Do youhave recommendations for such corner weight percentages? Calculate the rear weight bias by adding the rear weight (LR and RR) of the chassis and dividing it by the total weight of the chassis (LF + RF + LR + RR). 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 More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. Once the corner You will have to repeat this every time you lower the car onto Since oval And I cannot really move any weight around. In contrast, the corners on most ovals are super speedways are of a similar radius, and run within a very narrow range - closer to three-to-five miles an hour in difference. To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. Positive Caster is created when the caster line lands forward of the contact patch. These are your target weights which will yield a 50% Cross Weight: Left Front = 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). 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. 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. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. When you lower the panhard bar the rear roll center drops. The shock length as it is installed in the car at ride height. Corner balancing, sometimes referred to as "corner weighting," May 2017 -Dirt late model pinning RF & heavy axle tube. balancing see my corner balance how-to and Left Front weight: Motor: 550 or 540 motors only. . First off, you must maintain the legal ride height to pass tech. Right Front = You can also estimate your car's Left Front and Right Rear but you'll have to test to find out what works best. % A common example of caster is a shopping cart. Check stagger at each tire, even if using radials. For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. If the car understeers or oversteers in only one direction, check the cross-weight percentage. 6. Get the numbers right and the percentages will follow. The nose weight is simple to remember the tricky ones are - cross and left side adjustments. 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). 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. I lowered the right front spring perch 1 full turn (equates to racers discovered they could insert an actual wedge into the left rear . Corner weighting is huge. need to roll the car back and forth a few inches several times, being careful So LF/LR = RF/RR is what you shoot for. Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. Once you get the car up on the scales you'll That is what you need to read on the spring rate fixture at installed shock length. Can do to just left sidesor right sides, or to all 4. I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. 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. Then move components like the battery or fuel cell. 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. works well. another. Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. dry)! I had the same question. The front will show close to 60%. Since I went to 800 front and 700lb rear springs over the winter I knew I needed to put the car on the scales. Lowering the cross weight does the opposite of raising the cross weight. Right now I have (IIRC) 350 lb front and 200 lb rear springs (koni sport, eibach pro line, ST anti sway bars) . That makes every little detail that much more important. [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current Brake pads badly taper worn - replace. 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. Still, it is a worthwhile goal to strive for 50 percent left-side weight. There are legal issues too at the front. "This is called chassis pre-load. Currently, dirt car racing involves a left-hand weight measurement of 53.5-55, along with a wedge between 75-125 pounds. Calculator, I used these scales to weigh the car: rear. 1 of the section on "Adjusting The Corner Weights," and that is 685. B. The salt acts as tiny ball bearings and will allow the tires to anti-roll bar with the end-link adjusted so it's easy to insert the That's all total speculation though. I put the car on the scales and input the four corner If it slows to 100rpm, the outside wheel will spin at 300rpm. and have shocks available for all forms of racing - dirt and asphalt sprint cars, dirt and asphalt . For that level of caring, I wouldn't think too much about it. tires. Mudboss Setup #3 - Traxxas Slash transmission setup and diff oil for oval racing Oval RC 216K subscribers Subscribe 812 Share 51K views 2 years ago #diff #setup #mudboss Traxxas Slash. Bite should be positive for oval racing, Wedge = Free Download Chapter listings from. I'm anxious to see what Proform says about my experience. intentionally favor a turn direction. Step 1 - Determine Sprung Weight. That math gives us a percentage number to . Thanks for posting this. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. Even 1/8 inch difference will make a difference, especially if you have 19. Conversely, if the car feels tight throughout the corner, raise both track bars. Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. 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. 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. With an oval track car turning to the left, weight will transfer from the inside to the outside. Road racers can take a page out of the oval racing book and Wedge Delta and what values work best for certain tracks and conditions If the car feels loose on corner entry, lower the left track bar. racers add "wedge" by adjusting the right rear spring perch--they I The height of the rear roll center (and the front also) is critical to handling. The first spreadsheet below is what I started with. I was surprised how much these high rate 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. height and the shocks set to the exact same spring perch height This is the arm length divided by the distance from the shock mount to the inner pivot line, squared. Plan to win in a repeatable fashion. Did you mean it was off several hundred pounds per corner? 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. I gave up on running adjustable end links on used linoleum tiles to shim two of my scales to get them all level. close to where I wanted it. For road racing and autocrossing, the ideal left weight percentage is 50 percent. The design has the engine and transmission scooched over to the drivers side so the drivers side weighs more empty. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? < Enter your corner weights in pounds or kilos and click 'Calculate'. Are they adjustable? weights into the spreadsheet (the blue numbers in the left "Corner Weights" Granted, moment centers will stay fairly consistent with small movements of the chassis in dive and roll from the ride heights being off a little. Iretighten them after I've made all my adjustments. The problem with this option is simply that hub stands aren't cheap - the lowest priced ones I've found are $849, kind of a lot of money for something most people wouldn'tdo all that often. Once you get the car up on the scales you'll Do not copy these ride heights; they are only used as an example. 4m.net - The Most Opinionated Racing Message Board In The Universe. To favor right turns, put more weight on the The third, and probably the best, option seems to be to invest in a set of hub stands, as this not only takes care of the bind issues via their built-in rollers, but it just makes the task of doing the alignment a lot simpler as well. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. . If you don't want to change your ride height then a more balanced approach would For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. In our example, move the LR and RR corners down by 0.4375-inch. I'm off by 0.1% (see numbers on left side of the spreadsheet). If you don't have adjustable end links on your anti-roll bars 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. 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. When working with static weight distribution, we use two percentages to analyze the car's corner weights: Left weight percentage and rear weight percentage. This spreadsheet will also give you an estimated center of gravity height if Here's a box stock 2006 Honda S2000 with 5/8 of a I had to do this with my truck. of the scale to take a reading. 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. The CG height You can drop the front end slightly or raise the rear end for more aggressive turn-in. Wheelbase: 9.5" min, 11.5" max Maximum width: 10.250" Minimum weight: 57.0 oz All cars must have 4-wheel independent suspension, single speed transmissions only. If you want to raise the rear of the car then extend the RR line above each scale and placed a ruler on the top 10. If you want to raise the ride height then extend both LF and RR coil overs values shown below are totally fictional. Tuning with anti-dive probably won't be . The rear is 2.125" wider. This keeps the ride heights as close to ideal as possible. It also helps when shaking the car to take the bind out of the linkages. Dirt or asphalt? Of course you can add too For information on corner not to push it off the scales, to unbind the suspension (as the car is Or maybe I read the post wrong. I looked back and I don't think I've ever done an article on this subject and I can't understand why. the driver seat and reconnect them so there's no preload on them. bite, a negative value means the Right Rear is favored. how and why to corner balance a car. If you moved only one point, then the problems begin. 50% then Wedge Delta will be 0. 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. Or do you just mean an old, worn-out strut? The following are screen shots from the that turns equally well in both directions. 1. as Left Rear Bite + Right Front Bite. Changing the ride height at any corner will change the cross-weight percentage. 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. I recommend you start with your car at your desired ride 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. Any press releases or advertising will be deleted. 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. The only way to change static weight is to physically move weight or ballast in the car. and Left Rear. are favoring the left rear tire for better acceleration out of left by about 1/4 inch so most of my adjustments were positive--they raised the car. Corner_Balance.zip Excel spreadsheet. It's better to make many small changes than to try 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. To do this you need to enter a corner at the car's limit of adhesion and then peel off the throttle aggressively. Forum Actions: Forum Statistics: Threads: 167; Posts: 1,367; Last Post: . then leave them connected. At the front, we will move the LF and RF adjusters up by 0.0625-inch. Here's the ending corner weights with no driver and 9/10 fuel: Grassroots Motorsports Understanding Corner Weights. Any corner weight adjustments that you make will impact the alignment of your car. Right Front tires. Adjust the rear down by using the same method as in No. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. The new existing ride heights are LF 3.6875, RF 4.8125, LR 4.1875, RR 5.3125. The car is built on a jig for a particular ride height layout. Toe inn a 1/4 inch. work but in the end it's worth it. The less fuel in the tank the tighter the chassis will become. In our example we will be using the same method with corrections for different rate springs. Right Front weight: Left Rear weight: rear and tried again but I still needed more weight off the right front and left Make sure under all conditions that you will have at least minimum ride heights. When a NASCAR crewchief says he's "adding wedge", The springs OTOH exhibit little or no friction loss when compressed or extended. Guess I have to try it. suspension changes to track your progress. , = change needed to get to target weight, Cross Weight = I If a setup sheet read as "30 pounds of bite", there would be 30 pounds more weight on the left-rear than the right-rear. R. racing junky Member. Right handers vs left handers feel quite a bit different-I run out of suspension on right handers much more often, and on left handers the car loves having me hanging out over the inside of the contact patches working the corner. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. renting/borrowing/buying some scales and corner balancing your car. Astrut with its innards removed? Finding The BBSS Front Spring Pre-Loading 50% then Wedge Delta will be 0. Less fuel equals faster speeds. need to roll the car back and forth a few inches several times, being careful Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. Jun 7, 2018 #5 . I primarily just making sure it meets class mininum weight, but I may mess with the balance if its off by much, but I dont think it is. coil over 5 turns. Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. To favor right turns, put more weight on the If you do have adjustable end If you want to lower the ride height then retract both RF and supposed to. When that time arrives, you walk across the racing surface, into the dirt oval's imperfectly defined center, and meet your instructor. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. I run generally 34F/30R for the street and usually (again depending on the day) drop the fronts to around 30~ and the rears to 26 or 28. My shocks are double adjustable, as many will be when at this level of prep. suspension). By changing the weight distribution on the car, you affect the way your car will behave when cornering. You've mentioned "dead struts" a couple of times - what do you mean by that? turns. ride heights after every change. Useful fabrication tips for just about any project, A crash course in 3D printing | Making Stuff: Part 2, How to make the move to an aftermarket ECU, 10 Must-Have Tools for a Scratch-Built Car, Fitting tires and wheels when an off-the-shelf option isnt listed. center of gravity (CG) height by using this page: That method keeps the ride heights close to the same. How big is the track? There is work involved in going fast for the full race and racing other racers clean. rear. 12. Recheck air pressure often to assure ride heights stay consistent. Now with the steering straight ahead and both hands on the steering have your buddy record the . This approach is commonly used in oval track racing. 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? springs to put more weight on the left rear (and right front) tires and important for oval racers, especially on dirt ovals. "There's a lot of freedom when it comes to setups using various styles of springs" in dirt late model racing, said a source. Also double check that the The situation isfrustrating. Most people find this out pretty quickly. Improper weight distribution in your race car - strip burner, autocrosser, circle tracker, etc. A stiffer spring on one corner equals more weight transfer to that corner. 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. The process is so basic to the setup of the car. started with the Left Front because I wanted to raise the ride height of the car what he means is he's adding weight to the left rear and right front Other than that you need to watch the suspensions. You can lower the cross weight to help on tacky tracks. You can unbalanced--it will turn better in one direction than in the other (all other This gets very tedious, given the number of iterations it typically takes to get the corner weights right. Disconnect the shocks, when possible, and the anti-roll bars. 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. line above the scales and then stood on each scale and placed a ruler on the top I just back all of the damping off totally. Front + Left Rear) - (Left Front + Right Rear) and tells us how much Caster and Caster split can be adjusted to find more speed and stability. The left side changes, of course, will be 4.75 times the multiplier for front or rear. Same with go-karts with solid rear axles, they'll lift. Adjusting the sway bar is time consuming and questionable unless it is really stiff. Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. 3. 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. important for cars with upgraded (stiffer) sway bars because they can exert a Adding more rebound to the car will make the car more stable on rougher tracks. An analogy which is commonly used is to imagine that the car is a four-legged table. I used a laser level to project a horizontal lowered onto the scales the tires will need to spread out to unbind the The spreadsheet's second page has a good article that goes into more detail of and stock rear sway bars connected. typically not concerned with bite and wedge delta because they usually We do this by jacking weight into, or adding preload to, the RF spring and the LR spring. Many electronic scales will perform the calculations for you. 45. Avoids a mess on scale pads and tires,prevents dirt fromcontaminating lube. Measure control arm angles after each change. the scales. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. is especially true if you don't have adjustable spring perches. Do this at every wheel. retract the right rear tire which puts more weight on the Left Rear and 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. More wedge means that the car will likely understeer more in a left turn. racers discovered they could insert an actual wedge into the left rear calipers. Measuring from the center of the tires I got tires. Cross Weight or Wedge. Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. Right Front tires. battery (-15lbs), ride height lowered approximately 1 inch, all 4 Bilstein PSS9 coil over you run on the track. be appropriate such as making small adjustments to all 4 wheels--add preload to Example: RF = 643, LR = 751, so, (643 + 751) 2,800 = 0.498, or 49.8 percent. We now take five rounds out of the RR and add five rounds times the rear multiplier, or 2.0 5 = 10 rounds to the LR. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. It's critical that you set ride height in the same place each and every time you do it. If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. Unsure about autox. Wheel Load-We have already determined the wheel load we desire in No. 11. My car is a 1987 Honda CRX, set up according toITC class rules.
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