Cutlass Bearing Replacement
Version 1.0 – October 15, 2007
By: Bill Wildner
The cutlass bearing should be replaced from time to time. When and if you decide to do this in simple terms this is the procedure:
- Remove the rudder
- Remove the prop shaft
- Remove the old cutlass bearing
- Install new bearing
- Install prop shaft
- Install Rudder
The cutlass bearing is a stock part or available from most marine supply stores, I bought my last one from West Marine. I took my old one once removed to them and they matched the size from there catalog.
- Remove the Rudder
If you need help with this see the Rudder bearing replacement article will provide details of removing the rudder. If your lower bearing is loose you may want to replace it while you have the rudder out.
- Removing the prop shaft
To accomplish this you will need to separate the coupling from the shaft at the back of the transmission. Most shafts will not just pull out after loosening the 2 lock screw but it is worth a try. If it comes out consider your self lucky, if not I think this is the easiest way to remove the coupling from the shaft. Take the 4 bolts holding the shaft coupling to the transmission coupling. Slide the shaft back to open a gap between the 2 coupling halves. Place a socket or similar object between the end of the trans shaft and the prop shaft that is smaller diameter than the prop shaft. This socket will be used to push the shaft out of the coupling as you use the coupling bolts to draw the coupling halves back together. You will most likely need to do this twice, once with a short socket and again with one a bit longer. This is a tedious process in a confined space yet will get the job done. Once you have the coupling separated remove the key from the shaft and the shaft should slide out the back of the boat.
- Remove the cutlass Bearing
The Cutlass bearing is held in by set screws in the side of the strut, remove these screws. Try to press the bearing out of the strut. If you are lucky it will come out, if not do not despair. What to do is cut the bearing to release it from its press fit. Just get a fine tooth hacksaw blade, a - 1 - - 2 - new blade will help with this job. Assemble the hacksaw with the blade running through the inside of the bearing. Carefully cut the bearing with the saw. The object is to make one fine even cut along the length of the bearing. This will release the bearing and it will nearly fall out.
- Install new bearing
Before installing the new bearing de-burr the inside diameter of the strut so as not to cause problems when the new bearing is pressed in. The new bearing can be pressed in with a variety of methods. One way is to use a treaded rod long enough to go through the strut and the bearing with nuts and washers on both ends. Tighten the nuts to draw the bearing into the strut. Also a large C-clamp can be used but is a bit difficult to get the proper alignment. It can also be tapped in with a hammer of it is not a real tight fit. Just make sure not to deform the end of the bearing with a hammer. The most important part and what can cause this process to go bad is one of the following: Burrs or dents on the strut, or misalignment of the bearing, either one will cause the bearing to bind and deform if forced causing the prop shaft to be tight once installed, Once the bearing is in place you may need to trim or file the ends to clean them up. Tighten the lock screws very gently as this can also deform the bearing, I recommend some Loctite or epoxy on the set screws so they do not come loose.
- Reinstall the propeller shaft
Before reinstalling the prop shaft consider replacing the shaft packing or installing one of the drip-less seals. Inspect the shaft for excessive wear at the packing area. Also get the coupling and clean up the inside of it and the end of the shaft and check that they fit snug also inspect the key and replace if it has much wear. Once all of these items are confirmed to be ready reinstall the prop shaft. You may need to tap it into the coupling, have a friend do this from outside the boat as you watch for when the shaft is in the coupling as far as needed to line up the set screw hole with the accompanying depression in the shaft. Bolt it all up and safety wire the lock screws. Check that the shaft turns free. The new bearing may impart light friction on the shaft, this will free up after a few hours of use.
- Reinstall the rudder
Refer to the Lower rudder bearing replacement article for detailed instructions in replacing the rudder.