Timing of 12hr Clock Mechanism/Mainspring Combination

Hello Forum Members,
If anyone can help me in this DIY project, I'd greatly appreciate it. Please see the attached pictures. I've labeled parts in the pictures to aid in the description of the problem needing to be resolved. Objective: To use a 12 hour mechanical spring clock mechanism from an existing manufactured product in an alternative application. The attached file "1_AB" shows the rear of the product. The 12 hour clock mechanism (attached picture titled "clock") attaches to side B. The clock mechanism works in tandem with a mainspring spring. The mainspring attaches to side A. The attached file "2_AB" shows a top view of how the clock mechanism and mainspring are joined utilizing a wooden rod and a wide belt that's attached to the wooden rod. In this product, when the belt is pulled back entirely it takes 12 hours for the belt to be pulled entirely back in from the tension of the clock and mainspring.

I'm desiring to use this clock mechanism and mainspring combination to have the same overall effect in my project. However, the configuration of the two items needs to be different. The attached picture "Assembly" shows this new configuration. I had a custom stainless steel part made to join the clock and mainspring together, in essence, taking the place of the wooden rod. At this point, when I wind the clock and mainspring up and let me unwind, the tall square portion of the custom stainless steel part that sticks up through the mainspring in the "Assembly" picture makes 1 full rotation in around 2.5 hours. I was hoping it would match the 12 hour time of the original product. I'm completely at a loss as to how or why.

Any explanation or help would be greatly appreciated. Is what I'm wanting to accomplish here ridiculous or possible?