How to Search for Frame or Unibody Damage
It is widely known that vehicles with a damaged frame or unibody are undesired purchases. Lets see why this type of damage is is so bad, how to detect a major structural damage and what if you want to buy such a vehicle. Frame damage on cars and other vehicles can be repaired and such vehicies may be recognized fit for driving and registered. But their value will be much lower for a number of reasons you can read about below.
What is often referred to as a frame in modern cars is in actual fact called unibody. Historically, a frame is a metal construction of welded together steel rails that function as chassis and on whicn the vehicle's body is put. As automive industry developed, the frame on passenger cars evolved into a unibody structure uniting the frame and the body. One of the reasons for that were fuel efficency considerations as unibodies are lighter in weight. However, that approach also changed safety featuers of passenger vehciles and left from litle to no room for modifications in them. Trucks, buses, SUVs, Motorhomes, travel trailers, RVs and very few models of passenger cars still use traditional horizontal frames which are stronger, capabale to carry significant load and can stand stronger impacts during off-road driving. This is called body-on-frame type.
Unibodies: Functions, Pros and Cons and Effects of the Damage.
As a unibody is an whole consturction, a damage to one segment may result in the entire box being distorted or twisted, even unseen on the outside. This creates much more trouble than it might seen at first sight, some of them may be fatal.
A uniboby is a carcass that not just holds the entire vehile's weight but is also responsible for positioning and alignment of all the parts. On a bent or twisted unibody parts become misplaced. Even a slight shift causes rapid wear and failure of different components which not just burns a hole in the pocket but also compromises safety if brakes or steering mechanism are affected.
Another aspect of critical importance is that unlike a frame in heavy vehicles, in passenger cars the unibodies are scrupulously designed to protect passengers in case of a crash. The rigidness in every zone if the frame is calculated in such a way that in case of a collision or rollover the impact is directed to specialized 'crumple zones' bypassing or not reaching the people and so preventing them from being crushed by the vehicle's body and debris, while the 'crumple zones' collapse. This balance is carefully tested by the manufacturer in a series of crash-tests. Once the unibody is bent the balace is broken and diversion of the collision inpulse from passengers may fail. Even if the frame is straightened and does not seem to cause alignment issues and damage to components, the rigidness becomes permanently impaired and its behavior in an accidect can no longer be predicted. As a consequence, the metal cage designed to protect may crush. The proper function of airbags may also be compromised.
Cars with severely damaged frames are not eligible to repair and a good only for parts because the very basis of the vehicle is destroyed.
Frames on trucks, SUVs, Trailers, RVs / Motorhomes and Buses
These are relatively simple constructions compared to unibodies. Damaged frames can be fixed, rails be replaced or straightened, even the entire frame may be relaced (which is impossible with a unibody). The stumbling-block is the cost of the procedure and implementation time because not every truck sevicing shop has the equipment for that. While there is no issue with the calibration of crumple zones because they simply don't exist, even on a straightended frame reduced rigidless of the rails causes uneven tyre wear and may result in steering issues, which is critical for heavy duty trucks and affects their safety, including the safety of other vehicles sharing the road.
How can I tell the vehicle has a bent frame or a unibody damage?
Do VIN search and get a VIN history report. The following records point to frame damage: Unibody Damage, Frame Damage, Structural Damage, Severe Damage, Major Damage. Please note that although in most cases vehicles with a structural damage are totaled, in some cases the vehicle with a sturctural damage can preserve a clean title. This can happen if the vehicle is new and the damage was not bad enough and the repair cost didn't exceed 70% of the vehicle's actual cash value, so the insurance compaby decided to fix it. Another possible hole clean titles squeeze through are cases when no insurance claim is filed either due to absense of conprehensive coverage or the owner's unwillingness. In this case you can only determine the damage from the records in the VIN report, by searcing for observable signs of the damage or by hiring ax expert.
Check our page about signs of framge / unibody damage in a vehicle, how to detect it during test-drive and other diagnostic methods.
What are repair costs for structural damage?
From less than $1000 for non-severe damage to $10,000 and more for heavy or luxary vehicles. Unibody designs are specific for every models and repairs are estimated indivdually.