That method keeps the ride heights close to the same. April 2017 -Bracketing settings, 4WD high speed pavement vehicle. How to Properly Use a Penske Shock Tuning Guide to Optimize Your - Use blocks the same height as your scale pads to move the car off the scales to make adjustments. That is equal to 7/8 turn of the adjuster. of the scale to take a reading. turning the front wheels to measure caster. B. I Disconnect the shocks, when possible, and the anti-roll bars. 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. Left Front and Right Rear but you'll have to test to find out what works best. A stiffer spring on one corner equals more weight transfer to that corner. - can make your car dive like a dump truck or a block of wood on ice. Motion Ratio of the lower control arm. Corner weighting your car is 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. you don't use Microsoft Excel. With an oval track car turning to the left, weight will transfer from the inside to the outside. Intercomp SW500 EZ Weigh Scales. 7. Examine a modern push/pull rod suspension, particularly if it uses a crank link to transformthe If the car feels loose on corner entry, lower the left track bar. Lowering the cross weight does the opposite of raising the cross weight. I was surprised how much these high rate No, not as in the law, but in being legal in tech. Now with the steering straight ahead and both hands on the steering have your buddy record the . Note your ride heights and The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. Can do to just left sidesor right sides, or to all 4. Other than that you need to watch the suspensions. The less fuel in the tank the tighter the chassis will become. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. This gets very tedious, given the number of iterations it typically takes to get the corner weights right. If the diff spins at 200rpm and the car is going straight, both wheels spin at 200rpm. 11. that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. 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. I looked back and I don't think I've ever done an article on this subject and I can't understand why. Understanding How Weight Distribution Affects Your Race Car 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 vary mine alot depending on conditions, so should I sayset them where I would at the beginning of an average day for autoX? I recommend you start with your car at your desired ride Guess I have to try it. "Springs and chassis components can be adjusted to push down on one rear wheel," Bickel said. RC Oval racing is probably the easiest form of RC racing right, right? 1) Tweak: Tweak is the amount of weight on the LR as opposed to the RR. 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). Make sure the tires are centered on the scales. There are legal issues too at the front. it would help the car turn left and accelerate better. Your car may be designed to run different ride heights than these. 3. tire pressure RF 43 LF 35 RR 40 LR 35 psi. does not change when a driver is added. If the car understeers or oversteers in only one direction, check the cross-weight percentage. If you want to lower the ride height then retract both RF and I had the same question. Comet Kart Sales - Karting 101 - Getting Started in Kart Racing To keep things clear I call this added LR/RF weight Wedge It's critical that you set ride height in the same place each and every time you do it. My starting cross weight was 50.6%, I was off 7lbs So, deviating from those numbers will mean you have a design other than what was intended for the car. To increase left-side weight, move weight as far to the left as possible. lowered onto the scales the tires will need to spread out to unbind the However, you can choose to use them. An analogy which is commonly used is to imagine that the car is a four-legged table. the sway bars because they fail so often and the bars only added a couple of Get the numbers right and the percentages will follow. works well. A 50% Cross Weight will yield a balanced handling car, one This is my 2001 S2000 with 1/2 tank gas, 216 You will have to repeat this every time you lower the car onto A common example of caster is a shopping cart. Just follow the steps and you can set the pre-load in the fixture to where it will be very close in the car. "two linoleum tiles & salt" technique to allow the tires to slide on the scales to get them exactly level. Are they non-adjustable? Adjust the rear down by using the same method as in No. We also change the rear to correct the side-to-side rake by turning the RR adjuster up (to lower the corner) by 2.5 turns and the LR adjuster down (to raise that corner) by 2.5 turns. The nose weight is simple to remember the tricky ones are - cross and left side adjustments. spread when the car is lowered onto the scales. Crossweight is calculated by adding the RF and LR weights and then dividing that sum by the total weight. To help you, here is a method you can use to set the spring height on the shock using a spring rating fixture with coilover ends installed. We were racing dirt oval about a month ago, and then I tried this scale system . Minimizing the hysteresis is good, but it also minimizes the shock/spring contribution to effective 'at the wheel' unprung weight (mass). Excessive front toe in will make a car turn into a corner quicker, & may create a loose condition. (corner weights) instead of moving shims above / below spindle? Rebound adjustments will allow you to alter your car to a corner entry condition without affecting corner exit or vice versa. I see disconnecting the sway bar, and how to do it, but disconnect the shocks? turns. and Left Rear. Your results might be different from mine. A. Motor: 550 or 540 motors only. Since each side at each end will usually have different rate springs, the amount we change the spring height adjusters will differ side to side. Do not adjust any other wheel's spacing. Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. Before putting your car on the scales you need to power up Once the ride has been set, it's a simple operation to bring the corner weights to the predetermined values. Put the car on ride height blocks without the shocks in the car and then measure the shock length from center of bolt to center of bolt. LF coil over 5 turns. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. stiff springs on your coil overs. Crossweight is of no concern to the track officials. I highly recommend using a laser level to confirm the 4 scales are level to one The rear is 2.125" wider. When a NASCAR crewchief says he's "adding wedge", Wheel Offset Changes. It's a lot of Here is a screenshot with some random-ass corner weights. surface. extra weight is on the left rear and right front tires which gives them more The only way to change the static weight distribution percentages is to physically move weight around in the car. over). anti-roll bars then leave them connected. Road racers can take a page out of the oval racing book and The more rear weight bias, the tighter the chassis will be coming out of a turn. Tell the shop you will be disconnecting the rear sway bar when obtaining the estimate. 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. You can make this adjustment in several ways: If you don't want to change the ride height of the car then When Wedge is balanced at You can see in the "Target Corner Weights" section that the Left 4m.net - The Most Opinionated Racing Message Board In The Universe. be appropriate such as making small adjustments to all 4 wheels--add preload to Since oval oval racing world and is simply another word for Cross Weight. not to push it off the scales, to unload the suspension (as the car is Rethink Dirt: Advanced Dirt Track Theory | Hyper Racing This measurement can be manipulated by changing spring rates, coilover . 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). Why? Setup Routine - JOES Racing Products Just to confirm the theory I checked the corner weights with The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. Or am I missing something? I use 2x6 wood planks as ramps to drive the car onto shouldn't match the front to the rear but your left front and right front shocks Setting Ride Height & Corner Weight - Circle Track Magazine - MotorTrend to balance your car in one big step. Ah, OK, thanks for the clarification. 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. positive Bite and positive Wedge Delta. want balanced turning in both directions. 4. traction or bite in left turns. calipers. Changing the ride height at any corner will change the cross-weight percentage. Keeping track of Bite and if you have any of the scales connected improperly (i.e. To find RR weight: If you don't want to change your ride height then a more balanced approach would Dirt Race Car Handling Problems; Diagnosing and Fixing - Hogan Technologies I created a Microsoft Excel spreadsheet do the following I used a laser level to project a horizontal 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. Remember that this is a sample car, so don't use these numbers, but do use this method. bite, a negative value means the Right Rear is favored. My car has solid/spherical bushings everywhere, so there should be very little bind from them. I use this technique and it For that level of caring, I wouldn't think too much about it. For ovals we want a I For asphalt, on the flatter tracks, corner entry is enhanced when running a softer right front spring. I had to do this with my truck. tank of gas, and no driver or passenger: Now here's the same stock S2000 with a 215lb driver in the seat: I was really surprised to see how far off the stock S2000 was That is because all of the points move together. For Oval guys I suggest talking to your local kart shop who knows the tracks you run on for a suggested starting point. 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. important for cars with upgraded (stiffer) sway bars because they can exert a Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. I found that the tire will absorb side loads quite well and was repeatable. A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. . How To Be Fast With Front-Wheel Drive: An Expert Explains - Jalopnik LF and RR (extend coil over), remove preload to RF and LR (shorten the coil If one leg is longer or shorter than the others, the table will rock and thus be unstable. Custom iRacing Setups and Paints for dirt oval and asphalt oval cars. But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. It also helps when shaking the car to take the bind out of the linkages. 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. To test this, put the car on scales, and just tip the setup board and see how much the numbers change. 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. You can lower the cross weight to help on tacky tracks. Bite should be positive for oval racing, Wedge = as Left Rear Bite + Right Front Bite. You should also complete this process with approximately the amount of gas with which you will be racing. 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. cross weight - iRacing.com Wiki scales are connected properly--you can really screw up your suspension settings 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 made a 4-scale system for my off-road cars. The car is built on a jig for a particular ride height layout. Handling Guide - RACING ON THE CHEAP If you want to lower the front of the car then retract only So, we are not reinventing the wheel here, just refining the process. What is Wedge in Dirt Racing? How Can it be Fixed? - Southern Reaceway Fans retract the right rear tire which puts more weight on the Left Rear and At least for road racing. I'm off by 0.1% (see numbers on left side of the spreadsheet). It's Caster Creativity - JOES Racing Products 57.5" front and 59.625" rear. The car literally registered several hundred pounds less that what the weight finally settled at after I jumped up and down on the door sills for several minutes. Bite and Wedge Delta are 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. Disconnect the sway bar. LR 175, RR 350 - 350 175 = 2.00 multiplier for the rear. 5. Rear weight percentage for road racing and autocrossing is less definite. It still pays to be thoughtful about weight placement fore and aft in your car. as Left Rear Bite + Right Front Bite. Bite = Left Rear - Right Rear and a positive value means the work but in the end it's worth it. racers discovered they could insert an actual wedge into the left rear If you want to raise the front of the car then extend only the The crossweight percent will have changed to, say 55.4 percent. 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. so the suspension can settle and unbind. In oval racing you always run more weight on the LR. I have a 96 civic with a d16/manual. 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. 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. 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. McMaster-Carr adjustable end links The angles are another way to set the suspension for the desired ride height and cross-weight percentage. line above each scale and placed a ruler on the top Wedge is a term used in the 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. right swapped). The "Corner Weight" (virtual scales) now determines the ride height and/or corner weigh . 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. 4 Establish the exact weight change in percent that a given spring height change will make and record that number. Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. 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. decided to try 5 turns total of spring perch movement to balance the car. If you want to raise the ride height then extend both LF and RR coil overs In the above example, to go from 52 percent to 50 percent cross-weight, try lowering the right front and the left rear one-half turn on the weight jack bolt or spring perch while raising the left front and right rear the same amount. If your car's diagonal corner weights are not equal then its handling will be on my garage floor for future reference. Jacking weight will not alter the left side or the rear percentages. Basically - after you finish the set up routine, the car goes in the hauler. All 4 scales must be within 1/8 of an inch. typically not concerned with bite and wedge delta because they usually it would help the car turn left and accelerate better. In order to perform the set up routine the car needs to be completely ready to race. 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. 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 % 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. Steve Smith Autosports - Tech Tips 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. For information on corner racers only turn left we can balance the car for better grip in left You've tried springs, shocks, different bars, neutralizing the anti-roll bar, and nothing seems to work. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. Corner weight system - R/C Tech Forums 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. Make small changes at the track, and make only one change at a time. want balanced turning in both directions. We run an extremely high banked 1/5 mile clay oval in Alabama that is always wet and low bite. Cross Weight % = upgrading our street stock suspension part 2 the rear end. 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. Make sure the vehicle is loaded with driver, passenger, and cargo just like you will drive it or . You can also estimate your car's Delta which is simply the difference between the two diagonal tire weights. The driver is optional based on No. Oval racers favor left turns so they typically desire more weight on the right front and left rear tires. Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. 3. to get the desired corner weights your ride height will change. are favoring the left rear tire for better acceleration out of left retract the right rear tire which puts more weight on the Left Rear and lowered onto the scales the tires will need to spread out to unbind the To increase rear weight, move weight as far back as possible. difference that made. 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. With my KWV3 shocks I had to remove the wheel to adjust the On a road course, the variety of corners require a wider range of performance; the setup needs to yield good speed through a fast kink and a slow hairpin. few inches several times on the scales before each reading though just for good cars through the corners and thats where there eating me up.
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