Wednesday, May 18, 2011

Cutlass Bearing Installation

     Before beginning installation of the cutlass bearings into the strut, you should check the strut alignment. Ideally, the strut bore and shaft log should be parallel and coaxial. I my case, I used a 2 inch diameter shaft that was sanded down slightly in a lathe, and I carefully slid the shaft through the strut until it slid into the shaft log. Since the shaft passed into the shaft log "dead center", I was comfortable proceeding with the cutlass bearing installation.
     As an alternative, you could use a suitable straightedge, held tightly against the strut bore in several locations, to verify the strut alignment. If the strut is not well aligned, you would have to dismount the strut, and shim accordingly until the alignment was correct, then secure in position (with the proper sealant, of course). Since mine are both well aligned (Sea Ray uses a laser alignment system at the factory, so it should be correct unless the strut came in contact with something harder than water!), I am not going to enter into a lengthy discussion of the multiple ways a strut alignment can be corrected. There are many resources available for this information, and I would be happy to answer any specific questions in this regard, if necessary.
     So, on to the cutlass bearings. First, the strut needs to be prepared for the new bearing. I posted previously about removing the cutlass bearing, so I will pick up at that point. I first removed the 2 set screws, and re-tapped the threads. Then, I ran a cylinder hone, chucked in a 3/8" drill, through the bore, to remove accumulated deposits, and also to smooth the bore. The honed strut looked like this:

     Note that you are not trying to change the diameter of the bore with the hone - just clean it. The cutlass bearing is an interference fit with the bore, and this fit should not be altered.
     The next step is to fashion a tool for installing the bearing. I made it from a length of 5/8" fine threaded rod, with 2 large bearing washers and a nut at one end, and a machined fitting at the other end. The fitting is stepped, such that the smaller diameter is about 0.010" smaller than the cutlass bearing inside diameter, and the larger step is about 0.020" smaller than the strut bore, so the tool cannot get stuck inside the strut during installation. It looks like this:

     Out under the boat, I lightly greased the inside of the strut, and mounted the cutlass bearing / tool in position:

     It is important to start the bearing in straight, so proceed slowly, and make sure it is going in correctly as you tighten the nut. Continue tightening until the bearing is centered in the strut...


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