68 50hp Merc Lower unit shift algingment Installation

[mirage5058]

OK i have taken this apart five times searched the forum for picts,everytime i try to reinstall lower unit after putting new impeller in the shifter binds and will not shift forwar or reverse,if it does it either locks up in forward or i cant move shifter at all,if i back off the screws for lower unit and take pressure off it ,the shifter will move again f and r as soon as i tighten it down it binds again any help would greatly appreciated or pictures of how to do it correctly,i looked at some pictures posted of a differant model but not the same,

 

[seaking1]

Re: 68 50hp Merc Lower unit shift algingment Installation

Mirage5058,

I too have a 1968 Mercury 500 50 hp that I'm trying to install the lower unit. According to the Mercury manual, the shifter has to be in forward and the lower unit also has to be in forward gear. There is a reverse locking cam that fits over shift spline on the lower unit. The challenge is first to know when the lower unit is in forward gear and second is the proper orientation of the reverse lock cam. I've been working on this for several hours today and can only get the propeller shaft to turn counter clockwise in forward and clockwise in reverse, neutral works fine (when the LU is attached). I test by turning the flywheel clockwise by hand--pull the spark plugs out for ease of turning.

Challenge One: Getting lower unit in forward gear.
I used a vise grip on the lower part of the shift spline (lower unit) and turned it until I heard/felt it shifting. I can put it in neutral and rotate the prop shaft by hand. I just can't determine when it's in forward. I need some help here.

Challenge Two: Correct orientation of reverse locking cam. I've been trying different positions but just shooting in the dark. The Merc manual doesn't explain how it should be positioned. Again, I need help here. I know I'm close but it's taking quite a bit of time putting the lower unit on and pulling it down to readjust.

I haven't seen any solutions to this problem posted on the site. I may drop by a local Mercury dealer/service center and ask them if I can't get it to work. Perhaps between the two of us we can figure this out. Let me know if you have success.

 

[mirage5058]

Re: 68 50hp Merc Lower unit shift algingment Installation

I had someone tell me that if you put it in neutral and turn the prop shaft along with shift shaft you can feel it go in to neutral but you need access to flywheel in order to align the shaft,havent tried it yet but will in the morning,this is so frustrating it will be the tenth time i have dropped it,