Consistent, regular scaling...
Consistent, regular scaling is an important element in understanding how your car responds to the setup changes you make at home or at the track.To minimize the effects of differences in tire placement from weighing session to session, begin by leveling each scale pad front to rear and side to side.
Once there was a time when your average racer could jack his car's rear axle off the ground and determine enough about the relative weights and vehicle wedge to win the feature going away.
No more. As racing technology filters down, it becomes more important for you to know and apply as much of that technology as possible to make your racer do your bidding just so you can stay with the pack.
As for weights and wedge, everybody these days knows they need to place their race car on a set of scales, but there seems to be a lot of misinformation about the reality of why and how that should be done for best effect.
Too often, details are overlooked that can cause handling characteristics to change from race to race. That results in a driver who doesn't know what to expect from his car and, therefore, can't build up the self-confidence to push the vehicle to the winning edge. To accomplish that consistent performance, every time you put your car on a set of scales, you need to know that you are getting readings that are relative to the readings you have gotten in the past. To do that, the car needs to sit on the same surface the same way every time you weigh it.
In the case of a severely...
In the case of a severely sloped scaling location, one or more shims may be needed to attain level across the face of the pad and/or to lift the entire pad high enough to match the heights of the other pads.
Now that doesn't mean your car always needs to sit in the same place. But wherever you are, you have to recreate the "surface" provided by the scale pads as similar to your usual weighing place as possible.
The Equipment
While you may not be able to afford a set of laser levels, computerized digital scales and a surface plate, you can do quite well substituting inexpensive equipment you can afford. Essentially, you can scale your car with a single scale if that's all you can afford. It just takes longer to complete the process. For most classes of weekly racing, you can easily get by with the grain scales everybody was using a few years ago-you just need to do the process the same way every time.
If you can't afford new equipment, ask around your local track to find something you can use. Look in the local classifieds or racing papers or find an auction. It will be one of the best racing investments you will make.
On The Level
Now that you have a scaling system, the key to consistency is paying attention to details so your scales are reading accurately. Also, make sure the bottom of each of your car's tires always finds the tops of the scales in the same place regardless of where the bottoms of the scales are sitting. In other words, your scales need to be completely level in all directions in order to get a true weight. A true weight is really the only way to learn how various chassis changes affect your race car on the track so you can learn to apply the changes you want on the fly, without a full rescaling each time you touch a jackscrew or insert a spring spacer.
When you are reading one scale, you need to make sure that everything holding up the remaining tires is as level as possible and even with the top of that scale. So, at minimum you will need a scale, three similarly sized platforms, some kind of leveling tool, like a carpenter's level, some shims to slip under the platforms or the scale, and a jack.
First, make certain your scales are performing appropriately. Calibration is relatively simple but very important. You need to know what your scales are reading and that they are all reading the same thing across the range of weight you will be measuring.
Next, pick a place where you are planning to set one of your scales and mark the floor location of the scale temporarily with tape. Now level the scale fore and aft and side to side at this location using the carpenter's level and the shims if necessary. It is important that the scale be fully supported and not "teetering" or rocking as this can cause bending, distortion, and false readings. Remember to note what you had to do to achieve a level surface between the floor and the scale.