Precast concrete is an advanced construction technique characterised by high precision, quality, optimisation and is increasingly used in commercial and residential buildings. However, connections between precast elements are often constructed using in-situ casting, which can delay projects and complicate disassembly at the end of a structure's service life. Dry connections, aligned with the principles of manufacture-to-assemble (MTA), offer a practical and sustainable alternative but present significant challenges regarding seismic performance, particularly in earthquake-prone regions. This study addresses these challenges through a comprehensive parametric numerical investigation into the shear capacity of precast walls with dry connections. Using SeismoStruct 2024 software, more than 340 pushover simulations were conducted to evaluate the influence of various parameters, including concrete compressive strength, axial force percentage, wall section height, overall wall height, and connection characteristics such as bar diameter, quantity, and placement. This research provides critical insights into the combined effects of these parameters, identifying optimal configurations to maximise shear capacity, which is a vital factor for seismic performance. Key findings indicate that shear capacity is significantly enhanced by increasing section height, concrete strength, and axial load, with notable gains such as an 84% improvement in shear strength when section height increased from 2 m to 3 m under favourable conditions. Conversely, increasing overall wall height tended to reduce shear capacity, with a 58% decrease observed for walls extending from 1.5 m to 3.5 m. Adjustments in mechanical connections, including larger diameters, increased bar quantities, and optimised placements, further contributed to incremental improvements in shear strength, with increases ranging from 3% to 24%.