1955 Ford-O-Matic or Merc-O-Matic | Ford Thunderbird club group 1955-2005 T-Bird models

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1955 Ford-O-Matic or Merc-O-Matic

lbc3

lbc3

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Thunderbird Year
1955
Who Knew? My recently purchased "show car" leaks like a sieve. Not the least of which is the transmission pan. I was hoping it was just the gasket, and it may well be, but from the looks of one edge of the pan I suspect it is damaged. So I put out feelers here for a replacement source...Crickets. (unless you count the admonishment for not posting under the proper category initially). Anyway, I found a few NOS pans circa $600. Today I came across "Charlie's Trannies", no not the one on youporn, and he had one. Interestingly, I requested a pan for the "small case" transmission because that's what ChatGPT said the Ford o Matic in the '55 was. Charlies says nay, nay, it is a medium case and identified it as a Merc o Matic. Exchanging pics, turns out he is right. Apparently Chat reasoned that Ford put the small case in the small cars, of which the T Bird it considered one. Given the heavy feel of my Bird, it doesn't surprise me that it does not qualify as a lighter car. Anyway, this guy Charlies is pretty knowledgeable and has a myriad of parts, albeit no complete units, if anybody is in need.

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lbc3 said:
Who Knew? My recently purchased "show car" leaks like a sieve. Not the least of which is the transmission pan. I was hoping it was just the gasket, and it may well be, but from the looks of one edge of the pan I suspect it is damaged. So I put out feelers here for a replacement source...Crickets. (unless you count the admonishment for not posting under the proper category initially). Anyway, I found a few NOS pans circa $600. Today I came across "Charlie's Trannies", no not the one on youporn, and he had one. Interestingly, I requested a pan for the "small case" transmission because that's what ChatGPT said the Ford o Matic in the '55 was. Charlies says nay, nay, it is a medium case and identified it as a Merc o Matic. Exchanging pics, turns out he is right. Apparently Chat reasoned that Ford put the small case in the small cars, of which the T Bird it considered one. Given the heavy feel of my Bird, it doesn't surprise me that it does not qualify as a lighter car. Anyway, this guy Charlies is pretty knowledgeable and has a myriad of parts, albeit no complete units, if anybody is in need.
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Mercomatic is the name they used for mercury cars, Fordomatic for Fords. Same transmission for all practical purposes. They did use the medium case in the Tbird, probably because it was fairly high horsepower for it's day, perhaps more HP than they thought the small case could handle reliably.
 
Tom Alpers said:
Mercomatic is the name they used for mercury cars, Fordomatic for Fords. Same transmission for all practical purposes. They did use the medium case in the Tbird, probably because it was fairly high horsepower for it's day, perhaps more HP than they thought the small case could handle reliably.
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If I understood correctly, the only name for the Medium case transmission was Merc o Matic. The Ford O Matic name was only applied to the transmission with the smaller case. My internet search source maintained that small case was used in the 55, though the only engine option was the 292, but even that came in two variants, with the one with a manual transmission being higher in compression ratio and horsepower. Seems like they went out of their way to make it difficult?
 
lbc3 said:
If I understood correctly, the only name for the Medium case transmission was Merc o Matic. The Ford O Matic name was only applied to the transmission with the smaller case. My internet search source maintained that small case was used in the 55, though the only engine option was the 292, but even that came in two variants, with the one with a manual transmission being higher in compression ratio and horsepower. Seems like they went out of their way to make it difficult?
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The names used were for marketing were different even though it was the same transmission. If you look at the invoices for the first gen tbirds they list the automatic as a Fordomatic. Every source I've seen lists 56 and 57 water cooled as medium case. The only difference generally listed for the 55 is that it was air cooled rather than water cooled. I've never seen anything suggesting it was a small case version. Not saying it wasn't, just that I've not seen anything along those lines. In fact, the Tbird Fordomatic was a slightly heavier duty version of the standard medium case in that it had 5 clutch plates rather then the 4 clutch plates that were used for the Fordomatics in the regular line of ford cars. Given that they felt the need to upgrade the medium case for the Tbird it seems unlikely they would have ever used the lighter duty small case version.
 
The Ford-O-Matic was Ford’s first automatic transmission for mass-produced cars and trucks. There also was a Merc-O-Matic for Ford’s Mercury line of cars. The names were simply marketing terms at a time when automatic transmissions were new technology and a novelty for buyers. These transmissions featured a two-piece cast-iron case and a cast-iron or aluminum bell housing. The Ford-O-Matics transferred engine power for Cadillacs during a brief period in 1953 when General Motors’ transmission factory caught fire. Some Dodge and International-Harvester vehicles, as well as Checker Cabs, were also equipped with the Ford-O-Matic.

Attached is an article titled: The Automatic Transmission in the Early Birds.

doug7740
1955 Thunderbird Blue
 

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