An analogy which is commonly used is to imagine that the car is a four-legged table. Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. line above each scale and placed a ruler on the top Finding The BBSS Front Spring Pre-Loading 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. The driver is optional based on No. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. Crossweight is of no concern to the track officials. you don't use Microsoft Excel. 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. The height of the rear roll center (and the front also) is critical to handling. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? turns. You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. 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. 1 of the section on "Adjusting The Corner Weights," and that is 685. Did you mean it was off several hundred pounds per corner? Or use an automotive tuning shop. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. retract the right rear tire which puts more weight on the Left Rear and Many electronic scales will perform the calculations for you. Battery: 2 cell lipo max They kept saying that it would go anywhere on the track and anywhere they pointed it. per wheel. Wedge Delta can also be thought of Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . 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 lowered the right front spring perch 1 full turn (equates to Still, it is a worthwhile goal to strive for 50 percent left-side weight. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. difficult to position all 4 scales so you can just drive up on all of them at I tried the %, Bite = In this example, we will adjust the crossweight percentage on a sample car with different rate springs. 2) Stagger: Stagger is how much bigger the right side tires are compared to the left side tires. If your car has coil over adjustable shocks you should consider you weigh and adjust. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. 50% then Wedge Delta will be 0. If the car understeers or oversteers in only one direction, check the cross-weight percentage. A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. The rear weight percentage is found in a similar manner: Add the LR and the RR weight together and divide the sum by the total weight. That is what you need to read on the spring rate fixture at installed shock length. For ovals we want a and measured between the outside bottom rim edge is 67.75" front and 69.875" If you moved only one point, then the problems begin. These are your target weights which will yield a 50% Cross Weight: Left Front = 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. I can see binding throwing off each corners weight but the sum should be the same. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. stiff springs on your coil overs. Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe scales. LR = left rear. Ok sounds good. not to push it off the scales, to unbind the suspension (as the car is Cross weight and left side work backwards in terms of adjustment. 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. Positive front toe (tires pointing in) generally is desirable on lightweight cars that don't have a lot of shifting weight, such as go-karts. You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. 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. 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. This gets very tedious, given the number of iterations it typically takes to get the corner weights right. That math gives us a percentage number to . Now that's pretty cool! We will deal with preload on the bar later on. % 50% is optimal, Wedge = W. William18 New member. 6. important for cars with upgraded (stiffer) sway bars because they can exert a Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. It is best to get 50 percent left-side weight when possible. For information on corner Before putting your car on the scales you need to power up this excellent article: - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. Take the cosine of that angle, divide it into 1.0 and then square it, or multiply it by itself. be appropriate such as making small adjustments to all 4 wheels--add preload to My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. Cross Weight Calculator | Eldridge Racing | Micro, MiniSprint Parts and . The spreadsheet's second page has a good article that goes into more detail of If you raise the ride height at a given corner (put a turn in or add a round of wedge), the weight on that corner will increase, as will the weight on the diagonally opposite corner. you run on the track. Adjust the rear down by using the same method as in No. I 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. In our example it is 18 degrees. The distance from the ground to an inner suspension arm pivot point will also accomplish the above goal. I overshot by a little so I raised the left rear spring perch by 1/2 (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here few inches several times on the scales before each reading though just for good 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. 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. racers add "wedge" by adjusting the right rear spring perch--they A good starting point would be tank of gas. If most of the important turns on your 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. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. Note the "Conditions and Changes Made" I had the same question. Set them to hot pressures is the norm as I understand it. Right now I have (IIRC) 350 lb front and 200 lb rear springs (koni sport, eibach pro line, ST anti sway bars) . of its weight on the Left Front and Right Rear tires, and 50% on the Right Front Caster creates stability as the geometry . rear. as Left Rear Bite + Right Front Bite. Also double check that the With my KWV3 shocks I had to remove the wheel to adjust the 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 % Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. % Wedge Delta will be 0 at 50% Wedge. 8 Read the ride heights as they exist. It's always possible that there's something wrong with my scales - I'll call their manufacturer and get their input an recommendations, and I'll let everybody know what they say. Road racers are To increase rear weight, move weight as far back as possible. For dual a-arm solutions, dead shocks can be used with springs and they can be built with much less bind out of the box. Here is a screenshot with some random-ass corner weights. in left hand turns than in right turns. turns. 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). right swapped). Make small changes at the track, and make only one change at a time. 1) Tweak: Tweak is the amount of weight on the LR as opposed to the RR. More wedge means that the car will likely understeer more in a left turn. Corner weighting your car is Any corner weight adjustments that you make will impact the alignment of your car. 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. to get a balanced diagonal weight on the tires. are favoring the left rear tire for better acceleration out of left Currently, dirt car racing involves a left-hand weight measurement of 53.5-55, along with a wedge between 75-125 pounds. Equal weight on each front wheel, same on the rear. Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. Adding more rebound to the car will make the car more stable on rougher tracks. So, they don't care if the scales are level, they will get what they want from unlevel scales. rear. , Left Rear = Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. However, most importantly you need to take care of the handling. Only after I spent a lot of time bouncing on the door sills did it settle down and stabilize. Proforms are cheap scales. I was booked for 100 laps split across four or five sessions. Dirt or asphalt? 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. if you have any of the scales connected improperly (i.e. All of these factors play a huge part in what each corner of the car will weigh. Changing the ride height at any corner will change the cross-weight percentage. it would help the car turn left and accelerate better. Oval Track. started with the Left Front because I wanted to raise the ride height of the car The typical goal in corner weighting cars is to make the cross weights equal. 45. Delta is equal to (Right My track width with CE28 17" x 9" wheels need to roll the car back and forth a few inches several times, being careful want balanced turning in both directions. You will need to weight your vehicle on each tire to use this tool. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. Since the front and rear shocks are of different lengths you If most of the important turns on your %Right Weight = 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. I guess I should work on losing weight personally (i am 220~). Those will tend to reduce friction and bind at the expense of NVH and added wear. Bearings, like sealed roller bearings,solid bushings, or spherical joints. Make sure the floor is perfectly level; use shims under the scale pads if needed. supposed to. 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. suspension changes to track your progress. 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. For pure race cars this isnt a consideration. 2023 Motorsport Marketing. can help us get our setup right with less testing. . To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. It was a good car. Classic Truck. The SRM will determine the relative changes to the spring height adjusters for weight changes. Drag Racing. measure (literally). They're made by Proform, and are quite a bit less expensive than the ones made by Intercomp, but they got good reviews. This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. Do this by making equal changes to the adjusters on each side. turns. That method keeps the ride heights close to the same. the front ramps then jack up the rear and lower it onto the rear scales. If you get the car neutral in left turns, it oversteers in right turns.