TransGo reprogramming kit for 1967-69 Ford C4 valve bodies that raises line pressure and firms up the shifts for manual-shift or street use.
If you are building an early Mustang, Fairlane, Falcon or Cougar for the strip or for hard street use and want the 1967-1969 Ford C4 to hold every gear until you move the lever, this is the kit TransGo sells for it. The 47-3 is a valve body reprogramming kit, not a mild firm-up kit. Installed in its manual setup, the transmission makes no automatic upshifts or downshifts at all: it stays in the gear you select and changes only when you move the selector. That removes the long, slipping factory shifts that cook the intermediate band and high clutch behind a stronger engine.
The C4 is a three-speed Simpson gearset unit with an intermediate band for second, a low-reverse band, and forward and high clutches. TransGo lists the gear ratios on the first page of the instructions as 2.46 first, 1.46 second and 1.00 third. In stock form the valve body decides when to shift from vacuum modulator and throttle signals, and the 1-2 and 2-3 changes are deliberately soft.
The 47-3 changes that in two places. On the channel casting it adds a new 1/4 in check ball, spring and orifice control plug, and uses a manual separator gasket with extra holes, with one separator plate hole opened to .110 in with the supplied drill. On the main body it replaces the 1-2 and 2-3 shift springs with manual-use springs, adds a channel plate under the side plate, and fits new pressure regulator springs, a new cutback spring and a new downshift spring. The result is firm, quick band and clutch apply with the shift points under the driver's control.
The kit can be converted back to automatic shifting. TransGo supplies an automatic gasket plus blue 1-2 and red 2-3 springs for that, and page 5 of the instructions lists the steps.
A reprogramming kit will not restore pressure lost to worn parts. Hook a gauge to the line pressure tap and compare readings with the TransGo spec of 55-65 psi in Drive at idle and 150-185 psi at wide open throttle, then 60-110 psi in Reverse at idle and 240-270 psi at wide open throttle. Low numbers point to the pump, sealing rings or a leaking modulator. Our line pressure checking guide walks through the gauge hookup, and Shift Flare vs Slip helps you tell a hydraulic flare from a band or clutch that is already worn out. Dark, burnt-smelling fluid means the transmission needs a rebuild along with the kit.
This kit is for 1967-1969 Ford C4 transmissions only. TransGo lists the valve body casting numbers it fits as C7AP through C9AP, so read the casting number on your valve body before ordering. The C4 valve body was redesigned for 1970, and those later units take the TransGo 40-2 kit for 1970-1981 C4s instead. Swapped and rebuilt transmissions are common in these cars, so go by the casting and not the car's model year. If you are not sure what you have, send us the casting number. Browse our other rebuild kits for supporting parts.
Refill with Type F fluid, such as Valvoline Type F ATF, and seal the case with a C4 external reseal kit while it is apart. A manual valve body is best run with a ratchet shifter so each gear has a positive gate.
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Not in its manual setup. TransGo describes it as manual control only, with no automatic shifts. The transmission stays in the gear you select. The kit includes the gasket and springs to convert it back to automatic shifting, following page 5 of the instructions.
No. It fits 1967-1969 C4 valve bodies with casting numbers C7AP through C9AP. The valve body changed for 1970, and those transmissions use the TransGo 40-2 kit. Check the casting number on the valve body, not the car's year.
Yes. TransGo says the C4 must have a vacuum modulator connected to manifold vacuum, even with low-vacuum engines. Without vacuum the transmission runs full-time high line pressure, which wears the pump and sealing rings.
TransGo's spec is 55-65 psi in Drive at idle and 150-185 psi at wide open throttle, and 60-110 psi in Reverse at idle and 240-270 psi at wide open throttle, read at the line pressure tap.
Snug the intermediate band and back it off 1 1/4 turns, and snug the rear band and back it off 3 turns. If you feel a brief bind-up on the 1-2 shift, TransGo says to back the rear band off one more turn.
These early C4 transmissions were built for Ford Type F fluid. Refill with Type F, not a modern MERCON V or LV fluid.
