Logo
FULL SITE MENU

1979 80hp - issue with installation of the lower unit. Gear shift shaft alignment?

G

Gilnor

New member
Greetings! I have 1979 Mercury 80 hp. I removed the lower unit to replace the water pump and now I have an issue with installing it back. Looks like something preventing the gear shaft on the lower unit from entering inside of the gear shaft coupler on the outboard part.
Before removing the lower unit the gear was switched to forward. Everything was done according to the manual.
It seems that the drive shaft matches the cranckshaft correctly - when I turn the flywheel clockwise, the propeller turns in the forward direction.
However, something is preventing the lower unit from going completely up to its place leaving the gap about one inch between the lower unit and the upper part.

The plastic housing for the end of the upper shift shaft and the reverse lock rod is in place.
I tried to turn the gear shaft on the lower unit with plyers a little to try to re-align it with the upper shift shaft - no success. I tried to switch gears - no difference.
Looks like the lower shaft just doesn't go inside the upper shaft (coupler) for any reason. I don't see anything that may cause this problem - everything is clean, no obstacles, and the situation is the same with a grease or without it. So, nothing should mechaincally prevent the shaft from going inside the coupler. But it does.
My only guess is that there may be a difference in the temperature causing the squeezing of the metal. My boat with the outboard is outside with about 30 degrees at nighttime and the lower unite is kept in the garage with about 40 degrees. In my opinion, it's not the huge temperature difference to cause the trouble. But maybe I'm wrong?

Did anyone have the same problem? Is there any trick to solve the issue and install the lower unit easilly? Some real-life experience not described in the manual?

I greatly appreciate your help!
 
Well ---no it has nothing to do with temperature.-----Make sure the water tube enters the pump.-----I say the spline for the shift rod is not lined up properly.----Turn shift rod slightly or have an assistant move shift lever slightly.--------And you are not the first to have this issue.---Nor the last.-----It happens all the time.-----You can also try with control in neutral and lower unit in neutral.-----Or just visit a shop as they can assemble it in mere seconds.
 
Thank you, racerone!

>Make sure the water tube enters the pump.
== It does.

>Turn shift rod slightly or have an assistant move shift lever slightly.
== I tried it, it didn't help. So, I'll try again.

>You can also try with control in neutral and lower unit in neutral.
== I tried it.

>Or just visit a shop as they can assemble it in mere seconds.
== Yes, it's always the option. But I'm a kind of a DIY-person, so I'm always trying to do everything myself before going to a shop. Usually it works quite good but not this time. :)

My idea here that maybe I'm missing something what not described in the manual.
It looks like that the coupler on the upper part of the shift shaft just became too tight for the shift shaft on the lower unit. I know that from mechanical point of view it's a nonsence, so I thought that someone could teach me some trick how to align two parts of the gear shift shaft properly ;)
 
Make sure to grease the splines of the shift shaft and DS before you insert the DS, if your DS has the pre-load pin (image) you will find resistance when bolting it up.driveshaft850.jpg
 
Quicksilver said:
Make sure to grease the splines of the shift shaft and DS before you insert the DS, if your DS has the pre-load pin (image) you will find resistance when bolting it up.
Click to expand...

Thank you. My DS doesn't have this pin. I've greased it (but not too much). I'll try to catch the right positions of both drive shaft and gear shaft.
 
I do this all of time by myself.It's a PIA.
I pull the plugs to make it easier to rotate the flywheel by hand,clockwise.Line up the water tube and shift rod with the shift shaft, I look at the gear spline and shift rod to get a spline lined up with a grove.Push her up ,rotate the flywheel 'til she catches and slides up.Works nine times out of ten for me.When it doesn't, I go back and start all over.
 
haventaclue said:
I do this all of time by myself.It's a PIA.
I pull the plugs to make it easier to rotate the flywheel by hand,clockwise.Line up the water tube and shift rod with the shift shaft, I look at the gear spline and shift rod to get a spline lined up with a grove.Push her up ,rotate the flywheel 'til she catches and slides up.Works nine times out of ten for me.When it doesn't, I go back and start all over.
Click to expand...

Thank you!! I'll try it.
 
Back
Top