Typically, armoured vehicles have a tendency to sag forward, especially as they are modernized throughout their service life. Heavier cannons and frontal armour often strain the front suspension elements more than the rear. The T-34 was no exception, with the T-34-85's front springs having to be reinforced when the larger and heavier turret entered service.
The T-44 was a revolutionary shift for Soviet medium tanks. In order to rid the front of the hull of the vulnerable driver's hatch, the hatch had to be placed on the roof, which meant shifting the turret backwards. In order to keep the fighting compartment the same size, the engine had to be placed perpendicularly to the hull. This resulted in a lot of weight moving backwards, and the center of mass followed. Calculations may show some detailed insight, but one can even see with the naked eye that the tank is tilting backwards.