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My '51 has a 288 cu. in. engine and an automatic transmission. The engine is in need of a rear main seal and of course the transmission has several leaks that are also an annoyance for the garage floor.

So I'm considering removing the engine pan and replacing the engine seal. Not sure how I want to tackle the transmission's sins, but have seen ads for converting an Ultramatic to a Chrysler Torcflite 727 by Serra Grove Packards.

I'm looking for thoughts by other owners who may or may not tackled leak problems similar to mine.

We've been thru the real main seal business any number of times before, it's not the most pleasant of jobs but straightforward enough.

As to the Ultramatic, just my own opinion but I can see replacing a transmission with something non-authentic, most especially just for a few leaks. The Ultramatic gave good service behind the straight 8s, it really wasn't until the V8 era that they became a bit problematic. That aside, a lot depends on where the leaks are. If it's the front seal of course the transmission has to be removed but leaks at the selector shaft, throttle pressure shaft, and rear seal are all very easily dealt with with the transmission in the car. And if I had to remove the transmission to do the front seal, I'd think hard about taking the opportunity to replace some bushings and friction parts.

Dear Marston:

If you are going to do the work yourself I would try replacing the pan gasket first. The fluid level when parked is higher than the gasket.

For a sealer I recommend Mopar ATF RTV which is very good. Make sure the pan is not distorted and if so true up the surfaces. The original gasket was paper but today imitation cork is being sold, so I wouldn't over tighten the bolts. Tighten enough to compress the cork and let the sealer act as a threadlocker.

Finally, let the thing sit empty for at least 24 hours for the sealer to cure.

If the unit is a good performer I wouldn't change to a 727 Torqueflite, but if the trans is a clinker then the cost of switching to the 727 is about the same and worthwhile. The 727 will outperform a stick shift.

Hope this helps

One thing to consider is the Torque-Flite conversion seems to be hit or miss. Several have been done and from comments on various forum sites, some drivers are very satisfied while others have reported some serious vibration issues.

Whether those with issues are due to variations in the manufacture of the conversion kit itself or the workmanship when the unit was installed is the big question. I don't recall seeing any feedback from those with issues as to how or if they were resolved.

There is also a conversion available to a GM transmission that a few people have done. From reports it seems to be a successful conversion. On the downside, for the inline 8 it changes the starter motor. I believe the one they chose to use is only 12v. If so, unless you can find - or someone can rewind - the new starter motor into a 6v version, the car would also require a 12v conversion. Perhaps Jason from AER could comment on that.transmissionadapters.com/Packard%20to%20Chev%20adapter%20kit.htm

O-D, Tim, & Howard:

Thanks for the input. It seems that I have enough info to proceed. It is nice to know about the fluid level in the transmission.

Once in a while when the car shifts from low to high there a clunking/rattle noise that I hope is a loose muffler or loose transmission mount or a ????.

I'll take a look and figure out if the transmission leak is a front seal and go from there. The box has not given me any trouble so hopefully it is not the front seal.

Thank Again

After one shop's failure to rebuild my 53's ultramatic, I put in the 727 and have had great performance. Just get somebody who knows what they're doing if you decide to switch out, it takes some work.

if you are leaking transmission fluid, i would also check the torque converter for leaks, as there is an o-ring between the front (steel) and the rear (alum)of the converter, these transmissions do not shift from low range to high range, you will feel the change of the torque converter, and at about 25mph you should also feel the torque converter locking up too. the front seal is originally leather, from the front bearing there is a drain back hole, like the rear main of an engine, so there should be no pressure on the seal at all.

After examining everything it would appear that most of the oil comes from the pan and maybe the selector shaft seal. So I'll try replacing them both and see if that solves the leak problem.

On another note, when the transmission shifts from low to high it will sometimes make a rattling noise. It occurs more frequently when the car has been driven for 10 or 15 minutes. The noise stops as soon as one backs off on the gas pedal.

Any ideas as to what may be causing it?

When you do the pan make sure and flatten the sheetmetal where the bolt holes have probably been distorted and pushed up making the area around the holes higher than the flat space between. Once that happens the gasket doesn't seal well in the flat area and is a very common area of leaks.

You said "shift" but as you probably know, there is no automatic low to high shift in a 51. It's only in high or low unless you manually move the lever between the two. That manual movement is something Packard didn't recommend since there was no synchronization or timing between the shifts. It can be excessively hard on the trans if done under power. If this is a common way you use the trans, letting off on the gas is definitely recommended while it shifts. A timing kit was issued in 54 to partially help but the late 54 gearstart & later twin ultramatics were the only ones to automatically make the L-H shift.

If you just start and leave it in high, the "groan" is probably the direct drive clutch. Noise has been a symptom of linings dried out or hardened or possibly some cork has even worn or flaked off. 51s used the first generation large splined piston and that could even be sticking slightly. The clutch makes noise when engaging as it makes the transition from high range converter to direct drive. Many have the same noise and live with it by doing just as you do and let off the gas as it makes the transition.

Hi ,my ultramatic doesn't do so well up my big hill ,some times it will" downshift" in high range ,it drops down into its lower gear ,the rpm goes up and she climbs well,
but most of the time it just bogs down and I have to shift to the low range on the colomb to make it up
, it sounds from the threads that driving like this practice may be rough on the transmission
Down hills in low for engine braking ( a must as the drum brakes fade) it will rev up in low and then lock well

I've been thinking if getting a rebuild (70,000mi) vs a swap I've seen a lot of talk about a 727 in the threads I use my car as a daily driver which entails some time on the freeway .i try to keep it to 60 ,I know the speed limit in 52was45 mph
Will 60 blast the Packard 200 thunderbolt? The more modern trans fix this ?
I haven't found a local affordable person. To rebuild to ultramatic it sounds complex! I wonder if the average rebuilder would get the newances of the specifics like the o rings in the torque converter. transmissions by gene out here in nor cal was 3500 ,the ultramatic dynamic guy was2800 out in Virginia but I'm not sure if he's around
I have a selector shaft leak also which I fix with just adding fluid
I've added some b &m trick shift on recommendation of a post , I wonder if this screwed my shifting up by not using just some plain 10 wt or ATF