Prototype, XM561 & M561 Vehicles
Chorological History of the Gama Goat Program
March 1947 Drawings created by Roger Gamaunt’s depicting his first layouts of a six- wheel, two- body, articulated vehicle which would ultimately develop into what we now know as the “Gama Goat”. Drawings are now in author’s files.
January 1959 Chance Vought initiates a New Product Development program by the name of “Project Breakout” to explore other fields of design and manufacturing apart from its historical place in the military aircraft industry. One of the projects is a large machine that will process bed sheets from motels or large table clothes from restaurants. The articles will be feed in at one end of the device, be transported thru for cleaning, drying and delivered out the other end all folded ready for delivery. A prototype was built but ultimately the project was not successful. The one successful project was that of the Gama Goat whose history of development follows. Two other military vehicle programs were subsequently initiated as a result of the companies venture into the design and development of new military vehicles. These two programs are briefly reviewed later in this history.
July 23, 1959 First contact made between Roger Gamaunt and Chance Vought Corporation. Gamaunt has already begun detail layouts of proposed suspension, roll tube assembly and casting for light-weight, differential housings.
October 2, 1959 “Contract CV288 was signed by Chance Vought and Roger L. Gamaunt of Fawnskin,California, which provides that Mr. Gamaunt will manufacture a full scale prototype of a six- wheel rough terrain vehicle known as a Gama Goat. The vehicle was to be completed by Gamaunt 8 months and one week after the date of the contract and delivered to Chance Vought 10 months and one week after date of contract. The contract provided for certain partial payments to be made to Gamaunt during the performance of the contract.” Reference # 1
The contract stipulated that ”After the prototype vehicle has satisfied Chance Vought’s purposes and in the event Chance Vought has no further need therefore, Chance Vought shall transfer title to the vehicle, if then available, and shall return it to Gamaunt, F.O.B. Dallas, Texas, in it’s “as is” condition at that time”
October 1959 Machine equipment (mill, lathe and riveting equipment) shipped on loan by Chance Vought to Fawnskin, California (Gamaunt’s shop) to assist him in building the first prototype.
October 2, 1959 “A license agreement dated 2 October with Mr. Gamaunt provides for licensing to manufacture and sell Gama Goat throughout the world in consideration of payment of certain royalties to Gamaunt. Chance Vought agreed to apply for a patent on Gama Goat in the name of Gamaunt at its expense”. Reference # 1
May 1960 Author joins Gama Goat design group.
July, 1960 Due to slow progress at Gamaunt’s Fawnskin facility, the decision is made to return project for completion at Chance Vought plant in Grand Prairie, Texas.
”During the course of the program Mr. Gamaunt experienced several problems which had adverse effects on the program schedule. During February 1960, a change in gear train required the re-order of major components including a 3-speed Willy’s transmission and clutch in lieu of the existing 4 speed Corvette transmission. At the same time new sets of differential gears had to be reordered. These new components necessitated redesign of other related components. Complications were also experienced by long lead time requirements of such items as axles and wheels, which further effected schedules. In an effort to expedite the program, the tractor and carrier body shells of the vehicle were fabricated at Chance Vought. Both bodies were completed and shipped to Gamaunt in June 1960.” Reference # 1
“To insure readiness of the vehicle for the 24 October demonstration, the complete (sic) vehicle was transferred from Gamaunt in California to Chance Vought for completion, including the addition of several modifications and refinements. This included customer verification of Chance Vought recommendations to improve vehicle road clearance from 9 to 15 inches and increase the tire size. A change from a 3-speed transmission to a 4-speed (Mighty Mite?) and a specially designed transfer case utilizing M-38 internal gears was made as a result of the larger tires was also made. A total of 80 gallons fuel capacity was provided with two integral tanks incorporated into the front hull structure. The vehicle was shop complete on 30 September 1960.Vehicle shake-down was conducted on 1 and 2 October in preparation for Chance Vought field tests. The Gamaunt-Chance Vought contract was amended to agree with the program changes.” Reference # 1
The ability to realign the prototypes manufacturing schedule and completion and subsequent expedited modifications as a result of testing was the result of a small group of very dedicated individuals at Chance Vought. The good working relationship between the Gama Goat engineering design group and Experimental Manufacturing meant that the prototype evolved with a minimum of actual, formal drawings.
September 30, 1960 Corvair engine powered prototype “rolls out”. Figure 1
“Chance Vought tests of the vehicle began on 4 October 1960 and were scheduled for a period of three weeks in view of the 23 October demonstration date. However, difficulties experienced in the steering system necessitated redesign and thus postponement of the demonstration. To insure sufficient time for design and thorough testing of the steering system, as well as more thorough testing of other features of the vehicle, demonstrations were rescheduled to begin on 9 January 1961.Postponing until after the first of the year was also considered desirable in view of almost certain demonstration interruptions that would occur during the December holiday season Interim fixes were incorporated in the steering system to permit testing of other features of the vehicle until the new steering system was incorporated. The tests were conducted within the general vicinity of Mountain Creek Lake, where good testing conditions exist. The vehicle was subjected to rough terrain, ditch, mud, steep slope, highway, flotation and helicopter lift tests. The results definitely proved that the vehicle concept was sound. In each of the test conditions, the vehicle met or exceeded mobility expectations”. Reference # 1
Fall 1960 First marketing film “Gama Goat” produced.
December 31, 1960 Name changed from Chance Vought Aircraft, Incorporated to Chance Vought Corporation.
January-May 1961 Prototype demonstrated in United States at Ft. Benning Infantry School, Ft. Knox Armor Board, Ft. Monroe CONARC, Ft. Belvoir, D.O.D .,USMC Hq. Quantico, Detroit-Ordnance Tank Automotive Command (OTAC),and Ft. Sill Artillery Board.
“The primary objective of the demonstration tour was to show that the vehicle concept was sound. During the course of the demonstration the vehicle was subjected to practically every known and available mobility obstacle. This included such conditions as mud, steep slopes, rough terrain, salt water, salt rock, rock beds, snow, sand and vertical walls ranging up to 30 inches in height.
In each case the Gama Goat performed well and made very favorable impressions on military observers. The objective sought in the demonstration was attained”. Reference # 1
March 1961 An unsolicited proposal is submitted to government for 1¼ ton, Corvair powered Gama Goat “Concept Vehicle”. Proposal is later rejected by government as being premature due to planned competition for a 1¼ Ton vehicle planned for August, 1961. OTAC recommends centering efforts on upcoming competition.
April 1961 Doctorial Study approved (Mover Study) that would eventually lead to 1¼ Ton procurement program.
May 1961 An aggressive marketing program is undertaken along with scheduled, off-site vehicle demonstrations. During the month of May alone 27 individual government procurement agencies, military bases and Washington offices are visited. Figure 4
May, 1961 A study is completed of a comparison of Ackermann steering (as used on the prototype) versus various combinations of ram steering. It is concluded that the existing Ackermann steer system design is the best overall approach.
May 4, 1961 “On 4 May 1961 the vehicle performed in a mobility evaluation conducted by the Ordnance Tank Automotive Command (OTAC) at Auburn Heights, Michigan. A variety of vehicles of the Gama Goat class participated. The results again showed that the mobility of the Gama Goat exceeded that of the conventional vehicles.” Reference # 1
June 1961 Prototype had accumulated over 5000 miles during demonstrations; durability mileage accumulation and performance tests (including water propulsions and drag, highway rolling resistance and handling evaluation with front body only).
June 1961 Development Project Approved (OCTM 37758) for 1¼ Ton High Mobility, Development Program. .
Summer 1961 Chance Vought initiates a design program based upon prototype characteristics and directed towards new 1¼ Ton requirements. Figure 5
.September 1961 Prototype demonstrated to American 7th Army, Heidelberg Germany, German Army Technical Command, Trier Germany, French Air force, Paris, France and French Army Satory, France. The Goat was air-lifted from Dallas to Düsseldorf, Germany and driven to the various test sites accumulating a total of 1000 trouble-free miles. Up to this point in time the critical driving during demonstrations was accomplished by Roger Gamaunt.
November 7-8, 1961 Prototype participates in Tactical Mobility Symposium, Ft. Knox.
December, 1961 Military characteristics (MC’s) established for “Truck, Utility, High Mobility, Light Duty, XM561”.The XM561 was to replace the venerable but outdated M37,3/4 ton,4x4.
January 1962 1 1/4 Ton initial design completed. Chance Vought becomes a division of Ling-Temco-Vought, Inc.
January 2, 1962 RFPD 62-22, Research Engineering Purchase Description for Truck, Cargo, 1 1/4 Ton, XM561 published.
March 30, 1962 Proposal submitted for XM561.The proposal contained the options for two different engines which were the General Motors (G.M.), air cooled, gasoline, Corvair or the G.M., 3-53, two-stroke, diesel, water cooled, with an aluminum block. In addition, provision was made for nine special operating kits including, winch, weapons mounts and personnel heaters.
June 1962 Government makes initial selection of winning contractor for XM561 program.
July-August & October-December 1962 Corvair prototype participated in extensive mobility evaluations and engineering performance tests (author driving) conducted by Advanced Research Project Agency (ARPA) in Thailand’s jungles, rice paddies and canals. Tests were to evaluate vehicles capabilities in the Southeast Asia terrain. The vehicle was based in Bangkok, Thailand and was driven on public roads to most of the test sites in both Northern and Southern Thailand. Overall performance was considered quite good while experiencing a minimum of mechanical problems. At the conclusion of the activities, the vehicle had accumulated a total of over 7300 miles since initial roll out in September,1960.A movie of the Thailand operations,” The Goat In Thailand”, was produced by Chance Vought and widely distributed and shown for marketing purposes. A stop with the vehicle on the way back to the United States was made in Hawaii to give a demonstration to local military personnel. Figure 6 - Figure 7 - Figure 8
August 1962 Government gives final approval of LTV as the successful bidder for the XM561 competition.
January, 1963 LTV starts XM561 preliminary design with G.M., 3-53 diesel engines for two “Test Rigs”. Design effort required the creation of 24 individual procurement specifications to ensure individual components met requirements specified in the RFPD.
March 1963 LTV awarded contract for 2 Test Rigs (XM561) and 14 Prototype vehicles. Nine vehicles will incorporate the special General Motors 3-53 aluminum block and head, diesel fuel (only) engine (XM561). Five prototypes will have an experimental air cooled, aluminum, 2-stroke,”V” design, 102 H.P., Lycoming multi-fuel engine XM561(E1).Go ahead is given for fabrication of the two Test Rig with go ahead for the remaining Prototypes is given later in May 1963.
The expedited production and testing of “Test Rigs” was a new concept implemented by the procurement agency.
“Past experience has shown that many pilot model vehicles (military prototypes) experienced major failures and problems early in the test cycle causing extensive delays and sometimes cancellation of programs. Some of the vehicles were fabricated under extremely expedited conditions or with limited funds. Lack of suitable materials or component development programs meant installation of experimental or modified commercial components increasing the risk of a vehicle intended for type classification and production. These vehicles, in effect have been “Test Rigs”. The following definition of a test rig has been formulated based upon discussions with AMC and ATAC personnel”.
“A test rig is a full scale; operable vehicle built under expedited conditions generally representing the military prototype vehicle .It is desirable that it incorporate the maximum components of the military prototype vehicle. The purpose is to provide the manufacturer and government an opportunity to appraise performance, configuration, utility, human factors, maintainability and many other aspects of vehicle design. In, addition, the familiarization and training of manufacturing personnel are of inestimable value. It is intended to augment, not replace, the prototype vehicle and many changes are expected from test rig to military prototype.”
“It is understood that two test rigs are to be fabricated: one for the manufacturer and the other for government evaluation……”
“The tests described in this plan are intended to determine basic compliance of the test rig vehicle with many of the requirements of the Military Characteristics. Also, to eliminate major design defects and establish general suitability of the vehicle before fabrication of the military prototype vehicles”. Reference # 2
Testing was ultimately conducted on a 7-day,24 hour schedule on Test Rig #2 at Aberdeen Proving Ground with the author as the on-site Field Engineer. Results and problems observed during these tests of both test rigs were factored into the design of the following Prototype vehicles, where practical. The Chrysler XM410 (2½ Ton Cargo Truck) and Ford XM656 (5 ton cargo truck) programs were undergoing development at Aberdeen under the “Test Rig” development concept at the same time as the XM561.
April 1963 A wooden mockup of the proposed XM561 configuration is constructed.
May 14-15, 1963 Engineering Design Review meeting held in Grand Prairie plant with government representatives to review overall vehicle mockup and proposed kits.
Government mandated items included the requirement that a spare tire and appropriate tire changing tools be provided in the vehicles design.
July 1963 XM561 Technical Development Plan approved.
July 1963 A comprehensive engineering study is completed of the location for a spare tire. Eight different locations are considered, none of which are suitable without some compromises to overall vehicle performance, access and a myriad of other factors. A swinging spare tire horizontal mount on the right side of the front body is determined to be the least intrusive.
October 1963 XM561 Flat Bed Feasibility Study submitted at the request of the U.S. Marine Corps. Study examined the possibility of converting the cargo body to a flat bed type. Two configurations were examined but nothing ever came of the proposal.
November 1963 Corvair Prototype demonstrated at Ft. Benning. Figure 9
November 1963 Transfer begins of management and design personnel for XM561 program from Grand Prairie to Warren Ordnance Plant, Warren, Michigan as LTV Michigan Division. Move was mandated by the Government as condition for getting development contract. A few key project personnel elect not to move to colder country.
December 1963 XM561 # 1 (S/N 3E-3108) Test Rig rolls out and begins in-house testing at Grand Prairie, Texas. Early failures include yielding of lower suspension arms (beefed up), failure of wheel hub flange(torque limiting) shear bolts (replaced with conventional bolts), front body tilted to left (eventually incorporated split fuel tanks to even out front body weight) and a myriad of other smaller structural and component problems. A total of 681 miles were accumulated on highway and off-road including swim tests, prior to shipment to Michigan where testing was continued. In Michigan, highway and cross country mileage accumulation continued along with swim evaluations, engineering structural tests, brake system and rolling resistance measurements, trailer towing and five-wheel operations. Figure 10 - Figure 11 - Figure 12 - Figure 13 - Figure 14 - Figure 15 - Figure 16 - Figure 17 - Figure18
January 1964 An unsolicited technical proposal for a 1-Ton, 2-wheel amphibious Cargo Trailer and other trailer configurations is submitted by the LTV Michigan Division. The proposal is never implemented.
February 1964 # 2 Test Rig rolls out, goes thru shakedown in Grand Prairie and is delivered to Aberdeen Maryland Proving Ground for performance and projected 20000 mile durability testing. During performance and durability tests a number of significant problems are encountered. These problems include power train failures (axle shafts, differential ring gears, and limited-slip clutches - improved parts incorporated), poor brake system performance and durability (ultimately the conventional “open” drum type brake is replaced with “sealed” type), and overall swim performance was considered marginal due to low speed and minimal freeboard. The test environment that the vehicle was subjected was much more severe than any of the vehicle designers could have imagined (including the author).I sent back to Michigan, for the designers to see, a bottle of abrasive mud slurry the Test Rig was encountering at Aberdeen’s Perryman #4 test course, which was migrating into and wearing out the brakes shoes, steering joints and u-joints. These problems necessitated extensive redesigns. Overall, the vehicle was thought to be “maintenance intensive”. Nevertheless the vehicles mobility capabilities were considered to be excellent. From the experience with # 2 test rig it is decided to remove the spare tire (a get home truss kit to be used instead), add bilge pumps and flotation chambers as well as other modifications. A weight reduction program was instituted. Figure 19 - Figure19A
April 1964 Government Coordinated Field Test Plan approved.
1965 Under contract to U.S. Army Mobility Command, LTV Michigan Division prepares The Early Support Concept Plan (ESCP).The objective of the plan is to “provide improved material readiness and implementation of an effective, economical support plan by the Army-Industry
Team”. This would include concurrent development and integration of logistic support, training and performance methods for the XM561 program thru and including depot overhaul. The program is never implemented.
January 1965 SAE Paper 961C published, dated, January 1965, ”The XM561 Cargo Truck-A Breakthrough in Mobility”, Robert E. Zimmerman, U.S. Army Tank-Automotive Center
January 1965 LTV Michigan Division contracts with Gamaunt to overhaul modify and upgrade the Gama Goat Corvair Prototype vehicle. This work includes design of new transfer case, adapting a 4-speed Corvair transmission, redesign of center and rear differentials, reworking front body to accommodate four people and rear body for fold-down tailgate,(precluding swimming), painting vehicle international orange color and a multitude of other items. Work to be completed 30 July 1965.After the vehicles rework was completed, it was used for demonstration purposes before it was finally relegated to an LTV owned, executive getaway ranch in South Texas.
January - May 1965 XM561 and XM561 E1 Prototypes vehicles # 3 - # 16 are completed and delivered for military evaluation. Producing the remaining vehicles was done under a very tight and hectic schedule. One problem was in having the time and personnel in Michigan to accumulate a few break-in miles prior to delivery to the customer. On several occasions the author drove a completed vehicle home at night and took neighbors for rides in order to get mileage. Not the normal procedure but effective. In another instance the author accompanied a vehicle for delivery to the Marine Base at Quantico, Virginia. Arriving on a Friday, the first use of the vehicle was to fill the rear body with ice and beer for the weekly weekend party. The author was not impressed!
Kits are designed, manufactured and delivered for evaluation at various military test sites.
Kits include: Arctic Kit,XM561 (-65 F), Personnel Heater (-25 F),100 Ampere Power Source, Slave Cable, Winch, Radio Mount, Multipurpose Shelter, Front Line Ambulance, Machine Gun-7.62MM,Recoiless Rifle 106 MM, Mortar 81 MM Davey Crocket XM28 and XM29,Mortar 4.2 inch, Mortar 107 MM XM95,Arctic Kit,XM561E1(-65 F),Heater Kit-Ambulance-Arctic and Tow Weapon System. The concurrent development of kits is a “first” for the military and will insure that the M561 will be fully capable of performing all assigned missions upon deployment. Prototype # 5 is designated “Incentive Fee Vehicle” which will be used to provide an additional fee to the contractor if minimum target maintenance hours of not more than 100 unscheduled or 500 scheduled maintenance hours are accumulated over a 20,000 mile test cycle at Aberdeen Proving Ground. The vehicle accumulates 117.3 unscheduled hours (exceeding goal of 100.0 hours) while accumulating 268.4 scheduled hours (beating goal of 500.0 hours). Prototypes are tested at various sites from Alaska to Panama. Tests of vehicles and kits include engineering tests, service tests, climatic evaluation, air dropping, endurance and reliability evaluations. It is the goal to accumulate 20,000 miles on most vehicles. Due to nature of testing, some vehicles only accumulate around 5000 miles and some finish with as much as 36,000 miles. Primary overall test mileage accumulation of 232,500 was finished by March 1966. This eventually lead to the design being determined as acceptable for U.S. Army use and type classified Standard “A” in June 1966. Figure 20- Figure 21 - Figure 22 - Figure 23
The advent of user testing of so many vehicles brought with it a new series of problems and component failures. In addition, not all problems that needed resolution as a result of test rig experience could be incorporated in the early prototype vehicles either due to long component delivery dates or man power shortages to engineer “fixes” in a timely fashion. At times it seemed to the author that frequently there was not enough time to do the job right in the first place but always time to do it over. As a result, a fairly extensive “Deficiency/Modification Program” was required for field installation of mod kits. These modifications now had to be installed by military field personnel with guidance by LTV field engineers. A series of service bulletins was instituted to further assist military field personnel. In the end, all the work did get accomplished. Due to the around the clock test schedule, “Friday afternoon breakdowns” were fairly common due to the military test drivers not wanting to have to work over the weekend. Also, there was only one spare parts expediter assigned in Michigan which made for delays when spares were needed at some remote military test site.
March 1,1965 Automotive Industries magazine publishes an article titled “Army Mobility-The XM561”, by Major Robert L. Bergquist, Project Manager,XM561 Vehicle, U.S. Army Mobility Command, Warren, Michigan. Article discusses status of overall vehicle development program.
June-August 1965 XM561 Test Rigs #2A and #2B are tested in Thailand under the contract to Advanced Research Projects Agency. Purpose of tests is to determine ability of vehicles to operate under the various environments in Thailand. The two additional Test Rig vehicles were added to the initial contract for the XM561 development program. Vehicle #2A was provided with a front mounted winch and standard tires and vehicle #2B was modified from the base design with a front mounted winch, wide Goodyear Terra tires with power steering at front and rear steered axles. In addition, a water propulsion kit consisting of an outboard motor and mounting bracket were fitted to the rear body. In Thailand, the vehicles were driven by Wayne Mueller, LTV Field Engineer, to all test sites resulting in the combined total of 7035 miles during the various test operations which were similar but more extensive and covered a greater geographical area as compared to the tests performed on the Corvair Prototype in 1962. Figure 24 - Figure 25
June 1965 Contract awarded to LTV Michigan Division for four XM561 Advanced Production Engineering (APE) vehicles, kits, field support services and technical data package necessary for subsequent industry wide competitive procurement. Delivery to be complete by April 1966.
July 1965 “Noise level tests were conducted at Aberdeen Proving Ground to determine sound pressure levels of the vehicle under various operating conditions. The primary purpose was to determine whether the noise levels generated by the vehicle were within the limits specified by HEL Standard S-1-63A.The sound pressure levels produced by the vehicle exceeded the limits specified in the standard”. Reference # 3
Excessive “noise” levels would plague the vehicle through its deployment and necessitate the use of ear protection by driver and co-driver. Ear protection would become the norm in later military vehicle programs due to the utilization of noisy diesel engines and their close proximity to the driver and co-driver.
September 1965 Further tests were conducted in Thailand with a standard and flotation type Terra Tired XM561 test rigs and other wheeled and tracked vehicles to further assess operating capabilities over open roads and paddy fields. It was concluded that “further resources be allocated to the development of articulated vehicles”. Terra tires dramatically improve soft soil mobility but are a problem due to increase in overall width on narrow jungle trails. Only major mechanical problem encountered was with several failures in the power steering system on the Terra Tired Vehicle.
January 1966 Office of the Project Manager for XM561 Program prepares a staff study to consider a “Compromise Width Tire Kit” as a result of recent Thailand tests. The conclusion is that “The XM561 is satisfactory for operations in Thailand if the tire is optimized at the largest size width permissible without requiring the use of a power steering system”. . No such recommendation is ever perused. Reference # 4
February 1966 Author voluntarily left LTV to join another aircraft company in a military ground vehicle development program.
August 1966 Production contract put out for bid with six bidders responding. Initial schedule calls for delivery of 15274 vehicles over the years 1968-1972 along with spare parts and field support. G.M. diesel engine is specified and further use of Lycoming, air-cooled engine is terminated.
February 1967 Consolidated Diesel Electric is successful bidder in M561 production contract. Actual contract is awarded in June 1968.
The average quoted price per vehicle for the 13,050 Army vehicles:
Relative pricing and rank order for the 2,224 Marine vehicles were similar to that shown above. The gross contract differences between CONDEC and Ford was $21 million and LTV was $28 million.
“The feeling was that the Ford and LTV quotes were reasonable and in the ballpark for a decent profit. Ford was lower than LTV possibly due to the desire to use this contract as a foundation for opening a new assembly plant in Mt. Clemens, Michigan at which they had plans for the assembly of two other vehicles”. Reference # 5
The general theory was that CONDEC “low-balled” the bid with the possible intent to make any shortfall in subsequent “additional cost design changes”. (Author’s opinion).
February 1968 Detroit Diesel Engine Division, General Motors Corp. received a definitive contract from the Army for 15,624 aluminum, 103 H.P., 3-53 diesel engines.
August 1969 Testing of preproduction vehicles delivered under contract begins at Aberdeen Proving Ground. Eventually an M792 ambulance version was developed.
January 1970 SAE Paper, 700015, “The M561 Cargo Truck-The Gama Goat”, H.W.Austrow, Consolidated Diesel Electric Co. and Leonard Kelt, U.S. Army Tank Automotive Command.
Summer 1972 Author observed aluminum body remnants of numerous XM561 and XM561E1 Test Rig vehicles in Toledo, Ohio scrap yard. Figure 26
August 1972 Problems in manufacturing and performance of the production M561 vehicles led to a great deal of controversy and ultimately an inquiry by a House Armed Services Subcommittee. The following are excerpted comments reported in two different columns in the August 9, 1972 issue of “Army Times”. “After years of frustration and tests, the lawmakers said, the Army has fielded a vehicle $10,000 more expensive than planned. It features a bad design, sloppy craftsmanship, operational, maintenance and other problems, they said. While racking up repeated test failures, the report charges, the Army nonetheless continued to produce the Goat. The first 4400 vehicles were delivered to Army depots to await correction of major defects. Those vehicles are still awaiting retrofit of defective gears manufactured by a foreign (British) subcontractor, the subcommittee said.”(Authors note-the original Test Rigs had successfully proven the design and durability of the Rockwell (American) gear train for the specified 20,000 test miles per vehicle and those were the components that led to Type Classification of the Goat and subsequent production go ahead. Changing the component supply sources from that which was tested appears to have been a major mistake).
The second column stated “The problems were so numerous that the Army changed its reliability yard-stick. Instead of requiring that the Goat go 10,000 miles without a major component failure, the new rules said it had to have a 94 percent chance of going 75 miles without breaking down. The first 4400 vehicles were delivered, but testers and operators reporting hundreds of deficiencies ranging from the complete absence of a rear driveshaft assembly to stripped gears and leaky brake cylinders. The 4400 Goats were put in storage, to be retrofitted later.”
Later models have most of the bugs ironed out, and the Army is keeping those”. (Authors note-“The lowest bidder may not always be the lowest qualified bidder as the tax payer often learns. It is important to test before you buy, but equally important to buy what you tested”.
19?? Warren, Michigan ground vehicle operations are closed down. With this closure, a group of very dedicated and experienced design, test and field engineers are split up and a great deal of military vehicle development and test experiences is scattered to the winds. It was the authors intent to fill in the closing portion of the history of the Michigan Division with a scheduled visit to Vic Civiletto in Dallas in the early Summer of 2007.Unfortunately,Vic’s untimely passing before the visit could be accomplished ended any hope of obtaining the desired information. The author knows of no other key person still living that could be of help.
19?? Per the contractual agreement the Corvair Prototype in returned to Roger Gamaunt in Fawnskin, California.
Late 1980’s M561 vehicles finally phased out of military inventory. While the production version of the Gama Goat proved to be a highly mobile vehicle, it was beset by mechanical problems, excessive crew cab noise and the need for special driver training due to the vehicles unique handling and steering characteristics (steering was not self centering). The Goat was ultimately replaced by the more conventional M998, 4X4, High Mobility Multipurpose Wheeled Vehicle (HMMWV). Nevertheless, the importance of vehicle articulation and independent suspension with high suspension travel combined with relatively wide, large diameter, low pressure tires did have a positive and lasting effect upon future military vehicle designs.
A number of surplus M561’s were bought and restored by private individuals. There is a real cult following as evidenced by the referenced Gama Goat web site which is the conduit for information for these enthusiasts.
May 1980 Roger Gamaunt sold Corvair powered prototype to author for one dollar and other considerations. Author picked up Prototype Gama Goat in Fawnskin, California and transported it to Reno, Nevada where it was used as a support vehicle in tire traction testing (authors testing company) for several years. The vehicle which had been stripped of all paint when picked up was finally repainted olive drab when it was retired from other duties. A refurbishment was completed in 2007 and the vehicle and all associated documentation await a permanent home in some suitable museum. Figure 27 - Figure 28 - Figure 29 - Figure 30 - Figure 31 - Figure 32