39 ford transmission question

L

lonewolf

Senior Member
what is the benefit of a 91a gearset over a 81a gearset when did they put 91a gearsets in

I have an early 39 deluxe with a 81a motor and the 81a gearset and the early style grille thanks
 
Actual gear teeth between the 68 gearset (1936-1939) and the 81A some (1939--up) are the same...pretty sure these are the actual numbers you are pointing too. Big difference is the change to different synchro with the brass blocker rings, which affected design of the synchro surfaces of gears of course.
The 81A set (that prefix indicates 1938 Ford, which never used it as far as is known) was introduced in 1938 but only on the Lincoln Zephyr. Ford started getting it in 1939. Some sources say Deluxe got the late set, but I think I have seen to many '39 serial number cases with early type to believe that.
 
Like Bruce said the biggest change was the improved syncros system and better shifting. Another important change was changing the second gear bushing sleave to a bushing pressed into the gear. That created a larger, more stable bearing surface that reduced wear and held in 2-gear better. The 81A coded gears are miss-leading as they probably were designed and intended for 1938 introduction but for whatever reasons were delayed from full implimentation until mid 1939.
 
the trans has a *0688* above the inspection cover and the engine has a 81 infront of the pass head, the car was made in canada and has 22,000 original miles on it. with the original engine and trans, how can i prove what year the engine and trans are?

did they use a differant numbering system in canada?
 
Barn Junk said:
Like Bruce said the biggest change was the improved syncros system and better shifting. Another important change was changing the second gear bushing sleave to a bushing pressed into the gear. That created a larger, more stable bearing surface that reduced wear and held in 2-gear better. The 81A coded gears are miss-leading as they probably were designed and intended for 1938 introduction but for whatever reasons were delayed from full implimentation until mid 1939.
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81A on a part number does not indicate that it was used in 1938, it indicates that it was DESIGNED in 1938 and the introduction into production could be that year or later. It has been my experience that the Mercury had the good transmission from the start of production.
 
But the odd thing about the gearset was that it went right into production on the 1938 LZ, a secondary application, but went into Ford passenger later. The PN prefix indicates what its initial plan was for, Ford passenger, even though used on Merc, LZ, pickups, etc. The parts always kept their primary prefix though used on multiple lines.
I too think Mercs, as an upscale line, all got the late cogs, but the '39-48 Merc book does weasel and mention the 68 stuff as a possibility. This and the slow changeover maybe indicate a supply shortage??
 
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