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Truck Frame Holding & Pulling - Tips YOU NEED TO KNOW

Pro Line Systems International-Auto Body Shop Equipment
Published by Pro Line Systems in Informational · 4 April 2023
Tags: TruckFrameAnchoringAndPullingTipsYouNeedToKnow|ProLineSystemsInternationalInc

Truck Frame Anchoring And Pulling - We'll Explain What You Need To Know, And Reveal The Best Tools To Do It Right And Achieve Ultimate Productivity


Auto Body Repair Technicians have a unique challenge when they need to straighten Truck Frame Rail damage. The auto repair professional has probably read articles and attended seminars & classes on proper anchoring and pulling techniques for truck frames.

Despite this, many technicians still do not understand the appropriate methods for anchoring and pulling the heavy-duty truck frame. To address this, some fundamental pulling information and challenges repair shops face when working with aluminum and Advanced High Strength Steels (AHSS) will be discussed.

The Basics

Modern vehicles are designed to absorb significant energy from impacts, which dissipates throughout the structure, creating a "cone effect." In the past, conventional heavy truck frames could be repaired using a limited number of pulls in a single direction. However, repairing third-generation unibody vehicles is an entirely different process. The point of the impact area is often not strong enough to pull all the dissipated damage into alignment unless it's minor.
Previously, repair shops used sheer force to overpower the frame, but that approach could tear panels apart today. Finesse, rather than force, is essential for proper repairs. Adequate anchoring, blocking, pulling, and stress relieving are crucial when working on modern vehicles. Repair shops must follow four steps for a successful pull:

In many cases, a full truck frame replacement is recommended.

  1. Ensure the vehicle is correctly anchored and blocked;
  2. Guarantee the direction of pulls reverses the area moved;
  3. Precisely maintain control of the pulling force;
  4. Measure progress during and after the pulls, relieve the stress area, and repeat.

Anchoring

Anchoring a truck frame is vital as the pulling force applied to the vehicle is transmitted to the anchoring areas. The anchoring area must be secure enough to prevent movement and withstand pulling force without distorting or creating additional damage. Typically, the anchoring area on most unitized structures is at all pinch weld areas at the front and rear torque box (Center Section) since it usually has reinforcements and/or multiple layers of metal.

Truck frames are different, they require an anchoring system directly attached to the frame.


Examples of truck frame vise anchoring systems recommended by truck manufacturers.
  Click Photos To Learn More About These Two Highly Recommended Brands

Body Loc truck frame anchoring clamps                  EZ Frame Clamps For Truck Frame Anchoring    


 Watch The Body Loc BL-77D Truck Frame Vise Clamps Video

This Video features the most effective truck frame vise clamping systems.

                        The Body Loc BL-77D

     Take a minute, and learn why these truck frame clamps are the best solution
                                      for all your truck frame repairs.

Some vehicles might not have reinforced pinch weld areas or any pinch weld at all. These vehicles either need special anchor adapters designed for the pulling system or modifications to the structure for anchoring.
It's essential to follow the recommended anchoring locations and not to make any alterations. Truck frames, on the other hand, need a Vise-type clamping system that will attach to the frame and securely hold the frame in a stabilized position.

This directs all the corrective force to the damaged area and enables less pressure to be used, which in turn will be a positive safety factor as well as a big time saver.
Additionally, it's crucial not to restrict the number of pinch weld or frame clamps used. The pulling force is divided by the number of anchor points, and using more clamps helps prevent damage to the mounting areas.

Blocking

Blocking involves leveraging to concentrate the pulling force in the correct area of damage. Blocking helps reduce the flexing of the truck frame. The use of Vise Style Frame Clamps, and Turnbuckles is the recommended approach to achieve this process. It can also prevent an area from moving downward during the pulling process of another area.

Investing in a quality anchoring system designed specifically for your frame machine will reward you in making frame straightening much easier, less time-consuming, and will pay for itself very quickly. See our recommended truck vise clamps in the photos above.

Holding
Turnbuckle
Body Loc Chain Tightener TurnbuckleHolding fixtures, and Vise style frame clamps along with turnbuckles, can assist in eliminating body flex and vehicle movement. These units have small clamps on each end that can be mounted in a way to support the anchoring clamps and tightened to add additional support to reduce vehicle movement and upper body flex.

Direction of pulls

The direction of pulls is sometimes misunderstood. Pulling in the direction the damage needs to move is essential. Using proper directional pulls in secondary damage areas, along with blocking and holding, can dramatically reduce the amount of pressure needed to pull the vehicle structure.



Controlling the force

Minimal force should always be used when pulling unitized structures and truck frames. A system of measuring and monitoring referencing points during the repair process is critical. Monitor your pulling force carefully, pressure gauges should be used to determine pulling force; if excessive force is needed, it might indicate an incorrect pulling plan. Obstructions can restrict the damage from moving, so it's crucial to identify and address them to reduce the pulling force needed.


The pulling process

Proper pulling involves anchoring, blocking, and mounting clamps correctly. Continuously pulling without relieving the internal metal's state (Stress Relieving) can lead to cracking or tearing. Stress relieving can be achieved through vibration, either with minimal heat or mechanically. This process of pulling, holding, stress relieving, measuring, and repeating these steps is the most efficient way to repair truck frames.

Introducing New Substrates

The automotive industry has adopted new metals, specifically aluminum and high-strength steel (HSS), which call for new pulling guidelines. These advanced steels include dual-phase (DP) steels, transformation-induced plasticity (TRIP) steels, and martensitic steels, each with its unique properties. When working with these materials, technicians must consider four critical factors.

  • Firstly, the application of heat depends on the metallurgical category and the specific make, model, and usage of the steel. Most of these steels are sensitive to heat, which can compromise their properties. Consequently, heating is generally only recommended if the heated part will be replaced. Even Gas Metal Arc Welding (GMAW), commonly known as MIG welding, is not advised.

  • Secondly, sectioning might not be feasible. The entire part must be replaced following the manufacturer's procedure, as identified by the factory seams. This restriction is not exclusive to high-end European cars; domestic manufacturers also utilize these advanced steels in popular models. For example, the Dodge Caliber and Jeep Compass incorporate boron-alloyed steel in their B-pillar, roof rail, and A-pillar, which should never be sectioned.

  • Thirdly, the impressive strength of these steels, reaching up to 165,000 psi, limits pulling options. Due to their brittleness, these materials are prone to cracking or developing micro-cracks when bent. To ensure the part's structural integrity, technicians must inspect the bend areas using a dye penetrant.

  • Lastly, the force needed to manipulate these steels, commonly used for full-length reinforcement in rocker panels and B-pillars, can damage attachment points and cause collateral harm to anchor points. To avoid this, technicians should create access points to allow attached parts to be pulled. Even with these measures, the increased pressure needed for pulling necessitates careful inspection throughout the process and additional anchoring points to protect the anchoring area.

Addressing Aluminum Structures


Aluminum presents its own set of challenges when it comes to automotive repair. It is crucial to consult the vehicle manufacturer's guidelines. Straightening restrictions may apply depending on the type of aluminum part—whether it is stamped, extruded, or cast.
When aluminum bends, it tends to maintain its new shape and becomes work-hardened, requiring increased pulling force. Similar to working with new steels, this increased force demands careful consideration when choosing anchoring points.

Collision damage can cause aluminum to crack initially and potentially again during straightening. Technicians must use a dye penetrant to inspect for damage. In most instances, heating the aluminum is necessary if the part being pulled will be reused.
Significant heat range differences exist between aluminum and steel. While heating HSS to 1,200°F for two minutes is sometimes appropriate, this temperature would melt aluminum. Instead, aluminum requires a heat range of 400°F to 575°F to bend without cracking during pulling. It is crucial not to exceed the recommended 575°F. Unlike steel, aluminum does not have a defined cumulative time limit for heating. It can be heated for approximately two minutes, allowed to cool naturally, and then reheated as needed.

To effectively pull aluminum, technicians should make small adjustments to minimize cracking. This process involves heating the material within the allowed range, pulling slightly, stress-relieving, releasing the pressure, allowing the aluminum to cool naturally, and repeating as necessary. For more in-depth information on aluminum structural repair, I-CAR's SSA01 Course – Structural Straightening Aluminum, offers a comprehensive approach.

Going Forward

Modern pulling equipment and measuring systems require proper maintenance and upkeep. It is essential to clean each system weekly and keep all moving parts well-greased. Utilizing shadow boards and promptly repairing any accessories is also crucial.
Regular training by the equipment manufacturer, both in-house and at training institutions, is highly recommended. Additionally, independent training programs can help ensure that technicians are well-versed in both the equipment and the most efficient repair processes.
The landscape of pulling technology and processes has evolved significantly over the past five years and is likely to undergo further changes in the next five years. Staying informed and up-to-date with these developments is key to maintaining a successful automotive repair business.
ALLVIS Bluetooth Connect Computerized Electronic Measuring System

Before closing, we have mentioned the importance of measuring when   straightening truck frames. Here is a very popular and very affordable  computerized measuring system you should check out.
  The ALLVIS Bluetooth Connect - Click Photo To Learn More

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