1962 Lark IV popping out of gear

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chrismorlan

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New to me 40hp running on a vintage 14 ft wood runabout. Came with underpitched prop (11) that was in rough shape and then spun its hub. Replaced prop with higher (14) pitch and boat performs great. Latest issue is motor popping briefly out and then back into gear. Rpm independent. Shift cable is fine so I am sure the issue is somewhere in the lower unit. Will try to open case tonight but what shall I look for inside?
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

Worn fwd gear and clutch dog very likely.
 
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194269

Petty Officer 2nd Class
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Jul 9, 2011
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Re: 1962 Lark IV popping out of gear

You didn't say where the lark is a electric shift or mech. shift. If electric you might have a weak spring or an electrical problem, which would cause an interuption in power to the forward magnet. Thus making it to jump in and out of gear.
 
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krazebill

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Re: 1962 Lark IV popping out of gear

I do not believe the '62 Lark IV offered the selectric shift. Often times it is the clutch dog that is worn. You should replace it sooner than later as it will ruin the forward gear. Some say to turn the clutch dog around so what was forward facing is now rear facing but that only moves the problem to the reverse gear. Be careful dismantling the gear case-there is a phillips head screw different from the others that holds the cradle in place do not remove until you open up the gear case and can see how it is situated.
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

If the clutch dog is worn after 50 years, the odds are almost 100% the fwd gear (and maybe rev too) are shot. The wear is never just on the dog.
 
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chrismorlan

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Re: 1962 Lark IV popping out of gear

Manual shift. Hoping it is a simple fix because the motor runs great.
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

It's not hard if you have a parts list or OEM shop manual.
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

Hard to beleive there's no rounding of the mating surfaces. Why don't you post pictures of the fwd gear and dog?
 
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chrismorlan

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Re: 1962 Lark IV popping out of gear

One detail I forgot to mention is that new prop is bronze rather than aluminum and this problem started right after switching props..
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

Are you sure the prop is not slipping in the hub?

Prop slipping:
1. Mark inner and outer hubs with indelible marker
2. Run boat to planning speed
3. Compare marks ? if they?ve moved relative to each other, hub is slipping
4. Remove prop
5. Take it to a propeller shop and have it rehubbed
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

Not many likely choices left if that is true.
 
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chrismorlan

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Re: 1962 Lark IV popping out of gear

On closer inspection clutch dog and fwd gear have minor wear. I guess it does not take much..
 
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wilde1j

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Re: 1962 Lark IV popping out of gear

All it takes is a relatively small amount of rounding to wreck the gear and dog. Once it starts popping out of gear, they're done.
 
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