More than a few years ago, I remember the best frame tech in the shop I was working for measuring a vehicle he had on the frame rack. This particular shop had just purchased a state-of-the-art laser measuring system. Being curious, I wanted to see how it worked. I walked over to the frame area of the shop and watched the tech measuring the vehicle with a tape measure and the old standby — his thumb. The new, very expensive measuring system wasn't even turned on. I asked the technician why he was not using the system. "It's too hard to set up, and I can get this job done before I get the machine turned on," he said. My thought was that he really wasn't well trained in how to use it, and his fear of the unknown kept him from using it.
Actually, I don't think this scenario is that unusual, and my belief continues today. During that time, there were several different types of professional measuring systems in use and quite a few seat-of-the-pants methods being employed. Training was kind of an afterthought, and consequently many vehicles were repaired improperly.
In the past, "close enough" may have been good enough when measuring. With the vehicles built since the onset of the unibody, tolerances have been reduced to millimeters and in some cases, zero. Considering theses tolerances, it
would be virtually impossible to correctly repair unibody/frame damage without a precise measuring method. Accurate frame and unibody repairs cannot be performed unless they can be accurately measured.
Better than the tape measure
Don't throw that tape measure away — it still serves a purpose in certain situations. If you're going to measure a unibody accurately, it needs to be done with the following:
- a dedicated bench measuring system;
- a mechanical universal measuring system; and,
- a mechanical laser and computer laser/sonar system.
I will explain how each of these systems works, but initially we need to understand that measuring and pulling a vehicle are two different things. A universal frame rack, a floor system and a dedicated bench are all tools that help us pull and repair the unibody while it's being measured. They measure the damage, against control or reference points, while the vehicle is mounted to the apparatus.
Before the universal, the laser, computer and sonar systems came into prominence. Measuring was only two-dimensional. The advent of these systems provided the repairer with a three-dimensional measurement, insuring much greater accuracy. The three main control points that make up three-dimensional measuring are the vehicle centerline, its zero line and its datum line. These points indicate the vehicle height, length and width. All three of theses dimensions can be measured simultaneously using a computer or universal system.
Dedicated bench system
In the 1970s, vehicles with unibody construction were far more prevalent in Europe than in the U.S. Shops began using the dedicated bench system as early as the mid 1970s. When we began to see vehicles built with this type of construction technique here, the need for a repair system became apparent. Dedicated bench systems were widely preferred by vehicle manufacturers because they offered greater repair consistency and actually emulated the jigs with which the original vehicles were built.
In these systems, the bench is utilized as the device to anchor the vehicle to and becomes the mounting structure for the measuring devices. The measuring devices are set up in specific control points on the bench itself. The pulling arms are mounted to the bench, and the vehicle is pulled and repaired. As the vehicle is being pulled, the measuring attachments check for pulling accuracy. This procedure is an extremely accurate method of measurement.
However, setup time for this system is longer than any other system because of the time it takes to anchor the vehicle to the bench itself and set up all the various measuring fixtures to the factory control points. Many dedicated bench-measuring systems are still built in Europe. The main drawback to these systems is that all the fixtures are vehicle-specific and very heavy. Additionally, the technician must manually record reference measurements. No record of before or after repair measurements is available.
Mechanical universal measuring systems
Universal measuring systems came after the dedicated bench. Their name implies their function — one set of measuring devises measures many different vehicle applications using many different pulling platforms. A dedicated bench, frame rack and even a floor system can be used with these tools. Obviously, the multi use feature added much greater affordability for shops that already owned frame racks or benches since they could now do without the cost of purchasing the dedicated fixtures. The system is made up of telescoping bars and tram gauges that are utilized to measure the vehicle, using manufacturer information as reference. By referencing these dimension manuals, it is possible to accurately measure many different unibody applications.
These systems usually have the ability to make overhead or upper body measurements using a specialized overhead tram bar. Many shops still utilize this measuring method today. One issue with this system is that its setup must be performed very accurately. Since the undamaged side of the vehicle is often used for reference, improper alignment in this area can create an inaccurate reading on the damaged side, causing a technician to pull for repairs according to inaccurate specs. Any shifting or movement of a vehicle during the repair process can cause the measuring devices to shift, again creating accuracy problems. With this system, the technician must manually record the control points, and the before and after measurements.
Mechanical laser systems
Mechanical laser systems were the next to be introduced. With these systems, targets were installed at certain control points around the vehicle. The beam of light the laser emitted was then used during pulls to align and measure the distance between the targets and diagnose and repair the damage. Mechanical lasers generally are very accurate but again rely on proper target placement by the technician to create a proper measurement. Lasers, like mechanical measuring systems, can accurately measure door openings and center post placements that are usually symmetrical on vehicles.
I have used portable lasers that work really well on roof and side post damage. These lasers don't really provide a measurement. Instead, using the symmetrical approach, they allow the user to pull until the laser hits a reference point that matches the same control point on the opposite side of the vehicle. The device mounts to the roof and emits a beam on both sides of the vehicle at once. On the undamaged side where the control point is hit by the laser, a record is made of the reading. That same reading is duplicated on the opposite side of the vehicle, and the laser is then pointed to the reference point on the damaged side. The pulls are conducted until the beam from the laser hits the reference point on the damaged side. This system is simple but highly effective. Manual documentation also is required for this type of tool.
Modern day wonders
With the advent of DRPs, the need for documenting damage and repairs was becoming evident. It was easy to say a vehicle was properly repaired and another thing to be able to prove it. Computerized systems provided that type of necessary documentation.
There are many types of computer measuring systems on the market today. Some use lasers, and some use sonar, or sound waves. As with mechanical laser systems, targets or microphones/sensors are placed in specific reference spots around the vehicle. The computer then uses either sound waves or the laser light beam to take a reading of the distance between these reference points. That reading is calculated into a distance measurement. As the vehicle is pulled, the user can see the calculations changing on a computer screen, informing the technician of how much force to exert and in what direction. As these programs have become more and more sophisticated, advanced graphic displays that depict a rendering of the frame/unibody component itself, appear on the screen and show the progress of the pulls. At any point during the pulling process, a printout can be generated displaying the measurements of the unibody at that point. This is a great tool for documenting proper repairs.
Again, the accuracy of these measurements is dependent on the proper placement of the sensor/target. However, this is relatively a foolproof process since most manufacturers have perfected the location and mounting of the target over the years using specialized magnets and mounting shapes. This is the most widely accepted and most often used three-dimensional measuring system in use today. As computers become more and more powerful, I am excited at what the future might bring to this particular arena. In recent history, one manufacturer has made the printouts available in electronic formats so they can be sent via e-mail and stored in the shop-management system.
The innovations
Several months ago, I witnessed a demonstration of one of the new "touch" or mechanical arm measuring systems at a shop. It consisted of a unit, about the size of an A/C recycler, with a mechanical arm attached to one side. In this application, the user would touch reference points in a certain sequence on the undamaged side of the vehicle or in a reference book provided by the manufacturers of the device. These reference points were converted to measurements by a computer in a unit that stores a host of vehicle measurement data in its hard drive.
The measurements were displayed on a screen in the unit that corresponded to the vehicle being worked on. The user would then touch the same reference points on the damaged side of the vehicle, and a comparison would be made of the differences between the damaged and undamaged sides by the computer. The pulls would then be made, and subsequent measurements would be taken throughout the pulling process by the user. A printout was available throughout the entire process.
These systems require limited setup and can be used while the vehicle is on the floor rather than bolted to a dedicated fixture. I see a great benefit in using a device like this during the estimating process. The insurance company or shop estimator would be able to accurately prove the severity of damage when writing the initial estimate and could provide printed documentation of that damage to the customer along with the estimate copy. That would be a powerful tool.
The industry has come a long way since the days of the measuring tape and the thumb. As advanced electronics have helped streamline measurement, we as an industry should embrace these changes and exert a greater emphasis on getting our people trained in the proper use of this equipment. I would rather put my family in a vehicle repaired utilizing modern technology than in one repaired just "good enough" using old equipment. I'm sure you would as well.
