Re: '84 Mercury 50HP lower unit installation.

[Runder]

Re: '84 Mercury 50HP lower unit installation.

Hello all,<br /> This is my second time here and since the information was very very helpful last time, I am posting my most recent boat battle. <br /> I acquired an '84 Mercury 50 last season with the lower unit already removed. I replaced the water pump and now am attempting to install the lower unit. I got it to go in yesterday all the way up to approximatley 1/16 of an inch out. It won't mate to the motor. Now, on the spline in the front of the lower unit there is a round looking washer type piece. Now, I was wondering which way that piece goes into the motor. It looks as if the part is like a gear stoppage piece or something. I do have a book I got from the library, but I think because of the year, it is very vague. The lower unit in the book is not exactly like mine. So I don't know what that piece is exactly. Please help. Thanks,<br /> GreatSouthBay

 

[KCLOST]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

Spline in front of the lower unit?<br /><br />Are you talking about the lower shift shaft?<br /><br />The drive shaft splines should have a black plastic splined carrier attached to work as a seal...

 

[Runder]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

Yes, I believe that's it. It fits on the spline and has a curved side to it; kind of like a roller coaster. It's hard to explain, but that's the best I can describe it and on ther side it is flat. I don;t know which way the flat end goes.

 

[AMD Rules]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

For the drive shaft seal, often there is two pieces to it one above the other (seal & seat). Both rubber pieces have splines on the inside. They are there to keep the water and debris out of the splines on older motors.<br /><br />You can see the two rubber pieces in this image.<br />

 

[Ken G]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

It sounds like your reverse lock cam. It is about 1 1/2" in diameter and about 1" thick. One side is flat and the other side has a sloping ramp. It fits on the splined shift shaft.<br /><br />When reinstalling the LU put the LU and powerhead in forward and install the reverse lock cam with the ramped side to the front and the flat side to the rear. Read this: http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=010967;p=1#000011 and you should be in business.

 

[AMD Rules]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

Here's a blurry picture of an aluminum reverse lock cam.<br />

 

[Runder]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

First, You guys have been VERY helpful. <br />The reverse lock cam is it. Now, you say the ramped end goe forward and flat end goes rear. But what I need to know is the picture you have posted: Is that the way is goes onto the LU before it goes in. And, if so, what could be keeping the LU from mating completely to the motor. I get all the way in about 1/16 out. I feel it needs to completely connect to the motor. Anything. Thank you,<br /><br /> GreaSouthBay

 

[7-012]

Re: '84 Mercury 50HP lower unit installation.

Re: '84 Mercury 50HP lower unit installation.

When You install it the surface sloping downwards should be slightly port of the boats middleline. The flat surface should be from starboard and onwards. That means that the rod pushing the reverse lock will engage the lock when You put Your engine in neutral.. Of course this means that You have to put Your gearbox in neutral when installing the thing.