Packard Forum Index » Post-War (1946-54)

I have a '53 caribbean. 38,000 miles. When I drive it and come to a stop sign, car goes into neutral/idle as it should but hesitates when kicking back into gear or drops in abruptly at some point when kicking back in when given gas. Once driving along, no transmission issues that I'm aware of. Is this an issue with the Ultimatic itself or is there a vacuum issue with the carb that triggers the "shift" that could be causing this? Hoping the latter.

There is no vacuum associated with an Ultramatic. The throttle position is done by a long odd shaped rod on the passenger side going from the accelerator linkage on the head down to a lever on the side of the transmission. That adjustment is very critical on the Ultras and needs to be working and adjusted by the book.

If it is a transmission problem, it could be throttle or it could also be dirty or sticking valves in the trans or even an engine problem.

If you want to check the throttle linkage, there are several articles on adjusting the linkage. I would suggest you check the service index on the left menu, and under 51-4 and then Ultramatic find the latest service article pertaining to throttle linkage. IIRC, it is a Stude bulletin from around 1960. You can also do a search of the forums as that subject has been covered before.

You won't have the special gauge they mention to set the angle but once you read the article the measurement the gauge provides can be done with a ruler. I don't have the figure handy but will find it later on if you want it.

I'm wondering if you're familiar with the function and feel of an Ultramatic. When you say it goes into neutral or idle when stopped, it really isn't neutral though the engine should come to an idle. What has occurred is that the direct drive clutch disengaged and you dropped back into torque converter mode. Then you say it "kicks back" when you accelerate - it should simply begin to accelerate in torque converter mode. So I begin to think you may have an engine "stumble" problem and not a transmission issue. Potential culprits to check would be a vacuum leak and especially at the distributor vacuum advance, and perhaps poor performance from your carburetor accelerator pump.

If you are not familiar with Ultramatic and how it functions and feels, maybe you could find a local Packard owner with a similar car and let him take it for a drive and advise.

If I catch what you are saying correctly, the car falls into neutral at an idle and then jumps back into gear as you give gas. This is not normal--the car should stay in gear just like any modern automatic--and then accelerate away smoothly. At about 15 to 30 or so, depending how hard you are giving gas, the trans should shift into direct. That would feel about like high gear in a stick shift car. As you come back to a stop the direct drive will drop out by , oh, 10 or so but you are still in gear. If you take your foot off the brake the car should creep.

If the trans is really falling out of gear at an idle, then you have an internal pressure problem. The cheapest guess would be a stuck pressure valve, the more likely and more expensive guess would be worn bushings at the high range clutch.