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Does anybody have any suggestions? Our 35 12 shifts great when cold, but once it warms up it will not shift in to first or reverse. The idle is very low so that is not it. If I turn the ignition off, at first it will still not shift, but after a few up and down strokes will then go in easily.

A suggestion was that the engine vacuum is lower when hot and the issue is related to the vacuum assist. This was adjusted using the attached manual snippet.

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Not clear here. Do you mean you can put the car into 2nd and 3rd, but not 1st and reverse?

The Seniors have a big heavy gearbox and I always find it easier to almost put it into Second to allow the synchro ring to slow the gearsets, then put the gear lever into First or Reverse. Peter Toet

-Clutch not disengaging. Might just need an adjustment.
-Bad Pilot Bearing

I don't have any wisdom to add on this issue - but that is one beautiful car!

Wow but that color is incredible!

Thanks for the responses. Just to clarify:

1. From first startup to about 10 minutes of running, easily shift in to any of the gears including first and reverse.

2. After 10-15 minutes of running, you CANNOT under any amount of cajoling get the gear shift to go into reverse or first. Second and third are still fine. Going to second and then to first will not help.

3. Turn the ignition off, at first you still can't get into first or reverse but with a little up and down it will allow it and then easily after.

4. Start it again warm and you are back to step above.

Okay, that's a little better description of the problem and it sounds like the 1st and reverse action is stuck and when you move across to the 2nd and 3rd circuit everything is fine.

Where I would start is pull up the floor boards, get the car into malfunction mode, shut it off, and pull off the trans cover to see what might be binding.

The 1st and reverse circuit is the rod and shift fork to the right and moves the sliding gear.

If this is not what the car is doing please correct my interpretation.

One thing I found out about Packards is that sometimes those shifters are not interchangible from car to car because the manufacturing process was producing essentially a hand crafted unit.

So mixing Senior Packard transmission parts may cause problems. I found this out because I was working on a couple of Packard transmissions but had only one shifter on hand. I found that I couldn't use that single shifter to set up both of the transmissions. I had to have both shifters.

Can it have anything to do with the oil in the transmission? When the oil warms up it wont shift, so maybe the oil is too thin?

An earlier poster suggested a problem with the clutch, and from my experiences with other manual transmission cars and motorcycles, that would be where I would look first. I had a motorcycle that would become very hard to shift when warm, the clutch was out of adjustment because the cable was stretched. When it was cold, everything had not thermally expanded and so the clutch could still be disengaged, but when warm the tolerances had all closed up and the clutch would drag and it became very hard to shift. I think on the Packard the first and reverse gears are not synchronized, at least on downshifts, whereas the 2nd and 3rd gears are, so the clutch that is part of the synchronizers is helping you out on the upper gears, but not on first and reverse.

Could also be a binding action in the transmission as was suggested earlier, also perhaps caused by parts heating up and thermal expansion closing up tolerances, but I would double-check the clutch first, especially when it's warm. Might put the rear-end up on jackstands and see how much clutch drag you get when warm versus cold.