9.9 Yamaha seized shift shaft coupling

[Fish Hawk 52]

Greetings: I am trying to drop the lower unit on a Yamaha 1999 9.9 high thrust 4 stroke to replace the water pump. Bolts under cavitation plate came loose easily, but the shift shaft (rod) coupling is seized to the shaft. I backed off the nut below the connector but can't get the shaft loose from the coupling. When I put a wrench on the coupling the whole shaft turns and I know if I put too much into it something will break. I haven't force dropped the LU yet because I'm afraid of pulling something out of the gear case. Anyone have a solution on how to break this thing loose without tearing it up?
Thanks, Don

 

[yamatech43]

Re: 9.9 Yamaha seized shift shaft coupling

Wait....that's not a 4 stroke its a 2 stroke....what coupling are you referring to? Are you sure it's a coupling? Did you remove the one bolt up inside where the zinc was....when you remove the zinc there is also another bolt uncovered after you do that way inside. Sometimes if a motor in saltwater isn't properly taken care of the splines on drive shaft will sieze....did the lower unit drop half an inch or not at all....

 

[99yam40]

Re: 9.9 Yamaha seized shift shaft coupling

All of the T9.9 motors are 4 stroke. Always good to post a model #.

Can you get hold of the shift shaft at the top and disconnect it up there? Then you might be able to hold the shaft with some vise-grips while you turn the coupling without the fear of breaking something.

May need to use heat and a hammer, but you may have to cut it and then replace with new

 

[Fish Hawk 52]

Re: 9.9 Yamaha seized shift shaft coupling

Yes, sorry. It is 6G8 T9.9 EXHX It is a high thrust, 25" ultra long shaft. I bought it used, previously used as a sailboat aux power. It probably didn't get flushed much. It has the extension above the lower unit with four threaded studs that fit through the mounting holes in the lower unit and attach using nuts, (no bolts). The nuts came loose easily. The shift shaft coupling is visible in a space about half way between the lower unit and power head, on the front of the motor. There is a jam nut below the coupling, but it was not snugged up against the coupling (concerns me). The motor shifts perfectly, I can't get the coupling to budge, which leads me to believe the coupling is seized to the shaft. I did get the jam nut to turn on the shaft. I haven't pulled too hard, or used impact on the lower unit yet, as I am concerned about damaging the shaft either in the lower unit or up at the shift lever. I attached a pic of the couple and nut in the position I found them. Coupler is on power head side of the shift rod.

 

[99yam40]

Re: 9.9 Yamaha seized shift shaft coupling

If you can get the coupler down far enough by shifting or disconnecting at top end and separating the lower unit a little bit, then maybe cut the coupler , but may end up damaging one of the shafts.

I had a 30 do this and I broke the connector at the top of the shaft trying to get coupler to turn and once I removed the shaft I still never got the coupler to move on the shaft even with heat and beating on it against some solid metal as back up.
But I was able to remove the lower unit once the shaft was loose at the power head, the whole thing slipped out. Maybe yours would too, but I do not know for sure.
I was able to hold the shaft into lower unit and get it unscrewed from the coupler, but not the long shaft.

 

[Fish Hawk 52]

Re: 9.9 Yamaha seized shift shaft coupling

I got the coupling moving with some heat and penetrating oil. It looks like brass or bronze, connecting the SS shafts. Dissimilar metals in a salt water environment, go figure why it seized. The wrench rounded the side off the coupling so I used channel lock pliers and kept it moving. However now the coupling has moved into the steering tube so I can't get a good bite on it with the pliers. It is still attached to the lower shift rod. Now I need to drop the LU a bit to pull the coupling out of the tube so I can get the pliers on it and keep turning it. The LU is stuck. I saw a thread where someone built a device from 4x4"s and threaded rods to apply the needed force to pull the shaft free from the power head. Any one know where the thread is?
Thanks

 

[Fish Hawk 52]

Re: 9.9 Yamaha seized shift shaft coupling

OK, I got the lower unit to move south so I could get a better grab on the coupling. I built an impact puller from memory of what I saw on this forum and it worked great. I got the channel lock on the coupling and got a few more turns until it screwed of the lower shift shaft. The LU came off. Unfortunately, the coupling is a mess. I have search all my parts sites and looked in my shop manual but can't find a part # or a supplier. Can't believe I'm the only one to mess one up.
Would appreciate any help.

 

[Inducted]

Re: 9.9 Yamaha seized shift shaft coupling

Go to the yamaha- motor web site, look up your motor. go to the" control" sub heading and I'm pretty sure #42 is your coupler.You will find the upper shift rod and coupler in the "control" sub heading. The lower shift rod is in the "lower casing" sub heading. Good luck!!!

 

[Fish Hawk 52]

Re: 9.9 Yamaha seized shift shaft coupling

Thanks, that's it. Appreciate the help, hope the rest goes smoothly.