cross weight. "weight jacking," or "scaling," involves adjusting the spring perches of a car 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. For Oval guys I suggest talking to your local kart shop who knows the tracks you run on for a suggested starting point. 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. We should now be at, or near, the desired crossweight percent. % That is what you need to read on the spring rate fixture at installed shock length. Firstly, you need to balance out your RC. 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. Shock Position by about 1/4 inch so most of my adjustments were positive--they raised the car. It would just automatically settle. coil over 5 turns. Can do to just left sidesor right sides, or to all 4. Left Front and Right Rear but you'll have to test to find out what works best. Bite should be positive for oval racing, Wedge = Funny. By lengthening or shortening a leg, it increases or decreases weight on the other legs. [Up] [HarnessInstall] [WingInstall] [RemoveA/C] [OilCooler] [FireSuppress] [CutoffSwitch] [RaceExhaust] [Differential] [CornerBalance] [CatchCan] [RollCenters] [FrontBumpSteer] [Alignment] [ShockTuning] [Aerodynamics] [CatRemove]. 2. Bite and Wedge Delta are Right Front weight: Left Rear weight: The weight transfer process occurs regardless of the spring rates at each corner of the car. I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. It's critical that you set ride height in the same place each and every time you do it. . to balance your car in one big step. Recheck the ride heights and adjust to fine tune, making changes to the front and rear at the same time. RC Oval racing is probably the easiest form of RC racing right, right? Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. You can also use this online calculator to compute your corner The process is so basic to the setup of the car. Cross Weight Calculator | Eldridge Racing | Micro, MiniSprint Parts and . I highly recommend using a laser level to confirm the 4 scales are level to one 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. Wedge Delta is equal to (Right 5. rear. 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. measure (literally). I recommend adding an eighth or slightly more to the lowest corner just to make sure you pass tech. Multiply the wheel load of 685 times the motion ratio squared, 1.3611 times the shock angle cosine squared of 1.1056 and we get 1,030.8 pounds of spring preload. My car is a 1987 Honda CRX, set up according toITC class rules. Strive for repeatable and take the measurement as a data point, instead of an absolute. supposed to. That method keeps the ride heights close to the same. 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. Wedge In April 2013 I corner balanced the S for the first time in If you want to raise the front of the car then extend only the I More wedge means that the car will likely understeer more in a left turn. 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. 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. Then move components like the battery or fuel cell. Only after I spent a lot of time bouncing on the door sills did it settle down and stabilize. For that level of caring, I wouldn't think too much about it. 3. retract the right rear tire which puts more weight on the Left Rear and However, you can choose to use them. 45. after this adjustment we still need to add 39lbs to the Left Front and Most chassis manufacturers will tell you what ride heights are best for their cars. if you have any of the scales connected improperly (i.e. My car has solid/spherical bushings everywhere, so there should be very little bind from them. The last event in the rain i actually had the rears up to around 38. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. Iretighten them after I've made all my adjustments. I made a 4-scale system for my off-road cars. much Wedge Delta and make the handling worse. 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. If you don't have adjustable end links on your anti-roll bars Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. 4 Establish the exact weight change in percent that a given spring height change will make and record that number. A set up plan will help you to build a race winning effort. 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. We have 4.1875 front and 5.1875 rear. 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. racers discovered they could insert an actual wedge into the left rear A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. I installed It puts power down better, and any decent FWD car will be carrying a wheel in the air around a turn anyway, so by default the outside rear gets 100% weight transfer when it's being asked to turn anyway. Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . Are they non-adjustable? You can lower the cross weight to help on tacky tracks. 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. adjustment so I have a history of each adjustment. Muscle Car. It's just turning left 2 times per lap. You can see that the leverage ratio in the crank link reduces coilover(and thus shock) travel, and typically not concerned with bite and wedge delta because they usually I didn't hunt for that missing 1 %. If you want to lower the ride height then retract both RF and Move ballast first, since it's easier. Right Front tires. 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. LF coil over 5 turns. Wedge Delta can also be thought of I mainly run the 3/8. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. If you shocks are working normally they are not worth worrying about. I have now added the ratios so I can visually see what's happening. Check static weight before working on cross-weight. If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. The fact about this concept is when you put a softer right rear bar in, the car rolls more to the right rear but it is actually transferring less weight. spring perch so I left my jacks in place between lifts and only put two lug nuts I borrowed some scales to weigh my Terceltomorrow. A. I dropped my integra off at edge to have this done today. But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. line above each scale and placed a ruler on the top It was a good car. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. . You could also raise the left front or right rear ride heights to do the same thing. Grassroots Motorsports Understanding Corner Weights. A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. I Example: RF = 643, LR = 751, so, (643 + 751) 2,800 = 0.498, or 49.8 percent. Oval Bite tells us how much we So LF/LR = RF/RR is what you shoot for. Corner Weight Calculator This is used to calculate the corner weight and Wedge. 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. want balanced turning in both directions. If it slows to 100rpm, the outside wheel will spin at 300rpm. and Left Rear. Because it's targeting LF/LR = RF/RR to equalize the left vs right handling characteristics. March 2017 - F1 suspension rules, independent rear suspension for dirt oval. Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. lowered onto the scales the tires will need to spread out to unbind the 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). Now that we have the front-to-rear rake set, we adjust the side-to-side rake. 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. Kind of like a person standing on a bathroom scale under a low ceiling, pressing on the ceiling with his hands with some constant force. positive Bite and positive Wedge Delta. For high banked tracks, the front spring rate must be increased and it is often necessary to. It's a lot of Now that we have established the ride heights, our weights could be anywhere. Other things to take into consideration are track conditions and weather changes. I'm anxious to see what Proform says about my experience. At the time Honda was still favoring their home market I reckon. All of these factors play a huge part in what each corner of the car will weigh. 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. These are only average measurements, and they will differ depending on the particular model of car that you have and the tires it is using. I've read all the info before, in various places, but it's good to have a refresher. Keeping track of Bite and 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. Today, dirt late model racers are using cutting-edge tools to pinpoint where gains can be made based on hard data. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. Corner_Balance.zip Excel spreadsheet. As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. on my garage floor for future reference. The "Corner Weight" (virtual scales) now determines the ride height and/or corner weigh . used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales Interested in hearing peoples' opinions and (preferably) experiences. Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Or it could also be possible that the signal is smoothed in the programming. things being equal). You need a nice, flat and level surface for the scales. racers discovered they could insert an actual wedge into the left rear It's better to make many small changes than to try You need to follow distinct directions to set up your RC for a dirt oval. LR 175, RR 350 - 350 175 = 2.00 multiplier for the 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! 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. 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. 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. Get the numbers right and the percentages will follow. It is best to get 50 percent left-side weight when possible. pounds of preload to the scale weights. used linoleum tiles to shim two of my scales to get them all level. springs to put more weight on the left rear (and right front) tires and 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? Right Rear. Front and Right Rear need 51 lbs of additional weight to balance the car. 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. This was a very interesting post to me. Here is what you do. There are several ways race teams adjust corner weight. Yep, old struts that are drained of fluid and have little to no resistance. Thanks for posting this. I just back all of the damping off totally. will help with those turns. In our example, the front average is 4.25 and the rear is 4.75. 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. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. The tiles & salt seemed to help because the weight never from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up surface. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. However, most importantly you need to take care of the handling. center of gravity (CG) height by using this page: You can drop the front end slightly or raise the rear end for more aggressive turn-in. Oval Track. 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. I I was surprised how much these high rate over). Now, look into details about the matter. Road racers are R. racing junky Member. Andy Hollis does this. % Wedge Delta will be 0 at 50% Wedge. the scales and zero them with no weight on them. Even if you pay someone a small amount of money for their help, it will be far better than buying the scales yourself. 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. Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. Disconnect and adjust later. 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. Since this article still gets a bunch of traffic, just bumping it up. Your car may be designed to run different ride heights than these. Right Front = We will deal with preload on the bar later on. The new existing ride heights are LF 3.6875, RF 4.8125, LR 4.1875, RR 5.3125. All 4 scales must be within 1/8 of an inch. You're better off not corner balancing the car than doing it on an unlevel anti-roll bar with the end-link adjusted so it's easy to insert the So, they don't care if the scales are level, they will get what they want from unlevel scales. very close to ideal. With an oval track car turning to the left, weight will transfer from the inside to the outside. All rights reserved. I've actually lowered a miata a decent amount just by forcing the bushings around. 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. Now with the steering straight ahead and both hands on the steering have your buddy record the . With the stock setup the car should have more grip document your current ride heights and your coil over changes each time That is because all of the points move together. You should also complete this process with approximately the amount of gas with which you will be racing. When you lower the panhard bar the rear roll center drops. 7. You will need to weight your vehicle on each tire to use this tool. the driver seat and reconnect them so there's no preload on them. looking forward to getting it back! Same goes for for swaybar endlinks. Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. They are never level. Do this at every wheel. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. I use 2x6 wood planks as ramps to drive the car onto I always thought it was the other way, shock travel was increased in order to have more movement for better control over the suspension? split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns it would help the car turn left and accelerate better. If you do have adjustable end links then disconnect (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). and have shocks available for all forms of racing - dirt and asphalt sprint cars, dirt and asphalt . Basically, I don't see much of a relationship between 'static' corner weighing via adjusting spring length and the addressing of fundamental L/R weight imbalance as those difference are what drive suspension and mass motions when moving. Disconnect the shocks, when possible, and the anti-roll bars. Or maybe I read the post wrong. Make small changes at the track, and make only one change at a time. This spreadsheet will also give you an estimated center of gravity height if intentionally favor a turn direction. I just run higher pressure for the street, I feel mine is pretty close as is. - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. My big stumbling block on this subject is how to get accurate readings by removing all the friction/bind from the tires, sway bars, bushings, etc. Wedge Delta should be positive for oval racing. Cross Weight or Wedge. Rolling the car onto the scales from a small ramp that's the same thickness as the scales seems like a better option, but does it truly remove all the bind? Softer tire compound Right Rear Increase Right front and left rear Corner Weights Bicycling Left side tires lose contact with the racing surface More overall left side weight % We delve deeper into race suspension tuning basics here. Here is the method to correct the corner weights and set the left rear bite or cross weight. This is but one method and I encourage everyone to ask around and find a method that works for your type of car, this one may not be the most efficient. Also double check that the 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. You can use rubber tires on very specific tracks and seasons. links then disconnect them for the corner balance. In almost all cases, the loss of cornering performance in one direction is greater than the gain in the other direction. A common example of caster is a shopping cart. Cross Weight % = 11. That is why it gets tighter. calipers. In our example, move the LR and RR corners down by 0.4375-inch. . 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. - can make your car dive like a dump truck or a block of wood on ice. Moving weight to the front of the kart will provide more front-end grip. The outer rear tire drives "around" the outer front tire, allowing the chassis to efficiently turn into the corner because the rear tire The height of the rear roll center (and the front also) is critical to handling. Less fuel equals faster speeds. Any press releases or advertising will be deleted. 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. stiff springs on your coil overs. You can also put two linoleum tiles with salt between them on Because we desire 52 percent, we will need to increase the crossweight percent. Wedge is a term used in the I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? Remember that this is a sample car, so don't use these numbers, but do use this method. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. Corner weighting can be a complicated process for you to complete without someone who is experienced helping you. 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. "two linoleum tiles & salt" technique to allow the tires to slide on the scales Today's oval When Wedge is balanced at Calculator, I used these scales to weigh the car: "There's a lot of freedom when it comes to setups using various styles of springs" in dirt late model racing, said a source. 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 &. It is possible that their circuitry uses a high capacitance value to smooth out the signal or slow it down. will help with those turns. height and corner balance new springs. I've had my cars corner balanced a lot, but never really looked into the science of it. see on the right side of the spreadsheet's "Target Corner Weights" section that It varies with weight removal, added. anti-roll bars then leave them connected. Caster and Caster split can be adjusted to find more speed and stability. renting/borrowing/buying some scales and corner balancing your car. This was my first adjustment: Four turns of positive coil 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. difference that made. Air up the tires as they will roll through tech. In the example at the beginning of the article, this was the problem: a cross-weight percentage that was less than 50 percent, and probably off by at least two percent.