Transmission Kickdown Cable Adjustment

Adjust the mechanical kickdown cable connecting the accelerator linkage to the automatic transmission valve body to ensure proper downshift engagement during full-throttle acceleration.

Warnings

Tools required

Parts

• Kickdown cable (if damaged or frayed) × 1 — Mercedes-Benz 111-270-02-04 or equivalent

Preparation

1. Park vehicle on level ground and apply parking brake
2. Start engine and allow to reach full operating temperature (approximately 80°C/176°F on coolant temperature gauge)
3. Turn off engine
4. Ensure throttle linkage operates smoothly without binding from idle to wide-open throttle
5. Open hood and locate kickdown cable running from injection pump linkage to transmission bellhousing area

Procedure

1. 1

   Locate kickdown cable adjustment point
   Trace the kickdown cable from the throttle linkage on the Bosch mechanical injection pump (located on right side of engine) down to the transmission. The cable runs along the right side of the engine block and enters the transmission bellhousing. The adjustment mechanism is located at the transmission end, typically accessible from above near the bellhousing. It consists of a threaded barrel adjuster with locknut.
2. 2

   Inspect cable condition
   Examine the entire length of the kickdown cable for fraying, kinks, corrosion, or damage. Check that the cable outer sheath is intact and properly secured in its mounting brackets. Verify the cable moves freely when the throttle linkage is operated by hand. If cable is damaged, replacement is required before adjustment.
   ⚠A frayed or binding cable cannot be properly adjusted and must be replaced to prevent transmission damage.
3. 3

   Loosen cable adjustment locknut
   Using a 10mm open-end wrench, loosen the locknut on the threaded cable barrel at the transmission end. Do not remove the locknut completely; just loosen it enough to allow the barrel adjuster to rotate freely. The locknut is typically located on the cable mounting bracket near where the cable enters the transmission.
4. 4

   Set throttle to idle position
   Have an assistant in the driver's seat, or manually position the accelerator pedal to full rest (idle) position. Verify at the injection pump that the throttle lever is resting against the idle stop screw. The kickdown cable should have slight slack at this position—approximately 1-2mm of free play when depressed by hand.
5. 5

   Adjust cable tension at idle
   With throttle at idle, adjust the threaded barrel on the kickdown cable so there is 1-2mm of free play in the cable. Turn the barrel clockwise to increase slack, counterclockwise to tighten. The cable should not be under tension at idle, but should have minimal slack. Use a 13mm wrench on the barrel adjuster if hand pressure is insufficient.
6. 6

   Verify full-throttle cable travel
   Have assistant depress accelerator pedal fully to the floor (or manually move throttle linkage to wide-open position). At full throttle, the kickdown cable must pull completely tight and activate the detent mechanism in the transmission valve body. You should feel definite resistance at the end of cable travel. The throttle lever on the injection pump should reach its full-open stop simultaneously with the cable becoming fully taut.
7. 7

   Fine-tune adjustment
   If cable becomes tight before throttle reaches full-open position, loosen adjustment by turning barrel clockwise. If throttle reaches full-open but cable still has slack, tighten by turning barrel counterclockwise. The goal is for the cable to reach full extension precisely when throttle is fully open. Repeat testing and adjustment until correct relationship is achieved.
8. 8

   Lock adjustment in place
   Once proper adjustment is achieved, hold the barrel adjuster firmly in position and tighten the locknut with the 10mm wrench. Ensure the barrel does not rotate while tightening the locknut. Verify cable free play at idle is still 1-2mm after locknut is tightened.

Reassembly

1. Verify all cable mounting brackets are secure along cable routing path
2. Ensure cable does not contact exhaust manifold or other hot components
3. Check that cable does not interfere with other engine components throughout throttle range

Verification

• Start engine and verify smooth idle with no cable binding or tension
• With engine at operating temperature, perform test drive
• Accelerate gently at part throttle—transmission should upshift normally through all gears
• From 30-40 mph in 3rd gear, depress accelerator pedal fully to floor (kickdown position)—transmission should immediately downshift to 2nd gear
• From 50-60 mph in 4th gear, apply full throttle—transmission should downshift to 3rd gear
• If downshifts do not occur or are delayed, cable requires additional tightening
• If transmission downshifts too easily or hunting occurs between gears, cable may be too tight
• Verify normal upshift and downshift patterns under various driving conditions before considering adjustment complete

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