Logo
FULL SITE MENU

Pre Alpha (R) sterndrive -Problem connecting lower unit to upper unit

S

Scottybluewater

Contributing Member
Hello
Have a 1979 Mercruiser 228 engine and trying to connect my upper 228 unit to a MC-1 lower unit
Have connected both units together - looks great
Problem - the upper u joint drive shaft is jammed - will not turn
The difference from my old lower and the MC-1 is that the MC-1 has a preloaded pin - on the old one the pin was hacked off

Assembly - lowering the upper down had the shift shoe lined up straight but right at the very end it, moved off center -prop was locked
Wiggled the prop a bit and I was able to move the shoe back to center
as soon as I moved the prop backwards the shoe moved off center - moved shaft spline to neutral - spun freely - on reverse - same as fwd

Not sure what the problem is - the pre loaded pin - an old woren out shoe shaft = bad splines

all thoughts are greatly appreciated
 
Do you know what the purpose of the preload pin is? Also why was the other "hacked off"?

If the bronze shift arm did not align to 12:00 while in forward when upper and lower were assembled, you have to raise/lower the two halves and LINE IT UP CORRECTLY. Just moving the prop is not the only thing to do, you have to manipulate the shift arm and make sure the shift shaft is all the way clickwise while closing the gap between upper and lower which will make shift arm align to 12:00
 
Scottybluewater said:
Hello
Have a 1979 Mercruiser 228 engine and trying to connect my upper 228 unit to a MC-1 lower unit
Have connected both units together - looks great
Problem - the upper u joint drive shaft is jammed - will not turn
The difference from my old lower and the MC-1 is that the MC-1 has a preloaded pin - on the old one the pin was hacked off

Assembly - lowering the upper down had the shift shoe lined up straight but right at the very end it, moved off center -prop was locked
Wiggled the prop a bit and I was able to move the shoe back to center
as soon as I moved the prop backwards the shoe moved off center - moved shaft spline to neutral - spun freely - on reverse - same as fwd

Not sure what the problem is - the pre loaded pin - an old woren out shoe shaft = bad splines

all thoughts are greatly appreciated
Click to expand...
By 'shift shoe', you're referring to the shift shaft that has what many call a 'foot'?

You shifted into forward before removing the outdrive, right? You have to do that. Sounds like you need to make sure the drive is in forward before installing it and that requires holding the propshaft to prevent it turning backward and causing the shift spool returning to neutral. You can do this with the lower gearcase on the upper by threading the nuts on just enough to prevent the lower falling off, then rotating the shift shaft on the splines, then making sure of the forward/neutral/reverse positions. Merc has a tool for this, but leaving the prop on the shaft does the same job- lets you turn and hold the shaft in place without needing to grasp it by the shaft, which is smaller and usually greased.
 
I believe the Pre-load pin ensures proper alignment and keeps everything place The Pin in the old lower unit was broken off not sawed off - why I do not know?
The Splines on both unit do not mesh /align properly - in my first attempt I had the prop blocked fully in place in FWD
I am going to see if I can inspect the gears/splines in the upper unit
Thanks
 
I think all I can do is take the cap off and see what i can see - This broken off Pre-load pin has me concerned.
If the pin keeps everything in place then what is going in this Upper unit - This whole project was started because in the past when I shifted into gear there was tremendous loud BANG,_ I had assumed that this bang came from the lower unit - I bought a rebuilt lower unit.
Going to try again and with emphasis on keeping Shift Shoe in the full fwd postion and prop blocked in fwd
Thanks - Stuart
 
The purpose of the pin, Thus the name "preload pin" is to load the pinion gear assembly when assembled based on that old vertical shaft bearing design.

MR and Alpha gen 1 & 2 dont use a preload bearing set up and the bearing itself is upside down verses R and prior designs.


The big question is ,

Did it run/work with the missing preload lower or not?

If the lower bogarted that may be why, the preload pin broke off somehow

They are not exchangable.
If your outdrive worked with no preload pin something is F'ed up....

Or the pin is stuck up under the upper gear set and that is what is causing you jamming issue
 
Scottybluewater said:
I think all I can do is take the cap off and see what i can see - This broken off Pre-load pin has me concerned.
If the pin keeps everything in place then what is going in this Upper unit - This whole project was started because in the past when I shifted into gear there was tremendous loud BANG,_ I had assumed that this bang came from the lower unit - I bought a rebuilt lower unit.
Going to try again and with emphasis on keeping Shift Shoe in the full fwd postion and prop blocked in fwd
Thanks - Stuart
Click to expand...
Ayuh,...... Dog-clutch drives always engage with a Clunk,.... Lowerin' the idle helps,....

I wrap a bungee strap 'round the prop shaft, to hold tension against forward gear, so that it don't slip into neutral when assembling the halves,....
 
Back
Top