Jumping out of forward gear and shearing pin on johnson 25 hp 1969 motor

[JD ONE SHOT]

My 25 hp 1969 johnson had lower gears replaced but is still trying to jump out of forward and will shear the pin after a few jumps trying to slip forward gear. Dog gear and forward and reverse were replaced. ??

 

[racerone]

Where new ( $$$$$ ) parts used ??-------Was the cause of the original failure corrected ??------Worn shifter cradle.---Loose linkages and poor adjustment ??

 

[joereeves]

Play between botom portion of upper shift rod and shift handle.

Many shifter dogs install in one direction only. If reversed (even if new), the unit will jump out of gear. Dog may be imprinted with the words "Prop End" or something similar OR have scroll marks engraved on one end. The "Scroll Marks" usually face forward gear BUT check the manual.

(Centering Shift Linkages - Manual)(Joe Reeves)
The engagement of forward and reverse gear must be evenly set. The shifter dog and the gears both have what is called lobes. The lobes of the dog must be side by side with the gear lobes in order for the dog to engage one gear or the other which results in turning the propshaft.

To grasp this scenario, with your left hand form a "C" with your thumb and forefinger. Now, with your right hand, form a backwards "C" with your thumb and forefinger. Your fingers will represent the dog and gear lobes.

Slide the finger and thumb of your right hand alongside the thumb and finger of your left hand so that they overlap.

This is the position of the dog and gear lobes when properly in gear.

To have the gears adjusted so that they engage evenly, it is best to have those lobes set so that they butt up against and face each other.

To visulize this, butt the tips of the finger and thumb of your right hand up against the finger and thumb tips of your left hand. This represents having the gear and dog lobes directly facing each other. Should you atempt to force the engine into gear with this condition existing, damage to the shift mechanism will surely ocurr, so keep in mind that this is just for adjustment purposes only.

To obtain the above adjustment position, spin the propeller while shifting into forward gear (lobes alongside each other). Now, shift into neutral and turn the propeller ever so slightly to have those lobes face each other (1/4" would do it), then move the shift lever back into gear but only as far as it will go without forcing it.. Adjust the shift lever/linkages so that this point of engagement is half of the shift lever's travel. Now, do the same with reverse gear.

Also, if you're using brass shear pins, switch to stainless steel.