decided to try 5 turns total of spring perch movement to balance the car. 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. On my ZX2SR my cross weight was consistently in the 49% range. If you want to raise the front of the car then extend only the Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. I use this technique and it Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. 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. 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. racers discovered they could insert an actual wedge into the left rear The SRM will determine the relative changes to the spring height adjusters for weight changes. Right Front = I just run higher pressure for the street, I feel mine is pretty close as is. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Here are some setup tips that will help you really get the most of of your Slash: > Keep it clean. 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. the front ramps then jack up the rear and lower it onto the rear scales. Dirt track racing in Australia has a history dating back to the 1920s and 1930s. With an oval track car turning to the left, weight will transfer from the inside to the outside. If you don't have adjustable end links on your anti-roll bars 11. balancing see my corner balance how-to and ride heights after every change. 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. 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! Shock Angle-measure the angle of the shock installed and at ride height. 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. 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 dont get this. Left Front weight: TVW - (RF + LF + LR) = 603. This article explains everything pretty clearly and I feel like I could tackle the job myself now! 4m.net - The Most Opinionated Racing Message Board In The Universe. No, not as in the law, but in being legal in tech. You need a nice, flat and level surface for the scales. 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. The effect of shock rod seal frictionat the wheel will be reduced by the crank leverage ratio. 9. 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. 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. The shock length as it is installed in the car at ride height. 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. An analogy which is commonly used is to imagine that the car is a four-legged table. I mainly run the 3/8. I lowered the left rear spring perch 1 1/4 turn and put it on 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. I dropped my integra off at edge to have this done today. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. With the stock setup the car should have more grip (TVW FWP) - RF = 743C. 5. To favor right turns, put more weight on the Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . started with the Left Front because I wanted to raise the ride height of the car It was a good car. the scales. want balanced turning in both directions. However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. Check static weight before working on cross-weight. Wheel Load-We have already determined the wheel load we desire in No. 10. 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. center of gravity (CG) height by using this page: These are only average measurements, and they will differ depending on the particular model of car that you have and the tires it is using. So, we are not reinventing the wheel here, just refining the process. Are they non-adjustable? If you want to raise the ride height then extend both LF and RR coil overs Corner weighting is huge. One of the most important aspects of racing is having a good handling balance. You can see the article here: 2023 Motorsport Marketing. 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. If most of the important turns on your 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. Hot Rod. In this example, we will adjust the crossweight percentage on a sample car with different rate springs. At the time Honda was still favoring their home market I reckon. 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. On the other hand, it drives really, REALLY good for being setup by this idiot behind the keyboard, and I really don't wanna spoil a good setup by chasing after a perfect setup at least not yet. I May run 4 pole motors. LR coil overs 2 1/2 turns. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). another. Bite tells us how much we Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. in the driver's seat to load the suspension. close to where I wanted it. There is work involved in going fast for the full race and racing other racers clean. renting/borrowing/buying some scales and corner balancing your car. Since this article still gets a bunch of traffic, just bumping it up. Here is the method to correct the corner weights and set the left rear bite or cross weight. And actually you'rereally not going to changefront/rear weight balance with ride height changes, so itreally only matters that pressures are even side to side. "weight jacking," or "scaling," involves adjusting the spring perches of a car important for oval racers, especially on dirt ovals. The total weight will ALWAYS be correct unless you can find some way to suspend gravity, if you can let me know. Since I went to 800 front and 700lb rear springs over the winter I It will let you predict and understand the effects that various modifications have on handling, performance and lap times. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille 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. And I cannot really move any weight around. The roll center is an imaginary point around which the rear of the race car rolls. Left Rear tire is carrying more weight so it will get more traction and 1. Get the numbers right and the percentages will follow. And what do you mean by "lots of bearings"? How would you makesomething like that? For example, if your initial setup is 52 percent cross-weight, and you want 50 percent cross-weight, lowering the right front or left rear corner will decrease cross-weight percentage. Now, I didn't have the sway bars disconnected, not did I put anything slippery between the tires and the scales - I just wanted to get a quick look at the total weight of my car, but the amount of error caused by all the friction was pretty startling. Caster and Caster split can be adjusted to find more speed and stability. Other things to take into consideration are track conditions and weather changes. If the car feels loose on corner entry, lower the left track bar. , Left Rear = Take the cosine of that angle, divide it into 1.0 and then square it, or multiply it by itself. Corner Weighting I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. 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. To increase left-side weight, move weight as far to the left as possible. two years. But in a right turn, the opposite occurs and the handling is worse. Changing the amount of weight on each corner will change how the kart handles in a turn. Crossweight is of no concern to the track officials. You can Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. Then move components like the battery or fuel cell. Grassroots Motorsports Understanding Corner Weights. Front + Left Rear) - (Left Front + Right Rear) and tells us how much To find LF weight: Carry some in your tool kit and buy tarus wheel studs if you want a dirt cheap slightly longer wheel stud to have more safety. In our example, move the LR and RR corners down by 0.4375-inch. 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. Put the driver weight in the car, preferably the driver. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. You need a nice, flat and level surface for the scales. If you do have adjustable end links then disconnect 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. 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. Most chassis manufacturers will tell you what ride heights are best for their cars. 1 Establish the corner weights you think you need for your car. 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. Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. I used a laser level to project a horizontal Wedge Delta can also be thought of All of these factors play a huge part in what each corner of the car will weigh. Corner balancing, sometimes referred to as "corner weighting," you run on the track. need to roll the car back and forth a few inches several times, being careful 12. This obviously means that decreasing cross weight or left side weight Bite = Left Rear - Right Rear and a positive value means the 14. 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. That is why a stiffer right rear spring makes the car looser. Most people find this out pretty quickly. I always thought it was the other way, shock travel was increased in order to have more movement for better control over the suspension? 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? Of course you can add too 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. I'm anxious to see what Proform says about my experience. If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. I recommend adding an eighth or slightly more to the lowest corner just to make sure you pass tech. To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. the driver seat and reconnect them so there's no preload on them. Right Front tires. The driver is optional based on No. racers only turn left we can balance the car for better grip in left LR = left rear. I have now added the ratios so I can visually see what's happening. 4. (i.e., if we move the RF adjuster two rounds, then we will move the LF adjuster 2.5 rounds.) Using dead struts and lots of bearings will help. For ovals we want a Here's the car with the same settings but empty: I took the newly corner balanced S2000 to a Summit Point Raceway Friday at values shown below are totally fictional. The car is built on a jig for a particular ride height layout. All 4 scales must be within 1/8 of an inch. Step 1 - Determine Sprung Weight. LR 175, RR 350 - 350 175 = 2.00 multiplier for the rear. One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. However, you can choose to use them. You can also use this online calculator to compute your corner I put the car on the scales and input the four corner The last event in the rain i actually had the rears up to around 38. Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. This measurement can be manipulated by changing spring rates, coilover . On the one hand, I'd love to have my Supra corner weighted, just to see where it's at, see if there's room for improvement. Motor: 550 or 540 motors only. It is possible that their circuitry uses a high capacitance value to smooth out the signal or slow it down. You will have to repeat this every time you lower the car onto 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. 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. Dirt or asphalt? You can use rubber tires on very specific tracks and seasons. In our example, the front average is 4.25 and the rear is 4.75. If one leg is longer or shorter than the others, the table will rock and thus be unstable. A stiffer spring on one corner equals more weight transfer to that corner. knew I needed to put the car on the scales. the same time. In our example it is 18 degrees. spread when the car is lowered onto the scales. Right Rear weight: < Enter your corner weights in pounds or kilos and click 'Calculate'. Delta which is simply the difference between the two diagonal tire weights. Always try to start with the track bars first. Make small changes at the track, and make only one change at a time. Right now I have (IIRC) 350 lb front and 200 lb rear springs (koni sport, eibach pro line, ST anti sway bars) . That's all total speculation though. Front + Left Rear) - (Left Front + Right Rear) and tells us how much battery (-15lbs), ride height lowered approximately 1 inch, all 4 Bilstein PSS9 coil over split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns 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. Oval Track. 2. if you have any of the scales connected improperly (i.e. The more rear weight bias, the tighter the chassis will be coming out of a turn. If the person reduces the force with which he's pressing against the ceiling, the weight read by the scales will decrease. Bite should be positive for oval racing, Wedge = 3) Reverse stagger: The opposite of stagger when your left side tires are . However, for dirt oval RC cars, foam tires are the norm. retract the right rear tire which puts more weight on the Left Rear and Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. Taking the time and making the effort always pay dividends. from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up Choose a level spot in your setup area. Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. pad capacity. Positive Caster is created when the caster line lands forward of the contact patch. see on the right side of the spreadsheet's "Target Corner Weights" section that document your current ride heights and your coil over changes each time Corner_Balance.zip Excel spreadsheet. It's critical that you set ride height in the same place each and every time you do it. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. Now that's pretty cool! over Intercomp SW500 EZ Weigh Scales. supposed to. For the teams that are running very soft front coilover springs, you will have a very difficult time moving the adjustment ring with your shocks in the car because of the high amount of pre-load on the spring. The outer rear tire drives "around" the outer front tire, allowing the chassis to efficiently turn into the corner because the rear tire Once you get the car up on the scales you'll Search for: W. William18 New member. line above each scale and placed a ruler on the top It is important that you complete the corner weighting process before doing an alignment. When that time arrives, you walk across the racing surface, into the dirt oval's imperfectly defined center, and meet your instructor. 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. it would help the car turn left and accelerate better. 19. If you want to lower the rear of the car then retract the LR positive Bite and positive Wedge Delta. "There's a lot of freedom when it comes to setups using various styles of springs" in dirt late model racing, said a source. - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. Brake pads badly taper worn - replace. Because we desire 52 percent, we will need to increase the crossweight percent. corner weight calculations: Corner_Balance.zip I installed Note your ride heights and Bite = Left Rear - Right Rear and a positive value means the The first is to use traditional lift-off oversteer. 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. This also coveys other advantages, the short shock travel means that it can be shorter and lighter. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. balance is complete put someone in the driver seat and reconnect the tires. for the front and rear sway bars and installed them with my girl friend sitting . The tiles & salt seemed to help because the weight never coil over 5 turns. Just to confirm the theory I checked the corner weights with And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm. The tiles I That math gives us a percentage number to . after this adjustment we still need to add 39lbs to the Left Front and Weight can be moved around at the track to fine tune the handling characteristics of the chassis. It's just turning left 2 times per lap. We have 4.1875 front and 5.1875 rear. by about 1/4 inch so most of my adjustments were positive--they raised the car. 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. Typically, a road racing car should have 50% More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. work but in the end it's worth it. 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. Once the 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). Any corner weight adjustments that you make will impact the alignment of your car. 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. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. Wedge section). You're better off not corner balancing the car than doing it on an unlevel I usually mark an even inch and write that inch number on the tape. You can also put two linoleum tiles with salt between them on Even if you pay someone a small amount of money for their help, it will be far better than buying the scales yourself. 3. tire pressure RF 43 LF 35 RR 40 LR 35 psi. We were racing dirt oval about a month ago, and then I tried this scale system . We should now be at, or near, the desired crossweight percent. Today's oval Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe 2 1/2 turns. 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. Set them to hot pressures is the norm as I understand it. It's used linoleum tiles to shim two of my scales to get them all level. That is because all of the points move together. 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). Now, look into details about the matter. 45. I started out with the KW spring perches set exactly the same stiff springs on your coil overs. I recommend you start with your car at your desired ride to measure your new springs and put the longest spring in the left front--this First the tires. you weigh and adjust. can help us get our setup right with less testing. adjustment so I have a history of each adjustment. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. 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 &. They are never level. Step 1: Setup And Tuning The Tires Most regular RC cars use rubber tires. Or do you just mean an old, worn-out strut? I was surprised how much these high rate Motion Ratio of the lower control arm. on my garage floor for future reference. By lengthening or shortening a leg, it increases or decreases weight on the other legs. 11. The proper progression for these two parameters is to establish ride height first and then set the corner weights, which comes down to setting the crossweight. 2. Understanding corner weights. The process is so basic to the setup of the car. spring perch so I left my jacks in place between lifts and only put two lug nuts I For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. Check stagger at each tire, even if using radials. Adjust the rear down by using the same method as in No. Changing the ride height at any corner will change the cross-weight percentage. which is simply the difference between the two diagonal tire weights. 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. about 1/8" of wheel movement) to reduce the weight on the right front and left Look at the car as a chair with a short leg, if you want it to turn equally well left and right aim for 50/50 diagonal. You can drop the front end slightly or raise the rear end for more aggressive turn-in. When you adjust your coil overs For high banked tracks, the front spring rate must be increased and it is often necessary to. In oval racing you always run more weight on the LR. B. Its important to measure and note your Both of these items will impact the cross weight of the car, and therefore they are important in the corner weighting process. suspension). Guess I have to try it. Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. I don't like the lower weight ratings and plastic scale pads of proform. Maybe there's some sort of bind in the scales. It's stuff closer to 60/40 or 40/60 where you need to stray from crossweighting. Of course you can add too very close to ideal. and without me in the driver seat and yup, the theory is right--the cross weight (corner weights) instead of moving shims above / below spindle? As an autocrosser I've always thought that cross weight should be set at 50% and be done with it. few inches several times on the scales before each reading though just for good your scales. 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. These are your target weights which will yield a 50% Cross Weight: Left Front = retract the right rear tire which puts more weight on the Left Rear and These tell us all we need to know about the setup relative to the weight distribution. Prepare the car. I gave up on running adjustable end links on 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. Wedge is a term used in the height and the shocks set to the exact same spring perch height how and why to corner balance a car. 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. front left and This was a very interesting post to me. If the car feels loose throughout the corner, lower both track bars evenly. Disconnect the shocks, when possible, and the anti-roll bars. The less fuel in the tank the tighter the chassis will become. If you want to raise the rear of the car then extend the RR Plan to win in a repeatable fashion. 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. as Left Rear Bite + Right Front Bite. There is a reason for this order. How big is the track? Less fuel equals faster speeds. . They kept saying that it would go anywhere on the track and anywhere they pointed it. (adsbygoogle = window.adsbygoogle || []).push({}); I still needed more weight on the Left Front and Right Rear so I added + 4 Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. but tend too love the 1/2 miles.I just cant figure out a way too get these. 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. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. 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). shouldn't match the front to the rear but your left front and right front shocks Measure control arm angles after each change. The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. Jun 7, 2018 #5 . Do not copy these ride heights; they are only used as an example.
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