Re: "new" '57 evinrude 7.5 hp pics, etc.
When a clutch dog wears and "rounds off," it may or may not do the same to the matching surface on the affected gear - which is usually the forward gear. Merely replacing a clutch dog when this is the case is a temporary fix at best, because the worn, rounded off gear surface will eventually damage the new dog.
By sending the gear to a machine shop, or someone with the proper equipment and knowledge, the worn area can be cut with a drill bit. What is done is to lay the gear on its back, with the "teeth" facing upwards. This exposes the tabs (matching surface for the dog's tab) on the inside portion of the gear, to a drill bit placed in a drill press. The gear has to be held firmly in place so that the rounded off portion on the tab can be cut out. Essentially what is done is to cut half of a shallow hole in the edge of the tab. As you might imagine, the drill bit wants to wander off of the desired drilling point because it is only cutting into material on one side - this makes things a bit tricky and that is why the job needs to be done by someone with the necessary tools and skill.
As far as I know, this is pretty much a one time deal. I'm not going to say that it can never be done twice but, if so, I've never heard of anyone doing so. None-the-less, it can save a lot of money in repair costs, because new gear sets for these old motors are prohibitively expensive .... if you can even find one. The alternative is, of course, to find a decent used set and that is often a tall order too.
If you need to get this done to your motor, just ask your local OMC/BRP dealer who they send their jobs to - there will probably be someone near you.
