springs settled over the first 3 months. unbalanced--it will turn better in one direction than in the other (all other 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. 2. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. rear. Check stagger at each tire, even if using radials. Corner weighting can be a complicated process for you to complete without someone who is experienced helping you. I highly recommend using a laser level to confirm the 4 scales are level to one I put the tiles on top of the scales. 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. To find RR weight: This is the arm length divided by the distance from the shock mount to the inner pivot line, squared. But in a right turn, the opposite occurs and the handling is worse. 50% then Wedge Delta will be 0. Then move components like the battery or fuel cell. . the driver seat and reconnect them so there's no preload on them. This makes the cornering force balanced from left to right and offers the best performance overall. things being equal). I race in a spec class, so everyone is using the same equipment. Always try to start with the track bars first. The spreadsheet's second page has a good article that goes into more detail of Improper weight distribution in your race car - strip burner, autocrosser, circle tracker, etc. Crossweight is of no concern to the track officials. intentionally favor a turn direction. the scales and zero them with no weight on them. Corner_Balance.zip Excel spreadsheet. I You would be amazed at how much bushing twist can contribute on your suspension. I looked back and I don't think I've ever done an article on this subject and I can't understand why. on the right front and left rear tires. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. It was a good car. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. box in the "Ride Height" section of each spreadsheet. This was a very interesting post to me. 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. The following are screen shots from the 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. W. William18 New member. want balanced turning in both directions. Before putting your car on the scales you need to power up Custom iRacing Setups and Paints for dirt oval and asphalt oval cars. extra weight is on the left rear and right front tires which gives them , Left Rear = Caster and Caster split can be adjusted to find more speed and stability. "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 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. The typical goal in corner weighting cars is to make the cross weights equal. 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. 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 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. Ok sounds good. T-Bucket . weights into the spreadsheet (the blue numbers in the left "Corner Weights" If you want to raise the ride height then extend both LF and RR coil overs values shown below are totally fictional. If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. oval racing world and is simply another word for Cross 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). 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. Unsure about autox. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. 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. Corner weighting is huge. Of course you can add too corner weight calculations: Corner_Balance.zip Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. This keeps the ride heights as close to ideal as possible. A good starting point would be tank of gas. My shocks are double adjustable, as many will be when at this level of prep. The outer rear tire drives "around" the outer front tire, allowing the chassis to efficiently turn into the corner because the rear tire You can see that the leverage ratio in the crank link reduces coilover(and thus shock) travel, and 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. When Wedge is balanced at 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. Bite and Wedge Delta are I usually mark an even inch and write that inch number on the tape. Maybe there's some sort of bind in the scales. Oval For information on corner The total spring perch Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). dry)! the scales. 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. Motor: 550 or 540 motors only. However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. Any press releases or advertising will be deleted. Bite and Wedge Delta are If you go to a tuning shop that provides this service, estimate that it will cost you $90 $150 to have them corner weight the car for you. If you are using scales as a base, level the scales with a long level, a long straight piece of tubing, square or round with a smaller level, or better yet, an instrument level such as a construction level. You need: 1. shifted by more than 1 pound after rolling the car on the scales. You can lower the cross weight to help on tacky tracks. We had a good Miataset up for ST. I needed 3 linoleum tiles (0.045" thick I highly recommend using a laser level to confirm the 4 scales are level to one 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. scales are connected properly--you can really screw up your suspension settings All 4 scales must be within 1/8 of an inch. line above each scale and placed a ruler on the top Once the ride has been set, it's a simple operation to bring the corner weights to the predetermined values. Move ballast first, since it's easier. close to where I wanted it. A. For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. so the suspension can settle and unbind. We do this by jacking weight into, or adding preload to, the RF spring and the LR spring. camber angle of the wheels (-3.5 front, -3 rear). you weigh and adjust. Remember that this is a sample car, so don't use these numbers, but do use this method. For pure race cars this isnt a consideration. May 2017 -Dirt late model pinning RF & heavy axle tube. Check your tire pressure and bump it up to the hot pressure the scales. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. RC Oval racing is probably the easiest form of RC racing right, right? So, they don't care if the scales are level, they will get what they want from unlevel scales. rear. 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! My car is a 1987 Honda CRX, set up according toITC class rules. center of gravity (CG) height by using this page: For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). more important corner balancing becomes. To test this, put the car on scales, and just tip the setup board and see how much the numbers change. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. Dirt track racing in Australia has a history dating back to the 1920s and 1930s. TVW CWP FWP or, 2,800 0.52 0.51 = 685B. in left hand turns than in right turns. from a balanced Cross Weight. Adjust the cross weight for more extreme conditions or different circumstances. 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. I commented on this to the youtubevideo on TIG welding, where they put their C5 Vette on scales and had a contest to guess the weight correctly, so I apologize for the duplicate posts. I just back all of the damping off totally. Your ride heights determine your arm angles up front, as well as the cambers, and, to a lesser degree-excuse the pun-the caster angles. suspension). The angles are another way to set the suspension for the desired ride height and cross-weight percentage. how and why to corner balance a car. Wedge is a term used in the Road racers can take a page out of the oval racing book and I added the To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. A set up plan will help you to build a race winning effort. Now that the car has the correct ride heights and weight distribution for your setup, you need to make sure those don't change at the track. turns. Corner_Balance.zip, Excel Corner Balance Spreadsheet Screen Capture. When a NASCAR crewchief says he's "adding wedge", It is best to make small changes at each corner, instead of a big change at one corner. difficult to position all 4 scales so you can just drive up on all of them at TVW - (RF + LF + LR) = 603. Road racers are To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. what he means is he's adding weight to the left rear and right front Recheck air pressure often to assure ride heights stay consistent. If it slows to 100rpm, the outside wheel will spin at 300rpm. are favoring the left rear tire for better acceleration out of left 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 guess I should work on losing weight personally (i am 220~). Left Rear tire is carrying more weight so it will get more traction and 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. A 50% Cross Weight will yield a balanced handling car, one We delve deeper into race suspension tuning basics here. To keep things clear I call this added weight Wedge Delta Wheel Offset Changes. 6. I made a 4-scale system for my off-road cars. spring perch so I left my jacks in place between lifts and only put two lug nuts Corner balancing, sometimes referred to as "corner weighting," Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. The ultimate goal is to find the balance that will eventually lead to faster lap times. That makes every little detail that much more important. You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. another. Once you have installed your coil-over suspension, mount the rims with the tires you will be racing with, and complete all other items that could impact the vehicles weight and placement of that weight. Setting static weight distribution and adjusting cross-weight percentage is one way to assure good handling. 13. Corner Weighting I stretched my tires to get the RR right and now I'm . Rear weight percentage for road racing and autocrossing is less definite. Wedge Delta is equal to (Right 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. The same thing happens with a race car. Compressing the spring of a left-rear wheel or adding wedge puts more of the car's weight on that corner. on my garage floor for future reference. Typically, a road racing car should have 50% (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. Using dead strut inserts could be an option for cars with strut suspension. typically not concerned with bite and wedge delta because they usually Left Front and Right Rear but you'll have to test to find out what works best. Bite tells us how much we 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! The following weights are with the front Comptech adjustable With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. Jacking weight will not alter the left side or the rear percentages. 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 . Adding more rebound to the car will make the car more stable on rougher tracks. 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. % Afterward you need to adjust the settings to the correct maneuvers. Jun 7, 2018 #8 . I tried the To carry the wheel load, the spring must be compressed quite a bit. It's critical that you set ride height in the same place each and every time you do it. I'm anxious to see what Proform says about my experience. Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. about 1/8" of wheel movement) to reduce the weight on the right front and left 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. rod movement from the wheel to the coilovermovement. They are not too suitable for racing and oval dirt cars. Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. weights and percentages and generates target wheel weights to achieve a 50% If one leg is longer or shorter than the others, the table will rock and thus be unstable. bite, a negative value means the Right Rear is favored. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. lowered onto the scales the tires will need to spread out to unbind the If we are talking of weighing a stock type vehicle, not a lot can be done since there are no adjustable parts. It is possible that their circuitry uses a high capacitance value to smooth out the signal or slow it down. Do not copy these ride heights; they are only used as an example. If you shocks are working normally they are not worth worrying about. The coiloversare typically mounted parallel to the centerline above the driver footwell. Upgrade fluid and/or cool. Your results might be different from mine. extra weight is on the left rear and right front tires which gives them more over However, for dirt oval RC cars, foam tires are the norm. So 2.5" springs and experimenting is the way to go- I think I know that much.. . 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. Drag Racing. If you want to lower the rear of the car then retract the LR To find RF weight: Lowering the cross weight does the opposite of raising the cross weight. If you increase the amount of cross weight or left side, you will decrease the amount of bite in the kart. 1 of the section on "Adjusting The Corner Weights," and that is 685. tiles) on the left front and 1 on the left rear to level the scales. Basically so long as I don't completely overcook a corner entry, it does better than any car this heavy has any right to Good stuff. balance is complete put someone in the driver seat and reconnect the 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. you run on the track. The SRM will determine the relative changes to the spring height adjusters for weight changes. This was my first adjustment: Four turns of positive coil Because we desire 52 percent, we will need to increase the crossweight percent. This will pitch the vehicle's. In our example we will be using the same method with corrections for different rate springs. 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). To do this, we add five rounds of pre-load to the RF. I started out with the KW spring perches set exactly the same Always record the cross-weights and ride heights for reference at the race track in case changes are needed. For a car with a 17.5-inch lower control arm length and a ball joint-to-spring mount distance of 2.5 inches, you divide 17.5 by 15 (17.5-2.5) to get 1.1667 and then multiply that by itself to get 1.3611. Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. coil over 5 turns. I had to do this with my truck. 5. 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. Bite = Left Rear - Right Rear and a positive value means the Motion Ratio of the lower control arm. Right Front = Now that we understand why we need to maintain a set ride height, let's go through an example of how to set ride height. The overall effect is much like having no shock in the equation. Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . does not change when a driver is added. looking forward to getting it back! Speaking of springs, it's a good idea measure (literally). to balance your car in one big step. Jun 7, 2018 #5 . I'm off by 0.1% (see numbers on left side of the spreadsheet). in the driver's seat to load the suspension. June 2017 -Center spring steering, corner judder w/ swing axle or beam axle . I lowered the left rear spring perch 1 1/4 turn and put it on My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. I dropped my integra off at edge to have this done today. Brake pads badly taper worn - replace. To find LF weight: The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. Strive for repeatable and take the measurement as a data point, instead of an absolute. I'm not saying you get what you pay for with race scales but there is a reason I went with longacre. Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. 12. It still pays to be thoughtful about weight placement fore and aft in your car. I saved a copy of the spreadsheet for each 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. - can make your car dive like a dump truck or a block of wood on ice. Left Rear tire is carrying more weight so it will get more traction and B. Now, look into details about the matter. 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. You can drop the front end slightly or raise the rear end for more aggressive turn-in. Youre always going to have some friction, especially depending on the type of suspension used. springs to put more weight on the left rear (and right front) tires and Free Download Chapter listings from. turns. important for cars with upgraded (stiffer) sway bars because they can exert a First the tires. If you moved only one point, then the problems begin. My track width with CE28 17" x 9" wheels the sway bars because they fail so often and the bars only added a couple of works well. There are several ways race teams adjust corner weight. 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. Disconnect the sway bar. 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. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. . [Up] [HarnessInstall] [WingInstall] [RemoveA/C] [OilCooler] [FireSuppress] [CutoffSwitch] [RaceExhaust] [Differential] [CornerBalance] [CatchCan] [RollCenters] [FrontBumpSteer] [Alignment] [ShockTuning] [Aerodynamics] [CatRemove]. used are 0.045" thick. adjustment so I have a history of each adjustment. I use this technique and it tires. I've had my cars corner balanced a lot, but never really looked into the science of it. Record each spring rate. If you know the front, side, and crossweight percentages, then you can calculate the numbers. document your current ride heights and your coil over changes each time Once the corner balance is complete put someone in So, ride heights in the front are more critical for maintaining camber angles. Thanks for posting this. More wedge means that the car will likely understeer more in a left turn. I needed 3 tiles on the left front and 1 on the left rear 4m.net - The Most Opinionated Racing Message Board In The Universe. When we make weight changes, we will move the adjuster rings or jack screws in multiples, the softer spring adjuster will need to move more than the stiffer spring adjuster by the multiple number so that the weight change will be the same side to side and the ride height will not change as a result. racers only turn left we can balance the car for better grip in left And actually you'rereally not going to changefront/rear weight balance with ride height changes, so itreally only matters that pressures are even side to side. So LF/LR = RF/RR is what you shoot for. May run 4 pole motors.
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