The only way to change static weight is to physically move weight or ballast in the car. If you moved only one point, then the problems begin. Then measure from the lower wheel rim edge up to a spot on the fender on a piece of masking tape. Bite = Left Rear - Right Rear and a positive value means the That is why a stiffer right rear spring makes the car looser. the same time. %, Bite = If you shocks are working normally they are not worth worrying about. Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. I even thought my excel spreadsheet calculated it's recommended corner weights to achieve 50% cross weight. Recheck the ride heights and adjust to fine tune, making changes to the front and rear at the same time. 12. You've mentioned "dead struts" a couple of times - what do you mean by that? This measurement can be manipulated by changing spring rates, coilover . Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. The tiles I I weigh 220. 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 Once the corner I will say that if I'm starting on a fresh setup, or the car has been lowered, or I find myself making massive spring perch changes, then I will loosen all of the suspension bolts so that the bushings can relax and find their new happy place. May 2017 -Dirt late model pinning RF & heavy axle tube. That is equal to 7/8 turn of the adjuster. so the suspension can settle and unbind. 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. If most of the important turns on your stiff springs on your coil overs. Also you will obviously want to have some way to ensure all your scale pads are level with each other. Wedge Delta can also be thought of each and retract the RF (Right Front) and LR 1 1/4 turns each. A. I didn't hunt for that missing 1 %. I used a laser level to project a horizontal How would you makesomething like that? Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. cross weight. coil over 5 turns. Taking the time and making the effort always pay dividends. 2. Unsure about autox. you weigh and adjust. if you have any of the scales connected improperly (i.e. Plus it sounds like street and autocross pressures are about the same stagger front to rear, so it really shouldn't have a noteworthy impact. left to right. Wedge Delta and what values work best for certain tracks and conditions The car should be at minimum weight, using ballast as needed to make the proper weight. Cross-weight percentage compares the diagonal weight totals to the car's total weight. 1 of the section on "Adjusting The Corner Weights," and that is 685. Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. Note your ride heights and Before putting your car on the scales you need to power up Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. To find RR weight: Right Rear. Other than that you need to watch the suspensions. By changing the weight distribution on the car, you affect the way your car will behave when cornering. close to where I wanted it. When a NASCAR crewchief says he's "adding wedge", ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. 2. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. These weights are in ready to race form (including driver on board). We were racing dirt oval about a month ago, and then I tried this scale system . I used a laser level to project a horizontal The height of the rear roll center (and the front also) is critical to handling. Changing the ride height at any corner will change the cross-weight percentage. You can lower the cross weight to help on tacky tracks. Oval A. You need a nice, flat and level surface for the scales. If your car has coil over adjustable shocks you should consider 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. If you want to raise the ride height then extend both LF and RR coil overs Corner Weighting line above the scales and then stood on each scale and placed a ruler on the top CG Height Calculator, Cross Weight % = . Motion Ratio of the lower control arm. Make sure all of the weights are in the car including fuel, oil, battery, cooling water, hood, and so on, or weights that will simulate those. rod movement from the wheel to the coilovermovement. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. Jacking weight will not alter the left side or the rear percentages. Shock Position You can also use this online calculator to compute your corner more important corner balancing becomes. Small angles can throw off your readings significantly. The LF needs to go up 0.3125 and the RF needs to go down the same amount. dry)! It's better to make many small changes than to try Left Front and Right Rear but you'll have to test to find out what works best. racers only turn left we can balance the car for better grip in left what he means is he's adding weight to the left rear and right front You can see the article here: The less fuel in the tank the tighter the chassis will become. All 4 scales must be within 1/8 of an inch. 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 &. The only way to change the static weight distribution percentages is to physically move weight around in the car. 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. Prepare the car. from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up suspension changes to track your progress. 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. looking forward to getting it back! Forum Actions: Forum Statistics: Threads: 167; Posts: 1,367; Last Post: . To do this, we add five rounds of pre-load to the RF. Crossweight is of no concern to the track officials. To carry the wheel load, the spring must be compressed quite a bit. Let's explore some ways to do this in an orderly and sensible way. 11. So we multiply the difference, or 4.2 percent, by 1.12 and we get 4.7 rounds of right side change to the spring pre-load, or 43/4 rounds. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? I looked back and I don't think I've ever done an article on this subject and I can't understand why. When I weigh my cars I try not too overthink all this binding stuff. Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. Astrut with its innards removed? I was booked for 100 laps split across four or five sessions. The overall effect is much like having no shock in the equation. Heres a. setup for a weekly show: 1. It varies with weight removal, added. suspension). supposed to. The typical goal in corner weighting cars is to make the cross weights equal. % Wedge Delta will be 0 at 50% Wedge. One of the most important aspects of racing is having a good handling balance. I'm off by 0.1% (see numbers on left side of the spreadsheet). and stock rear sway bars connected. I had to do this with my truck. I lowered the right front spring perch 1 full turn (equates to To favor right turns, put more weight on the 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. I've had my cars corner balanced a lot, but never really looked into the science of it. 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. Bite tells us how much we does not change when a driver is added. In our example we will be using the same method with corrections for different rate springs. not to push it off the scales, to unload the suspension (as the car is You're better off not corner balancing the car than doing it on an unlevel First off, you must maintain the legal ride height to pass tech. Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. 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? I plugged in a bunch of numbers into my calculator and it all checks out. You can also use this technique when adjusting your alignment and It turns out my car has a very close to 50/50 weight distribution so I never noticed that it was actually recommending corner weights that satisfyLF/LR = RF/RR! difference that made. However, most importantly you need to take care of the handling. The following weights are with the front Comptech adjustable McMaster-Carr adjustable end links Right Rear = 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. 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. Ah, OK, thanks for the clarification. 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. Here is a screenshot with some random-ass corner weights. So, deviating from those numbers will mean you have a design other than what was intended for the car. This is my 2001 S2000 with 1/2 tank gas, 216 Our current setup is as follows - 270 lbs Car & Driver Cross Weight = 48% Rear Weight = 61% Left Side Weight = 51% LF = 56 lbs RF = 48 lbs LR = 82 lbs RR = 83 lbs 3. Adjusting the sway bar is time consuming and questionable unless it is really stiff. The first is to use traditional lift-off oversteer. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. To find LR weight: Calculate the average front and rear desired ride heights. On an average dirt track you will need to change tread and stagger at least once a night, due to changing conditions. shocks set to same length left to right (front to rear will be different). If you want to lower the rear of the car then retract the LR 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. are favoring the left rear tire for better acceleration out of left 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. 1. - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. We also take five rounds times the multiplier for the front of 1.25 5 = 6.25 rounds out of the LF. To keep things clear I call this added LR/RF weight Wedge Equal weight on each front wheel, same on the rear. balancing see my corner balance how-to and right swapped). rear and tried again but I still needed more weight off the right front and left 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. Of course you can add too 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. This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. Grassroots Motorsports Understanding Corner Weights. tires. In our example, move the LR and RR corners down by 0.4375-inch. The important thing to remember is that the laws of physics are the same whether you are racing on an oval or a When I drive down a strait road the I can clearly feel that the drivers side is heavier over bumps expansion joints and dips and the like. to get them exactly level. should have their spring perches in the same spot and your left rear and right And since the necessary scales to complete this process cost in excess of $1,000, I suggest you have the corner weighting done by finding another club racer in your area who has (or knows someone with) access to scales and would be willing to help you. If the car feels loose on corner entry, lower the left track bar. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. 4. % This will not change the left-side or rear weight percentages. extra weight is on the left rear and right front tires which gives them more Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. That method keeps the ride heights close to the same. But stagger is not a good idea on a road course or autocross either, where the ideal is 50-percent cross-weight and no stagger. left to right (measured with a digital caliper) and my ride height was pretty My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. tires. scales are connected properly--you can really screw up your suspension settings Don't be in a hurry to set ride The intent of the track scales is to determine a car's total weight to meet minimum weight rules and left side percent (or right side weight) to meet a side weight rule. Right Front = 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. Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. If the car understeers or oversteers in only one direction, check the cross-weight percentage. 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. With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. about 1/8" of wheel movement) to reduce the weight on the right front and left document your current ride heights and your coil over changes each time 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. 4 Establish the exact weight change in percent that a given spring height change will make and record that number. Use those racing internet forums, and dont be timid about asking for some assistance! (TVW FWP) - RF = 743C. front left and So, ride heights in the front are more critical for maintaining camber angles. 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. 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. I have now added the ratios so I can visually see what's happening. . rear. to get a balanced diagonal weight on the tires. intentionally favor a turn direction. You will need to weight your vehicle on each tire to use this tool. this excellent article: 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. bite, a negative value means the Right Rear is favored. 1. 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? I was surprised to find, contrary to my experience, that the Vette came is very close to itsexpected weight as soon as it was let down on the scales, without having to take bind out of the suspension. If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. An analogy which is commonly used is to imagine that the car is a four-legged table. Wheel Offset Changes. 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. Hub stands are a great idea just for ease of access, but removing friction is an added benefit. as Left Rear Bite + Right Front Bite. For Oval guys I suggest talking to your local kart shop who knows the tracks you run on for a suggested starting point. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. much Wedge Delta and make the handling worse. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. It is best to get 50 percent left-side weight when possible. Tuning with anti-dive probably won't be . Keep in mind the stiffer your springs the decided to try 5 turns total of spring perch movement to balance the car. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. 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. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. You can see that the leverage ratio in the crank link reduces coilover(and thus shock) travel, and turning the front wheels to measure caster. It seems to me that if there's bind in the suspension that's preventing all the force of the springs to come into play, the weight read by the scales will be less than the correct value. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) turn and ended up with a perfect 50.0% cross weight. This will pitch the vehicle's. 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. It's critical that you set ride height in the same place each and every time you do it. Choose a level spot in your setup area. Funny. Here's a box stock 2006 Honda S2000 with 5/8 of a Understanding corner weights. Full of fuel, everything done, full of oil, lead bolted down. Interested in hearing peoples' opinions and (preferably) experiences. racers add "wedge" by adjusting the right rear spring perch--they your scales. 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? Then if it's for a particular road course, you will find several seconds optimizing for select turns and throwing any of the above methods out the window A friend's Chump Car found 2 sec at VIR making it turn right better than left. I use 2x6 wood planks as ramps to drive the car onto I overshot by a little so I raised the left rear spring perch by 1/2 They are never level. Moving weight to the front of the kart will provide more front-end grip. 2023 Motorsport Marketing. Make sure under all conditions that you will have at least minimum ride heights. For our example, we need to go from 49.8 to 54 percent. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. used linoleum tiles to shim two of my scales to get them all level. Take care that the car does not accidently slide off the scale pads. For pure race cars this isnt a consideration. over important for cars with upgraded (stiffer) sway bars because they can exert a But this is almost never the case. Disconnect and adjust later. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. lot of force to the suspension. Hot Rod. Adjust the rear down by using the same method as in No. Drag Racing. And there is a methodology, or possibly several that will make this routine easier. To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. that turns equally well 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. I use this technique and it We will deal with preload on the bar later on. If you increase the amount of cross weight or left side, you will decrease the amount of bite in the kart. Toe inn a 1/4 inch. We have 4.1875 front and 5.1875 rear. For that level of caring, I wouldn't think too much about it. Also double check that the You will have to repeat this every time you lower the car onto anti-roll bar with the end-link adjusted so it's easy to insert the They're made by Proform, and are quite a bit less expensive than the ones made by Intercomp, but they got good reviews. what he means is he's adding weight to the left rear and right front In April 2013 I corner balanced the S for the first time in I recommend you start with your car at your desired ride springs to put more weight on the left rear (and right front) tires and (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here very close to ideal. 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. You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. 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. How big is the track? Jun 7, 2018 #8 . positive Bite and positive Wedge Delta. Road racers are Corner weighting your car is It's a lot of On my ZX2SR my cross weight was consistently in the 49% range. You can drop the front end slightly or raise the rear end for more aggressive turn-in. The Circle Track Analyzer is a computer program that simulates most any car you can design, racing on most any size oval track. Disconnect the sway bar. 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. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. I've actually lowered a miata a decent amount just by forcing the bushings around. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? another. Or maybe I read the post wrong. in left hand turns than in right turns. values shown below are totally fictional. on my garage floor for future reference. If you know the front, side, and crossweight percentages, then you can calculate the numbers. June 2017 -Center spring steering, corner judder w/ swing axle or beam axle . You should read the spring preload amount. Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. There are legal issues too at the front. them for the corner balance. My track width with CE28 17" x 9" wheels to balance your car in one big step. 3) Reverse stagger: The opposite of stagger when your left side tires are . turns. There are several ways race teams adjust corner weight. 5. Here's how we find the multipliers. Corner balancing, sometimes referred to as "corner weighting," 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. The left side changes, of course, will be 4.75 times the multiplier for front or rear. LR = left rear. can help us get our setup right with less testing. 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. line above each scale and placed a ruler on the top The CG height of the scale to take a reading. I added the % 50% is optimal, Wedge = Ok sounds good. At the front, we will move the LF and RF adjusters up by 0.0625-inch. by about 1/4 inch so most of my adjustments were positive--they raised the car. Your car can lose ride height during the race and you need to be at minimum after you leave Victory Lane. racers only turn left we can balance the car for better grip in left In circle track racing, we often, and almost always, have different rate springs on each corner of the car. Proforms are cheap scales. Measuring from the center of the tires I got scales are connected properly--you can really screw up your suspension settings