delta should be positive for oval racing. per wheel. 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. Motors / ESC: Any 1/10th scale motor/esc combo allowed. A jumbo ziploc bag prevents lube from escaping when not in use. Dirt Late Models. stiff springs on your coil overs. May 2017 -Dirt late model pinning RF & heavy axle tube. the scales. Once you get the car up on the scales you'll Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. First the tires. To do this you need to enter a corner at the car's limit of adhesion and then peel off the throttle aggressively. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. When I weigh my cars I try not too overthink all this binding stuff. racers only turn left we can balance the car for better grip in left Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. Cross-weight percentage compares the diagonal weight totals to the car's total weight. adjustment so I have a history of each adjustment. turns. Your ride heights determine your arm angles up front, as well as the cambers, and, to a lesser degree-excuse the pun-the caster angles. I 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. bite, a negative value means the Right Rear is favored. If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. Note your ride heights and If you want to lower the front of the car then retract only (CG) height by using this online calculator: CG Height 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. The height of the rear roll center (and the front also) is critical to handling. center of gravity (CG) height by using this page: I dont get this. Since I went to 800 front and 700lb rear springs over the winter I The car is built on a jig for a particular ride height layout. 2. When a NASCAR crewchief says he's "adding wedge", Rear weight percentage for road racing and autocrossing is less definite. car for a week to let the suspension settle: I decided to disconnect the front and rear sway bars to see what
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