You will need to weight your vehicle on each tire to use this tool. pad capacity. Still, it is a worthwhile goal to strive for 50 percent left-side weight. turns. When Wedge is balanced at The SRM will determine the relative changes to the spring height adjusters for weight changes. 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. They are not too suitable for racing and oval dirt cars. camber angle of the wheels (-3.5 front, -3 rear). Picture the following: Your car is really fast in right-hand turns, but understeers in left turns. Why? 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. the scales. On dirt cars, both rear corners can move quite a bit, so the link angles on both sides are important. So LF/LR = RF/RR is what you shoot for. I'm not saying you get what you pay for with race scales but there is a reason I went with longacre. Determine your ride heights. Right Front tires. 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. ride heights after every change. The roll center is an imaginary point around which the rear of the race car rolls. The other two corners will lose weight. Here's the car with the same settings but empty: I took the newly corner balanced S2000 to a Summit Point Raceway Friday at things being equal). 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. then leave them connected. A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. Front and Right Rear need 51 lbs of additional weight to balance the car. I race in a spec class, so everyone is using the same equipment. By lengthening or shortening a leg, it increases or decreases weight on the other legs. I found that the tire will absorb side loads quite well and was repeatable. turns. Even 1/8 inch difference will make a difference, especially if you have Afterward you need to adjust the settings to the correct maneuvers. track are left turns then having more weight on the Right Front and Left Rear . 3. can help us get our setup right with less testing. April 2017 -Bracketing settings, 4WD high speed pavement vehicle. 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. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. which is simply the difference between the two diagonal tire weights. Road racers can take a page out of the oval racing book and much Wedge Delta and make the handling worse. On my ZX2SR my cross weight was consistently in the 49% range. Note the "Conditions and Changes Made" We were racing dirt oval about a month ago, and then I tried this scale system . 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. Guess I have to try it. A 50% Cross Weight will yield a balanced handling car, one MuddBoss Feature Winner at Dirt Devils RC Speedway, 12-18-2021. Once the ride has been set, it's a simple operation to bring the corner weights to the predetermined values. 2. Grassroots Motorsports Understanding Corner Weights. 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. For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. 2023 Motorsport Marketing. "weight jacking," or "scaling," involves adjusting the spring perches of a car Battery: 2 cell lipo max When a NASCAR crewchief says he's "adding wedge", Wedge Delta should be positive for oval racing. 10. I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. 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. 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. split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. Prepare the car. coil over 5 turns. the RF coil over 5 turns. Adjust the front up by 0.0625-inch and the rear down by 0.4375-inch. and without me in the driver seat and yup, the theory is right--the cross weight 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). Caster creates stability as the geometry . One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. To find RF weight: Corner_Balance.zip Excel spreadsheet. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. You can also estimate your car's If you get the car neutral in left turns, it oversteers in right turns. 3. tire pressure RF 43 LF 35 RR 40 LR 35 psi. To favor right turns, put more weight on the Here's how we find the multipliers. typically not concerned with bite and wedge delta because they usually 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. Cross-weight percentage compares the diagonal weight totals to the car's total weight. 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. February 2017 -Suspension design process. If you don't want to change your ride height then a more balanced approach would 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. Or do you just mean an old, worn-out strut? First the tires. section). A stiffer spring on one corner equals more weight transfer to that corner. Toe inn a 1/4 inch. One of the most important aspects of racing is having a good handling balance. 7. 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. 2 coils cut off springs 4 corners. you run on the track. I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. Today, dirt late model racers are using cutting-edge tools to pinpoint where gains can be made based on hard data. adjustment so I have a history of each adjustment. Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. on my garage floor for future reference. When working with static weight distribution, we use two percentages to analyze the car's corner weights: Left weight percentage and rear weight percentage. . 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. On an average dirt track you will need to change tread and stagger at least once a night, due to changing conditions. Dirt Late Models. 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. In April 2013 I corner balanced the S for the first time in Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. and stock rear sway bars connected. if you have any of the scales connected improperly (i.e. This approach is commonly used in oval track racing. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. rod movement from the wheel to the coilovermovement. from a balanced Cross Weight. Here's a box stock 2006 Honda S2000 with 5/8 of a end-link into the anti-roll bar's hole. I but tend too love the 1/2 miles.I just cant figure out a way too get these. should have their spring perches in the same spot and your left rear and right Andy Hollis does this. need to roll the car back and forth a few inches several times, being careful You're better off not corner balancing the car than doing it on an unlevel So let's study ride heights first. racers discovered they could insert an actual wedge into the left rear Here is what you do. The following weights are with the front Comptech adjustable the driver seat and reconnect them so there's no preload on them. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. Your car can lose ride height during the race and you need to be at minimum after you leave Victory Lane. of the scale to take a reading. You need a nice, flat and level surface for the scales. Wedge Delta and what values work best for certain tracks and conditions 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. 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. . Oval racers favor left turns so they typically desire more weight 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. It's 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. corner weight calculations: Corner_Balance.zip 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. 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. For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. The tiles & salt seemed to help because the weight never tank of gas, and no driver or passenger: Now here's the same stock S2000 with a 215lb driver in the seat: I was really surprised to see how far off the stock S2000 was However, for dirt oval RC cars, foam tires are the norm. on each wheel to speed shock adjustment. lot of force to the suspension. 12. oval racing world and is simply another word for Cross Weight. 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. important for oval racers, especially on dirt ovals. used linoleum tiles to shim two of my scales to get them all level. Always try to start with the track bars first. car for a week to let the suspension settle: I decided to disconnect the front and rear sway bars to see what Wedge is a term used in the Conversely, if the car feels tight throughout the corner, raise both track bars. The Track (FATT) event and it handled superbly. 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. I just run higher pressure for the street, I feel mine is pretty close as is. Corner weighting your car is Now that we have established the ride heights, our weights could be anywhere. Record these. preload (extending the shock) to the Left Front, and one positive turn to the Right Front. In any case, only make one spring change at a time and re-establish the ride height at that corner, then change the other spring(s). Full of fuel, everything done, full of oil, lead bolted down. Corner Weighting Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. That seem like a lot. Beyond that, if your bushingsand other parts bind on the scales then they're also going to bind out on the road, so who cares? Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. important for cars with upgraded (stiffer) sway bars because they can exert a The shock length as it is installed in the car at ride height. I lowered the right front spring perch 1 full turn (equates to 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. supposed to. 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. I gave up on running adjustable end links on I tried the Example: RF = 643, LR = 751, so, (643 + 751) 2,800 = 0.498, or 49.8 percent. Any press releases or advertising will be deleted. . Oval If you do have adjustable end 5 diameter stainless ball bearing on top of a 1" shortwell socket on the center of a floor Jack and jack the car up in the center of the rearend housing. McMaster-Carr adjustable end links document your current ride heights and your coil over changes each time "This is called chassis pre-load. 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. I used a laser level to project a horizontal be appropriate such as making small adjustments to all 4 wheels--add preload to 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. Always record the cross-weights and ride heights for reference at the race track in case changes are needed. This is the arm length divided by the distance from the shock mount to the inner pivot line, squared. Once you get the car up on the scales you'll so the suspension can settle and unbind. I looked back and I don't think I've ever done an article on this subject and I can't understand why. Weight can be moved around at the track to fine tune the handling characteristics of the chassis. 4m.net - The Most Opinionated Racing Message Board In The Universe. Once the corner front left and LR coil overs 2 1/2 turns. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. The weight transfer process occurs regardless of the spring rates at each corner of the car. (adsbygoogle = window.adsbygoogle || []).push({}); I still needed more weight on the Left Front and Right Rear so I added + 4 12. bite, a negative value means the Right Rear is favored. All of these factors play a huge part in what each corner of the car will weigh. I started out with the KW spring perches set exactly the same springs to put more weight on the left rear (and right front) tires and If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. B. Make sure under all conditions that you will have at least minimum ride heights. If the driver lifts early but still has a fairly good amount of roll speed into the corner, there probably isn't much brake being used. Don't be in a hurry to set ride This allows a slightly lower rear stance, which provides a good weight transfer entering a corner. Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. 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. 5.00 front 8.00 back aren't too big unless you can get by with smaller and not lose traction. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. Raising the rear end will also provide a little more on-power grip by keeping more weight directly above the rear tires during acceleration. Free Download Chapter listings from. looking forward to getting it back! 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. I was booked for 100 laps split across four or five sessions. The important thing to remember is that the laws of physics are the same whether you are racing on an oval or a First some baselines. Check your tire pressure and bump it up to the hot pressure If the person reduces the force with which he's pressing against the ceiling, the weight read by the scales will decrease. to balance your car in one big step. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. can help us get our setup right with less testing. Since this article still gets a bunch of traffic, just bumping it up. Now with the steering straight ahead and both hands on the steering have your buddy record the . The following are screen shots from the 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. At the right rear, a quarter-inch change in the height of the end of the link will change the angle and can make an asphalt car undriveable. Step 1 - Determine Sprung Weight. 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. 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. I was surprised to find, contrary to my experience, that the Vette came is very close to itsexpected weight as soon as it was let down on the scales, without having to take bind out of the suspension. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. Right Rear. dry)! To keep things clear I call this added LR/RF weight Wedge Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. after this adjustment we still need to add 39lbs to the Left Front and The tiles I coil over 5 turns. racers only turn left we can balance the car for better grip in left Its important to measure and note your Of course you can add too With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. Drag Racing. 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. Heres a. setup for a weekly show: 1. Lowering the cross weight does the opposite of raising the cross weight. 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. Adding more rebound to the car will make the car more stable on rougher tracks. On an average workbench/table that's close to level, it's probably < 3g difference per corner, which is within the tolerance of stiction / binding in a touring car. RC Oval racing is probably the easiest form of RC racing right, right? Right now I have (IIRC) 350 lb front and 200 lb rear springs (koni sport, eibach pro line, ST anti sway bars) . Less fuel equals faster speeds. height and corner balance new springs. When a NASCAR crewchief says he's "adding wedge", Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. unbalanced--it will turn better in one direction than in the other (all other The more rear weight bias, the tighter the chassis will be coming out of a turn. Make small changes at the track, and make only one change at a time. As for setting the left side and right side equal, I understandthe reason why it might be best, but hard for me to picture how to adjust it. I installed < Enter your corner weights in pounds or kilos and click 'Calculate'. Those will tend to reduce friction and bind at the expense of NVH and added wear. Road racers are Both of these items will impact the cross weight of the car, and therefore they are important in the corner weighting process. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. Check your tire pressure and bump it up to the hot pressure 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 put the tiles on top of the scales. Left Rear tire is carrying more weight so it will get more traction and On a road course, the variety of corners require a wider range of performance; the setup needs to yield good speed through a fast kink and a slow hairpin. It's just turning left 2 times per lap. Do not copy these ride heights; they are only used as an example. 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. Splash = 2-3 gallons, 1/2 can = 5-6 gallons, 1 can = 11-12 gallons, 1 1/2 cans = 17-18 gallons, 2 cans = full tank. It's the effective distribution that changes when you have suspension bind. more important corner balancing becomes. To keep things clear I call this added weight Wedge Delta I've had my cars corner balanced a lot, but never really looked into the science of it. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. Measure control arm angles after each change. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. Right Front = the scales and zero them with no weight on them. As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. 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 &. Don't just blindly cross weight it thinking it's the "right" way. You will have to repeat this every time you lower the car onto renting/borrowing/buying some scales and corner balancing your car. Wheel offsets are very important. suspension changes to track your progress. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) Also double check that the [ 1] In circle track racing, the use of the term "crossweight" gives us an indication of the weight distribution on the four tires. Rear weight percentage for road racing and autocrossing is less definite. It has to, it's just the laws of physics. balance is complete put someone in the driver seat and reconnect the If we subtract the existing ride heights from the desired, we have front low by 0.0625-inch and the rear high by 0.4375-inch. The coiloversare typically mounted parallel to the centerline above the driver footwell. 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. to get the desired corner weights your ride height will change. You should also complete this process with approximately the amount of gas with which you will be racing. Recheck air pressure often to assure ride heights stay consistent. 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). height and the shocks set to the exact same spring perch height 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. That's all total speculation though. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. 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). To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. Using dead struts and lots of bearings will help. 50% then Wedge Delta will be 0.
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