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Sheer pin

L

lemorgan

New member
Were is the sheer pin located on a Mariner 60 Horse power 2 cycle. My engine spun something. it raves the engine when in gear and doesn't move. if you run it at a Idel it will move the boat barley. it got me to the boat ramp barley. Can anyone help with this.
 
Doesnt have a shear pin...uses rubber hub in prop for protection. Could be a gear issue or spun prop hub. Check lower gear oil for metal and if OK replace prop.
 
Just a bit of history. Back when I was a teen, OMC (Johnny-Rude and others builder) they used a rubber hub to connect the drive line to the engine proper but the method of connecting this rubber hub to that drive line was a "Shear Pin" (classified in the parts book as a "drive" pin.....as I recall).

Mercury on the other hand used a splined hub locked to the prop shaft with the rubber slip clutch. First of all the rubber hub was a convenient way to connect the prop shaft to the propeller proper.....just a press fit and your done. What the Mercury did for you that the OMC didn't (for me anyway as I started out as an OMC fan) was when you were fishing Rip Rap on the windward side ) where you usually found the fish feeding, if you accidentally got too close to it the prop would contact and the pin would shear before the hub would slip. Not what you want happening!!!!!!!!

My dad't 10 HP Scott-Atwater had a rubber insert on the tiller handle and in it were 2 shear pins, and 2 cotter pins (which pinned the hub to the prop shaft).........tell you anything? Pretty thoughtful if you ask me.

With Mercury, the impact would disconnect the hub from the prop, you would cut the throttle, shift into N, allowing the hub to reattach, shift back into gear and be on your way.......no banging your boat up on the rocks with that design.





c
 
Fact----Shear pins are a great concept.-----BUT----When motors got bigger in the early 1950's it was impossible to put / pull motor into the boat to change the pin.-----So Carl promoted ----" SHEARPROOF DRIVE "-----And forgot to tell the people that replacing props was more expensive than a pin.------If you are familiar with MARTIN outboards , you would know of a unique feature.-----You tilted motor all the way up.----Operated a pin and the motor could be turned so that powerhead was over the water.-----Prop was over the seat in the boat.-----Easy to change the pin and no chance of dropping parts / tools in the water.
 
racerone said:
Fact----Shear pins are a great concept.-----BUT----When motors got bigger in the early 1950's it was impossible to put / pull motor into the boat to change the pin.-----So Carl promoted ----" SHEARPROOF DRIVE "-----And forgot to tell the people that replacing props was more expensive than a pin.------If you are familiar with MARTIN outboards , you would know of a unique feature.-----You tilted motor all the way up.----Operated a pin and the motor could be turned so that powerhead was over the water.-----Prop was over the seat in the boat.-----Easy to change the pin and no chance of dropping parts / tools in the water.
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I know of Martin but didn't know of the convenience. In the White River around Carendon, Arkansas there were numerous Martins up to 7 1/2 as I recall back in the '50's. They were tough little engines on 14' John boats and never saw one down for any kind of repair and ran one at a good clip especially for a 7 1/2.

On his idea, when you are being blown onto the Rip Rap, you don't have time to exercise his clever design....at least I never did, course I never had one.

My later to be father in law had a 14' woodie runabout with a '56-57 (somewhere around there) 35 Rude and he had a pin on his drive line. His eldest son seemed to enjoy replacing it....his bad habits causing the problem.
 
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