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Lower unit attached to upper unit

G

Ghg

Contributing Member
I have a 1967 Mercruiser 120, trying to join the lower unit to the upper out drive, having difficulty getting them lined up to bolt together. Is it easier to have the outdrive in the full up position or down all the way. Are there any tips, I’m trying to do this my self, I might have better luck with another hand.
 
Ghg said:
I have a 1967 Mercruiser 120, trying to join the lower unit to the upper out drive, having difficulty getting them lined up to bolt together. Is it easier to have the outdrive in the full up position or down all the way. Are there any tips, I’m trying to do this my self, I might have better luck with another hand.
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do you have it locked in forward so you can turn the shaft to line up splines? i usually keep the upper at about a 45 degree angle, you can drop tongue of trailer to raise the stern some.

others also find it easier to remove complete drive so you can drop the upper onto the lower held in a vise
 
If it's too heavy to lift and hold with one hand, get a helper. You need to rotate the lower shift shaft to the Forward position, so the prop will have resistance when you try to turn it in the Reverse direction. Leaving the prop on makes it easier and you won't need to buy the tool for this.

You'll need the drive raised a bit, to make turning the lower shift shaft posible- if it's vertical, you won't be able to reach in where you need to.

Reinstalling the lower definitely isn't a walk in the park but it can be done.
 
What tool is it that you refer to? I plan on having a helper when I make another attempt to install it
 
Ghg said:
What tool is it that you refer to? I plan on having a helper when I make another attempt to install it
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Mercruiser and other companies sell it, but it's not really necessary (it's called a 'holding tool'). You can leave the prop on and it will accomplish the same purpose- turn the shaft in reverse (prop gives a visual clue, the tool doesn't) and hold it there while the drive shaft is going into position, turning it to align the splines. If you don't want to leave the prop on and the prop's hub is removable, you can slide it on and snug the prop nut to keep it on.

The photo shows the bearing carrier retainer tool (the larger tool) and the holding tool, which has the part number on it. You should be able to find used specialty tools online.

1748787797486.png
 
jimn said:
Mercruiser and other companies sell it, but it's not really necessary (it's called a 'holding tool'). You can leave the prop on and it will accomplish the same purpose- turn the shaft in reverse (prop gives a visual clue, the tool doesn't) and hold it there while the drive shaft is going into position, turning it to align the splines. If you don't want to leave the prop on and the prop's hub is removable, you can slide it on and snug the prop nut to keep it on.

The photo shows the bearing carrier retainer tool (the larger tool) and the holding tool, which has the part number on it. You should be able to find used specialty tools online.

View attachment 35194
Click to expand...
Isnt that tool for the pinion gear nut on the vertical shaft?
 
jimn said:
Mercruiser and other companies sell it, but it's not really necessary (it's called a 'holding tool'). You can leave the prop on and it will accomplish the same purpose- turn the shaft in reverse (prop gives a visual clue, the tool doesn't) and hold it there while the drive shaft is going into position, turning it to align the splines. If you don't want to leave the prop on and the prop's hub is removable, you can slide it on and snug the prop nut to keep it on.

The photo shows the bearing carrier retainer tool (the larger tool) and the holding tool, which has the part number on it. You should be able to find used specialty tools online.

View attachment 35194
Click to expand...
Also the word "reverse" should say Counter Clockwise......
 
kghost said:
Isnt that tool for the pinion gear nut on the vertical shaft?
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No, the one in the photo along with the bearing carrier tool fits onto the propshaft splines. I don't now why they couldn't have made it with plastic, but.....

I have searched the part number from the photo and didn't find anything- I'll post the number on mine later today.
 
jimn said:
I would have posted that but I haven't seen any counter-rotating propes on single engine boats.

Maybe that's a Southern Hemisphere thing... :)
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When adjusting the shift link to the 12:00 position (forward gear) you spin/turn prop in the C' clockwise direction...

Not sure where reverse comes into play.....
 
jimn said:
No, the one in the photo along with the bearing carrier tool fits onto the propshaft splines. I don't now why they couldn't have made it with plastic, but.....

I have searched the part number from the photo and didn't find anything- I'll post the number on mine later today.
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The large tool with the MR stamped into it, also has two other slots (total 3 slots) is the tool used for the nut on the pinion gear nut and looks exactly like the ones I have...the other part could be anything..
 
kghost said:
When adjusting the shift link to the 12:00 position (forward gear) you spin/turn prop in the C' clockwise direction...

Not sure where reverse comes into play.....
Click to expand...
I mentioned 'reverse' because it applies to normal and counter-rotating drives.
 
kghost said:
The large tool with the MR stamped into it, also has two other slots (total 3 slots) is the tool used for the nut on the pinion gear nut and looks exactly like the ones I have...the other part could be anything..
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I'm a dork. I wasn't actually l ooking at the large end of the tool, just noticing the size and general shape and then, didn't remember the photo two days later. I only used that photo because it was he first one I found with the holding tool. I should have cropped the photo.
 
The approximately 3" long hex/spline tool does indeed fit the prop shaft but its real purpose isn't for rotating the shaft to align the upper to lower splines.

It's purpose is IF the top of the vertical drive shaft shears off then you use the nut holding tool and turn the prop shaft with this to loosen the pinion nut. That is why it's made of tool steel & not plastic.
 
Just to be sure, you are assembling the original 2 halves back together and not a new marriage of mismatched units. In other words, you have the same spline count? 1969 & earlier was different than 1970 and later.
 
Yes, assembling matched units with same spline count, don’t know how the pinion nut tool got in this conversation?
 
Ghg said:
Yes, assembling matched units with same spline count, don’t know how the pinion nut tool got in this conversation?
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I just grabbed a photo and posted it, with a slight description of the holding tool and it's too late to edit that post.
 
Ghg said:
Exactly how is that tool used to join the two units together? I’m still lost
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Leave that alone. No need for that tool to be used for what you are doing....ever!

Where are you with reassembly? How far do you get when you have issues?
 
I’m at a stand still for now, the next time I attempt to join them I’ll have some help, I think I’ll be ok when I have someone turning the prop to align the splines, I’ll keep you posted, thanks for the help
 
Ghg said:
I’m at a stand still for now, the next time I attempt to join them I’ll have some help, I think I’ll be ok when I have someone turning the prop to align the splines, I’ll keep you posted, thanks for the help
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What I was asking,
What is your issue that is causing you not to be able to get it back together.

Does the Vertical drive shaft with the splines, is there a pre-load pin at the end of the shaft?

If there is, when you get all lined up, and get the lower almost all the way up, about a 1/2 inch or so gap will be left and you will need to use the two side pocket nuts to pull it the rest of the way. Tighten them an equal amount back and forth. Also be aware if there is a small square edged oring at the oil passthru hole. Make sure its there and doesnt fall out. I dont remember if that old drive has that oring or not....
 
Yes, there is a preload pin at the end of the spline, there is no oil pass through hole on my outdrive because it has two separate oil chambers, upper and lower. This is an early outdrive before they went to the joining oil chambers.
 
Reach into the opening at the front where you can see the drive shaft and water tube so you can make sure the water tube is entering the ring at the top, at the water pocket cover.
 
Yes, that’s one of my main concerns to get the water tube lined up. Is it better to have the water tube attached to the upper unit or into the water pump housing when joining them?
 
I think he still has upper on the boat. So can't see from the front.

Do you have the plastic guide tube on water pump?.
Best procedure I've found is be sure guide tube is in place on water pump. Put copper tube into top pocket FIRMLY. There is a small shoulder, it can't go in too far. A thin film of grease on both ends of copper help it slide into place both top & bottom. Then you have about 3" to see and verify copper tube is sliding into guide tube as the 2 come together.
Watch the gap between the 2 and keep it parallel otherwise the drive shaft may be heading into nowhere land.
 
Droid said:
I think he still has upper on the boat. So can't see from the front.

Do you have the plastic guide tube on water pump?.
Best procedure I've found is be sure guide tube is in place on water pump. Put copper tube into top pocket FIRMLY. There is a small shoulder, it can't go in too far. A thin film of grease on both ends of copper help it slide into place both top & bottom. Then you have about 3" to see and verify copper tube is sliding into guide tube as the 2 come together.
Watch the gap between the 2 and keep it parallel otherwise the drive shaft may be heading into nowhere land.
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It's not visible if the drive is vertical, but it is if the drive is angled- I raise it when I install a lower, to make it easier to lift and because it's easier to make sure the upper shift shaft 'foot' engages the lower shift shaft properly. It also make sligning the water tube possible.

My outdrive is off of the boat and to be honest, I would rather reinstall a complete drive than just the lower- I have done it both ways many times, but IMO, installing just the lower is a PITA because the lower shift shaft that mates with the upper is in the upper gearcase and alignment is far easier when the whole drive is laying on its side. If the water tube needs to be aligned, it's very easy.

The last time I installed the whole drive, I was still wearing a leg immobilizer after injuring my knee, so I was far from able to do it as easily as before. The odd thing- I think it went on far more easily than any I can remember and I had assumed it would fight me.

To make installation easier, I lowered the bow end of the trailer so the center of the opening in the gimbal was the same height as the yoke. I stood the drive up on the cardboard sheets on the floor (to prevent damaging the skeg), lifted the shaft, inserted it into the gimbal bearing & coupler, then rotated the prop to align the splines to allow pushing it in for starting the nuts.

My boat is a 17' 4 Winns so it's not very high, a larger boat will need something to raise the drive, but the procedure would be the same.
 
Ghg said:
Yes, that’s one of my main concerns to get the water tube lined up. Is it better to have the water tube attached to the upper unit or into the water pump housing when joining them?
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I find it easier to align the Copper tube if it's already in the top of the water pump, as I described in my previous post. I needed to remove the whoe drive because I found additional problems, caused by the previous owner being one of the people who should never own a boat. The seal for the yoke in the upper had been worn and it leaked gear oil, so I needed to clean the bellows, remove the whole assembly and replace the parts, as needed. I'm pretty sure someone had removed the drive & top cover for the upper (one of the 12 point bolts was bent) and when they reinstalled the upper carrier retainer, I found that it hadn't been fully tightened. Of course, the seller didn't tell me about that. In the process, I decided to replace all of the oil seals and O-rings, as well as the yoke seal and as required, the nut and tension washer at the end- it's 41 years old- it was time for proper maintenance and I didn't see any reason to go half way when it was already open.
 
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