Re: Method for Driving Twin Ultramatics

Posted by HH56 On 2019/8/20 14:20:30

Congratulations on your Packard and welcome to the forum. 55s are nice cars and I hope you will enjoy yours. As you said, the trans was by far the weakest link in 55s so if you are prepared to baby it a bit you should have a nice ride.

I would say the biggest help on a 55 is to ensure the extra extension piece for the throttle linkage is installed and then make sure the linkage is adjusted properly. The throttle pressure as controlled by the linkage is by far the most important adjustment you have any control over and the pressure being wrong in relation to throttle opening was probably one of the big destroyers of the 55s.

It is hard to say if any of the 56 valving and a few mechanical improvements were retrofitted but assuming none were then 55s had some learning curves with the valving and timing for certain things as well as the general weakness when coupled with the V8s. Best suggestion I can offer is just drive conservatively and try not to keep up with the muscle car crowd. Not knowing how thorough your rebuild will be there could be a noise when going into direct drive if the old hard and probably glazed direct drive clutch plate is still installed. The noise won't hurt anything but you can lessen it and save a bit of clutch lining and a jolt when the clutch grabs by letting off the gas when the transition is made.

The triangle to the left of D will provide you with smooth but somewhat lackluster acceleration since you are starting and staying in high range with a transition to direct drive just as the original Ultras operated. Throttle linkage and pressure is extremely important here because in addition to determining when the transition to DD happens the throttle pressure also determines how hard the high range clutch plates are squeezed together. If the linkage and pressure is out of spec the plates could be too loose and slide against one another causing heat and wear.

The triangle to the right of D will start in low, shift to high and then the transition into direct drive. The 55s had a bit of timing issues with the shift from low to high also determined by throttle pressure. Sometimes there would be no gear engaged for a brief period or both gears applied at once for an instant so just take it easy and don't force anything. Let the trans do its thing without a lot of power applied. The extension on the throttle link bar was to help in preventing unwanted kickdowns when nearing full thottle. 55s would actually kick down from DD all the way to Low at a fairly high speed which is another reason there were some serious issues with the trans longevity.