Being a truck mechanic i come across alot of applications that use shear pins/shear bolts. It is very important that when replacing shear pins or bolts that the same hardness of material is used as oem. The shear pin is designed to break at a pre determined force if the prop hits a object under water or hits bottom. The shear pin breaking obsorbs most of the initial shock load as well as prevents further shock loading before the lower drive gears are damaged. A tip I do on my 9.5 motor do to the conditions I run it in (rocky shallow bottom and dark coloured water that obscures obsticles) is duct tape a spare shearpin and cotter pin to the top case or under the top engine cover. You hope you never need it but its there so you don't get stranded.
The 40 does NOT use a shear pin. It uses a DRIVE pin, which is not intended to shear. A rubber hub in the propeller takes care of the impacts. The DRIVE pin is made of stainless steel. If you use brass, you will give up the benefits of the non-shearing pin and will be constantly replacing it. No fun doing that on the water.
thanks to all for the info on the shear pins.i assumed the pin was a shear pin,i did not know they had slip hubs for older motors.it is a 1971 model.so all i need to do is cut me a steel pin to to replace the old one?
To the best of my knowledge and belief, you will not find the term "shear pin" in any OMC two-stroke parts manual at least between 1965 and 1980; They are all called drive pins.
I don't believe for a second that they are not shear pins because they are called drive pins. The ones on my small engines from the sixties and seventies have sheared many times and they are always OEM parts listed as drive pins.
My personal opinion is that there is no justification for not using the OEM pin, and many good reasons in favor of doing so.
Shear/drive pins are cheap. Buy several and then you'll never have this issue But if it was me, I would have no problem putting in a pin that I knew was softer than the original if I had to. But again, I have an OMC dealer nearby and would always get the OEM part due to being cheap and easy.
Yes, if you really clobber something hard, it is possible to shear the drive pin. All OMC motors with gearshifts since the 1950's have had rubber protection in the props. Most of them you can't see, but they are in there. For every person doubting the rubber hub's existence, there is one wondering why their hub is slipping.
Then select the parts link in the upper right hand corner, then navigate to your specific motor, then to the gearcase diagram and click on the part's diagram number.
But if it was me, I would have no problem putting in a pin that I knew was softer than the original if I had to. But again, I have an OMC dealer nearby and would always get the OEM part due to being cheap and easy.
