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adjustment so I have a history of each adjustment. Yeah generally its the same stagger 9/10 times. Even 1/8 inch difference will make a difference, especially if you have ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. LR 175, RR 350 - 350 175 = 2.00 multiplier for the rear. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. If you want to lower the ride height then retract both RF and A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. 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 , = change needed to get to target weight, Cross Weight = Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. 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. Corner_Balance.zip, Excel Corner Balance Spreadsheet Screen Capture. Open timing on motor and esc. 45. 11. Ok sounds good. That is why it gets tighter. Unsure about autox. The new existing ride heights are LF 3.6875, RF 4.8125, LR 4.1875, RR 5.3125. For pure race cars this isnt a consideration. The outer rear tire drives "around" the outer front tire, allowing the chassis to efficiently turn into the corner because the rear tire turn to the RF simply to raise the ride height of the front of the car. as Left Rear Bite + Right Front Bite. Since I went to 800 front and 700lb rear springs over the winter I I always thought it was the other way, shock travel was increased in order to have more movement for better control over the suspension? If the car feels loose throughout the corner, lower both track bars evenly. That is why a stiffer right rear spring makes the car looser. A stiffer spring on one corner equals more weight transfer to that corner. We were racing dirt oval about a month ago, and then I tried this scale system . Picture the following: Your car is really fast in right-hand turns, but understeers in left turns. Wedge Delta is equal to (Right If you want more turn in one direction put extra weight into the inside rear or outside front. started with the Left Front because I wanted to raise the ride height of the car To find RF weight: Now that's pretty cool! That's all total speculation though. In this example, we will adjust the crossweight percentage on a sample car with different rate springs. 7. front left and more important corner balancing becomes. 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. You could also raise the left front or right rear ride heights to do the same thing. Some engines are used in two different classes with the only change being exhaust system. Cross-weight percentage compares the diagonal weight totals to the car's total weight. you weigh and adjust. May 2017 -Dirt late model pinning RF & heavy axle tube. as Left Rear Bite + Right Front Bite. the scales and zero them with no weight on them. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. In the old days when we ran close to equal springs at the front and at the rear, we could just put one round in the RF and one out of the LF, one in the LR and one out of the RR to put cross into the car. I was surprised how much these high rate You need to follow distinct directions to set up your RC for a dirt oval. Don't just blindly cross weight it thinking it's the "right" way. supposed to. Granted, moment centers will stay fairly consistent with small movements of the chassis in dive and roll from the ride heights being off a little. 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. 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? I'm not saying you get what you pay for with race scales but there is a reason I went with longacre. I use this technique and it . camber angle of the wheels (-3.5 front, -3 rear). The car should be at minimum weight, using ballast as needed to make the proper weight. If you do have adjustable end links then disconnect It would just automatically settle. Then just leave them attached. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. The nose weight is simple to remember the tricky ones are - cross and left side adjustments. Or do you just mean an old, worn-out strut? Tell the shop you will be disconnecting the rear sway bar when obtaining the estimate. 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. In order to perform the set up routine the car needs to be completely ready to race. I looked back and I don't think I've ever done an article on this subject and I can't understand why. Thanks. another. In contrast, the corners on most ovals are super speedways are of a similar radius, and run within a very narrow range - closer to three-to-five miles an hour in difference. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille However, most importantly you need to take care of the handling. 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. Avoids a mess on scale pads and tires,prevents dirt fromcontaminating lube. 2. My shocks are double adjustable, as many will be when at this level of prep. Softer Right Front and Right Rear Springs 10 lbs at a time Car Loose at Corner Exit Reduce stagger rear tires Raise the Front ride Height Move the Right rear tire in. Doing the multiplication to square that number, we get 1.1056. Setting static weight distribution and adjusting cross-weight percentage is one way to assure good handling. hard work but it makes all that high dollar suspension work together the way its The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. The roll center is an imaginary point around which the rear of the race car rolls. coil over 5 turns. However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. You can see in the "Target Corner Weights" section that the Left 1. and stock rear sway bars connected. (corner weights) instead of moving shims above / below spindle? Make sure the tires are centered on the scales. These are your target weights which will yield a 50% Cross Weight: Left Front = Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. If you want to raise the front of the car then extend only the Right Front weight: Left Rear weight: It is important that you complete the corner weighting process before doing an alignment. the same time. is especially true if you don't have adjustable spring perches. Corner weighting your car is First some baselines. So, we are not reinventing the wheel here, just refining the process. 9. With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. 19. Left Front and Right Rear but you'll have to test to find out what works best. 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. to get a balanced diagonal weight on the tires. Bite tells us how much we Prepare the car. In April 2013 I corner balanced the S for the first time in But this doesn't explain why the Vette's readings came in so well, while I had to jump up and down on my door sills quite a bit before my car's weight stabilized at its expected value. Do not adjust any other wheel's spacing. . right swapped). Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. Beyond that, if your bushingsand other parts bind on the scales then they're also going to bind out on the road, so who cares? The less fuel in the tank the tighter the chassis will become. The coiloversare typically mounted parallel to the centerline above the driver footwell. 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. Calculate the average front and rear desired ride heights. 57.5" front and 59.625" rear. Right Rear = The third, and probably the best, option seems to be to invest in a set of hub stands, as this not only takes care of the bind issues via their built-in rollers, but it just makes the task of doing the alignment a lot simpler as well. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). You need: 1. . Because we desire 52 percent, we will need to increase the crossweight percent. It also helps when shaking the car to take the bind out of the linkages. Adjust the cross weight for more extreme conditions or different circumstances. 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. 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. LF coil over 5 turns. No, not as in the law, but in being legal in tech. As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. If the person reduces the force with which he's pressing against the ceiling, the weight read by the scales will decrease. Delta which is simply the difference between the two diagonal tire weights. The total spring perch Now with the steering straight ahead and both hands on the steering have your buddy record the . 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. 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. I've read all the info before, in various places, but it's good to have a refresher. Recheck the ride heights and adjust to fine tune, making changes to the front and rear at the same time. Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. 13. suspension). I needed 3 tiles on the left front and 1 on the left rear (adsbygoogle = window.adsbygoogle || []).push({}); I still needed more weight on the Left Front and Right Rear so I added + 4 Step 1: Setup And Tuning The Tires Most regular RC cars use rubber tires. oval racing world and is simply another word for Cross Weight. Keeping track of Bite and 4. Here is a screenshot with some random-ass corner weights. 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. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. 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. Air up the tires as they will roll through tech. turns. I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. rear and tried again but I still needed more weight off the right front and left by about 1/4 inch so most of my adjustments were positive--they raised the car. Road racers are Motion Ratio of the lower control arm. This also coveys other advantages, the short shock travel means that it can be shorter and lighter. So, ride heights in the front are more critical for maintaining camber angles. This can make maneuvering in traffic difficult, even dangerous. Since the front and rear shocks are of different lengths you 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. Tuning with anti-dive probably won't be . Heres a. setup for a weekly show: 1. You can also use this online calculator to compute your corner "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. Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. that turns equally well in both directions. Once you get the car up on the scales you'll Shock Position 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? important for oval racers, especially on dirt ovals. If not, adjust the ring until you read that number and then you can install the spring in the car and be very close to the correct ride height. Check static weight before working on cross-weight. 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. Since this article still gets a bunch of traffic, just bumping it up. Calculate the average existing ride heights front and rear. 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 The other two corners will lose weight. 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. W. William18 New member. 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. upgrading our street stock suspension part 2 the rear end. They are not too suitable for racing and oval dirt cars. 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? 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). Basically - after you finish the set up routine, the car goes in the hauler. Make sure under all conditions that you will have at least minimum ride heights. "There's a lot of freedom when it comes to setups using various styles of springs" in dirt late model racing, said a source. A place where you can add in your Photo Galleries. I usually mark an even inch and write that inch number on the tape. 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. Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. I added the 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). 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. Other than that you need to watch the suspensions. Using dead strut inserts could be an option for cars with strut suspension. I plugged in a bunch of numbers into my calculator and it all checks out. 5. A. If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. So we turn the RF adjuster up (to lower that corner) 2.5 turns and the LF down (to raise that corner) 2.5 turns. When that time arrives, you walk across the racing surface, into the dirt oval's imperfectly defined center, and meet your instructor. You need a nice, flat and level surface for the scales. Bite tells us how much we If you know the front, side, and crossweight percentages, then you can calculate the numbers. decided to try 5 turns total of spring perch movement to balance the car. Oval racers favor left turns so they typically desire more weight on the right front and left rear tires. The SRM will determine the relative changes to the spring height adjusters for weight changes. Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. % Wedge Delta will be 0 at 50% Wedge. turns. I made a 4-scale system for my off-road cars. 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 most of the important turns on your Lowering the cross weight does the opposite of raising the cross weight. 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. Take your shock, compute the spring preload, and compress the shock/spring combo to the installed spring height in your spring rate fixture. Once the corner We run a fixed chassis meaning no suspension and the Briggs lo206 so we aren't sliding it around the corner but tracking almost like an asphalt Kart. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? scales. I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. Thanks for posting this. When I weigh my cars I try not too overthink all this binding stuff. adjustments were 1 turn to the right front and 3/4 turn to the left rear. The typical goal in corner weighting cars is to make the cross weights equal. For ovals we want a This spreadsheet will also give you an estimated center of gravity height if Speaking of springs, it's a good idea typically not concerned with bite and wedge delta because they usually I used a laser level to project a horizontal lot of force to the suspension. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil Right handers vs left handers feel quite a bit different-I run out of suspension on right handers much more often, and on left handers the car loves having me hanging out over the inside of the contact patches working the corner. And don't ever believe the track scales. Hot Rod. Additionally, it is much more difficult to change rear percentage much, since rear weight is mostly a design function. Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. racers only turn left we can balance the car for better grip in left Adjust the rear down by using the same method as in No. I lowered the right front spring perch 1 full turn (equates to Search for: A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. looking forward to getting it back! What you're saying makes sense, but I can't explain why it took so long for my car to settle into its final weight reading. 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. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. on the right front and left rear tires. For street cars it certainly can be. All of these measurements are widened by the TVW CWP FWP or, 2,800 0.52 0.51 = 685B. That is because all of the points move together. the driver seat and reconnect them so there's no preload on them. CG Height Calculator, Cross Weight % = Do youhave recommendations for such corner weight percentages? Always try to start with the track bars first. 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. Or use an automotive tuning shop. The angles are another way to set the suspension for the desired ride height and cross-weight percentage. Choose a level spot in your setup area. . Disconnect and adjust later. 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. Here's a box stock 2006 Honda S2000 with 5/8 of a To keep things clear I call this added LR/RF weight Wedge Moving weight to the front of the kart will provide more front-end grip. At the front, we will move the LF and RF adjusters up by 0.0625-inch. it would help the car turn left and accelerate better. Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. Leebo's Corner. Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. . If your car's diagonal corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. in the driver's seat to load the suspension. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. 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. A good starting point would be tank of gas. 4. 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. balance is complete put someone in the driver seat and reconnect the Check stagger at each tire, even if using radials. I used a laser level to project a horizontal We delve deeper into race suspension tuning basics here. 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. Left Front weight: In oval racing you always run more weight on the LR. And I cannot really move any weight around. Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. Proforms are cheap scales. 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). 6. On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. 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. Wedge bite, a negative value means the Right Rear is favored. If you don't have adjustable end links on your intentionally favor a turn direction. 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. 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. Drag Racing. Yep, old struts that are drained of fluid and have little to no resistance. For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. Using dead struts and lots of bearings will help. 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. There are many ways to corner balance a car. but tend too love the 1/2 miles.I just cant figure out a way too get these. 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. (CG) height by using this online calculator: CG Height This approach is commonly used in oval track racing. Did you mean it was off several hundred pounds per corner? 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. lowered onto the scales the tires will need to spread out to unbind the Adjusting the corner weights is how we establish the crossweight percent, or what is often referred to as the amount of bite, left rear weight, or wedge. I highly recommend using a laser level to confirm the 4 scales are level to one 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. Rock or bounce the car helps. 50% then Wedge Delta will be 0. 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 to right (measured with a digital caliper) and my ride height was pretty turning the front wheels to measure caster. - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. Here is the method to correct the corner weights and set the left rear bite or cross weight. for the front and rear sway bars and installed them with my girl friend sitting Both of these items will impact the cross weight of the car, and therefore they are important in the corner weighting process. 8 Read the ride heights as they exist. Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. Wedge is a term used in the Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. McMaster-Carr adjustable end links The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. On the one hand, I'd love to have my Supra corner weighted, just to see where it's at, see if there's room for improvement.