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Re: 1956 400 Ultramatic Transmission Questions
Quite a regular
Quite a regular

Andrew M

HH56 wrote:
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?

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.

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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Posted on: 2021/2/24 20:18

1956 400 Ultramatic Transmission Questions
Quite a regular
Quite a regular

Andrew M
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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Posted on: 2021/2/24 11:47

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