worn driveshaft splines?

[crash Jason]

My father in law just got a 1972 20 hp Johnson. motor seemed to run great till he got it in the water then it seemed like it was jumping out of gear. I figured the clutch dog was worn but it looks good. turns out the top splines of the drive shaft are worn and slipping. Does anyone have any ideas on what would cause this? I would hate to replace the drive shaft only to have the same thing happen again.

 

[Joe Reeves]

Re: worn driveshaft splines?

The majority of driveshafts have a groove just beneath the top driveshaft splines. This is where a O Ring is to be installed. Some people neglect to install that O Ring with the result being that water has access to both the driveshaft and crankshaft splines....... RUST!

Also, those splines must be greased thoroughly in addition to having that O Ring installed. Both of these operations are a must. To neglect either results in the problem you have.

Before spending $$$ for a driveshaft, remove the powerhead so that you can inspect the crankshaft splines. If they are also worn, replacing the driveshaft alone would be a waste of time and money.