Auto body repair & detailing: Auto body Question, rear axle assembly, perimeter frame

Question
which type of vehicle construction uses a frame only in areas requiring extra support and a strong attachment point?

A.Combination frame construction
B.Semi-unitized stub rail construction
C. First generation unitized perimeter frame construction
D. Fully unitized construction

Answer
Hi Alex!....The answer to your question is a Semi-unitized or Platform Frame design....They use heavy duty " Stub " rails that are welded or bolted into place, on both the front and rear. The stub rails are used to accomodate the engine, transmission, suspension, etc. on the front, and the rear axle assembly and suspension on the rear....A Combination Frame construction is an assembly that has a full frame on the bottom side, with a unitized body attatched on top the top side. The full frame is where all of the driveline components are attatched....A Perimeter Frame is similar in construction to the Ladder or Full Frame...The full length side rails support the body at its greatest width, which provides more protection to the passengers in the case of a side impact to the body...The areas behind the front wheels and in front of the rear wheels are stepped to form what is called a " Torque Box "...These areas are what absorbs much of the energy in a side collision....A Fully Unitized Frame construction is exactly that...Unitized, or " ONE "....There are no parts attatched being bolted on what so ever....Everything is welded into place....To which all components are attatched....This type of design is also called the " Stressed Hull Design "....Similar to how an aircraft is built...I hope I have answered your question....If you have any more questions, please write me back....Take care....Dave