Re: Potential Packard 48-50 owner and the Ultramatic Transmission

Posted by HH56 On 2018/12/10 10:34:29

The 50 Ultramatic is almost identical to the 51 with the exception of throttle linkage. In 52 there was a major change to the direct drive clutch inside the torque converter but the remainder of the transmission stayed essentially the same until late 54. Ultramatics were designed and built by Packard alone so work differently from other mfgs automatic transmissions. As was noted above, because of that difference most mechanics today will not be familiar with their construction and operation so will not take on a repair. If you do find a shop willing to work on them most would not know where the typical areas that need attention might be and could be a waste of money or worst case, do more damage than good. There are a few direct drive parts specific to the 50 and 51 so those items are slightly harder to come by than most of the other parts. If the car is a very early 50 and still has the original sand casting for the valve body then parts for the valve body and portions of the hydraulics are very hard to find. If repairs are needed it might need the trans out of a parts car so it can be converted to the later design.

Properly driven the 50-54s are very reliable units but as it was a transmission built in the very first days of automatic transmissions the performance and operation cannot be compared to anything you might be used to. They are absolutely not a racing transmission and if you treat them poorly they will respond accordingly. Essentially the Ultra is a single speed transmission with a torque converter to provide a change to the power curve. If you select H the transmission starts and stays in high range and depends on the torque converter to provide some multiplication of engine torque to simulate the lower gearing an actual set of gears would provide for starting the car in motion. Acceleration from a dead stop is best described as smooth and leisurely. As the car approaches around 20 mph, depending on throttle position the direct drive clutch will lock out the torque converter and essentially you will have a stick shift transmission running in third gear. That operation in a properly functioning transmission with a good clutch plate will be a silent and smooth action with the major perception being a lowering of noise rather than an actual shift. If the clutch has hardened then the change will be more noticeable. The transmission will stay this way until the car slows to about 11 when the direct drive will drop out and you are back in converter drive. At speeds between about 20-45 you can kickdown for faster acceleration but over about 50 there is no kickdown and it stays in direct drive. Low gear range works the same way except the maximum speeds are all lower.

To provide better acceleration, many drivers would start out in L and then manually shift to H as speed increased. The original Ultramatic transmission was not designed for this operation so there is no synchronization between gears. Depending on conditions, that could result in no gear selected for a short period allowing the engine to race away or both gears could be selected at the same time and fight against each other. Either could cause excessive wear or depending on how fast or hard the engine was turning damage the trans. If you elect to buy the car and do the manual select operation be sure to let off on the accelerator while the transmission does the shift to minimize chances of any stress or possible damage. Done carefully and not under power you can get away with the manual operation. In late 53 and retrofittable to most earlier models, Packard made a change in the valve body that modified gear timing to address this issue but it was not totally successful so caution is still urged.

The late 54 introduction of the Gear Start Ultramatic which became the 55-6 Twin Ultramatic was the first Packard transmission which was designed for actually shifting between L and H. You could select either the original no shift operation if you wanted to stay smooth and leisurely or a different range would provide the new automatic shift and faster but rougher acceleration.