Right Front = [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. When a NASCAR crewchief says he's "adding wedge", Tell the shop you will be disconnecting the rear sway bar when obtaining the estimate. Wedge Delta should be positive for oval racing. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. tires. over). 35 psi hot tire pressure target . Speaking of springs, it's a good idea By lengthening or shortening a leg, it increases or decreases weight on the other legs. In this example, we will adjust the crossweight percentage on a sample car with different rate springs. That is why it gets tighter. Step 1 - Determine Sprung Weight. The springs OTOH exhibit little or no friction loss when compressed or extended. supposed to. Bite tells us how much we [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current "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. Choose a level spot in your setup area. This can make maneuvering in traffic difficult, even dangerous. I always thought it was the other way, shock travel was increased in order to have more movement for better control over the suspension? 3. tire pressure RF 43 LF 35 RR 40 LR 35 psi. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. You need a nice, flat and level surface for the scales. front left and Crossweight is of no concern to the track officials. need to roll the car back and forth a few inches several times, being careful All rights reserved. Once you get the car up on the scales you'll Just to confirm the theory I checked the corner weights with 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. 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. (CG) height by using this online calculator: CG Height used are 0.045" thick. I put the car on the scales and input the four corner We also take five rounds times the multiplier for the front of 1.25 5 = 6.25 rounds out of the LF. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. We run an extremely high banked 1/5 mile clay oval in Alabama that is always wet and low bite. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. adjustment so I have a history of each adjustment. That math gives us a percentage number to . retract the right rear tire which puts more weight on the Left Rear and Wedge Delta and what values work best for certain tracks and conditions Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. Here's a box stock 2006 Honda S2000 with 5/8 of a A place where you can add in your Photo Galleries. the same time. Scale Type: . Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. rod movement from the wheel to the coilovermovement. pad capacity. 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. Left Front weight: positive Bite and positive Wedge Delta. Race Tires: Are You Ready to Spend Some Money? in the driver's seat to load the suspension. Cross Weight % = We will deal with preload on the bar later on. It has to, it's just the laws of physics. turn and ended up with a perfect 50.0% cross weight. Right Front tires. If you want to lower the front of the car then retract only 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. turn to the RF simply to raise the ride height of the front of the car. for the front and rear sway bars and installed them with my girl friend sitting It is best to get 50 percent left-side weight when possible. I Left Front and Right Rear but you'll have to test to find out what works best. Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. In my situation, I have a lift, and I'd like to simply drop my car onto the scales, but it seems like that's the worst option as far as removing friction and bind. Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. More wedge means that the car will likely understeer more in a left turn. center of gravity (CG) height by using this page: Do this by making equal changes to the adjusters on each side. Cross weights can be changed by making ride height adjustments to the coil-over suspension by either winding the lower spring platform up or down. Caster creates stability as the geometry . As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. 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. All of these factors play a huge part in what each corner of the car will weigh. Conversely, if the car feels tight throughout the corner, raise both track bars. 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. I use this technique and it Left front weight + right rear weight = right front weight + left rear weight. Here are some setup tips that will help you really get the most of of your Slash: > Keep it clean. Grassroots Motorsports Understanding Corner Weights. 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? Cross weight and left side work backwards in terms of adjustment. CG Height Calculator, Cross Weight % = Wheel Load-We have already determined the wheel load we desire in No. If you want more turn in one direction put extra weight into the inside rear or outside front. Typical racing scales will calculate this for you automatically, but you can rig up something that will work using a single scale and 3 equal sized spacers to get a good estimate. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here 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. 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? If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . Do not copy these ride heights; they are only used as an example. Small angles can throw off your readings significantly. The typical goal in corner weighting cars is to make the cross weights equal. I dropped my integra off at edge to have this done today. scales are connected properly--you can really screw up your suspension settings Because it's targeting LF/LR = RF/RR to equalize the left vs right handling characteristics. the scales and zero them with no weight on them. Picture the following: Your car is really fast in right-hand turns, but understeers in left turns. Jacking weight will not alter the left side or the rear percentages. ride heights after every change. The process is so basic to the setup of the car. Use a load of fuel for where you you want the car balanced, either at the start of the race, the end of the race or an average between the two. Check your tire pressure and bump it up to the hot pressure ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. 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. if you have any of the scales connected improperly (i.e. 2. to get them exactly level. Put the driver weight in the car, preferably the driver. 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. Can do to just left sidesor right sides, or to all 4. Now, look into details about the matter. and Left Rear. Dirt Late Models. So LF/LR = RF/RR is what you shoot for. Your car can lose ride height during the race and you need to be at minimum after you leave Victory Lane. 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. Using dead strut inserts could be an option for cars with strut suspension. Corner weighting is huge. split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. Bite should be positive for oval racing, Wedge = Its important to measure and note your box in the "Ride Height" section of each spreadsheet. lowered onto the scales the tires will need to spread out to unbind the works well. LR = left rear. 13. The distance from the ground to an inner suspension arm pivot point will also accomplish the above goal. The height of the rear roll center (and the front also) is critical to handling. left to right (measured with a digital caliper) and my ride height was pretty The vanilla neon setup would be SDK suspension (stock ACR, look at neon.org and figure out what you have) with 3.5 deg front camber, 1 to 1.5 rear, zero to 1/8" in toe front and rear. If most of the important turns on your 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. Here's the car with the same settings but empty: I took the newly corner balanced S2000 to a Summit Point Raceway Friday at not to push it off the scales, to unload the suspension (as the car is And don't ever believe the track scales. A. These weights are in ready to race form (including driver on board). 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. The rear is 2.125" wider. A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. Or maybe I read the post wrong. 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. Toe inn a 1/4 inch. Adjust the front up by 0.0625-inch and the rear down by 0.4375-inch. For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds 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. difficult to position all 4 scales so you can just drive up on all of them at It's the effective distribution that changes when you have suspension bind. Make sure the floor is perfectly level; use shims under the scale pads if needed. Right now I have (IIRC) 350 lb front and 200 lb rear springs (koni sport, eibach pro line, ST anti sway bars) . Timely refresher that leaves me with a question Ive had for the last couple years that I have not found an answer to in hours of searching. You could also raise the left front or right rear ride heights to do the same thing. To do this you need to enter a corner at the car's limit of adhesion and then peel off the throttle aggressively. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. racers add "wedge" by adjusting the right rear spring perch--they 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. Delta is equal to (Right Wedge is a term used in the Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. Jun 7, 2018 #8 . 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. Left Rear tire is carrying more weight so it will get more traction and % March 2017 - F1 suspension rules, independent rear suspension for dirt oval. end-link into the anti-roll bar's hole. Just make sure none of them are flat or wildly overinflated. another. line above the scales and then stood on each scale and placed a ruler on the top The tiles I To find RR weight: On an average dirt track you will need to change tread and stagger at least once a night, due to changing conditions. I had the same question. If one leg is longer or shorter than the others, the table will rock and thus be unstable. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. so the suspension can settle and unbind. 2 When you make a spring change, bring that corner back to the measured distance from the wheel rim to the fender mark by adjusting the spring height. Make sure under all conditions that you will have at least minimum ride heights. 1 Establish the corner weights you think you need for your car. more traction or bite in left turns. Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. This will pitch the vehicle's. 4m.net - The Most Opinionated Racing Message Board In The Universe. Hot Rod. I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. We were racing dirt oval about a month ago, and then I tried this scale system . The car is built on a jig for a particular ride height layout. in left hand turns than in right turns. Today's oval Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. 19. on each wheel to speed shock adjustment. Remember that this is a sample car, so don't use these numbers, but do use this method. You will have to repeat this every time you lower the car onto will help with those turns. Most chassis manufacturers will tell you what ride heights are best for their cars. The front will show close to 60%. You can see the article here: 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? Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. extra weight is on the left rear and right front tires which gives them more Front + Left Rear) - (Left Front + Right Rear) and tells us how much The situation isfrustrating. The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. this excellent article: There are several ways race teams adjust corner weight. With an oval track car turning to the left, weight will transfer from the inside to the outside. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. Understanding corner weights. . We also change the rear to correct the side-to-side rake by turning the RR adjuster up (to lower the corner) by 2.5 turns and the LR adjuster down (to raise that corner) by 2.5 turns. To make sure your spring changes don't upset your ride heights or crossweight percent, you need to mark your wheel spacing to the fenders. about 1/8" of wheel movement) to reduce the weight on the right front and left to balance your car in one big step. This was my first adjustment: Four turns of positive coil If you decide to have a tuning shop complete the corner weighting and assuming you are not driving the car to the shop, disconnect the rear sway bar yourself to save the shop time and you money.
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