then the fluid coupling, followed by the rear gear assembly (2.63:1 reduction) and through the reverse gear assembly (normally locked) to the output shaft. That is, the input torus of the fluid coupling ran at a slower speed than the engine, due to the reduction of the forward gear assembly. This produced an exceptionally smooth startup because of the relatively large amount of slippage initially produced in the fluid coupling. This slippage quickly diminished as engine RPM increased. When the transmission upshifted to second gear, the forward gear assembly locked and the input torus now ran at engine speed. This had the desirable effect of "tightening" the coupling and reducing slippage, but unfortunately also produced a somewhat abrupt shift. It wasn't at all uncommon for the vehicle to lurch forward during the 1-2 shift, especially when the throttle was wide open. Upon shifting to third, the forward gear assembly went back into reduction, and the rear gear assembly locked. Due to the manner in which the rear gear assembly was arranged, the coupling went from handling 100 percent of the engine torque to about 40 percent, with the balance being handled solely by the gear train. This greatly reduced slippage, which was audible by the substantial reduction that occurred in the engine RPM when the shift occurred. The shift from third to fourth gear locked the forward gear assembly, producing 1.00:1 transmission. The fluid coupling now only handled about 25 percent of the engine torque, reducing slippage to a negligible amount. The result was a remarkably efficient level of power transfer at highway speeds, something that torque converter equipped automatics could not achieve without the benefit of a converter clutch. Many Hydramatics did not execute the 2-3 shift very well, as the shift involved the simultaneous operation of two bands and two clutches. Accurate coordination of these components was difficult to achieve, even in new transmissions. As the transmission's seals and other elastomers aged, the hydraulic control characteristics changed and the 2-3 shift would either cause a momentary flare (sudden increase in engine speed) or tie-up (a short period where the transmission is in two gears simultaneously), the latter often contributing to the failure of the front band. Much of the difficulty in staging a "clean" 2-3 or 3-2 shift in any cast-iron Hydramatic was the changing elasticity of the governing springs in the valve bodies. Even ambient temperature would