Adjust the kickdown cable on the automatic transmission to ensure proper downshift points and transmission performance.

Warnings

Tools required

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine and transmission to cool completely if recently operated
3. Ensure transmission is filled to proper level with Dexron III ATF
4. Verify carburetor throttle linkage operates smoothly through full range without binding

Procedure

1. 1

   Locate the kickdown cable
   Open the hood and locate the throttle valve (TV)/detent linkage at the carburetor — note the 1966 Powerglide may use a mechanical rod linkage and electrical detent switch rather than a cable. The cable runs from the transmission up to the carburetor linkage on the driver's side of the engine. The cable housing attaches to a bracket near the carburetor, and the inner cable connects to the throttle linkage.
2. 2

   Inspect cable condition
   Examine the kickdown cable for fraying, kinks, or damage. Check that the cable housing is securely mounted in its bracket and that the cable moves freely without binding. If the cable is damaged or binds, replacement is required before adjustment.
3. 3

   Release cable adjustment lock
   At the carburetor end, locate the throttle valve (TV) detent linkage adjustment; note that the 1966 Powerglide may use a mechanical TV rod linkage rather than an adjustable cable — verify actual configuration before proceeding. The 1966 Corvette uses the 2-speed Powerglide automatic, whose detent (kickdown) system uses a slotted bracket or adjuster with a lock tab. Loosen the lock mechanism (typically a small bolt or squeeze-tab) that holds the cable housing in position within the bracket. This allows the cable housing to slide for adjustment.
4. 4

   Set throttle to closed position
   Ensure the carburetor throttle is completely closed (idle position). Verify the throttle return spring has pulled the throttle lever to its full closed stop. Do not touch the accelerator pedal during this step.
5. 5

   Adjust cable slack at idle
   With the throttle at idle, pull gently on the kickdown cable housing away from the carburetor (toward the firewall) to remove all slack from the inner cable. The cable should be just barely snug with no visible slack, but not pulling on the throttle linkage. This ensures the cable will begin actuating the transmission valve body immediately when throttle opens.
6. 6

   Lock cable adjustment
   While maintaining the correct cable position from Step 5, tighten the cable housing lock mechanism. Ensure the housing does not shift during tightening. The adjustment bolt or lock tab should be secure but not over-torqued to avoid crushing the cable housing.
7. 7

   Verify full throttle cable travel
   Have an assistant slowly depress the accelerator pedal to wide-open throttle while you observe the kickdown cable at the carburetor. The cable should pull smoothly through its full range of travel. At wide-open throttle, verify the cable has moved approximately 1.5 inches from the idle position and that the carburetor throttle reaches its full open stop. The cable should not bind or prevent the throttle from opening completely.
8. 8

   Check throttle return
   Release the accelerator pedal and verify the throttle returns fully to idle and the kickdown cable relaxes to its adjusted position without binding. The throttle should snap closed crisply with the return spring.
9. 9

   Perform road test
   Start the engine and take the vehicle for a test drive. Accelerate moderately from a stop and verify the 2-speed Powerglide shifts smoothly from Low to High at the appropriate speed (typically around 15-25 mph at part throttle). Test a full-throttle kickdown by accelerating at about 40 mph in high gear, then flooring the accelerator. The transmission should downshift immediately. If shifts are too early, too late, or kickdown does not occur, readjust the cable.

Reassembly

1. No disassembly required for this procedure

Verification

• Verify smooth 1-2 and 2-3 upshifts at normal throttle positions
• Confirm immediate downshift occurs when accelerator is floored at highway speeds
• Check that transmission does not slip or delay during shifts
• Ensure no binding or interference in throttle linkage operation

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