Re: 55 Packard Transmission Cooler Mockup ?

Posted by Peter Packard On 2009/12/21 5:09:40

G'day all, I have found over tha past 40 years that the only part of the Packard Ultramatic cooler that rusts are the easily replaced inlet/ exit ends. I would also urge caution as the maximum allowable backpressure from the converter is 30 PSI. The backpressure lowers the direct drive clutch application pressure. That is if your DD Clutch pressure from the rear pump is supposed to be 180 PSI, a converter return line pressure through the cooler of 30 PSI will result in a 150 PSI application pressure. I have found that some of the non OEM Packard coolers installed are restrictive and have a back pressure around 20 PSI. I am not saying not to use them, just get a larger rather than smaller cooler with plenty of flow. I would also recommend a three-eighth inline transmission magnetic/10 micron particle filter in the cooler line. If you find that there is over 20 PSI back pressure you can replace the restrictor in the upper outlet of the cooler line at the trans with a non restrictor fitting, as installed in the bottom( return) line. The Ultramatic will very rarely overheat if it has correctly changed over from the large front to the smaller rear pump. best regards Peter Toet.