1978 25hp forward gear and clutch dog question

[Steve2517]

I hope someone can answer this question. I have a 1978 Johnson 25hp 25r78c motor. Had an issue with foreard gear and clutch dog, seems like the classic skipping back to neutral when cranking throttle in forward gea . Having a hard time finding parts used or cheaper. I have the chance to get forward gear reverse gear and clutch dog from a 1984 25hp Johnson. Parts being 390295, 325258 and 325263. My part numbers that I would need for my 78 are 390030 for clutch and 390972 for my forward gear Would the parts from the 84 would if I changed the two gears out and clutch dog. Any help on this matter would be a great help

 

[oldboat1]

At least the clutch dogs differ, as you seem to know. If mine, I think I would drain the l.u., checking for debris/metal shavings. Then open it up and visually check gears and clutch dog for wear. But check shift linkage before going through disassembly, particularly if the water pump was recently replaced.

 

[Steve2517]

Already have it apart. Clutch dog and forward gear seem worn. Got on opinion. But will go to local boat shop to see what they say. Never changed the impeller since having the motor for 3 years.

 

[Steve2517]

What would I have been looking for with shifter linkage?

 

[oldboat1]

Connecting link for upper and lower shift rods can be an issue. Screw has to be fully removed, and it sometimes helps to spread the link a little using a bladed screwdriver. Screw or bolt has to pass through the machined indentation in the rod.

 

[Steve2517]

And that would stop the forward gear from fully engaging. ? Then the heavier throttle/load would make gear slip

 

[oldboat1]

Typically would have difficulty shifting into gear -- would not engage, or not completely, maybe with some chattering (which can result in gear damage). Not sure if engine load would be a factor, but conceivable. The brass connector can clamp onto the rod end, deceiving you into thinking the link is properly connected. Overall shift rod length is changed, which changes shifting -- close tolerances.

 

[Steve2517]

If parts would differ. Would they still work using the clutch dog and gears from the 84 motor.

 

[54bobby]

google is your friend. cross reference both engines to parts numbers.

 

[racerone]

Somehow i do not believe this interchange will work.

 

[F_R]

You have a challenge there. I guess the first thing you need to do is decide if any of the parts have been replaced in the past. There have been a few upgrades through the years. The numbers you quoted for your '78 are for the latest version, and expensive. If your motor is original, you might be better off looking for some NOS original parts. Those would be 316501 dog and 389236 forward gear.. If it has the upgraded gear, it will have a roller bearing, and will be obvious. The dog change is the cradle and not so obvious.

 

[Steve2517]

The roller bearing would be on the same side of the clutch dog as the forward gear. ? If so then there is deff no roller bearing

 

[Steve2517]

I've looked over Ebay and can not find the original parts. Any guidance on such ? And basically your saying if I replace the forward gear and clutch dog with the newer parts I have to change a lot more things.

 

[F_R]

The roller bearing would be on the nose of the forward gear, if you had them. Very obvious

If you use the updated part numbers that you came up with, those will include the stuff you need to make the switch. That;s why they are so expensive. I suspect the are the same as the '84 you asked about, but can't prove it. The part numbers are different because on one hand we are talking update kits, and on the '84 we are talking individual items.

 

[racerone]

What about the bushing above the pinion in 78 and needle bearing there in 84 ?????

 

[Steve2517]

Are you saying that because of those it would not work ?

 

[F_R]

We are going astray with this topic. Are you contemplating removing the forward gear and bearings from the '84 and putting them in your '78? That is what I was thinking when I said I think it will work but can;t prove it. Yes, the pinion setup is different. Stuff like that illustrates what happens when you start mixing parts.

 

[Steve2517]

Ok. Thank you. I will just try looking for the original forward gear and clutch dog. Which is proving hard without paying 200 plus dollars at least.

 

[F_R]

Post a want ad on the Antique Outboard Clubs forum. The ad is free.
www.aomci.org.

 

[Steve2517]

Thank you.