After an accident, most cars need frame straightening, or at least a check to see if the car sustained damage to the frame. When the body of your car is repaired without the frame being fixed, you may find that your car is always out of alignment and that your tires wear unevenly and need frequent replacement.
How does a Shop Assess Condition of your Frame?
Modern cars either have a straight rail system or unibody construction that determines how the shop will approach your frame straightening. In any case, they will put your car on a frame machine that measures your car to make sure all parts are properly aligned.
Full-size cars, pickups, and vans with a straight rail system have a frame that consists of two steel beams running the length of the vehicle attached to a front beam. The transmission, engine, and suspension are mounted on the rail system, and the body of the car is set on top.
Cars with unibody construction, which describes cars built after the 1980s, have a skeleton formed by metal panels and a subframe where the transmission, engine, and suspension are mounted. Exterior panels of the car are attached to the skeleton. Although there may be less damage to the frame if the unibody construction absorbs some energy from the crash, cars are built with crumple zones that crush if a collision occurs to protect the driver and passengers from the impact of the crash. As a result, even a car involved in a low speed accident may need frame straightening.
How Frame Straightening Works
In examining the frame, a body shop technician puts the car on the frame machine, secures it with chains and clamps, and raises it up for greater visibility to assess the damage. They compare what they can see visually with a computer readout, which targets areas of the car that need straightening. Then using hydraulics and torque, they get it back to factory specs. Continuous printouts verify that the car is aligned correctly down to the last millimeter.
They used to straighten cars with straight rail frames by softening the middle with heat before straightening. Newer cars use high molecular steel that changes structure in the presence of heat, so heat is no longer used. On badly damaged unibody cars, the shop may replace damaged parts if straightening does not get the frame back to normal.
In selecting a body shop, you should verify that the facility has straightening equipment in-house or if they send the car elsewhere for that part of the repair. A place that claims to do it on-site should have straightening machines, laser measurement tools, and laser frame straightening tools, plus technicians who are qualified to do the work. It is more convenient to use a shop with straightening equipment on hand.
Future Problems with Frame Straightening
What is important is that a proper frame straightening takes place. You may find yourself paying out-of-pocket later if your car has problems that relate to the frame. Since accidents weaken the frame and result in small cracks that can make the car more susceptible to future damage, driving around with a bent frame can be dangerous. Unresolved frame issues also affect the resale value of your car.
After an accident, make sure that your car is thoroughly inspected for damage and that any necessary frame straightening is properly done.