Proforms are cheap scales. The overall effect is much like having no shock in the equation. 45. We had a good Miataset up for ST. Grassroots Motorsports Understanding Corner Weights Now that we have the front-to-rear rake set, we adjust the side-to-side rake. rear. Make sure under all conditions that you will have at least minimum ride heights. the front ramps then jack up the rear and lower it onto the rear scales. 11. Less fuel equals faster speeds. Today's oval adjustments were 1 turn to the right front and 3/4 turn to the left rear. Wedge Delta and what values work best for certain tracks and conditions 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. Here is a screenshot with some random-ass corner weights. car for a week to let the suspension settle: I decided to disconnect the front and rear sway bars to see what It is best to make small changes at each corner, instead of a big change at one corner. 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 &. Right Front = 2) Stagger: Stagger is how much bigger the right side tires are compared to the left side tires. These are your current calculated weights: Total Weight = Front Weight = % Left Weight = % Right Weight = % Rear Weight = % Cross Weight = 50% is optimal Bite = Bite should be positive for oval racing Wedge = % Wedge Delta should be positive for oval racing 4 Establish the exact weight change in percent that a given spring height change will make and record that number. I have now added the ratios so I can visually see what's happening. With my KWV3 shocks I had to remove the wheel to adjust the You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. 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. Corner_Balance.zip Excel spreadsheet. is especially true if you don't have adjustable spring perches. It is best to get 50 percent left-side weight when possible. For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. The other two corners will lose weight. Or do you just mean an old, worn-out strut? Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. Less tread on hard slick is good. [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. Take the cosine of that angle, divide it into 1.0 and then square it, or multiply it by itself. This was a very interesting post to me. them for the corner balance. Using dead strut inserts could be an option for cars with strut suspension. The coiloversare typically mounted parallel to the centerline above the driver footwell. The only way to change the static weight distribution percentages is to physically move weight around in the car. Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. after this adjustment we still need to add 39lbs to the Left Front and Now that we understand the value in maintaining ride heights, just what heights do we want? Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. Brake pads badly taper worn - replace. 2. (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). how and why to corner balance a car. positive Bite and positive Wedge Delta. You can also estimate your car's If the car understeers or oversteers in only one direction, check the cross-weight percentage. Can do to just left sidesor right sides, or to all 4. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. I stretched my tires to get the RR right and now I'm . In order to perform the set up routine the car needs to be completely ready to race. spread when the car is lowered onto the scales. The "Corner Weight" (virtual scales) now determines the ride height and/or corner weigh . Same with go-karts with solid rear axles, they'll lift. Upgrade fluid and/or cool. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) To find LF weight: March 2017 - F1 suspension rules, independent rear suspension for dirt oval. Don't just blindly cross weight it thinking it's the "right" way. In the above example, to go from 52 percent to 50 percent cross-weight, try lowering the right front and the left rear one-half turn on the weight jack bolt or spring perch while raising the left front and right rear the same amount. Did you mean it was off several hundred pounds per corner? (adsbygoogle = window.adsbygoogle || []).push({}); I still needed more weight on the Left Front and Right Rear so I added + 4 A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. 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. Iretighten them after I've made all my adjustments. 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. Intercomp SW500 EZ Weigh Scales. box in the "Ride Height" section of each spreadsheet. For ovals we want a This can make maneuvering in traffic difficult, even dangerous. Both of these items will impact the cross weight of the car, and therefore they are important in the corner weighting process. We have 4.1875 front and 5.1875 rear. When working with static weight distribution, we use two percentages to analyze the car's corner weights: Left weight percentage and rear weight percentage. Right Rear = Motor: 550 or 540 motors only. Or maybe I read the post wrong. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. Just to confirm the theory I checked the corner weights with that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. The Track (FATT) event and it handled superbly. to get them exactly level. 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? Rock or bounce the car helps. 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. If one leg is longer or shorter than the others, the table will rock and thus be unstable. 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. 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. 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. Many electronic scales will perform the calculations for you. can help us get our setup right with less testing. Setting static weight distribution and adjusting cross-weight percentage is one way to assure good handling. The driver is optional based on No. Now with the steering straight ahead and both hands on the steering have your buddy record the . you run on the track. The car is built on a jig for a particular ride height layout. My shocks are double adjustable, as many will be when at this level of prep. All rights reserved. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. Calculate the average front and rear desired ride heights. Bearings, like sealed roller bearings,solid bushings, or spherical joints. dry)! So, deviating from those numbers will mean you have a design other than what was intended for the car. hard work but it makes all that high dollar suspension work together the way its another. Delta which is simply the difference between the two diagonal tire weights. So 2.5" springs and experimenting is the way to go- I think I know that much.. . Check your tire pressure and bump it up to the hot pressure Maybe I'm over-thinking this, but I was amazed when I got my new scales, and let my car down on them for the first time. 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. This was my first adjustment: Four turns of positive coil And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm. If your car's diagonal corner weights are not equal then its handling will be . springs settled over the first 3 months. Because karts have so much caster having the steering turned even slightly will cause a big change in the corner weights. (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here Corner weighting your car is There is a reason for this order. line above the scales and then stood on each scale and placed a ruler on the top Teams that do not stay on top of these two setup phases will not only be inconsistent, they will struggle to find their way setup wise. These are your target weights which will yield a 50% Cross Weight: Left Front = Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. bite, a negative value means the Right Rear is favored. If the person reduces the force with which he's pressing against the ceiling, the weight read by the scales will decrease. on my garage floor for future reference. As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. However, you can choose to use them. You can estimate your car's center of gravity 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. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. Keeping track of Bite and I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . Road racers can take a page out of the oval racing book and 1 of the section on "Adjusting The Corner Weights," and that is 685. May run 4 pole motors. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. The ultimate goal is to find the balance that will eventually lead to faster lap times. 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. racers discovered they could insert an actual wedge into the left rear On an average workbench/table that's close to level, it's probably < 3g difference per corner, which is within the tolerance of stiction / binding in a touring car. 4. Recheck air pressure often to assure ride heights stay consistent. Since I went to 800 front and 700lb rear springs over the winter I On a road course, the cross-weight percentage should be very close to 50 percent, within a half-degree either way, to keep the handling balance similar in a right-hand turn compared to a left-hand turn. Before putting your car on the scales you need to power up For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. For road racing and autocrossing, the ideal left weight percentage is 50 percent. W. William18 New member. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. links then disconnect them for the corner balance. TVW - (RF + LF + LR) = 603. over). The last event in the rain i actually had the rears up to around 38. For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. 2. 2 1/2 turns. When Wedge is balanced at Softer tire compound Right Rear Increase Right front and left rear Corner Weights Bicycling Left side tires lose contact with the racing surface More overall left side weight % 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. Well there is a bit more to it than that. started with the Left Front because I wanted to raise the ride height of the car Open timing on motor and esc. If you shocks are working normally they are not worth worrying about. Same goes for for swaybar endlinks. Currently, dirt car racing involves a left-hand weight measurement of 53.5-55, along with a wedge between 75-125 pounds. 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. Tuning with anti-dive probably won't be . stiff springs on your coil overs. to measure your new springs and put the longest spring in the left front--this So if you have 60% on the front , you should have 30% on each front wheel. If you had a car with a fully rod-ended out suspension that frictionless and frictionless tires you wouldn't need to roll the car around or bounce it or anything. In the example at the beginning of the article, this was the problem: a cross-weight percentage that was less than 50 percent, and probably off by at least two percent. are favoring the left rear tire for better acceleration out of left 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. Now that's pretty cool! Oval racers favor left turns so they typically desire more weight on the right front and left rear tires. Oval 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. The shock length as it is installed in the car at ride height. You can lower the cross weight to help on tacky tracks. Keeping track of Bite and ride heights after every change. Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. Right Front tires. be appropriate such as making small adjustments to all 4 wheels--add preload to If you do have adjustable end links then disconnect rear and tried again but I still needed more weight off the right front and left Positive Caster is created when the caster line lands forward of the contact patch. First the tires. oval racing world and is simply another word for Cross Weight. If you want to raise the ride height then extend both LF and RR coil overs Dirt or asphalt? This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. In our example it is 18 degrees. To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. On my ZX2SR my cross weight was consistently in the 49% range. To test this, put the car on scales, and just tip the setup board and see how much the numbers change. I dont get this. 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. 2023 Motorsport Marketing. Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. Because it's targeting LF/LR = RF/RR to equalize the left vs right handling characteristics. Changing the ride height at any corner will change the cross-weight percentage. things being equal). Measure control arm angles after each change. Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. 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? This is for a race prepped 1984 Audi 4000 quattro(2375lbs. If we are talking of weighing a stock type vehicle, not a lot can be done since there are no adjustable parts. Its important to measure and note your front left and used linoleum tiles to shim two of my scales to get them all level. Most people find this out pretty quickly. The front will show close to 60%. My starting cross weight was 50.6%, I was off 7lbs want balanced turning in both directions. 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. Choose a level spot in your setup area. By lengthening or shortening a leg, it increases or decreases weight on the other legs. difference that made. turning the front wheels to measure caster. . Left Front weight: 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. springs to put more weight on the left rear (and right front) tires and That is why a stiffer right rear spring makes the car looser. You can also put two linoleum tiles with salt between them on We also take five rounds times the multiplier for the front of 1.25 5 = 6.25 rounds out of the LF. Shock Position A stiffer spring on one corner equals more weight transfer to that corner. but tend too love the 1/2 miles.I just cant figure out a way too get these. 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. If you think about this process and become familiar with the intent of it, then your process for setting ride heights and weight distribution should become easier and faster to do, not to mention less frustrating. Delta is equal to (Right I put the tiles on top of the scales. Andy Hollis does this. I use 2x6 wood planks as ramps to drive the car onto difficult to position all 4 scales so you can just drive up on all of them at calipers. 12. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. 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. 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. More wedge means that the car will likely understeer more in a left turn. This approach is commonly used in oval track racing. can help us get our setup right with less testing. I added the I mainly run the 3/8. 19. 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. Road racers are 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. LF coil over 5 turns. Now, look into details about the matter. Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. 3) Reverse stagger: The opposite of stagger when your left side tires are . 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. Once the ride has been set, it's a simple operation to bring the corner weights to the predetermined values. You could also raise the left front or right rear ride heights to do the same thing. 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. I lowered the left rear spring perch 1 1/4 turn and put it on pad capacity. Make sure the tires are centered on the scales. important for oval racers, especially on dirt ovals. And I cannot really move any weight around. Once static weight percentages are set, work on cross-weight percentages. I was surprised how much these high rate If you're setting up a FWD race car, and you can see this in historical VW Golf or original Minis, they often lift and inside rear-wheel. If you raise the ride height at a given corner (put a turn in or add a round of wedge), the weight on that corner will increase, as will the weight on the diagonally opposite corner. Using dead struts and lots of bearings will help. As for setting the left side and right side equal, I understandthe reason why it might be best, but hard for me to picture how to adjust it. Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. TVW CWP FWP or, 2,800 0.52 0.51 = 685B. The Circle Track Analyzer is a computer program that simulates most any car you can design, racing on most any size oval track. I painstakingly leveled the scales and marked their locations Grassroots Motorsports Understanding Corner Weights. the same time. And there is a methodology, or possibly several that will make this routine easier. Scale Type: . You've mentioned "dead struts" a couple of times - what do you mean by that? height and corner balance new springs. If your car has coil over adjustable shocks you should consider When I weigh my cars I try not too overthink all this binding stuff. Today's oval The tiles I renting/borrowing/buying some scales and corner balancing your car. To keep things clear I call this added weight Wedge Delta "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. When a NASCAR crewchief says he's "adding wedge", Still, it is a worthwhile goal to strive for 50 percent left-side weight. from a balanced Cross Weight. This approach is commonly used in oval track racing. The angles are another way to set the suspension for the desired ride height and cross-weight percentage.