The Ford Barn - View Single Post - Fordomatic: Are there different output shafts for different Fordomatics?

rotorwrench · 01-22-2021, 04:05 PM

From info I'm finding (parts book & internet) the original slip yoke depended on the engine installation and associated transmission. When the T-bird came out, they used the new medium case transmissions. The medium case came out for heavy duty applications like the 312 T-bird but the 292 also had the medium case PMB-C transmission. There were two PAW (PAW-C & F) and two PME transmissions (PME-B & C) used for 1956. 1957 had different part numbers. Most transmissions are similar but they changed to water cooled in 1956 so that would be a distinct difference between 1955 & early 56 and late 1956. I think the output shaft splines changed in 1957 to a finer spline with a higher count.
Early ones were likely 16-spline but there was a standard part (P/N B5C-4841-A) that was likely for standard transmissions and a heavy duty part (P/N B6S-4841-A) for 312 engines in T-birds, police cars, and others with the FOM and the overdrive T85 standard shift. The parts book doesn't list the spline count for the 1956 T-bird with FOM.

What is the spline count? Most of the differences between transmissions of the same basic type would have been for mounting and tail shaft length with consideration for speedometer gearing. Otherwise they are pretty much the same. If the spline count & diameter is a match then it may just be that the air gets trapped during installation and makes it hard to go on. Some manufacturers drilled a small hole in the knuckle plug so that it could breath.

01-22-2021, 04:05 PM	#3
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Fordomatic: Are there different output shafts for different Fordomatics? From info I'm finding (parts book & internet) the original slip yoke depended on the engine installation and associated transmission. When the T-bird came out, they used the new medium case transmissions. The medium case came out for heavy duty applications like the 312 T-bird but the 292 also had the medium case PMB-C transmission. There were two PAW (PAW-C & F) and two PME transmissions (PME-B & C) used for 1956. 1957 had different part numbers. Most transmissions are similar but they changed to water cooled in 1956 so that would be a distinct difference between 1955 & early 56 and late 1956. I think the output shaft splines changed in 1957 to a finer spline with a higher count. Early ones were likely 16-spline but there was a standard part (P/N B5C-4841-A) that was likely for standard transmissions and a heavy duty part (P/N B6S-4841-A) for 312 engines in T-birds, police cars, and others with the FOM and the overdrive T85 standard shift. The parts book doesn't list the spline count for the 1956 T-bird with FOM. What is the spline count? Most of the differences between transmissions of the same basic type would have been for mounting and tail shaft length with consideration for speedometer gearing. Otherwise they are pretty much the same. If the spline count & diameter is a match then it may just be that the air gets trapped during installation and makes it hard to go on. Some manufacturers drilled a small hole in the knuckle plug so that it could breath.