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. If you want to raise the ride height then extend both LF and RR coil overs
Bottom line, you can strive for perfection, but ultimately youll just make yourself crazy. The car should be at minimum weight, using ballast as needed to make the proper weight. Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. This was a very interesting post to me. 12. Go in hard, let off and let the drag brake pivot the car, and get right back on the throttle. We have 4.1875 front and 5.1875 rear. 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. Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. 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. Open timing on motor and esc. I have now added the ratios so I can visually see what's happening. One of the problems with cross-weight is that it will change the handling balance from a left to a right turn. 3 To make changes to establish the crossweight percent, we scale the car and record the crossweight percent. the scales. Are they non-adjustable? Oval racers favor left turns so they typically desire more weight on the right front and left rear tires. This obviously means that decreasing cross weight or left side weight 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. It would just automatically settle. of the scale to take a reading. I still rolled the car back and forth a
Struts and trailing arms generally arent great in this case as they have a lot of inherent bind. is especially true if you don't have adjustable spring perches. coil over 5 turns. suspension). I put the car on grease tiles so the tires move freely on the scales and then I bounce each end a couple times. The front will show close to 60%. 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. On oval track cars, cross-weight is usually used in conjunction with stagger (where the right rear tire is larger in circumference than the left rear tire) to balance handling. Wedge Delta can also be thought of
It varies with weight removal, added. The angles are another way to set the suspension for the desired ride height and cross-weight percentage. Cross Weight % =
Because it's targeting LF/LR = RF/RR to equalize the left vs right handling characteristics. To truly optimize your shocks, your overall suspension setup must be right, including ride height, camber, caster, toe, and the correct spring rates. I highly recommend using a laser level to confirm the 4 scales are level to one
Since the front and rear shocks are of different lengths you
2) Stagger: Stagger is how much bigger the right side tires are compared to the left side tires. And don't ever believe the track scales. If you do have adjustable end
And what do you mean by "lots of bearings"? It is best to get 50 percent left-side weight when possible. The vanilla neon setup would be SDK suspension (stock ACR, look at neon.org and figure out what you have) with 3.5 deg front camber, 1 to 1.5 rear, zero to 1/8" in toe front and rear. At least for road racing. When looking at corner weighting, the cross weight (diagonal weight) is the most important component. To keep things clear I call this added weight Wedge Delta
Scale Type: . used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales
I overshot by a little so I raised the left rear spring perch by 1/2
Check static weight before working on cross-weight. The first is to use traditional lift-off oversteer. To find RF weight: I just back all of the damping off totally. If you want to lower the front of the car then retract only
I use 2x6 wood planks as ramps to drive the car onto
In almost all cases, the loss of cornering performance in one direction is greater than the gain in the other direction. To favor right turns, put more weight on the
The height of the rear roll center (and the front also) is critical to handling. over).
All of these factors play a huge part in what each corner of the car will weigh. Corner_Balance.zip Excel spreadsheet. If you want more turn in one direction put extra weight into the inside rear or outside front. Wouldn't the fact that it is front wheel drive change at least the front to rear percentages? on the right front and left rear tires. For pure race cars this isnt a consideration. document your current ride heights and your coil over changes each time
want balanced turning in both directions. When Wedge is balanced at
At the rear, your rear control link angles are critical to maintaining rear alignment and determining rear steer angles and/or reducing rear steer altogether. 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. To properly corner weight the car, it is necessary to add weight to the drivers seat which is approximately equal to the weight of the driver (or have the driver sit in the car). The CG height
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. are favoring the left rear tire for better acceleration out of left
The following weights are with the front Comptech adjustable
You should read the spring preload amount. retract the right rear tire which puts more weight on the Left Rear and
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
Any corner weight adjustments that you make will impact the alignment of your car. corner weight calculations: Corner_Balance.zip
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. Smaller will scrub less speed of if your not sideway threw the corner. When a NASCAR crewchief says he's "adding wedge",
In contrast, the corners on most ovals are super speedways are of a similar radius, and run within a very narrow range - closer to three-to-five miles an hour in difference. racers only turn left we can balance the car for better grip in left
You would be amazed at how much bushing twist can contribute on your suspension. Once you get the car up on the scales you'll
Right Rear =
Measure control arm angles after each change. Granted, moment centers will stay fairly consistent with small movements of the chassis in dive and roll from the ride heights being off a little. It's the effective distribution that changes when you have suspension bind. For most karts, the following weight distribution is recommended: 43% Front Weight 57% Rear Weight 50% / 50% Left / Right Weight These are just recommended starting points. Plan to win in a repeatable fashion. The new existing ride heights are LF 3.6875, RF 4.8125, LR 4.1875, RR 5.3125. Thanks for posting this. of the scale to take a reading. Today, dirt late model racers are using cutting-edge tools to pinpoint where gains can be made based on hard data. To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. Left Rear tire is carrying more weight so it will get more traction and
Wedge is a term used in the
Adjusting the sway bar is time consuming and questionable unless it is really stiff. All rights reserved. Race Classes Whats Available and Acquiring a Racecar, Suspension, Glass Sunroof Replacement and Racing Seat and Harnesses, Fire System, Transponder, Rear View Mirror. Of course you can add too
If you don't have adjustable end links on your
5. The left weight percentage is found by adding the LF weight to the LR weight and dividing the sum by the total weight. You need: 1. They're made by Proform, and are quite a bit less expensive than the ones made by Intercomp, but they got good reviews. right swapped). If you want to lower the rear of the car then retract the LR
3. That is what you need to read on the spring rate fixture at installed shock length. Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. 4m.net - The Most Opinionated Racing Message Board In The Universe. turns. (TVW LSP) - LF = 769D. Right Front =
This is my 2001 S2000 with 1/2 tank gas, 216
rear. And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm. 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. This adds pressure to that end of the car just like putting the paper wedge underneath the table leg. I dropped my integra off at edge to have this done today. 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. So if you have 60% on the front , you should have 30% on each front wheel. few inches several times on the scales before each reading though just for good
You can also put two linoleum tiles with salt between them on
You can also use this online calculator to compute your corner
Today's oval
For road racing and autocrossing, the ideal left weight percentage is 50 percent. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. Do not copy these ride heights; they are only used as an example. renting/borrowing/buying some scales and corner balancing your car. But stagger is not a good idea on a road course or autocross either, where the ideal is 50-percent cross-weight and no stagger. You've mentioned "dead struts" a couple of times - what do you mean by that? Corner weighting your car is
There are many ways to corner balance a car. 6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup. weights and percentages and generates target wheel weights to achieve a 50%
Road racers are
Less fuel equals faster speeds. 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. rear should be the same. that turns equally well in both directions. Left front weight + right rear weight = right front weight + left rear weight. difficult to position all 4 scales so you can just drive up on all of them at
So LF/LR = RF/RR is what you shoot for. supposed to. 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! track are left turns then having more weight on the Right Front and Left Rear
14. Step 1 - Determine Sprung Weight. Cross-weight is also called wedge: If the percentage is over 50 percent, the car has wedge; if below 50 percent, the car has reverse wedge. turns. More stagger usually loosens the handling in left turns, so more cross-weight is used to tighten it up. traction or bite in left turns. LR coil overs 2 1/2 turns. Many electronic scales will perform the calculations for you. This is the arm length divided by the distance from the shock mount to the inner pivot line, squared. 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). Drag Racing. That is why a stiffer right rear spring makes the car looser. For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00. Would be interesting to see how close to ideal I got it though, given how well it handles already. So, we are not reinventing the wheel here, just refining the process. R. racing junky Member. Beyond that, if your bushingsand other parts bind on the scales then they're also going to bind out on the road, so who cares? Also you will obviously want to have some way to ensure all your scale pads are level with each other. So let's study ride heights first.
positive Bite and positive Wedge Delta. not to push it off the scales, to unload the suspension (as the car is
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. you raise the rear of the car 10 inches or more and re-weigh it. Unsure about autox. But this is almost never the case. You can make this adjustment in several ways: If you don't want to change the ride height of the car then
Afterward you need to adjust the settings to the correct maneuvers. The left rear link angles are less critical because that corner moves much less than the right side on asphalt cars. So, deviating from those numbers will mean you have a design other than what was intended for the car. suspension changes to track your progress. it would help the car turn left and accelerate better. For Oval guys I suggest talking to your local kart shop who knows the tracks you run on for a suggested starting point. Proforms are cheap scales. tires. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. Intercomp 102030 5X5 Hub-Mounted Corner Weight Scale. it would help the car turn left and accelerate better. positive Bite and positive Wedge Delta. 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. 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. My left rear is something like 150lbs heavier than the right rear, with both fronts even at ~740lbs each on a 2425lb FWD car. 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. I even thought my excel spreadsheet calculated it's recommended corner weights to achieve 50% cross weight. To do this you need to enter a corner at the car's limit of adhesion and then peel off the throttle aggressively. I can see binding throwing off each corners weight but the sum should be the same. . I used a laser level to project a horizontal
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. 2. 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. The last event in the rain i actually had the rears up to around 38. about 1/8" of wheel movement) to reduce the weight on the right front and left
For now, we don't want the bar to influence the ride height or the weights we set later on. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. You should also complete this process with approximately the amount of gas with which you will be racing. LF coil over 5 turns. 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. the scales. Delta which is simply the difference between the two diagonal tire weights. For example, if you are racing the Briggs Light class at 305 pounds, your corner weights should be: LF = 68 pounds RF = 68 pounds My car has solid/spherical bushings everywhere, so there should be very little bind from them. Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. RC Oval racing is probably the easiest form of RC racing right, right? Lay the bag flat onto the scale pad, partially open to vent, lower the car into the bag. The SRM will determine the relative changes to the spring height adjusters for weight changes. you weigh and adjust. A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. so the suspension can settle and unbind. 50% then Wedge Delta will be 0. I saved a copy of the spreadsheet for each
Measuring from the center of the tires I got
It will let you predict and understand the effects that various modifications have on handling, performance and lap times. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. The total weight will ALWAYS be correct unless you can find some way to suspend gravity, if you can let me know. McMaster-Carr adjustable end links
Rear weight percentage for road racing and autocrossing is less definite. I used a laser level to project a horizontal
works well. are favoring the left rear tire for better acceleration out of left
Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille
Be sure to have the weight of the driver in the seat. 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. %, Bite =
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.
A lowered rear roll center promotes side bite at the rear which tends to tighten corner handling. 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. the driver seat and reconnect them so there's no preload on them. Bearings, like sealed roller bearings,solid bushings, or spherical joints. The more power a car has, the more that static weight over the drive wheels helps acceleration off the corners. Left Rear tire is carrying more weight so it will get more traction and
But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm.
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