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HELP wiith 1957 Johnson RDE 19 35HP outboard motor

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oilgasman

New member
Hi, I bought a 1957 boat, motor and trailer. See motor details in message title. When I put it in the water everything worked good except every 15-20 seconds while driving the motor/lower end would sound as though it was coming out of gear or possibly missing for a very split second. I took the lower unit off and did not see alot of wear or metal shavings in the lube. Do you have any idea what I should look at closer or what the problem may be? Clutch dog? Any help would be appreciated! Thank you.
 
If the engine races up and the boat slows down, either the prop is cavitating (drawing air) or the prop hub is slipping. However, if it feels like the lower unit is hitting something every so often, read on............

(Jumping Out Of Gear - Manual Type)
(J. Reeves)
This pertains to lower units on all OMC manual shift outboard engines, or any OMC engine with lower units defined as a Shift Assist or a Hydro Electric Shift unit which incorporates a "Shifter Clutch Dog".
Within the lower unit, splined to the prop shaft is what is most often referred to as a clutch dog, hereafter simply called dog. The dog has at least two lobes protruding from it on both ends, facing both forward and reverse gear. The forward and reverse gears also have lobes built into them near their center area. When the engine is running, in neutral, the gears are spinning constantly via the driveshaft being connected directly to the powerhead crankshaft, but the propeller does not turn due to the fact that the dog is centered between the two gears, and the dog lobes are not touching either of the gear lobes.
When the unit is put into either gear, shift linkages force the dog (and its lobes of course) to engage the lobes of the gear. The lobes of the spinning gear grab the lobes of the dog, and since the dog is splined to the prop shaft, the propeller turns.
The lobes of the dog and gears are precisely machined, most with right angled edges that could be installed in either direction, and some with angles slightly varied that must be installed in one direction only (one end only must face the propeller). Dogs that can be installed in one direction only, if reversed, even if the dog and both gears were new.... would jump out of gear almost immediately. Keep in mind that the lobes are precisely machined with sharp angles!
Due to improper adjustment or worn shift linkages, but usually due to improper slow shifting, those precisely machined sharp edges of the lobes become slightly rounded. Now, with those lobes rounded, as the rpms increase, the pressure of the gear lobes upon the dog lobes increases to a point whereas they are forced apart (jumping out of gear), and due (usually) to the shift cable keeping tension on the engines shift linkages..... the unit is forced back into gear giving one the sensation that the engine has hit something, and the cycle continues.
Some boaters with manual shift engines have the mistaken belief that shifting slowly is taking it easy on all of the shifting components..... Wrong! Shifting slowly allows those precisely machined sharp edges of the dog and gears to click, clank, bang, slam against each other many times before they are finally forced into alignment with each other..... and this is what rounds those edges off! The proper way to shift is to snap the unit into gear as quickly as possible.
 
Did you check the adjustment of the shift lever / mechanism before diving into this work ???----------Look closely at the edges of the forward gear and clutch dog.-------They may be rounded off.-------------Now on this model you can reverse the gears ( bushing needs to be pushed out of forward and installed in the reverse) and the clutch dog can be turned around.
 
Thanks to the 2 replies. Yes, I did check and adjust the linkage before pulling the lower unit. It does sound like you are hitting something when this happens. Sounds as though I can turn the dog around and change the forward and reverse gears around as well as long as I change out the bushing. Correct?
Thanks again for your input. It is appreciated.
 
I was able to turn the clutch dog around. However, The gears are not interchnageable due to the ID of the gears even by chnging the bushing. Does anyone know where I can buy a forward gear? Thanks for all your help.
 
Over time the splines on the gears shaft become nicked prevent the clutch dog from becoming fully engaged, althought the shifter shows it in a gear there is just that little bit of tolerance being not fully in position, the lower end on these is pretty basic just make sure you have good seal/seals,,take a points file to each spline a test fit the dog so it travels the full length,, hope this helps I have been rebuilding these old motors for years and the old 35 are very tough cases,,,
 
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