70 HP Johnson Lower Unit Replacement Shifting Problem

[ettenho1]

Hi All,<br /><br />I recently bought a used replacement for my burned out 1980 70 HP Johnson lower unit, and visually everything appears to match up (dimensions, splines, etc.). However, I noticed that on the "new" lower unit, the prop shaft rotates in the opposite direction than on the "old" lower unit, when the shift lever is in a specific gear. Also, the shift rod on the "old" unit has a lot more travel when shifting gears than the "new" one, which moves only a little bit. <br /><br />My first question is, will I need to adjust the shift rod, or the shift linkage, to make sure that it shifts properly? Second, is there any serious problem with me driving around in "reverse" gear to go forward, considering the controls will now be mismatched to the unit?<br /><br />Any help is appreciated!<br />Mark

 

[OBJ]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

Mark....first thing to know is from what year the "new" lower unit is from. That may help answer your questions. If by chance you got hold of a lower unit from around 73' or 74', it won't work. The throw on the shift rods on these lower units is opposite from your 80'. You won't get WOT throttle with the control in reverse.

 

[Chinewalker]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

Hi Mark,<br /> OBJ's right on the money. The 1974-1976 model gearcases are "Hydro-assisted Mechanical Shift" type units and use a different shift pattern than the straight mechanical units used from 1977 onwards. A simple tell-tale - if the trailing edge of the skeg is swept back, it's a straight mechanical, and if the trailing edge comes straight down (right angle to the propshaft) then it's a hydro-mechanical unit (unless it's an electric shift, in which case there would be a wire coming out instead of a shift rod..) There may be exceptions to the rule, but it's worked for me...<br /><br /> Now, for your issue, you have two options - either get another unit of the correct era (1977 to 1985) OR you can swap out the shifter bellcrank from a 1974-1977 model to change your motor's shift pattern. The bellcrank is the part that runs horizontally under the lower carb, with the elbow that comes up to accept the shift rod, as well as the throttle/shift advance assembly that rotates on the side of the block.<br /><br />- Scott

 

[ettenho1]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

Thanks for the feedback! According to the seller, the replacement unit is from a '78 unit, 65HP. Any ideas about why it appears to be reverse from my '80, or what I can do about it?<br /><br />Thanks!<br />Mark

 

[Chinewalker]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

Hi Mark,<br /> There's no such animal as a 65hp in 1978. The '73 65hp used the Hydro-Assist unit, too..., same as the '74 70hp... Best option is to buy yourself the correct unit ('77 to '85) from a reputable dealer. Possibly, ask the guy you bought this one from to exchange it for you, or ask for your money back as it was misrepresented - whether it be knowingly or unknowingly..<br /> If the guy you bought it from won't deal, then youcan likely sell it outright for what you paid for it.....<br />- Scott

 

[tomshear]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

i have a 1971 evenrude 65 horse never had a problem all of a sudden forward gear the prop spins but no power dont move in the water seems forward is somehow not fully engaged you can stop it with a stick but it is in forward because the shifting unit shifts fine. reverse and neutral work fine and that is what is what usually goes bad.

 

[Daviet]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

tomshear, welcome to the forum, you should start a new post as this one is over seven years old.
To try and help, it almost sounds like you might have a spun prop hub, do you know how to check it?

 

[mikehealy17]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

hey guys - I think I have a similar issue. I have a 1976 Johnson 70 hp and just replaced the lower unit with a 1985 70hp lower unit. It seems as though there is not enough travel in the shift linkage under the powerhead top fully engage the lower into gear. Is this because of the change in shift pattern that was noted in this thread above?

Sounds like a simple fix would be to shange the linkage...any chance you guys can confirm the linkage that I want? Also - do I have to remove the powerhead to change the linkage?

Thanks in advance for any help.

~ Mike

 

[tomshear]

Re: 70 HP Johnson Lower Unit Replacement Shifting Problem

tomshear, welcome to the forum, you should start a new post as this one is over seven years old.
To try and help, it almost sounds like you might have a spun prop hub, do you know how to check it?

I tried changing props no luck the center shaft also stops turning this engine had a new clutchdog and reverse gear 3 yrs ago.Its funny because it shifts into reverse and neutral fine and thats where the problems are at because of the hydro electirc shifting. I put the boat away for the season when i went to use it i put it in forward and had no power.the gear should always be in forward when the shift wires are disconected but still u can stop the prop with a oar but it does turnj when in forward Im confused.I changed the lower end oil,checked the electric shift current,when i put it away for winter it was fine .