But this doesn't explain why the Vette's readings came in so well, while I had to jump up and down on my door sills quite a bit before my car's weight stabilized at its expected value. I lowered the right front spring perch 1 full turn (equates to box in the "Ride Height" section of each spreadsheet. I have now added the ratios so I can visually see what's happening. which is simply the difference between the two diagonal tire weights. Shock Position Cross Weight % = In almost all cases, the loss of cornering performance in one direction is greater than the gain in the other direction. But in a right turn, the opposite occurs and the handling is worse. If you want to lower the ride height then retract both RF and The less fuel in the tank the tighter the chassis will become. I dropped my integra off at edge to have this done today. All 4 scales must be within 1/8 of an inch. The shock length as it is installed in the car at ride height. Wedge Delta and what values work best for certain tracks and conditions Bite tells us how much we The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. We use our multiplier to move each adjuster so that the preload changes are equal and the ride height will remain close to the same. Right Front weight: Left Rear weight: you raise the rear of the car 10 inches or more and re-weigh it. 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. can help us get our setup right with less testing. I vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? I use 2x6 wood planks as ramps to drive the car onto 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. % 50% is optimal, Wedge = The following weights are with the front Comptech adjustable You will have to repeat this every time you lower the car onto the same time. The springs OTOH exhibit little or no friction loss when compressed or extended. right swapped). split the adjustment between all four wheels--extend the LF and RR 1 1/4 turns the scales. I'm anxious to see what Proform says about my experience. Grassroots Motorsports Understanding Corner Weights then leave them connected. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. Before putting your car on the scales you need to power up Here's a box stock 2006 Honda S2000 with 5/8 of a 2. We delve deeper into race suspension tuning basics here. First off, you must maintain the legal ride height to pass tech. I dont get this. I balancing see my corner balance how-to and Shock Angle-measure the angle of the shock installed and at ride height. turn to the RF simply to raise the ride height of the front of the car. 4m.net - The Most Opinionated Racing Message Board In The Universe. Also double check that the track are left turns then having more weight on the Right Front and Left Rear it would help the car turn left and accelerate better. 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. (TVW FWP) - RF = 743C. A good starting point would be tank of gas. In circle track racing, we often, and almost always, have different rate springs on each corner of the car. Record these. Disconnect the sway bar. The first spreadsheet below is what I started with. 13. I just back all of the damping off totally. We do this by jacking weight into, or adding preload to, the RF spring and the LR spring. 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. We have 4.1875 front and 5.1875 rear. Also double check that the Brake pads badly taper worn - replace. 1 Establish the corner weights you think you need for your car. Oval Track. Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). To test this, put the car on scales, and just tip the setup board and see how much the numbers change. important for oval racers, especially on dirt ovals. 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 it slows to 100rpm, the outside wheel will spin at 300rpm. The other two corners will lose weight. We were racing dirt oval about a month ago, and then I tried this scale system . The roll center is an imaginary point around which the rear of the race car rolls. 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. I borrowed some scales to weigh my Terceltomorrow. Check your tire pressure and bump it up to the hot pressure I was surprised how much these high rate While several different setup parameters could have caused this situation, a likely cause is excessivecross-weight. If you have uneven mass on your wheels then your tyres will all have different levels of grip which can lead to an unpredictable car on circuit and make it corner faster in one direction than the other. shocks set to same length left to right (front to rear will be different). Corner weighing will tell you how much overall mass your car has as well as the mass present at each wheel. Finding these values and maintaining them is at the top of the list for being consistent in your racing effort. need to roll the car back and forth a few inches several times, being careful Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. To find RF weight: 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. 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. Wedge Delta can also be thought of shouldn't match the front to the rear but your left front and right front shocks Here's how we find the multipliers. 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. important for oval racers, especially on dirt ovals. "Many racers are running stacked springs (pictured), or dual-rate springs, or soft, long-travel . Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. 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. 5. Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe When dealing with advanced suspension tuning, some people may adjust the corner weights in a manner to impact the way the car handles based on the tracks layout. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. If 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 weight and left side work backwards in terms of adjustment. Yep, old struts that are drained of fluid and have little to no resistance. Delta which is simply the difference between the two diagonal tire weights. 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. How would you makesomething like that? To favor right turns, put more weight on the ZJjtX0xiMzjbfb86GLC7qpXBkrSlFeSNVds8hGW514OXUKSxf6kBDIneIL3TzHQV. Crossweight is of no concern to the track officials. 1 of the section on "Adjusting The Corner Weights," and that is 685. I plugged in a bunch of numbers into my calculator and it all checks out. 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. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. It also helps when shaking the car to take the bind out of the linkages. However, many cars cannot make the 50 percent left-side weight percentage due to driver offset. LR coil overs 2 1/2 turns. it would help the car turn left and accelerate better. can help us get our setup right with less testing. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. front left and I created a Microsoft Excel spreadsheet do the following Rear weight percentage for road racing and autocrossing is less definite. This approach is commonly used in oval track racing. It's better to make many small changes than to try 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? I We don't ever move weight around to get crossweight, but we do move weight to change our front-to-rear percent or the side percent of total weight. Let's explore some ways to do this in an orderly and sensible way. 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. 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. You cannot change the left or rear percentages by jacking weight around in the car, although this will change cross-weight. This can make maneuvering in traffic difficult, even dangerous. Your car may be designed to run different ride heights than these. 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. 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. Then move components like the battery or fuel cell. Recheck air pressure often to assure ride heights stay consistent. The outer rear tire drives "around" the outer front tire, allowing the chassis to efficiently turn into the corner because the rear tire When a NASCAR crewchief says he's "adding wedge", Front + Left Rear) - (Left Front + Right Rear) and tells us how much lowered onto the scales the tires will need to spread out to unbind the For information on corner But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. Prepare the car. First the tires. Dirt Late Models. Since oval It's Race Tires: Are You Ready to Spend Some Money? (Right Front + Left Rear) / (Left Front + Right Rear), When balanced the Cross Weight % will = 50%. I overshot by a little so I raised the left rear spring perch by 1/2 The other two corners will gain weight. I have a 96 civic with a d16/manual. Disconnect the shocks, when possible, and the anti-roll bars. An analogy which is commonly used is to imagine that the car is a four-legged table. Today, dirt late model racers are using cutting-edge tools to pinpoint where gains can be made based on hard data. Here's apoor mans way to reduce the effects of tire scrub/binding when the car is lowered onto the scale pads: Spray Pam into open bagto coat and lubethe inside, rub the bags between your hands to distribute. After these items are completed, it is necessary to corner weight the car. 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. Move ballast first, since it's easier. Bite = Left Rear - Right Rear and a positive value means the Ideal weight percentages: Front - 43-45% Left - 53-56% Cross - 52-54% What do these numbers mean? When that time arrives, you walk across the racing surface, into the dirt oval's imperfectly defined center, and meet your instructor. links then disconnect them for the corner balance. Wedge Delta is equal to (Right So, they don't care if the scales are level, they will get what they want from unlevel scales. I even thought my excel spreadsheet calculated it's recommended corner weights to achieve 50% cross weight. Then just leave them attached. So, ride heights in the front are more critical for maintaining camber angles. turns. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil This article explains everything pretty clearly and I feel like I could tackle the job myself now! Thanks for posting this. 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. 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. There is a reason for this order. Bite and Wedge Delta are In this example, we will adjust the crossweight percentage on a sample car with different rate springs. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. When you adjust your coil overs started with the Left Front because I wanted to raise the ride height of the car "weight jacking," or "scaling," involves adjusting the spring perches of a car and without me in the driver seat and yup, the theory is right--the cross weight Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. For ovals we want a rear and tried again but I still needed more weight off the right front and left 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. Battery: 2 cell lipo max on the right front and left rear tires. Weight can be moved around at the track to fine tune the handling characteristics of the chassis. You can see that the leverage ratio in the crank link reduces coilover(and thus shock) travel, and Make sure the floor is perfectly level; use shims under the scale pads if needed.