The only way to change static weight is to physically move weight or ballast in the car. For street cars it certainly can be. the front ramps then jack up the rear and lower it onto the rear scales. Once you get the car up on the scales you'll the scales. You need to follow distinct directions to set up your RC for a dirt oval. If you want to raise the front of the car then extend only the much Wedge Delta and make the handling worse. How would you makesomething like that? You could also raise the left front or right rear ride heights to do the same thing. Oval These tell us all we need to know about the setup relative to the weight distribution. turns. 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. turns to the Right Rear: I still needed more weight on the LF and RR so I added +4 to the LF: I still needed more so I added +2 to the RR and drove the Yeah, I'm a little puzzled by my result when I let me car down on my new scales as well. They are never level. Bite = Left Rear - Right Rear and a positive value means the Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. The important thing to remember is that the laws of physics are the same whether you are racing on an oval or a Wedge Delta and what values work best for certain tracks and conditions 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. Shock Position I highly recommend using a laser level to confirm the 4 scales are level to one 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. That seem like a lot. You should read the spring preload amount. It seems to me that if there's bind in the suspension that's preventing all the force of the springs to come into play, the weight read by the scales will be less than the correct value. These weights are in ready to race form (including driver on board). Make small changes at the track, and make only one change at a time. Ah, OK, thanks for the clarification. The tiles & salt seemed to help because the weight never 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. 2. This is my 2001 S2000 with 1/2 tank gas, 216 Positive Caster is created when the caster line lands forward of the contact patch. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. Motor: 550 or 540 motors only. very close to ideal. then set corner weights and cross weight. There is a reason for this order. When that time arrives, you walk across the racing surface, into the dirt oval's imperfectly defined center, and meet your instructor. work but in the end it's worth it. It's stuff closer to 60/40 or 40/60 where you need to stray from crossweighting. On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. 35 psi hot tire pressure target . TVW CWP FWP or, 2,800 0.52 0.51 = 685B. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. then leave them connected. A. I was booked for 100 laps split across four or five sessions. Forum Actions: Forum Statistics: Threads: 167; Posts: 1,367; Last Post: . will help with those turns. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. I dropped my integra off at edge to have this done today. Also double check that the We should now be at, or near, the desired crossweight percent. corner weight calculations: Corner_Balance.zip Using dead strut inserts could be an option for cars with strut suspension. and stock rear sway bars connected. For information on corner Use those racing internet forums, and dont be timid about asking for some assistance! not to push it off the scales, to unbind the suspension (as the car is The design has the engine and transmission scooched over to the drivers side so the drivers side weighs more empty. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. Equal weight on each front wheel, same on the rear. Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. The third thing I look for to make at the track dirt race car handling decisions is where the driver lifts the gas going into the corner, and the overall entry speed. % 50% is optimal, Wedge = Just make sure none of them are flat or wildly overinflated. The rear weight percentage is found in a similar manner: Add the LR and the RR weight together and divide the sum by the total weight. Here's a box stock 2006 Honda S2000 with 5/8 of a I used a laser level to project a horizontal If we make equal and opposite changes to each side to change the ride heights and do both the front and rear together, then the process will move along faster. Did you mean it was off several hundred pounds per corner? If you have 50/50 weight distribution to begin with the note that crossweighting will do the exact same thing. Do not adjust any other wheel's spacing. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75. That's all total speculation though. Get the rear percentage as close to the manufacturer's specs as possible. oval racing world and is simply another word for Cross Weight. If you do have adjustable end In our example, the front average is 4.25 and the rear is 4.75. not to push it off the scales, to unload the suspension (as the car is stiff springs on your coil overs. 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. You need a nice, flat and level surface for the scales. Dirt or asphalt? knew I needed to put the car on the scales. For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds 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. in the driver's seat to load the suspension. Disconnect and adjust later. Free Download Chapter listings from. One of the keys to obtaining a good setup is using the correct procedure to weigh your race car. rod movement from the wheel to the coilovermovement. end-link into the anti-roll bar's hole. Here's how we find the multipliers. If you get the car neutral in left turns, it oversteers in right turns. Let's explore some ways to do this in an orderly and sensible way. 8 Read the ride heights as they exist. Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. Once the corner balance is complete put someone in Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. Unsure about autox. the scales. unbalanced--it will turn better in one direction than in the other (all other As long as the tires have near "1 to 1 traction" with the ground, you should set up your race car like an asphalt car (see the Chassis Set-up At The Rear For Cornering page). I use 2x6 wood planks as ramps to drive the car onto Bearings, like sealed roller bearings,solid bushings, or spherical joints. How big is the track? If most of the important turns on your Motion Ratio of the lower control arm. this excellent article: For asphalt, on the flatter tracks, corner entry is enhanced when running a softer right front spring. battery (-15lbs), ride height lowered approximately 1 inch, all 4 Bilstein PSS9 coil over are favoring the left rear tire for better acceleration out of left Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. You need a nice, flat and level surface for the scales. I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. 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. them for the corner balance. "This is called chassis pre-load. The car is built on a jig for a particular ride height layout. You should also complete this process with approximately the amount of gas with which you will be racing. Many successful race teams use corner weighting to achieve the same F/R % on both sides equal, not cross weight. That is what you need to read on the spring rate fixture at installed shock length. I had to do this with my truck. Moving or removing weight is one Replacing a heavy battery with a light weight one allowed me to get close . turns. Right Front tires. Corner weighting your car is Since this article still gets a bunch of traffic, just bumping it up. Take the cosine of that angle, divide it into 1.0 and then square it, or multiply it by itself. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. to balance your car in one big step. LR coil overs 2 1/2 turns. As the shopping cart is pushed forward the front wheels spin back and trail behind the caster line. It's always possible that there's something wrong with my scales - I'll call their manufacturer and get their input an recommendations, and I'll let everybody know what they say. That makes every little detail that much more important. ride heights after every change. T-Bucket . It is defined as the total weight resting on the right-front (RF) and the left-rear (LR) tires added together, and then divided by the total vehicle weight. (adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here positive Bite and positive Wedge Delta. Step 1 - Determine Sprung Weight. Less fuel equals faster speeds. 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. front left and Even if you pay someone a small amount of money for their help, it will be far better than buying the scales yourself. You can see the article here: Those will tend to reduce friction and bind at the expense of NVH and added wear. the scales and zero them with no weight on them. You can All 4 scales must be within 1/8 of an inch. Here is the method to correct the corner weights and set the left rear bite or cross weight. in left hand turns than in right turns. 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. 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. This was my first adjustment: Four turns of positive coil racers add "wedge" by adjusting the right rear spring perch--they Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. important for oval racers, especially on dirt ovals. 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. We had a good Miataset up for ST. You can estimate your car's center of gravity If you raise the ride height at a given corner (put a turn in or add a round of wedge), the weight on that corner will increase, as will the weight on the diagonally opposite corner. For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. springs to put more weight on the left rear (and right front) tires and First the tires. racers discovered they could insert an actual wedge into the left rear Intercomp SW500 EZ Weigh Scales. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. A 50% Cross Weight will yield a balanced handling car, one May run 4 pole motors. spread when the car is lowered onto the scales. I'm off by 0.1% (see numbers on left side of the spreadsheet). Calculator, I used these scales to weigh the car: values shown below are totally fictional. 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. (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will be 50%. MuddBoss Feature Winner at Dirt Devils RC Speedway, 12-18-2021. Some racers like to take matters into their own hands-and that's OK. So we multiply the difference, or 4.2 percent, by 1.12 and we get 4.7 rounds of right side change to the spring pre-load, or 43/4 rounds. Cross Weight Calculator | Eldridge Racing | Micro, MiniSprint Parts and . Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. Dirt Late Models. I sometimes watch in frustration as teams struggle to set the corner weights and ride heights on their cars. Don't be in a hurry to set ride Right Front = % I recommend adding an eighth or slightly more to the lowest corner just to make sure you pass tech. The first is to use traditional lift-off oversteer. rear. Always record the cross-weights and ride heights for reference at the race track in case changes are needed. If you don't want to change your ride height then a more balanced approach would You will have to repeat this every time you lower the car onto Understanding corner weights. Wedge Delta can also be thought of I didn't hunt for that missing 1 %. RC Oval racing is probably the easiest form of RC racing right, right? weights: Corner Weight Calculator if Softer tire compound Right Rear Increase Right front and left rear Corner Weights Bicycling Left side tires lose contact with the racing surface More overall left side weight % weights into the spreadsheet (the blue numbers in the left "Corner Weights" 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). Note the "Conditions and Changes Made" Now with the steering straight ahead and both hands on the steering have your buddy record the . "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. Classic Truck. renting/borrowing/buying some scales and corner balancing your car. The crossweight percent will have changed to, say 55.4 percent. 3) Reverse stagger: The opposite of stagger when your left side tires are . I stretched my tires to get the RR right and now I'm . Don't just blindly cross weight it thinking it's the "right" way. lowered onto the scales the tires will need to spread out to unbind the You will need to weight your vehicle on each tire to use this tool. 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. 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. Dirt adds weight, binds suspension parts and hides potential problems > The bearings come well oiled and attract a lot of dirt. Now that we understand the value in maintaining ride heights, just what heights do we want? Plan to win in a repeatable fashion. To do this, we add five rounds of pre-load to the RF. 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). Keep in mind the stiffer your springs the 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? bite, a negative value means the Right Rear is favored. supposed to. The shock length as it is installed in the car at ride height. (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). 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. To favor right turns, put more weight on the B. Brake pads badly taper worn - replace. 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. tires. If one leg is longer or shorter than the others, the table will rock and thus be unstable. Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Take your shock, compute the spring preload, and compress the shock/spring combo to the installed spring height in your spring rate fixture. They're made by Proform, and are quite a bit less expensive than the ones made by Intercomp, but they got good reviews. if you have any of the scales connected improperly (i.e. 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. The situation isfrustrating. 45. Leebo's Corner. LF coil over 5 turns. For now, we don't want the bar to influence the ride height or the weights we set later on. 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. 13. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. I mainly run the 3/8. Astrut with its innards removed? Calculate the average existing ride heights front and rear. 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. more important corner balancing becomes. Road racers can take a page out of the oval racing book and The ultimate goal is to find the balance that will eventually lead to faster lap times. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? 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. No, not as in the law, but in being legal in tech. LR = left rear. In our example it is 18 degrees. I'm anxious to see what Proform says about my experience. This approach is commonly used in oval track racing. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? 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. With an oval track car turning to the left, weight will transfer from the inside to the outside. retract the right rear tire which puts more weight on the Left Rear and 1 Establish the corner weights you think you need for your car. - can make your car dive like a dump truck or a block of wood on ice. track are left turns then having more weight on the Right Front and Left Rear you run on the track. split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns coil over 5 turns. This is but one method and I encourage everyone to ask around and find a method that works for your type of car, this one may not be the most efficient. important for oval racers, especially on dirt ovals. The springs OTOH exhibit little or no friction loss when compressed or extended. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. There are legal issues too at the front. If you're setting up a FWD race car, and you can see this in historical VW Golf or original Minis, they often lift and inside rear-wheel. 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. section). My big stumbling block on this subject is how to get accurate readings by removing all the friction/bind from the tires, sway bars, bushings, etc. "two linoleum tiles & salt" technique to allow the tires to slide on the scales Also you will obviously want to have some way to ensure all your scale pads are level with each other. 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. Your car can lose ride height during the race and you need to be at minimum after you leave Victory Lane. left to right. Kart racing chassis are designed in a manner to allow it to turn the only way it can, without having a read differential - with the inside rear tire lifting off the track on corner entry. Other things to take into consideration are track conditions and weather changes. TVW - (RF + LF + LR) = 603. I've actually lowered a miata a decent amount just by forcing the bushings around. Bite should be positive for oval racing, Wedge = 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. 50% then Wedge Delta will be 0. anti-roll bars then leave them connected. camber angle of the wheels (-3.5 front, -3 rear). 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. 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. Of course you can add too Before putting your car on the scales you need to power up To properly corner weight the car, it is necessary to add weight to the driver's seat which is approximately equal to the weight of the driver (or have the driver sit in the car).
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