really confused

2confused

Recruit
Joined
Apr 22, 2019
Messages
2
I have an 1986 mercury 35 hp 2 stroke with shift control not tiller.
I changed all the gears on the lower unit. when I put into forward gear and turn by hand it clicks clockwise, when I turn on the motor it still turn clockwise but locks ccw.
in reverse motor on it turns ccw,
is this correct?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
I like to help people figure things out for themselves as it helps them with these simple physics problems down the road. 1) keep in mind a prop will ratchet in one direction and lock in the other. 2) Look at the prop blades. It should be obvious which way the prop must turn in order to PUSH water. 3) With what you just described, what the engine does vs what you do by manually turning the prop should allow you to answer your own question. Remember, the engine turns the prop which is offering resistance because it pushes water. You are manually turning the prop but not the engine so ratcheting occurs. Now then, is your engine operating properly or not.
 

The Force power

Commander
Joined
Feb 3, 2019
Messages
2,359
In addition to what Silvertip already explained (beautifully) the reason it clicks/ratchet when turning the Prop-shaft clockwise in forward is;
to prevent the motor to be "push-started" when in forward gear for example the boat is still in forward motion motor off, if it did not ratchet it could turn the motor over and start the motor and other safety reasons
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,520
^^^ ???. The ratcheting is a normal function of the dog clutch's design. Gear case FWD and REV gears are always meshed with the drive pinion, and spinning when the engine is running. The prop shaft has a sliding dog clutch barrel splined to it. When the operator shifts into gear the dog clutch's teeth are forced into that gear's mating teeth and the prop shaft spins. The clutch teeth on the gear and clutch have a negative rake on their contact surfaces that 'sucks' them together and locks them under engine torque.

The shift spool which slides the clutch holds the clutch in place with a spring load. When you spin a prop that's in gear it locks against the clutch in one direction, but in the other direction the teeth climb up the tooth's back taper and snap back into the next teeth from the spring load.

Safety isn't a design consideration. VP and Merc Bravo stern drives use cone clutches. No ratcheting or free wheeling.
 

2confused

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Joined
Apr 22, 2019
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2
thanks Harringtondav , your explanation was very clear. I was going to pull the lower unit off again and after reading your answer I think it`s all good. silvertip also want to thank you for the physic lesson I now grasp the way the lower unit works.
keep in mind this was my first time to overhaul the gear case. so I'm a complete novice was afraid to do it a first.
thanks all for helping me out.
 
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