Packard Forum Index » V-8 (1955-56)

Hi guys,

So I tried taking my '55 around the block for the first time. It hasn't been on the road in 10 years. Filled the trans fluid to the full mark while it was idling (it was low because I believe it leaks from the pan and has a new gasket but wanted to take it around the block to make sure it went through the gears before putting a new trans pan gasket on it). It goes into drive and goes forward, but nothing in reverse. I revved it up and it wouldn't creep backwards but it seemed like it was trying.

My first solution I'm going to look into is the trans cable travel, perhaps it isn't going far enough to engage reverse?

My plan B after that is to change the fluid over to B&M trick shift trans fluid and maybe that will make reverse grab?

Any advice is greatly appreciated. Tomorrow morning I'm still going to drive around the block anyway.

Thanks,
-Chris

There are no cables used on Ultramatics.

One question would be if there is any slop in the shift lever. Reverse is the last position the manual selector valve can travel to and your idea of not traveling far enough may be valid. There are some wear spots but one place to check is the bellcrank assy. That is mounted between the frame and engine. It transfers the vertical rod motion from the gearshift lever to horizontal movement going to the trans lever. It has some rubber bushings and also a mount on the engine side which can loosen. Make sure there is no lost motion there.

One issue with Twin Ultras is an internal setscrew which can strip out of a potmetal lever. If it has loosened, the lever which moves the valve may not be able to pull it to the required position. There is a stop the setscrew also holds and that could be out of position blocking full travel. I would check that loose screw possibility by removing the long rod from the lever on the drivers side of transmission. Grasp the lever and move it thru the positions.

Park and Neutral share a position on the valve. Assuming the gearshift lever was in park when you started, the valve should be in the neutral detent when you start. Moving the lever out of park to neutral is a fairly long throw and then it will be very short movements between the other selections. A strong detent should be felt at each stop. Including neutral, there are 5 in total. The final one is reverse and should feel like the others. There should be a minimal amount of slop in the action. After you go thru and check the number of detents, move the lever in the opposite direction to about the middle and check the amount of movement. There should be almost no motion at the end of the lever when it is in a detent. If the end of the lever moves more than a tiny bit as you try to move the lever back and forth the setscrew may be loose.

Another issue is a pin which holds the piston to band levers so they pivot to tighten the bands can break. If that has happened the reverse piston may be operating but without the full lever action, it may not be able to tighten the band enough to keep the planetary ring from rotating.

If everything in the linkage checks good, it is possible one of the valves has stuck. In addition to the manual valve there is a small auxiliary valve which has to move so fluid can bleed out of the other side of reverse piston. After years of sitting it is possible that valve cannot move to allow fluid out and the piston cannot move.

In addition to what HH pointed out.
Have you looked at the service manual?
https://www.packardinfo.com/xoops/html/downloads/servicemanual5556/Sect07_TwinUltra.pdf

My Packard also wouldn't go into reverse. on inspection I found a hose had come loose and fallen between the transmission linkage and a crossmember.
When trying to shift into reverse the shift rod would hit the hose and stop the rod from hitting the reverse detent.
Check for any interference and recheck the fluid level.
Just a thought.

Thanks for the info everyone! I'll get to it when I have some free time tomorrow.

So I finally got around to looking at the linkage and played with it to the point where I can get the wheels to spin with reverse engaged with the car in the air. Unfortunately when I set the car on the ground and engage reverse it won't go anywhere, even with a little throttle. Now I'm prepared to drop the pan and do some digging.

Looking at the service manual troubleshooting for 'car does not move with the selector lever in the reverse position', it says:
(a) Remove the control body (I assume this is the valve body?) and free up the reverse shuttle valve.

- My question is where can I find the reverse shuttle valve?

(b) Remove the oil pan and position the strut properly

- My question is where is the strut and how do I determine the proper position?

Any help is greatly appreciated.

Thanks,
-Chris

All the valves and the three separate sections of valve bodies containing them are shown in the Twin Ultramatic section of 55-6 service manual but here is a photo of the 55 valve body containing the reverse shuttle valve.

The struts are located directly above the two piston (or brake) assemblies which are connected to the valve bodies. In addition to what is mentioned in the manual re proper positioning of the strut (means make sure the little inch long piece of metal connecting the band to the actuator is actually in position so the piston can bring in the band) there is a pin which forms the pivot for the actuator. That pin has a groove in the middle which has proven to be a weak point and many of the 55-6 pins have broken. If a pin breaks it can come out and actuator no longer has a way to transmit piston force. Also make sure the band adjustment is good. If the band has worn excessively for whatever reason, the piston cannot clamp it tightly enough around the reverse drum to stop drum from rotating..

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Awesome, thanks for the info Howard! I'll let you know what I find when I get around to digging into it.

Dropped the pan on my '55 400 because it wouldn't move in reverse (I checked the linkage). Wheels would spin in reverse when the car was in the air, but didn't move on the ground. I found these parts sitting at the bottom of the pan. Any thoughts?

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A little hard to tell without something in the photo to give scale but it might just be a portion of the reverse servo piston, which would explain your symptoms.

That servo is easy to remove: just remove the 4 bolts that hold it down and pull it sideways away from the valve body. The two supply pipes will pull free from the valve body.

Then let us see a picture of it.