Packard Forum Index » Post-War (1946-54)

I dunno if it's already been mentioned, but a critical tool would be the test oil pan that had external pressure taps. There was a rig with multiple gauges hung on the driver's window so the pressures could be checked during an actual road test (and later adjusted accordingly).

I'm no expert by any means but besides correct standard shop techniques, these trannys require close attention to the bushings and proper pressure more than most other units...of course a myriad of updates should be done per the TSB's

Of course, it's never a bad idea for owners to compare notes on what others have run up against with their Ultramatics, looking for the most common and relevant failures. Thankfully, topics from the SCs, STBs, and SSBs are neatly referenced (and hot-linked to scans of actual documents - where available) here, in this site's Service Index feature for 1951-54 and 1955-56 vehicles. Same for 1948-1950 is currently in the works.

Yet, the best transmission men that I've known (regardless of brand) have always run a comprehensive pressure test. Comparing the results against factory benchmarks helps them quickly pinpoint the problem area. (Sure beats those old cardboard diagnostic wheels.)

While most guys get by with a couple of gauges for most transmissions, there must be some reason for having a third gauge with the Ultramatic, but darned if I can remember. I've only ever helped replace a front pump seal that let go and had the torque converter apart for a quick peek in one of my V8s and cleaned the filter screen in the other two.

Having managed special service tools for a GM dealer, I have a feeling that many of the tools needed to rebuild the Ultramatic can be substituted with or adapted from more modern versions. However, I'd like to lay my hands on a set of those gauges in good working order and a complete pan adapter, as there are a couple of take-off points on the valve body that you cannot get to otherwise. The adapter had an aperature to run hoses to those points. It also had a rubber plug that could be removed to permit insertion of a pair of wrenches to adjust the throttle valve presure setting - though that is probably one of the last things that anyone ought to be messing with.

Another point which is sometimes overlooked is that just the replacement of bushings doesn't always restore the correct clearances and at times it will become necessary to have shafts metallized oversize and then machined/polished back to standard dimension.

Getting the right fluid level can be a pain. I serviced one recently and I thought I got it right. Five minutes later I was taking fluid back out. The owner thought the car had a leak and was low, but almost everything I put in ended up being taken back out. So the leak was probably due to overfilling. The car has been sitting for months now with no puddles.

Filling ultramatic can be a total pain better done on a lift using a pump bottle calibrated in half pints. That is when there is no access plate on floor like is shown in the manual - oh brother.

If you replace the pan gasket, remove any dimples by the bolt holes, use the proper torque (10-12 ft lbs - that is snug using a little 1/4 drive ratchet), use a sealer sparingly and let the unit sit at least twenty four hours finger tight squish prior to torqeing.

I have had cars come in on the back of a wrecker because they wouldn't move. The transmissions were overfilled as a result of a special at xxxxxx xxxxxx or whatever.

The risk with ultramatic is that too low a level and the fluid gets hot and that is a whole new problem.

Packard had a lot of faith in the oil tightness of the unit and I do remember some original owner cars that did not leak at all.

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Very good point, 50 plus years later and standard bushings and seals may no longer be enough!

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Front pump, rear pump, and shift pressure?

So overfilling can cause issues too then. Food for thought. Another strange thing I've noticed, and even when it was working great and not overfilled, etc. When i do an oil change per the service manual, when completely taking out the converter drain plugs, i never, ever, ever get a drop out. Not even a little. When i refill though per the manual it takes a ton. That's what made me suspect the front pump seal, doing enough to get some fluid in there but not enough to keep it full.

Who knows, getting another tranny and motor this week, will throw this one in the garage and ship it to Eric when he gets into rebuilds. :)

G'day all, The factory gauges come up on ebay reasonably often. I purchased a set with all of the adaptors in the original wooden box for $US40. As Owen mentioned the wear on the gearbox shafts can nullify the benefit of new bushes. NOS output shafts do come up on ebay and i purchased a NOS 55 Twin Ultra shaft on ebay for $US 35 about six months ago. To grind, hard chrome and resize the shaft costs around $US110. The large converter seal at the transmission is very rarely at fault as it handles only exhaust oils. The culprit is either the converter ring seal or the loosening of the 6 screws holding the converter hub drive. The converter hub is very sensitive to imbalance caused by reconditioners not adequately marking the original balancing on converter items. I have made up most of the specialist tools for the trans overhaul and I shall post details when i get a chance. Best regards Peter Toet

The access panel is no help. at least not for me. fluid just wont go down, takes forever.And not worth the effort. just use the one on the underside.I did not try adding fluid while the motor was running.my fluid always seems to be low.when to check level is not so clear either. Brian

I had a rather long-standing minor but annoying leak from the front that eventually turned into a gusher. It was the large "O" ring seal between the converer halves.