1954 Hydramatic Transmission

[MercMontMars]

Hi there, I’m posting to hopefully learn more about my 54’ Pontiac Hydramatic transmission. In the few times I got to run the transmission it functioned but was very fussy. I believe it has 4 gears and gets fussy around 3-4. Downshifts perfectly fine at stops. It’s fluid levels are normal, it doesn’t leak at all. I’m well aware it’s a very old transmission, but I can tell it still has some kick left in it. What can I do to it while it is still in the car to make it run just a bit better/healthier? I will eventually overhaul it, but for now I just want to enjoy it and know that I’m not destroying anything. 
 

Thanks in advance! 

[roysboystoys]

First step is adjust the control rod to the transmission. You'll need a manual or pdf.

[pfloro]

This may help...

 

What exactly is happening (fussy) during the 3-4 upshift...?   The most problematic shift was the 2-3 upshift and the 3-2 downshift.  Because of the "power flow" design,

coordination of the clutches and bands ("apply" & "release") was critical for smooth 2-3 & 3-2 shifts.   Proper band adjustment was critical but even then, that shift could

be rough.   Buick folks who were used to the smooth Dynaflow called this unit "Hydra-jerk"...!

 

Paul

DUAL-RANGE HYDRA-MATIC

The Hydra-Matic received a variety of minor changes throughout its life, including revised gearing, new clutches, and several new oil pump designs. For 1951, there was also a new reverse planetary gearset engaged via a hydraulically operated cone clutch. The previous pawl was retained, but now served only as a parking brake.

From an owner standpoint, the most significant revision was the introduction for the 1952 model year of the new Dual-Range Hydra-Matic. The production Dual-Range transmission was designed by corporate transmission engineer Kenneth W. Gage, although the basic idea had been described in Earl Thompson’s patent disclosures as far back as 1934.

As the name implied, the Dual-Range Hydra-Matic now provided two Drive ranges. For the sake of clarity, we’ll describe them as “D4” and “D3,” although depending on the make of the car, “D3” might also be called “DLeft” or “S” (for Super) while “D4” might be alternatively described as “DRight” or just “D.” In D4, the transmission would shift normally through all four gears. In D3 range, line pressure was applied to hold the 3–4 shift valve closed, just as if the throttle were floored. The other shift valves were unaffected, so the transmission could still shift normally between the three lower gears. However, it wouldn’t shift into fourth until road speed reached the maximum full-throttle upshift point, which was typically between 65 and 72 mph (105 and 115 km/h), depending on axle ratio and tire size. If you did floor the throttle in D3, the transmission would kick down into second as long as you were below the maximum allowable downshift speed for that gear. (The normal Low range was also retained, but was revised to give second-gear starts at part throttle, a useful feature in slippery conditions where first would cause too much wheelspin.)

Since the maximum speed of the 3–4 upshift speed was the same in both Drive ranges, selecting D3 didn’t make much difference in flat-out acceleration. (You could slightly improve your times by also using Low to delay the two-three upshift.) The additional Drive range was mostly intended to provide greater flexibility in hilly terrain, although being able to force a manual downshift to third was sometimes handy for highway passing.

 

 

 

Edited July 25, 2023 by pfloro (see edit history)

[The 55er]

A smooth-shifting Dual-Range Hydramatic is a thing of beauty. There are some external linkage adjustments that can be made and they're explained in detail in a Pontiac shop manual, Hydra-Matic Manual or a Motors Manual. I've had a few cars where the 2-3 upshift wasn't as smooth as the others and sometimes the adjustments in the manual fixed the problem. The shifts should be precise and consistent with no "hunting" for the correct gear. You should follow the instructions to a tee and do them in the correct order. I would write down EXACTLY what adjustments you made so if all else fails you can set the linkage back to the way it was. There might be some trial & error involved but it's definnitely worth a shot, you might be surprised at how smoothly you can get that old Hydra-Matic to shift. 

[NailheadBob]

The best manual for Hydra-Matics, is 1953 Pontiac Hydra-Matic Drive shop manual (1949 thru 1953) I purchased mine on e-bay

 

Bob

[MercMontMars]

@The 55er Good to know! I’m glad to hear you got positive results from your manuals. I will be getting one soon. Feeling a bit more optimistic if yours came around with just some basic adjustment.

[MercMontMars]

@pfloro Lots of great information here, thank you! I’ll be looking over all of this as I tinker with it. After reading your comment I have a feeling my throttle linkage may be at fault, but it’s only one piece of the puzzle so far.
 

Thanks again!