Transmission Kickdown Cable Adjustment

Adjusts the kickdown cable on the automatic transmission to ensure proper shift timing and transmission longevity by setting the correct cable tension and throttle linkage relationship.

Warnings

Tools required

Parts

• Kickdown cable (if damaged or frayed) × 1 — C2AZ-7E395-A or equivalent

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine to cool to warm or cold temperature if recently operated
3. Ensure transmission is filled to proper level with Type F ATF
4. Verify throttle linkage operates smoothly with no binding from idle to wide-open throttle

Procedure

1. 1

   Locate the kickdown cable and adjustment mechanism
   Open the hood and locate the kickdown (downshift) rod linkage connecting the carburetor throttle lever to the downshift lever on the transmission. On the C4 transmission the downshift lever is on the left (driver's) side of the case; on the FMX the linkage connects to the throttle/kickdown lever. Identify the adjustable rod between the carburetor throttle lever and the transmission downshift lever. Verified detail (1972 Ford F-100 with automatic transmission typically used a throttle valve rod linkage system, not a cable. C4 and FMX transmissions of this era used mechanical rod linkage for kickdown/downshift control, not cables. Cable-operated TV systems came later.): locate the throttle valve (TV) downshift rod linkage running from the carburetor throttle linkage to the left side of the transmission. The linkage consists of metal rods and bellcranks along the driver's side of the engine.
2. 2

   Inspect cable condition
   Visually inspect the entire downshift rod linkage for bent rods, worn bellcrank pivots, loose rod ends, or damaged bushings. Check that the linkage moves freely without binding by manually operating the throttle linkage. Check that the cable moves freely within the housing by manually operating the throttle linkage. If the cable is damaged, binding, or corroded, it must be replaced before adjustment. Check the rubber grommet where the cable passes through the firewall or bellhousing for damage.
3. 3

   Set carburetor to curb idle position
   With the engine off, ensure the carburetor throttle is fully closed at curb idle position. The throttle lever should rest against the idle speed screw with no tension on the throttle return springs. Do not touch the idle speed screw during this procedure.
4. 4

   Locate the cable adjustment sleeve
   At the carburetor end of the downshift linkage, locate the threaded adjustable rod/trunnion where the rod connects to the throttle lever. This adjustable rod sets the downshift lever position. Loosen its jam nut or trunnion clamp before adjustment. Verified detail (Rod linkage uses a different adjustment method, typically at the bellcrank or with an adjustable rod end, not a cable sleeve/ferrule adjuster.): At the transmission end of the downshift linkage, locate the adjustment point. This is typically at the slotted connection point where the rod attaches to the downshift lever on the transmission, or at an adjustable rod end with a threaded section and jam nuts.
5. 5

   Release the adjustment lock
   Loosen the jam nut or trunnion clamp on the threaded downshift rod at the carburetor throttle lever so the rod length can be changed. Verified detail (Rod linkage adjustment involves loosening jam nuts or clevis pins, not cable housing manipulation.): Loosen the jam nut on the adjustable rod end or remove the clevis pin securing the rod to the transmission downshift lever to allow adjustment.
6. 6

   Position the transmission kickdown lever
   At the transmission, manually push the kickdown lever fully forward (toward the front of the vehicle) against its internal stop. This is the full kickdown position. The lever should move approximately 1.5 inches of travel and stop firmly. Hold the lever in this position or have an assistant hold it.
7. 7

   Adjust cable tension at idle
   With the carburetor at curb idle, adjust the threaded downshift rod length so that when the throttle is moved to wide-open, the transmission downshift lever simultaneously reaches its full-travel (kickdown detent) position. Adjust per the Ford shop manual specification for this transmission rather than a fixed freeplay figure. This slight freeplay ensures the cable is not holding the transmission valve body in a partial kickdown position at idle. The cable should be snug but not tight.
8. 8

   Lock the adjustment
   Once the proper linkage relationship is achieved, tighten the jam nut or trunnion clamp on the downshift rod to lock the adjustment. Ensure the lock is fully seated to prevent the adjustment from changing during operation. Verified detail (Should reference securing rod linkage adjustment, not cable components.): Once the proper adjustment is achieved, tighten the jam nut on the adjustable rod end or reinstall the clevis pin to secure the linkage connection.
9. 9

   Verify full throttle operation
   Manually move the carburetor throttle linkage to the wide-open throttle position. Verify that the transmission downshift lever moves to its full rearward travel (toward the rear of the vehicle) and that the rod linkage does not bind or contact any obstructions. The kickdown lever should reach its full travel just as the throttle reaches wide-open position. If the lever reaches full travel before the throttle opens fully, the cable is too tight.
10. 10

    Check for binding throughout range
    Slowly move the throttle from idle to wide-open and back several times while observing the downshift rod linkage and lever. The cable should move smoothly without binding, and the transmission lever should return fully forward to the idle position each time with the assistance of its return spring. Listen for any scraping or rubbing sounds.

Reassembly

1. No disassembly was required for this procedure

Verification

• Start the engine and allow it to reach normal idle speed. The transmission should remain in gear without slipping or hunting
• With the engine at operating temperature, perform a test drive on a safe road. Accelerate gently from a stop and verify smooth 1-2 and 2-3 upshifts occur at approximately 10-15 mph and 20-25 mph respectively
• Perform a moderate to heavy acceleration from a stop. The transmission should hold each gear longer (kickdown function working) and upshift at approximately 25-35 mph and 45-55 mph
• At 45-50 mph in third gear, quickly press the accelerator to the floor (forced kickdown). The transmission should immediately downshift to second gear if the cable is properly adjusted
• If shifts are harsh, occur too late, or forced kickdown does not occur, readjust the cable by adding slight tension (shortening cable length at adjuster)

More procedures for this vehicle