Korean engineers were sent to the United States Army Depot in Alabama for training, such as armor cast steel welding and production, precision manufacturing, assembling skills, quality inspection, and test evaluation.

[6][7] Not satisfied with the M48 Patton upgrade, South Korea began looking for a new tank that could overwhelm every North Korean counterpart, as the existence of the T-62 and its manufacturing facility were confirmed by satellite images in 1976.

According to the MOUs, the United States would provide its state-of-art Special Armor Package (SAP), in which the material and protection were identical to the M1 Abrams while limiting Koreans from access until the installation due to national security reasons.

Exporting of the K1 is strictly controlled and needs authorization from the United States as many sensitive systems are installed, and South Korea was required to pay a royalty to Chrysler Defense.

PV-2 also reported issues with its fire control system; LOS (line of sight) was shaking due to frost in the winter season, taking too long for warmup, interference from electromagnetic waves, and lockup of the ballistic computer.

Although the contract limits technological access to Koreans, engineers from both nations freely shared information during friendship interactions, including a classified specification of the M1 Abrams.

Koreans could only go to the specified path, but they memorized types of machinery and calculated the required sizes of the facility by counting theïr footsteps, which helped them to build the new factory at Changwon.

[7][8] In 1983, Hyundai accepted GDLS' new offer and acquired special welding of armor plates, assembly of major devices, and weapon testing technologies.

However, Hyundai realized that GDLS had made a crucial mistake by providing outdated blueprints that did not reflect the latest fixes, and XK1s began to experience the same issues they saw from early prototypes.

GDLS, which acquired Hughes in 1985, revealed that the system uses parts from Canada, West Germany, and Switzerland, and thus requires time-consuming multi-national cooperation to solve to problem.

[16][17] The K1 has a size of 9.67 m (length with gun forward) x 3.60 m (width) x 2.25 m (height) and weighs 51.1 t or 51.5 t.[17] It is powered by a German power pack consisting of 1,200 hp (23.5 hp/t) from MTU Friedrichshafen MB871Ka-501 8-cylinder water-cooled turbocharged diesel engine licensed by Ssangyong Heavy Industries (now STX Engine) and ZF Friedrichshafen LSG 3000 transmission licensed by Hyundai Precision Industry (now Hyundai Transys).

It allows the tank to use kneeling to supplement the depression of the main gun, which is limited by the small-sized turret to -10 degrees, and provides comfort on rough terrains.

[9][10][16][17][18] For comparison, M1 Abrams is 9.77 m x 3.66 m x 2.37 m and weighs 54 t. The Gun/Turret Drive and Stabilization System (GTDSS) measures and compensates yawing and pitching, which occur on uneven and curved roads for gun turret to be capable of the precise fire while running.

Despite Koreans having decided to upgrade the existing GPSS, Samsung Electronics signed a deal with Texas Instruments to supply and locally produce the GPTTS (Gunner's Primary Tank Thermal Sight) in 1986.

Regardless of the involvement of lobbies, upgraded GPTTS showed superior performance when shooting the hidden target behind the smoke screen, which the GPSS failed to do so during the test on 2 September 1993.

The vehicle lacks an overpressure system for CBRN defense, and thus requires tank crews to wear personal protective gear to operate in chemical, biological, radiological, and nuclear warfare environments.

Originally, GDLS wanted to participate in the K1 series to maintain its level of influence, and it proposed a partnership for the project due to concerns about Koreans lacking such skills.

However, South Korean engineers declined the offer, and decided to take full responsibility on the project even if it fails, because they could learn about the main battle tank throughout the process and to maximize localization by reducing the technological reliance from GDLS.

[26] In addition, South Korea began to deploy K276 120 mm armor-piercing fin-stabilized discarding sabot (APFSDS) ammunition with the most sophisticated tungsten heavy alloy penetrators during that time, created after several technological breakthroughs that were new to the world.

[50][51][52] Therefore, based on the available sources, K1A1 is fitted with domestic armor, in which the technology has influence from American M1 Abrams and Russian T-80U, and ERAs are located behind the outer shell of the tank.

On 22 September 2008, the Defense Acquisition Program Promotion Committee approved the K1A1 upgrade plan to install the battlefield management system, identification friend or foe, driver's thermal sight, and front and rear surveillance cameras.

[62][63] To suit the jungle environment of Malaysia, Hyundai suggested a 47.9 t variant K1M based on the K1; the tank carries a total of 41 rounds and is equipped with KGPS for the gunner's sight and an overpressure device for CBRN protection.

[71] On 26 September, the ADD announced the development of insensitive gunpower that does not explode in shock, fire, or heat that can occur in the transport, storage, and operation of warheads and ammunition.

[72] In September 2003, Typhoon Maemi caused seawater damage to the domestic circular cooler prototype for K1 tanks and its test and evaluation facilities at Hanjo Company in Busan.

The STX engine, which had joined with Hanjo to localize core components since 2002, also dispatched a team to recover the sight and requested an extension of the project to the Ministry of Defense as the due date was only six months away.

[76][77] On 6 September 2009, North Korea released the floodgates of Hwanggang Dam at dawn without warning, leaving six South Korean civilians missing and one K1 tank trapped in the swollen river, which was rescued after hours.

[81][82] However, the Army reinvestigated and claimed the August 2009 incident was due to fatigue failure caused by long usage of the barrel, which is a human error for failing inspection.

[83] On 19 November, the investigation team concluded that the August 2010 barrel burst was caused by the tensile residual stress remaining in the metal during the processing stage and a long period of use and exposure to corroded environments such as humidity, oxygen, and temperature.

[84][85] On 15 September, the Ministry of Defense revealed that the LSG 3000 transmission used for the K1 and the K1A1 has defects, and the production of the K1A1 has been suspended since February and expects a delay of one year until fixing the problem.

On 30 December 2010, the Defense Acquisition Program Promotion Committee resumed the production of the K1A1 before the transmission durability test results, with a condition for recalling all vehicles if found to be manufacturer's fault, due to changes in national security situation.