Unitized Structural Body Repair- Exam Questions with Correct Solutions Current Version (2024-2025)
Unibody - Answers Lightweight stamped sheet metal components that are welded to each other to
create a single unit.
Space Frame - Answers Body panels can be made from plastic are steel. Steel may be Mild,
Intermediate, or HSS. Panels may hide damage to frame or structure.
Crush Zones - Answers Structural components such as rails are designed to collapse and bend at specific
points.
Collision Energy Management - Answers Goal is passenger protection. Front and rear structures act as
crush-able energy absorbers.
Direct Damage - Answers POI. Easily located and diagnosed.
Indirect Damage - Answers transmission of collision energy beyond the area of immediate impact.
Examples; Split seam sealers, pulled spot welds, misaligned panels, buckles in steel, cracked glass, and
cracked or chipped paint.
Passive Restraint Systems - Answers Must have service manual. No two are alike.
Datum - Answers Imaginary plane or line beneath the vehicle. Measures height.
Centerline - Answers Vertical plane that passes from the front of the vehicle to the rear. Measures
Width. May have stamped marks on vehicle body structure. Is confirmed by referencing at last 3 width
measurements in the undamaged portion of the vehicle.
Zero Planes - Answers Vertical plane that passes from side to side. Confirmed by measuring 3 length
measurements from the undamaged portion of the vehicle.
Symmetry - Answers Equal on each side of the vehicle.
Asymmetrical - Answers Unequal on each side of the vehicle. (spare tire well)
Reference Points - Answers Bolts or nuts, Holes, Mechanical attachment points, Edges of panels, Door
strikers, Corner of openings. Common tolerance is =/.3mm (1/8) or all the way to 1mm (1.32).
Loaded Measurements - Answers Drivetrain In
Unloaded Measurements - Answers Drivetrain out
Point to Point Measurements - Answers shortest distance between 2 reference points. AKA "as the crow
flies". Uses tram or steel tape measure.
, Datum Measurements - Answers Taken at Datum plane, height differences between reference points.
Laser measuring system
Computerized Measuring System - Answers compare data stored in a software program or a central
database. Get hard copy of measurements. Can watch while pulling.
Steel - Answers Cannot know what kind by visible. Must check service manual.
Tensile Strength - Answers Amount of pressure/force necessary to fracture or tear steel.
Yield Strength - Answers Amount of force/pressure necessary to deform steel permanently.
PSI - Answers Pounds per inch /// tensile and yield strengths are expressed. Higher the number the
stronger the steel.
Mild Steel - Answers Cosmetic, used on Space frames, May be stressed relieved with heat, tears can be
welded without a loss of strength. Yield strength 30,000 PSI
Intermediate Steel - Answers Yield strength 30,000-70,000 PSI, structural and cosmetic, may be affected
by excessive heat, small tears can be welded w/o loss of strength.
High Strength Steel (HSS) - Answers Yield strength between 30,000-100,000 PSI, used in cosmetic and
structural, is destroyed by exceeding temperature or time limits, should be replaced if kinked or torn
excess of 1/4 inch, should be straightened cold whenever possible.
Ultra High Strength Steel (UHSS) - Answers Very high yield strength exceeding 100,000 PSI, must never
be repaired, door intrusion beams and re-bars.
MIG/GMAW Welding - Answers
Stick-Arc, and Oxy-Acetylene - Answers Are not recommended for unibody repair. They heat up to large
of an area that is not needed. you want to weld the smallest area possible.
Compression Spot Welding - Answers Used by manufactures, but is not recommended for collision
repair. Our equipment makes welds 70-80%of the strength of manufactures. Manufactures may have
technicians use but must follow service manual and special procedures.
MIG Welding Wire (Electrode) - Answers AWS ER70S-6 AWS ER70S-7
AWS - Answers American Welding Society Standard
E - Answers Type of standard-ELECTRODE
R - Answers Electrode Type-ROD (MIG Wire)
70 - Answers Tensile strength Expresses in Thousands of PSI (70,000)
S - Answers Electrode Type-SOLID
Unibody - Answers Lightweight stamped sheet metal components that are welded to each other to
create a single unit.
Space Frame - Answers Body panels can be made from plastic are steel. Steel may be Mild,
Intermediate, or HSS. Panels may hide damage to frame or structure.
Crush Zones - Answers Structural components such as rails are designed to collapse and bend at specific
points.
Collision Energy Management - Answers Goal is passenger protection. Front and rear structures act as
crush-able energy absorbers.
Direct Damage - Answers POI. Easily located and diagnosed.
Indirect Damage - Answers transmission of collision energy beyond the area of immediate impact.
Examples; Split seam sealers, pulled spot welds, misaligned panels, buckles in steel, cracked glass, and
cracked or chipped paint.
Passive Restraint Systems - Answers Must have service manual. No two are alike.
Datum - Answers Imaginary plane or line beneath the vehicle. Measures height.
Centerline - Answers Vertical plane that passes from the front of the vehicle to the rear. Measures
Width. May have stamped marks on vehicle body structure. Is confirmed by referencing at last 3 width
measurements in the undamaged portion of the vehicle.
Zero Planes - Answers Vertical plane that passes from side to side. Confirmed by measuring 3 length
measurements from the undamaged portion of the vehicle.
Symmetry - Answers Equal on each side of the vehicle.
Asymmetrical - Answers Unequal on each side of the vehicle. (spare tire well)
Reference Points - Answers Bolts or nuts, Holes, Mechanical attachment points, Edges of panels, Door
strikers, Corner of openings. Common tolerance is =/.3mm (1/8) or all the way to 1mm (1.32).
Loaded Measurements - Answers Drivetrain In
Unloaded Measurements - Answers Drivetrain out
Point to Point Measurements - Answers shortest distance between 2 reference points. AKA "as the crow
flies". Uses tram or steel tape measure.
, Datum Measurements - Answers Taken at Datum plane, height differences between reference points.
Laser measuring system
Computerized Measuring System - Answers compare data stored in a software program or a central
database. Get hard copy of measurements. Can watch while pulling.
Steel - Answers Cannot know what kind by visible. Must check service manual.
Tensile Strength - Answers Amount of pressure/force necessary to fracture or tear steel.
Yield Strength - Answers Amount of force/pressure necessary to deform steel permanently.
PSI - Answers Pounds per inch /// tensile and yield strengths are expressed. Higher the number the
stronger the steel.
Mild Steel - Answers Cosmetic, used on Space frames, May be stressed relieved with heat, tears can be
welded without a loss of strength. Yield strength 30,000 PSI
Intermediate Steel - Answers Yield strength 30,000-70,000 PSI, structural and cosmetic, may be affected
by excessive heat, small tears can be welded w/o loss of strength.
High Strength Steel (HSS) - Answers Yield strength between 30,000-100,000 PSI, used in cosmetic and
structural, is destroyed by exceeding temperature or time limits, should be replaced if kinked or torn
excess of 1/4 inch, should be straightened cold whenever possible.
Ultra High Strength Steel (UHSS) - Answers Very high yield strength exceeding 100,000 PSI, must never
be repaired, door intrusion beams and re-bars.
MIG/GMAW Welding - Answers
Stick-Arc, and Oxy-Acetylene - Answers Are not recommended for unibody repair. They heat up to large
of an area that is not needed. you want to weld the smallest area possible.
Compression Spot Welding - Answers Used by manufactures, but is not recommended for collision
repair. Our equipment makes welds 70-80%of the strength of manufactures. Manufactures may have
technicians use but must follow service manual and special procedures.
MIG Welding Wire (Electrode) - Answers AWS ER70S-6 AWS ER70S-7
AWS - Answers American Welding Society Standard
E - Answers Type of standard-ELECTRODE
R - Answers Electrode Type-ROD (MIG Wire)
70 - Answers Tensile strength Expresses in Thousands of PSI (70,000)
S - Answers Electrode Type-SOLID
