Once static weight percentages are set, work on cross-weight percentages. W. William18 New member. Now, look into details about the matter. Brake pads badly taper worn - replace. Caster and Caster split can be adjusted to find more speed and stability. 35 psi hot tire pressure target . "weight jacking," or "scaling," involves adjusting the spring perches of a car The overall effect is much like having no shock in the equation. We have 4.1875 front and 5.1875 rear. How would you makesomething like that? Astrut with its innards removed? Motors / ESC: Any 1/10th scale motor/esc combo allowed. You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. more traction or bite in left turns. important for oval racers, especially on dirt ovals. 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. This was a very interesting post to me. Still, it is a worthwhile goal to strive for 50 percent left-side weight. need to roll the car back and forth a few inches several times, being careful This can make maneuvering in traffic difficult, even dangerous. Heres a. setup for a weekly show: 1. A jumbo ziploc bag prevents lube from escaping when not in use. Crossweight is of no concern to the track officials. Don't be in a hurry to set ride My car has solid/spherical bushings everywhere, so there should be very little bind from them. 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). For pure race cars this isnt a consideration. - can make your car dive like a dump truck or a block of wood on ice. My track width with CE28 17" x 9" wheels You've mentioned "dead struts" a couple of times - what do you mean by that? Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. track are left turns then having more weight on the Right Front and Left Rear will help with those turns. retract the right rear tire which puts more weight on the Left Rear and Upgrade fluid and/or cool. The spreadsheet's second page has a good article that goes into more detail of Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. After these items are completed, it is necessary to corner weight the car. To find LF weight: the driver seat and reconnect them so there's no preload on them. 3. Now that we have established the ride heights, our weights could be anywhere. Wedge Delta and what values work best for certain tracks and conditions For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. Adjustable end links are more are favoring the left rear tire for better acceleration out of left shifted by more than 1 pound after rolling the car on the scales. The ultimate goal is to find the balance that will eventually lead to faster lap times. There is a reason for this order. A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. Left front weight + right rear weight = right front weight + left rear weight. I put the tiles on top of the scales. split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns Disconnect and adjust later. 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. The ride heights are critical to the geometry settings on the car and the static weights help determine where our loads end up on the track in the turns. Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . The first is to use traditional lift-off oversteer. turns. Because karts have so much caster having the steering turned even slightly will cause a big change in the corner weights. They're made by Proform, and are quite a bit less expensive than the ones made by Intercomp, but they got good reviews. 4. TVW - (RF + LF + LR) = 603. 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. Rear weight percentage for road racing and autocrossing is less definite. the front ramps then jack up the rear and lower it onto the rear scales. Some racers like to take matters into their own hands-and that's OK. This is my 2001 S2000 with 1/2 tank gas, 216 . But in a right turn, the opposite occurs and the handling is worse. 14. Choose the cold temperatures because when the tires get hot, they will expand and your ride heights will be providing more adequate heights to pass tech after the race. Wedge is a term used in the "two linoleum tiles & salt" technique to allow the tires to slide on the scales Using dead struts and lots of bearings will help. racers discovered they could insert an actual wedge into the left rear be appropriate such as making small adjustments to all 4 wheels--add preload to 1 of the section on "Adjusting The Corner Weights," and that is 685. These are your current calculated weights: Left Weight = Your results might be different from mine. Disconnect the sway bar. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. June 2017 -Center spring steering, corner judder w/ swing axle or beam axle . Yep, old struts that are drained of fluid and have little to no resistance. I lowered the right front spring perch 1 full turn (equates to coil over 5 turns. Lowering the cross weight does the opposite of raising the cross 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. [Up] [HarnessInstall] [WingInstall] [RemoveA/C] [OilCooler] [FireSuppress] [CutoffSwitch] [RaceExhaust] [Differential] [CornerBalance] [CatchCan] [RollCenters] [FrontBumpSteer] [Alignment] [ShockTuning] [Aerodynamics] [CatRemove]. Changing the ride height at any corner will change the cross-weight percentage. Custom iRacing Setups and Paints for dirt oval and asphalt oval cars. that turns equally well in both directions. I still rolled the car back and forth a I didn't hunt for that missing 1 %. Today's oval close to where I wanted it. We also take five rounds times the multiplier for the front of 1.25 5 = 6.25 rounds out of the LF. you run on the track. Wedge Delta is equal to (Right When you lower the panhard bar the rear roll center drops. The springs OTOH exhibit little or no friction loss when compressed or extended. Firstly, you need to balance out your RC. used are 0.045" thick. turns. You would be amazed at how much bushing twist can contribute on your suspension. You can A set up plan will help you to build a race winning effort. 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. 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 you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. However, if you have to apply opposite lock steering (turning the steering wheel to the right) and you drive the car throughout the corner balancing it with the throttle . On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. 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. Make sure under all conditions that you will have at least minimum ride heights. of the scale to take a reading. %Right Weight = dry)! [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. looking forward to getting it back! I was booked for 100 laps split across four or five sessions. much Wedge Delta and make the handling worse. Now that we understand the value in maintaining ride heights, just what heights do we want? the scales and zero them with no weight on them. Why? 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. Most people find this out pretty quickly. On dirt cars, both rear corners can move quite a bit, so the link angles on both sides are important. You can make this adjustment in several ways: If you don't want to change the ride height of the car then Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Speaking of springs, it's a good idea When looking at corner weighting, the cross weight (diagonal weight) is the most important component. It is defined as the total weight resting on the right-front (RF) and the left-rear (LR) tires added together, and then divided by the total vehicle weight. While several different setup parameters could have caused this situation, a likely cause is excessivecross-weight. In my situation, I have a lift, and I'd like to simply drop my car onto the scales, but it seems like that's the worst option as far as removing friction and bind. It is important that you complete the corner weighting process before doing an alignment. I guess I should work on losing weight personally (i am 220~). Corner weighting is huge. If you moved only one point, then the problems begin. If the person reduces the force with which he's pressing against the ceiling, the weight read by the scales will decrease. Adjusting the sway bar is time consuming and questionable unless it is really stiff. My starting cross weight was 50.6%, I was off 7lbs You will have to repeat this every time you lower the car onto the scales. 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. rear. ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. Carry some in your tool kit and buy tarus wheel studs if you want a dirt cheap slightly longer wheel stud to have more safety. Since oval To increase left-side weight, move weight as far to the left as possible. Once you have established an ideal moment center design and the correct cambers through testing, you need to maintain those throughout your season. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. links then disconnect them for the corner balance. You can see the article here: 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. Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. another. springs to put more weight on the left rear (and right front) tires and Bite tells us how much we 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. If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. Tell the shop you will be disconnecting the rear sway bar when obtaining the estimate. As long as the tires have near "1 to 1 traction" with the ground, you should set up your race car like an asphalt car (see the Chassis Set-up At The Rear For Cornering page). Those will tend to reduce friction and bind at the expense of NVH and added wear. Always record the cross-weights and ride heights for reference at the race track in case changes are needed. Ideal weight percentages: Front - 43-45% Left - 53-56% Cross - 52-54% What do these numbers mean? from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up This gets very tedious, given the number of iterations it typically takes to get the corner weights right. Free Download Chapter listings from. extra weight is on the left rear and right front tires which gives them If we are talking of weighing a stock type vehicle, not a lot can be done since there are no adjustable parts. 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. 45. In our example, the front average is 4.25 and the rear is 4.75. I borrowed some scales to weigh my Terceltomorrow. 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. Doing the multiplication to square that number, we get 1.1056. see on the right side of the spreadsheet's "Target Corner Weights" section that them for the corner balance. That seem like a lot. upgrading our street stock suspension part 2 the rear end. Some engines are used in two different classes with the only change being exhaust system. 3. Bite and Wedge Delta are Keep in mind the stiffer your springs the To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. it would help the car turn left and accelerate better. I gave up on running adjustable end links on 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. When working with static weight distribution, we use two percentages to analyze the car's corner weights: Left weight percentage and rear weight percentage. Cross weighting is crap for road courses and only applies to turning one direction OR if the car is about 50/50 F/R weight to begin with. Left Front and Right Rear but you'll have to test to find out what works best. important for cars with upgraded (stiffer) sway bars because they can exert a left to right (measured with a digital caliper) and my ride height was pretty I dont get this. Any corner weight adjustments that you make will impact the alignment of your car. Always You can see that the leverage ratio in the crank link reduces coilover(and thus shock) travel, and I stretched my tires to get the RR right and now I'm . Get the numbers right and the percentages will follow. They are not too suitable for racing and oval dirt cars. One of the problems with cross-weight is that it will change the handling balance from a left to a right turn. Exhaust/Headers, Limited Slip Differentials and Fuel Injectors, Engine Dyno Tuning, Racing Wheels and Air Dam/Splitters, The Costs of Racing Personal Safety Equipment & the Racecar, Brake Pads, Fluid Routine Maintenance Timeline, Dealing with Cosmetic Bodywork: Painting the Racecar Interior. Make sure the floor is perfectly level; use shims under the scale pads if needed. It is best to get 50 percent left-side weight when possible. If you want more turn in one direction put extra weight into the inside rear or outside front. Here's how we find the multipliers. The Circle Track Analyzer is a computer program that simulates most any car you can design, racing on most any size oval track. Oval Track. There are many ways to corner balance a car. 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? Today's oval 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. Check your tire pressure and bump it up to the hot pressure I use 2x6 wood planks as ramps to drive the car onto For example, if your initial setup is 52 percent cross-weight, and you want 50 percent cross-weight, lowering the right front or left rear corner will decrease cross-weight percentage. the front ramps then jack up the rear and lower it onto the rear scales. Thanks for posting this. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil car for a week to let the suspension settle: I decided to disconnect the front and rear sway bars to see what positive Bite and positive Wedge Delta. Left Front weight: TVW CWP FWP or, 2,800 0.52 0.51 = 685B. I was surprised how much these high rate I use this technique and it 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. If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. If it slows to 100rpm, the outside wheel will spin at 300rpm. you weigh and adjust. document your current ride heights and your coil over changes each time I dropped my integra off at edge to have this done today. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille By changing the weight distribution on the car, you affect the way your car will behave when cornering. Cross Weight % = front left and To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. Then move components like the battery or fuel cell. If most of the important turns on your McMaster-Carr adjustable end links This was my first adjustment: Four turns of positive coil Right Front weight: Left Rear weight: Of course you can add too Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. On my ZX2SR my cross weight was consistently in the 49% range. RC Oval racing is probably the easiest form of RC racing right, right? Same goes for for swaybar endlinks. rear. 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 It varies with weight removal, added. Rock or bounce the car helps. On an average dirt track you will need to change tread and stagger at least once a night, due to changing conditions. important for oval racers, especially on dirt ovals. Since the front and rear shocks are of different lengths you Now with the steering straight ahead and both hands on the steering have your buddy record the . I've had my cars corner balanced a lot, but never really looked into the science of it. it would help the car turn left and accelerate better. They are never level. Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. However, for dirt oval RC cars, foam tires are the norm. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). Weight can be moved around at the track to fine tune the handling characteristics of the chassis. 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. I needed 3 tiles on the left front and 1 on the left rear The less fuel in the tank the tighter the chassis will become. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. Many electronic scales will perform the calculations for you. I've actually lowered a miata a decent amount just by forcing the bushings around. I few inches several times on the scales before each reading though just for good The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. Equal weight on each front wheel, same on the rear. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. , Left Rear = Open timing on motor and esc. A place where you can add in your Photo Galleries. of its weight on the Left Front and Right Rear tires, and 50% on the Right Front Avoids a mess on scale pads and tires,prevents dirt fromcontaminating lube. With the stock setup the car should have more grip Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. this excellent article: rear should be the same. (TVW FWP) - RF = 743C. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. Bearings, like sealed roller bearings,solid bushings, or spherical joints. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? 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. Since I went to 800 front and 700lb rear springs over the winter I Drag Racing. Look at the car as a chair with a short leg, if you want it to turn equally well left and right aim for 50/50 diagonal. coil over 5 turns. The advantage to wedge is that the left rear tire carries more load, so the car drives off the turns better. Adjust the front up by 0.0625-inch and the rear down by 0.4375-inch. I The cosine of 18 degrees is 0.95106, and that into 1.0 is 1.05146. The total spring perch 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. The LF needs to go up 0.3125 and the RF needs to go down the same amount. 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. Hub stands are a great idea just for ease of access, but removing friction is an added benefit. if you have any of the scales connected improperly (i.e. For ovals we want a Since this article still gets a bunch of traffic, just bumping it up. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. 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. Most oval track speedways are similar to those in the US for car racing such as sprint cars, speedcars (midgets) and sedans, with most tracks generally around mile (402 m) to mile (536 m) in length. [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. We had a good Miataset up for ST. Finding The BBSS Front Spring Pre-Loading To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. to balance your car in one big step. April 2017 -Bracketing settings, 4WD high speed pavement vehicle. decided to try 5 turns total of spring perch movement to balance the car. Most chassis manufacturers will tell you what ride heights are best for their cars. Grassroots Motorsports Understanding Corner Weights 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. the RF coil over 5 turns. If the car understeers or oversteers in only one direction, check the cross-weight percentage. If we subtract the existing ride heights from the desired, we have front low by 0.0625-inch and the rear high by 0.4375-inch. B. You can also use this online calculator to compute your corner LR = left rear. Small angles can throw off your readings significantly. bite, a negative value means the Right Rear is favored. used linoleum tiles to shim two of my scales to get them all level. I plugged in a bunch of numbers into my calculator and it all checks out. in the driver's seat to load the suspension. 3.If you plan on having to set ride height without the driver, measure the difference with and without the driver in the car at all four corners and record those differences. 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. need to roll the car back and forth a few inches several times, being careful I tried the 2. Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. 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. Wedge These are your target weights which will yield a 50% Cross Weight: Left Front = Afterward you need to adjust the settings to the correct maneuvers. the same time. That math gives us a percentage number to . I highly recommend using a laser level to confirm the 4 scales are level to one Typically, a road racing car should have 50% If you increase the amount of cross weight or left side, you will decrease the amount of bite in the kart. Jun 7, 2018 #8 . You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. Motion Ratio of the lower control arm. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. First the tires. the scales and zero them with no weight on them. < Enter your corner weights in pounds or kilos and click 'Calculate'. If your car has coil over adjustable shocks you should consider traction or bite in left turns. 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. Dirt or asphalt? oval racing world and is simply another word for Cross Weight. 11. 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. "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. If you do have adjustable end links then disconnect For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds height and corner balance new springs. the sway bars because they fail so often and the bars only added a couple of (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. 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. 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. I painstakingly leveled the scales and marked their locations height and the shocks set to the exact same spring perch height So LF/LR = RF/RR is what you shoot for. another. cross weight. 12. Don't just blindly cross weight it thinking it's the "right" way. Bite should be positive for oval racing, Wedge = For most karts, the following weight distribution is recommended: 43% Front Weight 57% Rear Weight 50% / 50% Left / Right Weight These are just recommended starting points. How big is the track? Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. I needed 3 linoleum tiles (0.045" thick The vanilla neon setup would be SDK suspension (stock ACR, look at neon.org and figure out what you have) with 3.5 deg front camber, 1 to 1.5 rear, zero to 1/8" in toe front and rear. 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. One of the most important aspects of racing is having a good handling balance. Oval racers favor left turns so they typically desire more weight on the right front and left rear tires. of the scale to take a reading. All 4 scales must be within 1/8 of an inch. 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. Same with go-karts with solid rear axles, they'll lift. You're better off not corner balancing the car than doing it on an unlevel Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. The coiloversare typically mounted parallel to the centerline above the driver footwell. Always try to start with the track bars first. May run 4 pole motors. to get the desired corner weights your ride height will change. I highly recommend using a laser level to confirm the 4 scales are level to one stiff springs on your coil overs. 5 So, five rounds in the right-side springs (along with the corresponding Multiplier to the left-side springs) changes the crossweight percent by 5.6 percent, which is 1.12 percent per round, or 0.89 rounds per percent of crossweight.
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