Packard Forum Index » V-8 (1955-56)

I recently purchased a 1956 Packard 400. I've have several classic cars, but this is my first Packard. The car was restored in 2002-2003 and the engine and transmission were rebuilt as well. The previous owner of the car rebuilt a lot of Packard drivelines and cars over the years. According to the previous owner's notes on the car, the original transmission was taken out at the time of restoration and replaced with another Ultramatic. In 2009, the previous owner took out the transmission that was installed in 2003 and replaced it back with the original transmission out of the car in order for it to be all original. In 2011 the previous owner stopped driving the car due to health reasons. He passed away several years ago, and his son got the car. It was started and driven some since 2011, but not much.

I bought the car earlier this year and got it running again. It runs smooth and gets good oil pressure so far. It is a little below the half way mark when the engine is hot. Besides driving it up and down my driveway about one mile, it haven't driven the car much. I took it down the road about 3 miles yesterday, and noticed the transmission seems to be slipping. When driving, the car will accelerate to about 20 mph with no problem. Then after that it doesn't seem like it will go into any other gear. I put it in Low, Drive, and High, and it didn't seem to make any difference. It still won't go above about 15-20 mph according to the speedometer. It will pull fine at very light acceleration, but as soon as you start mashing the gas very much, it will slip.

The transmission doesn't have but maybe 500 miles on it at the most according to service records that the previous owner had. According to the previous owner's notes, when the transmission was rebuilt, the low range pivot shaft was replaced due to the old one being broken. Also according to the notes, the previous owner added what he called 5 updates to every Ultramatic he built.

They were:
1. Plug case side vent
2. Add vent from tail case
3. Put feed hole in rear check valve
4. enlarge passage from rear pump to reduction gear rear support bearing
5. Put hole at 12 o clock position on rear pump housing


If the transmission can't be fixed relatively easily I have two never installed rebuilt ones on the shelf I can trade out. I would rather fix the original though. I also have a rebuilt 374 engine on the shelf.


Here are some notes on the updates that he did in the transmissions he rebuilt:

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Ross would be the one to tell you the most about these transmissions and alterations done to them over time to improve them.

Yes. John is correct above . Beautiful car BTW. There may be a few things to check. Have you performed the band check and adjustment procedure? Info to the manuals here. I had one where the band control pistons were seeming to get stuck may have been debris or corrosion from long sleep as yours. Adjustments and exercise seemed to free things up. Have you read the normal operation and shift detents positions as they are a bit unique to the ultra. One detention starts in high and only lockup after. The other starts in low-shift to high at a very low speed then the lock up converter should give a sensation of almost another shift. Possible the converter clutch slipping?

What a great problem to have.
Best wishes & great car!

With all the transmission changes in and out I would also wonder about the throttle linkage being adjusted properly or maybe not hooked up.

If the Direct drive clutch was slipping the car would still get over 20mph but you would hear the engine revs be a bit high and louder since it is still driving thru the converter. If the high range clutch was slipping then the torque might not be able to get to the rear wheels and the high range clutch is needed with either drive range. It is not used in low though and if it still won't get over 20 when low is selected then it might be a stuck reactor inside the converter. I believe Ross has mentioned the reactor issue being a common malady and also one that quickly causes the trans to overheat. What is the condition of the fluid -- bright red or dark and brownish and does it smell burned? Was the fluid level checked in park or neutral with the engine running or within 1 minute after engine was stopped?

The clamping force of the high range clutch plates is very dependent on having the correct throttle pressure as determined by the linkage and adjustment. At low engine speed and torque not much clamping force is required but more engine power needs more throttle pressure which in turn controls and increases the modulated pressure being applied to the high range clutch to force the plates more tightly together so the higher torque can reach the wheels.

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Here is a picture of the linkage on the carburetor. It is adjusted pretty much to the front. The measurement of where the gas pedal meets the linkage to the firewall is 3 1/2". I think I read somewhere that the linkage to the transmission was supposed to be closer to the middle, instead of at the front.

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Make sure the fluid level was checked in park or neutral with engine running or immediately after it was stopped as mentioned above.

How about the end where rod connects to the lever on the passenger side of the transmission. Make sure the rod is attached to the lever and clamp at bottom attaching to the shaft is tight. Is the lever pointing up as this photo shows?

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Here is the final version.

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In L. you have one shift.

In H. You have one shift.

In D you have 2 shifts.

Move the rod to the center hole.

Someone was trying to change the shift point

My 400.

Which is modified. But. in D. My first shift is firm. Then the 2nd going into DD. Direct drive. Is smooth.


The first shift. At that sometimes people would get flare. Then it would go into DD.

Flare to me is that the first shift isn't holding.

The cause. You can look in service letters.

But Ross can figure it out. But... Pressure test will come up. So if your inclined. Buy about 6 gauges and make a test gauge..


My dad ran lines from trans to under the left fender he had gauges on clear plexiglass fit outside by wiper. So he could drive and see the pressures.

Lines are capped off .. When not in use...