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b.wilson, Packard newbie, more...





ULTRAMATIC: Ultramatic Transmission - A Primer
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Joined:
2006/11/29 20:35
From Western Pennsylvania
Posts: 2838
The Ultramatic automatic transmission was designed and built, in-house, by Packard - a feat accomplished by no other independent U.S. automaker. While other manufacturers started out with a plain fluid coupling to connect the power flow from the engine to a two-speed transmission, Packard jumped into the deep end of the pool not only with a power-multiplying torque converter, but a lock-up clutch that eliminated slippage - the next best thing to an automatic overdrive.

From 1949 through 1954, the Ultramatic allowed you to start out, forward, with one of two gears, either High Range (1:1 ratio) or Low Range (1.82:1), each combined with a multiplication of power (of up to 2.33:1) from a true torque converter. While Low Range was provided for long hard pulls or traversing steep grades (or quick starts), there was NO automatic upshift from Low to High in the original design; you had to accomplish that manually.

Regardless of which forward driving range selected, the Direct Drive torque converter clutch mechanism would automatically engage at steady speeds or when decelerating, above 15 MPH (IIRC) - resulting in the ONE and ONLY sensation of an automatic upshift in those units. Direct Drive effectively bypasses the torque converter, with the intent of eliminating the slippage of a fluid coupling for a true 1:1 transfer of power. Yet, push the gas pedal, and the DD clutch automatically disengages, returning you to the power multiplication provided by the torque converter.

To sum it up, you had a choice of only two forward driving ranges with the original Ultramatic:

'H': High Range Converter <=> High Range Direct

'L': Low Range Converter <=> Low Range Direct
(with manual shift available to/from High)

Appearing late in the 54th Series production run, the Gear Start version of the Ultramatic finally offered an automatic shift from Low to High (and vice-versa) by way of a new, third choice of forward driving ranges:

'D': Low Range Converter <=> High Range Converter <=> High Range Direct (with a kickdown to Low Range Converter available, below a certain speed)

However, High Range was now identified on the Gear Start quadrant with a mere '' (dot) - as if to emphasize the use of 'D'. In addition to the shift in/out of Direct Drive, you will feel an automatic shift from Low to High using the new Drive Range. These two-shift points often give the less-informed operator a false impression that this is a three-speed transmission.

Gear Start also added a conventional dipstick and tube under the hood. Prior to this, you had to go under-car or lift the carpet (or mat) to check/add fluid.

Due to its late introduction, you won't find ANY service information on the Gear Start Ultramatic in the 51-54 shop manual. Perhaps because of its similarity to the Twin Ultramatic, the Gear Start is referenced in the 55-56 Shop Manual. However, for complete coverage of the Gear Start, I prefer the 1954 Gear Start Ultramatic Service Training Manual, with its own GS-specific hydraulic flow charts.

While the quadrant symbols changed a bit for the Twin Ultramatic in '55 ('^D' for High and 'D^' for Drive) and again in '56 (back to simple letters, 'H' and 'D'), the basic operation was the same. (Curiously, the 1956 Studebaker Golden Hawk used the 1955 style quadrant.)

The engineering intent for the Gear Start and Twin Ultramatic was to provide an automatic low-to-high upshift for all-around driving, but decades later, many long-time users of Ultramatics will tell you that you'll get a lot more life out of this transmission if you use High Range, instead.

*****

Shift Quadrants Compared:

1949-54 Ultramatic selector quadrant -
P NHLR

1954 Gear Start Ultramatic selector quadrant -
P N•DLR

1955 Twin Ultramatic manual selector quadrant -
P N^D^LR

Take note that 'D' is actually comprised of two positions:

- the triangle (^) to the left of the D is the same as 'H' on the original Ultramatic or '' on the Gear Start (starts out in High Range)

- the triangle (^) to the right of the D is the same as 'D' on the Gear Start edition (starts out in Low range and automatically shifts to High range)

1956 Twin Ultramatic manual selector quadrant -
P NHDLR

1956 Twin Ultramatic pushbutton selector layout -
N L H
P R D

At a glance, the pushbutton layout may not seem logical, but the factory brochure, 'A Woman's Place', advises that the bottom row - P-R-D - buttons are used most often (and a Tip o' the Hat to member HH56 for that factoid).

Also, the 'N', 'P' and 'R' buttons are grouped together on a common buss bar so they can be deactivated, all at once, at speeds above 5-8 MPH by a governor oil pressure switch.

However, that pressure switch is bypassed by an automatic park relay. That is, when the ignition is turned off, the transmission automatically shifts into park - regardless of speed/direction. The factory later provided (by way of a confidential bulletin) a procedure to safely eliminate the park relay, if desired.

*****

For additional more information see:

Ultramatic Drive Serviceman's Training Book - covers the original 1949 version, with theory of operation, overhaul, maintenance, and diagnosis.

1951-1954 Packard Service Manual (see 'Section VII - Ultramatic Drive') - covers the original version, with theory of operation, overhaul, maintenance, hydraulic pressure tests, and troubleshooting; 25th Series supplement covers changes/improvements in torque converter, direct drive clutch, planetary system, and pump check valves.

Gear Start Ultramatic Serviceman's Training Book - covers the late 1954 version, with theory of operation, overhaul, maintenance, hydraulic pressure tests, and troubleshooting; includes hydraulic pressure flow charts.

1955-1956 Packard Service Manual (see 'Section VII - Twin Ultramatic') - covers overhaul, maintenance, hydraulic pressure tests, and troubleshooting with reference to Gear Start; includes hydraulic pressure flow charts. 56th Series supplement also covers pushbutton control.

Auto-Lite Service Manual: 1956 Packard Transmission Control - covers the operation, maintenance, troubleshooting, and overhaul of the optional electric push button control system.

This site's Packard Service Index, for 1948-1950, 1951-1954, and 1955-56 models, will direct you to supplemental information on the Ultramatic transmission from factory-issued service newsletters and bulletins.

See also the FAQ on ULTRAMATIC: What Fluid to Use.

Posted on: 2011/9/10 18:11
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