STAGES: Lost in Space (Frames)

From the outset, one of the objectives in writing Monster Truck Technology: The Definitive History of Monster Truck Evolution was to dispel some of the long-standing misconceptions which have seemingly ingrained themselves into our lore.  One glaring example relates to the various stages of development. 

Over the past 40+ years, monster trucks have observed four distinct phases of technological development, however inexplicably the most recent has remained largely unrecognized.  Whereas there exists a general consensus on the terminology used to reference the first three phases, there seems to be inconsistency in how they are applied and what they actually entail. 

Individual phases are generally referenced based on chassis types which include:

Stage 1 – Stock Frame

Stage 2 – Straight Frame

Stage 3 – Tubular Frame

These descriptions are also often conflated with suspension types, i.e. Stage 1 – Leaf Spring Suspension and Stage 3 – 4-Link Suspension.  However, the truth of the matter is vehicles assigned to those categories often defied such designations.  As delineated in the book, there were examples of Stage 1s with straight frames, and Stage 2s with stock frames, as well as Stage 1 and 2s with 4-Link suspension and even Stage 3s with leaf spring suspension.  Although chassis are referenced in the book utilizing said terminology, this was largely done due to the public’s familiarity with the general application of these terms.   Be that as it may, I believe conceptually these stages actually entail a combination of frame types, componentry and more fundamentally, their intended purpose.

Following their progression from street and exhibition use, in the early 1980s Stage 1s gradually evolved to incorporate features oriented towards low-speed car crushing.  Defining features for Stage 1s were typified by:

• Reinforced Stock Frame
• Military Type Axles
• Military Transfer Case
• 0-6” Suspension Travel

 By 1985 the steady increases in capability made possible through the adoption of new technologies crossed a threshold where the vehicles were by then predominantly designed for the purposes of wheelstands and eventually jumping cars altogether.  The defining features for Stage 2s which made this possible were:

• Straight Military or Fabricated Frame
• Planetary Axles
• Front Traction Bars
• In-Cab Rollcage
• 0-12” Suspension Travel

 In 1989 a major transition occurred which fundamentally changed the landscape prompted by the increase in popularity of side-by-side racing. This significant change in purpose reshaped the composition of the vehicles with a major focus toward racing.  The defining characteristics of Stage 3s were:  

• Two Dimensional Tubular Frame Design
• V or Abbreviated Truss
• Integral Multi-Point Rollcage
• Above Frame Engine Placement
• Below Frame Transmission Service Access
• Centrally Located Transfer Case
• Symmetrical Length Drivelines
• Lightweight Planetary Axles with Stock Componentry
• Monster Truck Specific Aluminum Transfer Case
• Lightened Agricultural Flotation Tires
• Lightweight Monster Specific Wheels
• Suspension Seat
• 16-26” Suspension Travel

At the turn of the 21^st century, a polar shift occurred and as a result in 2005 a new generation of monsters emerged to contend with the ever-increasing demands of freestyle competition.  The stresses placed on these vehicles prompted the development of more robust construction and an explosion in the number of monster specific components they incorporated.  The unique characteristics of Stage 4s are:

• Three Dimensional Space Frame Design
• Low Center of Gravity Architecture
• Spread Cradle
• Cradle Mounted Batteries & Pump
• Within the Chassis Engine Placement
• Side of Frame Transmission Service Access
• Forward Mounted Transfer Case
• Asymmetrical Length Drivelines
• 2-Piece Rear Driveline
• Production Fabricated Axle Housings
• Billet Spindles
• Billet Knuckles
• Billet Champagnes
• Forged or Girdled Hubs
• Wheel Restraints
• Monster Specific Tires
• Monster Specific Beadlock Wheels
• Powerglide 2-speed Transmissions
• Complex Multiaxial Rollcage Design
• Robust Shock Tower Construction
• Full Containment Seat
• Engine Combination with focus on Reliability
• Low Ride Height
• 26-30” Suspension Travel

I personally find irony in the fact that Stage 4 actually reflects the most significant number of advancements over the preceding stage, yet as stated, has thus far remained largely unrecognized. 

As if the preceding were not convincing enough, further evidence of the drastic changes in their composition may be observed in the average weight of the vehicles through each of those phases.    

Stage 1 - 10,000-11,000 lbs avg.

Stage 2 - 14,000-15,000 lbs avg.

Stage 3 - 9,000-10,000 lbs avg.

Stage 4 - 12,000-13,000 lbs avg.

Clearly, something significant was occurring at each of those phases to so radically have affected their average weight. 

Yet further evidence of the firm establishment of Stage 4 can be observed in the relative strength of the components in use during each of the preceding stages. At the twilight of Stage 1 the adoption of planetary technology which initiated Stage 2 increased axle strength to the point that by the dawn of Stage 3 these components were thought to be virtually indestructible.  Yet, the demands faced by Stage 4 made the once unfathomable failure of those components so commonplace that they were no longer considered viable.  Components which survived unscathed for 20 years suddenly could no longer survive 20 seconds in this new environment.  But fortunately, there were individuals who rose to the occasion and created solutions to largely negate such failures.  The oft-stated and ludicrous suggestion that certain Stage 2 trucks could still be competitive today in a stadium freestyle environment illustrates just how little is understood about the dynamics faced by the builders of these mechanical wonders today. 

Having said all of that, it is important to recognize that each of these four stages of development was the result of the gradual introduction of new individual technologies.  Eventually, certain vehicles combined enough of the new technologies so as to create a new paradigm.  Therefore, new stages did not establish cutoff dates but instead coexisted with the previous stages most often with considerable overlapping of technologies.  There were also those vehicles which defied stages altogether and existed in a classification of their own.

In a general sense the timeline for the phases of development is as follows:

Stage 1 - 1978-1984

Stage 2 - 1985-1988

Stage 3 - 1989-2004

Stage 4 - 2005+

Explanation of the developments within the various realms of Tires & Wheels, Axles, Chassis, Suspension, and Drivetrain which occurred during those periods are discussed in considerable detail within dedicated chapters of the book.  Once read I am confident that the reader will come away with a much better understanding of not only the technologies but why each of those advancements was pursued.  And at that point, the Stage 4 – Space Frame generation will finally receive the recognition it so richly deserves.

Vive Le Quatre