Fordomatic to C4 Conversion

[55blacktie]

If anyone has replaced their Fordomatic with a C4 transmission, which year C4 did you use?

Happy New Year!

[Allans]

My 57 came with a c4. The engine is a 302 out of a 78 fairlane. I think the c4 came with it

[Al Hodge]

I did mine. Pretty much any C4 will work. You can get everything you need from Flat O Products.

[55blacktie]

I could not locate a C4 core in my area, and I did not want to buy a "rebuilt" transmission from CL/ebay. After reading How to Rebuild and Modify Ford C4 and C6 Transmissions, I bought a C5 core that came out of a 1985 Tbird/w V6. The C5 has 2 more clutch plates than the C4, better fluid circuitry, including 1/4 NPT vs 1/8 NPT cooler line fittings, and 26-spline output shaft, like found on 70-up C4s. However, the C5 lockup converter, bell housing, and valve body have to be replaced by C4 components. The Flat-O Products conversion kit includes a replacement bell housing. The C5 pan also holds an additional quart of fluid.

Depending on what engine performance upgrades you might have, you might want to consider replacing the transmission governor with a Dynamic Racing Transmission C4 governor secondary weight kit, which will raise the WOT upshift RPM. Three weights are included, ranging from 5600-6000. The 1966 HP289 C4 transmission came from the factory with a 6000 rpm governor. Dynamic can also supply a custom governor secondary weight, if you are seeking a different WOT RPM upshift. Automatic downshifts, which are controlled by the governor's primary weights/valves, will not change.

Of course, you may have the option of manually upshifting to a desired rpm, keeping in mind that using the OEM Tbird shifter, without modification, will not allow you to manually shift through all 3 forward gears.

[55blacktie]

If you converted your 55 to C4, which speedometer cable did you use? I know a 57 cable will fit a C4/C5 transmission (they use the same style gear), but I just learned that the 55 cable, unlike the 57 cable, uses a retaining clip at the speedometer. I prefer not to use the angle drive at the transmission.

[paul2748]

I used an angle drive at the trans when I put in my C4. Saved clearance problems and bending the cable too much. The angle drive had a end like the end of the speedo, had a custom cable made. Even with the smaller C4, there still isn't a lot of room under there.

[55blacktie]

Paul, did you attach the cable to the transmission before installing the transmission?

[paul2748]

NO, I installed the cable after the trans was in the car. But what I should have done, is install the angle drive before installing the engine/trans in the car. It fit, but wasn't real easy.. As I said, still tight even with the C-4

Paul, did you attach the cable to the transmission before installing the transmission?