Frame or Unibody Damage on Rebuilt Vehicles
Rebuilt vehicles may be previously totaled due to frame damage. When speaking about frame damage, it is necessary to take into accout the type on the vehicle and so distinguish between the frame and the unibody.
The term frame comes from earlier automotive years when the construction was as primitive as a number of metal rails welded together to serve as a basis for all the other body. That's why the term chassis is sometimes used, although it's not always the right term. On modern passenger cars the frame is replaced with unibody (aka unitized body) where the frame and the body work are integrated. Rare modern passenger cars have fame and body as separeate units, eg, BMW i3 electric car. On trucks, SUVs and buses the frame and the body and two separate entitities and the body in mounted onto the horisontal frame, which also comes in different steuctures. This type of construction is called body-on-frame.
Rebuilt cars with unibody damage
Unlike a frame, the unibody design which was introduced in car production in 1930s serves a number of purposes at a time:
- bearing the full weight of the vehicle
- being the skeleton to which all other vehicle parts and components are attached
- protecting the people inside the vehicle in case of an accident
For this reason a unibody damage impairs the vehicles functionality in multiple ways at a time as well as the possibilty to restore it to a normal condition. If the cost of straightening the unibody to its initial shape plus other repair expenses is less than approximately 75% of the vehicle's actual cash value the vehicle can be fixed, get a rebuilt title and return on the road. In such cases the vehicle with a damaged frame can have a clean title. Unibody straightening is a costly procedure all by itself and even when it is done well it will not restore the rigidness, the safety balance tuned and checked in crash tests and alignment and fitting of the parts . For this reason cars with unibody damage are in most cases written off by insurance companies and experience significant value loss after being fixed.
The meaning of a frame damage extends from most severe types with the vehicle turns into scrap to a relatively minor when a damaged unibody section can be replaced.
Safety of rebuilt / repaired unibodies
Unibody design is carefully calibrated and crash tests are performed to make sure the carcass redirects the impact force from the driver and passengers into special “crumple zones” that accept the impact and fold. On a vehicle with a damaged unibody this balance is often broken without the possibility to restore it properly. One of the reasons is that the metal that has been straightened after a collision is permanently fatigued and the calculations and tests at the manufactuting stage are done for the non-impaired material. That means that the people inside the vehicle no longer have the 'safety box' around them that prevents vehicle parts crushing into them during an accident. The work of airbags may also be affected because the deployment speed, power and other factors are calculated and tested based on the intended behavior of the rigid unibody. In most severe cases parts of the unibody may be cut off and replaced with silimar pieces taken from another vehicle. There also the so-called clipped cars literally consising of 2 halves of damaged unibodies welded together. Even if this vehicle won't fall apart as you drive at full speed it may collapse during an accident.
Breakage and failures
The least severe effects of a unibody damage and premature breakage of other vehicle parts and wear. Alignment of such vehicles is often affected resulting in different parts being misplaced and not fitting properly which makes them more prone to wear, malfanction and damage. Brakes, steering mechanism, suspension or unevenly worn tires are examples of such an imbalance. Failure of any of such mechanisms also compromises safety. For example, even after having an alignment done the vehicle is pulling on one side.
It’s important to have the unibody / frame check done because it’s the basic skeleton of your car. Please note that cars with serious damage not eligible for reconstruction in one state may be eligible in another state! This means that they are dirven on public roads and legally sold as roadworthy cars.
A rebuilt vehicle with a frame damage may be a worse option than that with a salvage title or certificate that only needs to be fixed for an apparent reason: frame repair is a costly procedure the cost of which is already welded into the price but you have no control of how well it was fixed and which methods were used. What you can do if your find out about a unibody damage in the history and still want to go for that car is hire a mechanice who checks the unibody for you with professinal equipment, like ultrasound scanners.
Rebuilt Trucks, Buses and SUVs with Frame Damage
The frame on trucks and SUVs bears the vehicle body. It does not have "crumple zones" like a car unibody so frame damage mostly affects the vehicle's alignment and part wear. Bent frame elements may be straightened by pulling. In certain cases, as the traditional frame consists of metal rails connected in different structure type (ladder, backbone), damaged rails and cross units may be replaced.
Sometiems at entire frame can be replaced. However, the procedure is very expensive and may take months. For many truck owners that means that the vehicle will fall out of business for months and for this reason many prefer to total the truck and get an insurance settlement. Take this into considereation when buying a rebuilt used truck or a truck with a frame damage.
How does VIN history report point to frame damage?
VIN history reports may use different terms. You should watch out for such records as Unibody damage, Severe Damage, Major damage, Structural Damage, Frame Damage in your vehicle history reports.
Should You Buy a Vehicle with Frame / Unibody damage?
It is generally a bad idea and really hard to recommend buying a rebuilt vehicle with a unibody / frame damage even though sometimes frame / unibody damage can be fixed well so that all parts are in place, at least a dertain period. A lot depends on how severe the damage was. On new write-offs the chance of having a severe damage is greater because they need a more serious damage to get totaled compared to older vehicles. For this reason sometimes an older vehilce may be both a safer and a cheaper option.
If your current needs for a cheap car or pickup outweigh all the cons you may opt for a car with a restored frame / unibody having the following in view. If you are planning to drive the vehcile in a safe environment and not on highways or city roads and need a car / pickup to satisfy the basic transportation needs, say, on your farm, this may be a cheap and easy solution. Make sure all of the wheels are well aligned. Please note that you will most likely be unable to resell that unibody later if evetually part breakage will pile up being too costly to repair. Such a vehicle would need more investment in repairs later on or your should be ready to abandon it as a scap one day. Rebuilts with a unibody damage should be driven with extra caution.
How else do I know about frame damage?
Read our article on how to determine frame / unibody damage by youself and professional diagnostics.