upper drive shaft replacement....help!

i am an ameteur at repairs, but slowly learning.... i replaced the head gasket on my 1990 90hp force today, changed my thermostat, and now working on changing the impeller.... ok, so after i figured out getting the lower unit off, changed the impeller. i am now ready to put it all back to gether... i put the the "upper driveshaft (there are 2 sections of driveshaft) back up in, just tyring to get a feel for what and how this will ultimately seat itself when i do the final step of putting the whole lower unit back in... IS IT supposed to "seat " itself into the gear? i could n't seem to feel one... once i put it all together and slide up the whole lowere unit, will the upper driveshaft seat itself? i wondered that i just couldn't get it up high enough by hand with only the "upper"driveshaft".... ???


i probably am making no sense, but i am persistant and am gonna make this all work out ok... any comments?

Re: upper crank shaft replacement....help!

Re: upper crank shaft replacement....help!

Yes, actually you are making sense. It is easier to assemble the upper drive shaft into the crankshaft first, before mounting the lower unit. Now: you have the option of leaving the coupler on the upper drive shaft or the stub shaft in the lower unit. The coupler has an internal clip that locates it in relation to both shafts AND both shafts are designed so that their length will give just enough clearance to prevent binding or end loading when assembled.

UNLESS there is something stuck inside the crankshaft or the coupler, or you used excessive anti-seize on the shaft splines, it should assemble correctly when you mount the lower unit.

As a double check, just look inside the coupler. You should see the internal clip centered in the coupler and in its groove.

The drive shaft only slides up into the crankshft about two inches, not the full length of the splines. On the other end, there is a machined pin that fits into the hole in the stub shaft. If it takes excessive force to raise the lower unit this pin may not have seated (not very likely) However, if this happens then assemble the two shafts and coupler before mounting the lower unit.