Precision Work" "Pull & Square Body" - BodyShop Business

Precision Work” “Pull & Square Body”

How many of you use the term "pull and square body"? How many of you know exactly what it means? To an adjuster, it’s a non-specific repair term that often leads to a reduction in time and pay. But being more descriptive about frame damage and pulling procedures on your estimates can change that

Rather than looking at vehicle measuring in terms of necessary equipment or its importance in the repair process, we as estimators, owners and managers need to understand how using more descriptive and accurate terminology can affect the estimating process and, ultimately, what you’re paid.

For starters, we must commit to memory the terms for measuring and how they apply to our businesses. How many of you use the term "pull and square body" or a similar phrase? What does this term mean? It was coined when we went from full-frame cars to unitized vehicles and we were still handwriting our estimates. Let me ask you another question. How many field adjusters reduce the figure associated with that term when they examine your estimate? It’s a nebulous term that isn’t very descriptive, which allows the procedure to be adjusted. To change that, we must fully understand the measuring and pulling processes and the terms associated with them.

Vehicle Construction
Let’s look at how a unitized vehicle is constructed: Vehicle manufacturers begin by placing the floor section on some sort of fixture at the control points. We have these four control points mounted at a height above the holding fixture. The distance from the fixture to the control points is known as datum height. The flat surface of the fixture is known as a datum plane. You need to understand that datum plane and datum height are arbitrary.

Think of all the different frame machines on the market and the different types of pinch-weld clamps available. If you place a 1998 Ford Mustang on these different frame machines, you’ll get 20 or 30 different datum heights (in this scenario the datum height is measured from the bed on the frame machine to the control points). Don’t despair — each measuring system will show you how to establish datum height and a datum plane, which will be constant with your particular frame machine and measuring system. With the car on the frame machine, you can determine a height measurement for every point on a vehicle.

Next, you must look at the second part of any measurement on a unitized vehicle: width. Think of a car as an Oreo cookie, without the filling. (I know it’s not fun thinking of an Oreo without the filling, but try to visualize the next principle with the cookie.) Place the cookie on its side, with the edge of each half facing you. Now place a piece of paper between the two halves. You can measure the distance from the outside of one cookie half to the piece of paper as well as to the other cookie half; that distance will be equal.

As with the datum plane, vehicle manufacturers establish a center plane that splits the vehicle in half. This center plane has a dimension point of zero on the measuring scale. We can now measure from zero all points to the right and left of the center plane.

When measuring points, you must remember that there are two types: symmetrical and asymmetrical. Symmetrical means any point on the left side of the plane will have the same length, width and height as the coordinating point on the right side of the center plane. Asymmetrical means that a point on the left of the plane will be different than the same point on the right side of the plane. Most asymmetrical points are usually found in the width dimensions.

Define Dimensioning
With vehicle construction in mind, you need to commit to memory several terms that will aid in accurately estimating and repairing a collision repair job:

• The first term you need to know and use when writing an estimate is mash. It’s defined as a shortening of the length of the vehicle. When analyzing a mash condition, pay particular attention to crush zones and kinks that might occur as a result of the collision. These items should be noted on the estimate and most often replaced per I-CAR recommendations.

• Another term to understand is sway. It’s defined as the movement of the structure to the right or left of the center line or center plane. When looking at a sway condition, pay particular attention to sealant, which has a tendency to open up. I find this very helpful when trying to determine how far back the damage has traveled through the inner structure.

• The next important term is sag, which refers to the movement of a structure up or down.

• Diamond is also a term to remember. It refers to a condition of one rail being farther back than the other. This particular condition is very common on ladder or full-frame vehicles (trucks).

• The last term is twist, which is usually associated with the height of the center section of the vehicle.

Now that you understand these terms, use them in the damage description when writing an estimate. For example, write "pull and correct sag condition" and "pull and correct sway condition" (two-line entries) instead of "pull and square body." By using these terms, you can now visualize the type of vehicle damage. After you’ve analyzed the damage, you can begin the measuring process.

Let’s Get to Work
The first step in the measuring process is to establish reference points or location points to set up the measuring system. Because most accidents involve front or rear damage, I’ll concentrate on those types of repairs.

We know that a vehicle is divided into three sections: the front, center and rear. The center or passenger section is the strongest of the three for obvious reasons. A front or rear section can have as much as 45 percent reduction in length, but the passenger section would only suffer a 3 percent reduction. As the strongest section and the one that will suffer the least amount of damage, the center is where we start to set up our measuring system.

On unitized vehicles, the location of the reference points is usually at the four corners of the floor/passenger compartment. Most measuring systems will use three of these points to set up the system and establish a base or zero measurement. Once the zero points are determined, we have the ability to measure every point for width, length and height and can begin the pulling process.

It’s difficult to describe how to pull a vehicle, and I strongly urge you and your techs to enroll in a hands-on technical program, but I’d like to give a couple of procedures that should be utilized when pulling a vehicle.

When we begin to pull and correct damage, we need to repair the last damage in first. For example, we have a front-end collision and the damage has traveled back to where the rail attaches at the firewall. This is the area that needs initial attention. Once that part is corrected, proceed to move to the front of the vehicle, correcting each point to length, width and height. When you write an estimate, you need to note how far the damage has traveled to justify the hours needed to correct the structure.

Let’s say we have a vehicle that’s been in a front collision, and a sway condition exists where the left rail moved 15 mm farther than the right. We would pull the structure and correct the right rail first. Since they’re tied together by way of the core support, we’d want to isolate the right rail with either another tower or with a cable/strap. With the right rail isolated so it can’t move, we can now pull the left rail.

Take the Time to Be Precise
I realize these concepts are hard to visualize, but take some time with your frame techs to analyze the damage, construct a pulling plan, measure the vehicle and observe the pulling process. Using the aforementioned terms — which are more descriptive than "pull and square body" — be as accurate as possible when writing an estimate. Believe me, the time you spend up front will pay off in the end. If all this seems like added work in an already busy schedule, ask yourself this: If I haven’t got the time to do it right, when will I find the time to do it over?

Contributing editor Toby Chess is director of technical training for Caliber Collision Centers. He’s also the Los Angeles I-CAR chairman, an I-CAR instructor and a certified ASE Master Technician.

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