Re: Twin Ultramatic Shifting

Posted by HH56 On 2008/5/23 8:26:14

You asked about the conditions when to use D vs H. It kind of depends on your preference so a short explanation might help.

In H (or drive L), the trans is identical to older ultras as there is no shift at all. It starts & stays in high, and what you feel as a shift is the direct drive clutch locking out the torque converter. The acceleration is leisurely at best.

In 54, to compete with other mfg, the twin ultra was introduced which actually has a low to high shift and then to direct drive (D or drive R). Acceleration was acceptable and with more time, all the bugs would have been worked out.

Unfortunately, there were a lot of valve timing and linkage issues even into 56 so a heavy foot and mis-adjusted anything tends to shorten the life of bands & clutches as well as cause some weaker components to fail. So keeping that in mind, H is preferred, but if you let up on the gas at the shift points, stress on things will be greatly reduced and a satisfactory life to components can be expected.