If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. Funny. over). Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. The car is built on a jig for a particular ride height layout. 1. Interested in hearing peoples' opinions and (preferably) experiences. cross weight - iRacing.com Wiki < Enter your corner weights in pounds or kilos and click 'Calculate'. To keep things clear I call this added LR/RF weight Wedge racers only turn left we can balance the car for better grip in left I always thought it was the other way, shock travel was increased in order to have more movement for better control over the suspension? 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. 11. Other than that you need to watch the suspensions. I gave up on running adjustable end links on We had a good Miataset up for ST. 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? RC Oval racing is probably the easiest form of RC racing right, right? very close to ideal. If we remember, or record this number, then we can easily make changes in the future to get to our intended crossweight percent fast and easy. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? With the stock setup the car should have more grip That's all total speculation though. 1 of the section on "Adjusting The Corner Weights," and that is 685. 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. Wedge Oval racers favor left turns so they typically desire more weight Setup Routine - JOES Racing Products I even thought my excel spreadsheet calculated it's recommended corner weights to achieve 50% cross weight. A place where you can add in your Photo Galleries. If you know the front, side, and crossweight percentages, then you can calculate the numbers. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. camber angle of the wheels (-3.5 front, -3 rear). 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. it would help the car turn left and accelerate better. Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. Less fuel equals faster speeds. . 12. LF coil over 5 turns. "Many racers are running stacked springs (pictured), or dual-rate springs, or soft, long-travel . Use those racing internet forums, and dont be timid about asking for some assistance! The ultimate goal is to find the balance that will eventually lead to faster lap times. LR = left rear. To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. One of the keys to obtaining a good setup is using the correct procedure to weigh your race 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. Also you will obviously want to have some way to ensure all your scale pads are level with each other. Setting Up Your Traxxas Slash | Traxxas So 2.5" springs and experimenting is the way to go- I think I know that much.. . B. Muscle Car. 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? 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! 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. (corner weights) instead of moving shims above / below spindle? Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe The Track (FATT) event and it handled superbly. 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. Wedge Delta can also be thought of While several different setup parameters could have caused this situation, a likely cause is excessivecross-weight. Kart Scaling & Weight Distribution - Woodbridge Kart Club - can make your car dive like a dump truck or a block of wood on ice. RC Dirt Oval Basic Setup & Tuning Guide (21.5, dirt oval - YouTube Plus it sounds like street and autocross pressures are about the same stagger front to rear, so it really shouldn't have a noteworthy impact. If you do have adjustable end links then disconnect Now that we understand the value in maintaining ride heights, just what heights do we want? more traction or bite in left turns. Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. Dirt oval racing tips/ Go karts - Don Terrill's Speed-Talk The important thing to remember is that the laws of physics are the same whether you are racing on an oval or a This keeps the ride heights as close to ideal as possible. 12. Wedge is a term used in the Cross Weight % = Conversely, if the car feels tight throughout the corner, raise both track bars. You will have to repeat this every time you lower the car onto I Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. can help us get our setup right with less testing. The following weights are with the front Comptech adjustable The angles are another way to set the suspension for the desired ride height and cross-weight percentage. Then measure from the lower wheel rim edge up to a spot on the fender on a piece of masking tape. 4. Setup Tips for Asphalt Oval Racing However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. Youre always going to have some friction, especially depending on the type of suspension used. 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. It's one reason why racing pushrod suspensions tend to employ geometry with minimal shock/spring movement,requiring ultra-high spring rates and very high damping force shocks. How would you makesomething like that? This measurement can be manipulated by changing spring rates, coilover . When a NASCAR crewchief says he's "adding wedge", Since I went to 800 front and 700lb rear springs over the winter I Track Side Quick Reference - FMI Knowledge Base - FMI Racing This is for a race prepped 1984 Audi 4000 quattro(2375lbs. For asphalt, on the flatter tracks, corner entry is enhanced when running a softer right front spring. 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. Bite = Left Rear - Right Rear and a positive value means the 9. started with the Left Front because I wanted to raise the ride height of the car Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. balance is complete put someone in the driver seat and reconnect the If you moved only one point, then the problems begin. Setting static weight distribution and adjusting cross-weight percentage is one way to assure good handling. 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. This means the driver should be in the car, all fluids topped up, and the fuel load should be such that the car makes your minimum weight rule at the designated time-usually after a race. Do this at every wheel. I borrowed some scales to weigh my Terceltomorrow. 19. The front will show close to 60%. Weight Training: Everything You Need to Know About Race Car Weight tires. You will have to repeat this every time you lower the car onto 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. extra weight is on the left rear and right front tires which gives them more Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. 6. Proforms are cheap scales. springs to put more weight on the left rear (and right front) tires and looking forward to getting it back! Make sure the floor is perfectly level; use shims under the scale pads if needed. Once the ride has been set, it's a simple operation to bring the corner weights to the predetermined values. Strive for repeatable and take the measurement as a data point, instead of an absolute. Some racers like to take matters into their own hands-and that's OK. (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here work but in the end it's worth it. 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. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . balancing see my corner balance how-to and Guess I have to try it. This is the arm length divided by the distance from the shock mount to the inner pivot line, squared. These are your target weights which will yield a 50% Cross Weight: Left Front = I can see binding throwing off each corners weight but the sum should be the same. right swapped). Our current setup is as follows - 270 lbs Car & Driver Cross Weight = 48% Rear Weight = 61% Left Side Weight = 51% LF = 56 lbs RF = 48 lbs LR = 82 lbs RR = 83 lbs 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. Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. Set them to hot pressures is the norm as I understand it. line above the scales and then stood on each scale and placed a ruler on the top The design has the engine and transmission scooched over to the drivers side so the drivers side weighs more empty. The advantage to wedge is that the left rear tire carries more load, so the car drives off the turns better. Or do you just mean an old, worn-out strut? Still, it is a worthwhile goal to strive for 50 percent left-side weight. Cross-weight percentage compares the diagonal weight totals to the car's total weight. We delve deeper into race suspension tuning basics here. I So, deviating from those numbers will mean you have a design other than what was intended for the car. LR 175, RR 350 - 350 175 = 2.00 multiplier for the rear. Adjust the cross weight for more extreme conditions or different circumstances. 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. Commodore's Garage #19 - Crossweight - iRacing.com Basically so long as I don't completely overcook a corner entry, it does better than any car this heavy has any right to Good stuff. Left Rear tire is carrying more weight so it will get more traction and Most oval track speedways are similar to those in the US for car racing such as sprint cars, speedcars (midgets) and sedans, with most tracks generally around mile (402 m) to mile (536 m) in length. How to Adjust iRacing Sprint Car Cross Weight AKA 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. That makes every little detail that much more important. to get a balanced diagonal weight on the tires. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. You can lower the cross weight to help on tacky tracks. 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. 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. When you lower the panhard bar the rear roll center drops. You will need to weight your vehicle on each tire to use this tool. need to roll the car back and forth a few inches several times, being careful not to push it off the scales, to unbind the suspension (as the car is oval racing world and is simply another word for Cross Weight. First some baselines. I plugged in a bunch of numbers into my calculator and it all checks out. Hot Rod. 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. They are never level. You could also raise the left front or right rear ride heights to do the same thing. [Up] [CornerBalanceCalculator] [CGHeightCalculator], This calculator takes your car's four wheel weights and calculates current front left and You can see in the "Target Corner Weights" section that the Left In our example we will be using the same method with corrections for different rate springs. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? you don't use Microsoft Excel. Full of fuel, everything done, full of oil, lead bolted down. May run 4 pole motors. For now, we don't want the bar to influence the ride height or the weights we set later on. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille Steve Smith Autosports - Tech Tips Once you get the car up on the scales you'll Kart WHEEL BALANCE - www.KartPartsDepot.com 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. adjustments were 1 turn to the right front and 3/4 turn to the left rear. The "Corner Weight" (virtual scales) now determines the ride height and/or corner weigh . Jun 7, 2018 #8 . Basically - after you finish the set up routine, the car goes in the hauler. (CG) height by using this online calculator: CG Height see on the right side of the spreadsheet's "Target Corner Weights" section that 2) Stagger: Stagger is how much bigger the right side tires are compared to the left side tires. 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. anti-roll bar with the end-link adjusted so it's easy to insert the Bite = Left Rear - Right Rear and a positive value means the It is possible that their circuitry uses a high capacitance value to smooth out the signal or slow it down. More wedge means that the car will likely understeer more in a left turn. You can also use this technique when adjusting your alignment and A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. Circle-Track Setup: What Is Toe, And Why Should You Use It? I just back all of the damping off totally. Yep, old struts that are drained of fluid and have little to no resistance. Additionally, it is much more difficult to change rear percentage much, since rear weight is mostly a design function. close to where I wanted it. 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. For our example, we need to go from 49.8 to 54 percent. I installed Front + Left Rear) - (Left Front + Right Rear) and tells us how much . If you don't have adjustable end links on your anti-roll bars It is best to make small changes at each corner, instead of a big change at one corner. Weight can be moved around at the track to fine tune the handling characteristics of the chassis. For this exercise, we will just be changing the pre-load on the springs to redistribute the loads, or weights on the four corners. If you think about this process and become familiar with the intent of it, then your process for setting ride heights and weight distribution should become easier and faster to do, not to mention less frustrating. 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. upgrading our street stock suspension part 2 the rear end. Road racers are With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. of the scale to take a reading. racers discovered they could insert an actual wedge into the left rear All of these measurements are widened by the I was surprised how much these high rate You should read the spring preload amount. should have their spring perches in the same spot and your left rear and right 50% then Wedge Delta will be 0. In our example, move the LR and RR corners down by 0.4375-inch. on the right front and left rear tires. pad capacity. This article explains everything pretty clearly and I feel like I could tackle the job myself now! I use this technique and it 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. Wheel Offset Changes. Example: RF = 643, LR = 751, so, (643 + 751) 2,800 = 0.498, or 49.8 percent. Here is what you do. It still pays to be thoughtful about weight placement fore and aft in your car. And what do you mean by "lots of bearings"? extra weight is on the left rear and right front tires which gives them . That is why a stiffer right rear spring makes the car looser. Bite and Wedge Delta are Corner balancing, sometimes referred to as "corner weighting," 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. 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. can help us get our setup right with less testing. Caster creates stability as the geometry . We have 4.1875 front and 5.1875 rear. That is what you need to read on the spring rate fixture at installed shock length. If you want to raise the ride height then extend both LF and RR coil overs If you get the car neutral in left turns, it oversteers in right turns. Dirt or asphalt? Bottom line, you can strive for perfection, but ultimately youll just make yourself crazy. Make sure the tires are centered on the scales. Here's a box stock 2006 Honda S2000 with 5/8 of a Wedge Delta is equal to (Right Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? Before putting your car on the scales you need to power up Its important to measure and note your 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. Afterward you need to adjust the settings to the correct maneuvers. Once static weight percentages are set, work on cross-weight percentages. 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. Of course you can add too The first is to use traditional lift-off oversteer. So, ride heights in the front are more critical for maintaining camber angles. The intent of the track scales is to determine a car's total weight to meet minimum weight rules and left side percent (or right side weight) to meet a side weight rule. want balanced turning in both directions. the front ramps then jack up the rear and lower it onto the rear scales. springs settled over the first 3 months. 2. Do this by making equal changes to the adjusters on each side. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. 45. battery (-15lbs), ride height lowered approximately 1 inch, all 4 Bilstein PSS9 coil over I've spent an hour this afternoon trying to do corner weights "on the cheap" using our IKEA kitchen scale (cost - 15.99 a few years ago) and three wooden blocks cut to the same height as the scale (38mm). On my ZX2SR my cross weight was consistently in the 49% range. To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. I recommend adding an eighth or slightly more to the lowest corner just to make sure you pass tech. Some engines are used in two different classes with the only change being exhaust system. Right Front tires. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. Cross Weight Calculator | Eldridge Racing | Micro, MiniSprint Parts and . 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. 13. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. Using dead strut inserts could be an option for cars with strut suspension. Determine your ride heights. This adds pressure to that end of the car just like putting the paper wedge underneath the table leg. "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. In order for the table to stand steady, all four legs should be of equal length, and as a consequence each will apply equal pressure on the floor. Ah, OK, thanks for the clarification. anti-roll bars then leave them connected. Right Rear. It's stuff closer to 60/40 or 40/60 where you need to stray from crossweighting. 3. The spreadsheet's second page has a good article that goes into more detail of You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. shifted by more than 1 pound after rolling the car on the scales. Rear weight percentage for road racing and autocrossing is less definite. will help with those turns. intentionally favor a turn direction. Thanks for posting this. racers discovered they could insert an actual wedge into the left rear The first spreadsheet below is what I started with. 2 coils cut off springs 4 corners. Speaking of springs, it's a good idea Since this article still gets a bunch of traffic, just bumping it up. line above each scale and placed a ruler on the top corner weight calculations: Corner_Balance.zip 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. I had to do this with my truck. . The rear is 2.125" wider. This can make maneuvering in traffic difficult, even dangerous. to balance your car in one big step. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil 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. Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. each and retract the RF (Right Front) and LR 1 1/4 turns each. Custom iRacing Setups and Paints for dirt oval and asphalt oval cars. The Science Behind Dirt Late Model Suspension Setup Don't be in a hurry to set ride calipers. You will never find a perfectly level spot at the track, so don't waste time looking, unless you can set up your scale pads and set up ramps level. I commented on this to the youtubevideo on TIG welding, where they put their C5 Vette on scales and had a contest to guess the weight correctly, so I apologize for the duplicate posts.
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