Inspection of the vehicle is always the first
and foremost evaluator for any collision repair. And with a rollover,
the significance of a good inspection can make all the difference
in the world. Why? Because insurance companies may total a rollover
vehicle if the initial inspection reveals damage requiring repairs
that will exceed the value of the vehicle.
Some vehicles involved in a hard collision
may look totaled, but are oftentimes still repairable. On the
other hand, vehicles involved in a rollover may look repairable
but are oftentimes totaled.
Why?
A number of variables could be at work, but
the complexity of the necessary repairs and the possibility of
hidden damage are the most common.
It’s important, then, that you conduct a thorough
inspection and know just what kind of damage you may be faced
with. I spoke with a few shop owners well-versed in the art of
rollover repair who offered their suggestions for successfully
inspecting and repairing a roll-over vehicle.
Identifying Stress
A basic computerized measuring system can
be utilized to provide a picture of the damage incurred in a rollover.
Mechanical and other direct measuring systems may not be as quick,
but they’ll set up a datum or other diagnostic tables for tracking
structural and other related control-point problems. Gathering
all this data will help draw a complete picture of what is and
isn’t wrong with the vehicle, which is, of course, key to writing
an effective estimate.
Keep in mind that metal extrusion and stretching
are often red flags for insurance adjusters. A make or break deal
can easily slip away if your shop can’t formulate a plan to get
the vehicle back into shape while maintaining the integrity of
the metal.
Stress – metal stress, that is – can wreak
total havoc on a vehicle. Specific pulling procedures, especially
those involving large sections of steel designed for strength
through granular formation, depend upon working metal backward
toward its original state. This doesn’t, however, always coincide
with the metal’s original shape; this is the case when relieving
stress in the roof structure, which must be worked on from a defined
angle. As a vehicle rolls, several induced states of metal extrusion,
compression and even fracture are possible. If the vehicle rolls
over more than once, damaged areas already stressed by the first
impact are further affected.
Metal has a “memory,” or elastic
quality, that will provide for the least amount of stress and
granular deformation when it’s returned to its original state.
Unbent metal contains layers of grain molecules that lay in a
relatively relaxed state. A rollover taxes this built-in flexibility
of metal.
Once the “granular tensile” has
been superseded by 10 percent (moderate to severe impact), the
outside of the bend must be relieved to accommodate the tension.
If it’s not relieved, tearing will occur. The reverse is true
on the inner or lower granular areas of the structure, which will
suffer from distortion from compression.
Indications of stress include:
- Doors that don’t fit or panel/structures, such as the trunk
or hood, that don’t sit right in their brackets or hinge mounts. - Buckles, dents, sway, etc., in aprons, rails or stringers.
- Engine mounts that are under tension or mounts that must be
twisted into alignment. - Cradles that won’t align with spotting holes or that require
more than a little coaxing to establish a thrust line that’s livable. - A steering rack that favors one side or slips over center.
This is a sure sign of a damaged section at the fixture mount.
High stress here may be dangerous because of cyclic loading from
the steering inputs, which can lead to fretting and cracking of
the stressed metal. Loss of vehicle control in such a case is
likely. - Damaged or buckled floor pans. Even after the panel is cut
out and replaced after the rollover, problems may continue unless
the damage path is recognized and stress is relieved. This is
most readily accomplished by working the area backward from the
direction of damage and re-establishing strength to the deformed
metal areas. Pull backward on the vehicle structure while the
floor pan is cut out to save yourself from overcorrecting because
of resistance from floor-pan distortion. - Cracked paint, undercoating and/or broken or pulled seams
and spot welds. If the area isn’t buckled anywhere that you can
discern, you can beat away with a light spoon, (pressure on the
reverse side) while taking care of the pull at the same time,
when required. This will help prevent strain on roof panels that
don’t pull back into shape readily.
Stress Relievers
One shop owner recalls learning his lesson on stress the hard
way while pulling a roof structure back into position on a late-model
pick-up truck.
It seems the roof line wasn’t very far off, so the owner and his
technicians chose to try a simple pull with their floor system
and a couple extension pieces. When the repair was completed,
the truck seemed OK, or so they thought.
One month after the vehicle was released, the owner brought it
back with a section of the roof ripped out. The problem: The shop
technicians didn’t stress relieve the area. After the repairs,
the owner added a front roof shade that conflicted with the aerodynamics
of the roof line. And the holes drilled in the roof to accommodate
the shade had been drilled in areas with uneven granular structure.
The shop paid big time for its mistake, and now the technicians
stress relieve everything using controlled heat or cold working.
To relieve stress, a “dolly” or a short section of a
2×4 can be used to cold work any stressed area that can’t be heated.
The heating process, when controlled, will work a lot better with
less residual wrinkles to work out for finish prep, but you must
use a method of heat control, such as a heat-parameter control
unit or a heat crayon, to protect the job.
Don’t forget that stress concentrators built into the structural
element of the vehicle must be left intact so collision forces
induced in the future will traverse the paths as engineered. This
protects the vehicle occupants by using energy re-direction.
Rules of thumb are few and far between when repairing roof damage
that’s occurred during a rollover. (But when to cut out the roof
may be easy to decide if over-stress from your first pull caused
ripped edges to butt and then buckle.) Take time to pull in a
controlled manner in a reverse-force direction. While you’re pulling,
observe what’s moving back into place and what isn’t. It may be
a wise decision to halt the pull and go after a panel replacement
if the controlled damage areas will be altered severely and the
safety of the occupant structure is in question. The concern for
occupant safety needs to be the primary consideration during any
rollover repair.
Panel Replacement
Most shops reserve panel replacement for vehicles that are extensively
damaged. Technicians will try to save panels whenever possible
to keep the repair costs down. Because of the expense, you’d have
a lot more vehicles totaled by insurance companies if you replaced
every panel. However, panel repalcement is sometimes the only
option.
Other important considerations may involve sectioning a roof at
the “A” and “B” pillars. This requires a straight-cut
butt joint with an insert for alignment and strength. The “A”
pillar may be 4 to 6 inches in length. Plug weld to secure the
insert, then continuous butt weld the whole arrangement into place.
“B” pillars are a bit easier to section but require
more finesse. Since they’re structurally weaker by design, sometimes
it’s easier to pick up a recycled item and replace it as a unit
with no splicing, etc.
Rollover Rules
Roll-over vehicles can tax even the capabilities of the best collision
repair technicians. The difficulty in setting up for high pulls
rivals only the importance of establishing critical geometry,
which will allow the windshield to fit, the stress areas to be
relieved and the finished job to exhibit the same degree of quality
and safety as the original design.
The lessons to be learned from repairing rollovers often come
hard -they can be costly, too. Unfortunately, no matter how often
you repair vehicles involved in rollovers, new challenges await
you with each job. But don’t let that stop you. With experience,
the profit will far outweigh the effort.
Contributing editor Bob Leone, a retired shop owner, is ASE
Three-Way Master Certified and is completing qualifications as
a post-secondary automotive instructor in the vocational school
system in Missouri.
