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Help with installing and adjusting the stern drive shift cable

  • Step by step instructions on how to adjust the shift cable
  • How to modify the bell housing to install the new style cable
  • Mercruiser/MR/Alpha 1 shift cable kits OEM 865436A03
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21450 shift cables OEM 865436A03
21450 shift cables OEM 865436A03


By author Trish Dougherty

Installing the New Style Cable

After years of use, the shift cable tends to stretch out over time. Shifting problems can sometimes be fixed by simply adjusting the cable. However, if the cable is stretched out more than an adjustment can fix - you'll need to replace the cable. The newer style cable has a larger core wire, and installs from the aft end of the bell housing. Since you'll be working in the bell housing area of the drive, you may also want to replace the bellows as well if they have never been changed or if you're taking in water. You can view it here.


Boats made from 1966 - 1983 with MC-1 or R/MR model Mercruiser sterndrives, had the shift cable installed from behind (boat side) of the bell housing. If you have this setup, you'll need to modify the bell housing by using a 1/4-20 NC tap with a # 7 or 13/64" drill bit - or a 1/4-28 NFC tap to create new threads in the aft end of the bell housing. The existing threads already go through the housing - use this tap from the other side of the housing.


Make sure to use some lubricant when driving in the tap from the opposite side. The fitting on the end of the cable will almost touch the bottom of the bell housing when fully tightened.

How To Adjust the Cable


First, examine the condition of the connections on the shift cable. If there is any corrosion on the connections, make sure to clean it with a wire brush. You can access the cable by removing the cover of the engine, and looking for the shift control which is located on the shift plate towards the back left side of the engine. Loosen the nut on the bolt that is located on the left side of the shift plate. Make sure to push the bolt down when re-tightening the bolt if it was not in the lowest position.


Manually turn the propeller counterclockwise with your hands, while someone else slowly pushes the shift control into the forward position all the way. The prop shaft should stop as soon as forward gear has engaged. Remove any slack in the cable by pulling on the cover that goes over the shift cable on the side near the shift lever bolt. Look for the brass cylinder and pin, and remove them. Turn the cylinder to remove any extra cable. The hole where the pin was should be lined up with the end of the cable when it is adjust correctly.


Turn the brass cylinder away from the plastic guide a few turns after you have aligned the pin hole and the end of the cable. Return the cylinder and end of the cable into where they were on the shift plate. Install the pin and nuts. Manually turn the propeller clockwise this time, while someone else pulls the shift lever in the full reverse position. The shaft should lock out once reverse gear is engaged.


If the drive did not engage into reverse, loosen the shift lever bolt located on the rear left side of the engine that you loosened and tightened earlier. This time instead of pushing the bolt down, push it up a little and re-tighten the nut. Check to see if you can engage the drive into reverse (step 3 by turning propeller clockwise while someone pulls the shift lever into reverse). If it doesn't engage into reverse, keep adjusting the position of the stud in the shift plate until it does. Make sure to double check all the connections before closing up the engine cover. *Note - if you can't get the drive to engage into gear after you make several attempts at adjusting it, the cable has stretched out more than an adjustment can fix. You will need to replace this cable a new one (P/N 21450 OEM 865436A03).

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