10305 Hull Street Rd.
Midlothian, VA 23112

Uni-body frame vs. Full frame explained

Have you ever gotten a repair estimate on your vehicle only to see repair time to the frame on the estimate and thought, “great, the frame is damaged on my vehicle, now it can’t be fixed!” Well, that statement is not necessarily true. Prior to the 1960’s cars and trucks were produced using the Body-on-Frame procedure. This meant that the vehicle’s structural frame was completely separate from the body and if the frame became damaged, chances were, the vehicle would be deemed non-repairable. That all changed in the 1960’s with Chevrolet releasing the Corvair, it’s first unitized frame vehicle and Ford also mass producing unitized frame vehicles in the same decade.


A unitized frame or uni-body vehicle has been designed from the ground up to have the main cabin of the vehicle act as the structure. Metal, was folded and welded to the front and back of the cabin and these became frame rails which strengthened the structural integrity of many cars on the road. These rails were and are designed with “crush zones” in place to help absorb the kinetic energy which travels through a vehicle during an accident. This design serves two purposes, to protect the cabin’s occupants and to minimize the structural damage to a vehicle. These “crush zones” are also designed to be repaired using a structural alignment machine and various repair methods depending on the type of material with which the rails are constructed.


There is also a separate sub-frame located in your vehicle. This is a smaller frame structure in the front of the vehicle and sometimes in the rear that holds the motor and suspension components. Along with the motor mounts, this frame is what helps distribute the vibrations from the running engine and drive-train away from the cabin so as not to disturb the occupants.


Now, almost every car and practically all midsize and smaller Sport Utility Vehicles on the road are uni-body vehicles. Many pickup trucks are still produced using the body-on-frame method. So, the next time your damage appraiser goes over your estimate and there is frame repair time, just remember that it usually means they will put your vehicle on the structural alignment machine and use the proper methods as prescribed by your manufacturer and / or industry standards to bring your uni-body back to factory specifications and it is not an immediate death sentence for your vehicle.


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    10305 Hull Street Rd.
    Midlothian, VA 23112

  • Phone: (804) 674-1173
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    7:00AM - 6:00PM

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