Shifting Issues with the Drive Unit Shift Shaft Coupler

iambatman

Cadet
Joined
Apr 16, 2016
Messages
6
Long story short, had to rebuild the lower untit ended up at a boat mechanic due to a no reverse issue. Problem was fixed until Well today I started only to find that it does engage into reverse but it knocks. I'm somewhat familiar with this problem end of the boat lol. I know that the prop is supposed to lock one way for reverse and the other for forward. When I throttle forward the prop locks solid. When I engage reverse it will lock but slip its not solid like forward. For agrument and time sake lets say that the shift cable is where it needs to be and all is good with that. Which it is. Ive tried unhooking and pulling on cable to lock prop with no avail. Now with that mind, I can reach under the lower unit and grab the Drive Unit Shift Shaft Coupler, put a very small amount of pressure with my hand, then the prop will engage solid and will not slip at all. I mean its in between a 1/16 and a 1/8 inch of a movement that engages the prop solid, and if i release pressure, it will lock/slip again. Any advise before I bring it back to the mechanic?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,469
due to a no reverse issue. Problem was fixed until Well today I started only to find that it does engage into reverse but it knocks.

Ayuh,.... Welcome Aboard,...... I wanta hear some more of the back story 1st,.....

What was the issue found causin' the problem in the 1st place,..??
How was it resolved,..??
What's just been fixed/ changed/ worked on,..??
 

iambatman

Cadet
Joined
Apr 16, 2016
Messages
6
Well like i was saying initially brought in for the "no reverse" issue, mechanic found out quite a bit of issues. Ive attached the receipt of work done, boat ran fine for one outing then started up with issues again. Sorry im dont really know, look at the attachment of the invoice it will tell all work done
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Was the shift cable replaced? It is possible it was not screwed all the way in.
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Sure sounds like linkage is not adjusted properly, if an Alpha1 the washer could have been left off the lower shift shaft, or the lower shift cable housing is bad.

If you can push on the shift shoe and get it to lock up then the problem is linkage/cable connecting to it. Did you try increasing the lower cable travel by moving the lower attachment pin on the linkage?
 
Last edited:

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
A couple of things. The upper brass shoe is loose on the lower splined shaft, the lower splined shaft is badly worn, the shift spool is worn
the shift slide is not recessing enough because its hitting the white plastic guide. This is a rare occurance and is fixed by removing a 1/4 inch of the white plastic tube.
Compare against this video
 
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