1 GM Gearbox Swap

[geoffdan]

Is it possible to swap a Yanmar 1 GM gearbox without removing the prop shaft?

 

[Tranona]

Depends on how far you can push the shaft back when you disconnect the coupling.. The gearbox needs to slide back far enough for the input shaft to clear the drive damper on the flywheel.

 

[garymalmgren]

Is it possible to swap a Yanmar 1 GM gearbox without removing the prop shaft?
You have to remove the pro shaft from the gearbox.
Are you meaning removing the prop shaft from the boat. if so that all depends on how much room you have.

Photos would help.
Three options.
1. Disconnect gearbox from shaft. Push coupling and prop shaft back. Disconnect gear box from engine. Push gearbox back. Then how do you get the gearbox out over or around the engine.
2. Disconnect engine and gearbox from shaft.
Pull both forward into the cabin. Disconnect gear box and remove it from boat.
3. Disconnect engine and gearbox from shaft.
Pull both forward into the cabin. Remove both from boat as one unit..

Without a lot of information, I would go for the third option

PS. Do you have a removable cockpit sole?

Gary

 

[DownWest]

What Gary said. You should be able to slide the engine forward enough to get the box out. Though, if you have a shaft seal of the older type with packing, rather than a face seal, you might be able to slide the prop shaft back enough to get the box out.

 

[geoffdan]

Is it possible to swap a Yanmar 1 GM gearbox without removing the prop shaft?
You have to remove the pro shaft from the gearbox.
Are you meaning removing the prop shaft from the boat. if so that all depends on how much room you have.

Photos would help.
Three options.
1. Disconnect gearbox from shaft. Push coupling and prop shaft back. Disconnect gear box from engine. Push gearbox back. Then how do you get the gearbox out over or around the engine.
2. Disconnect engine and gearbox from shaft.
Pull both forward into the cabin. Disconnect gear box and remove it from boat.
3. Disconnect engine and gearbox from shaft.
Pull both forward into the cabin. Remove both from boat as one unit..

Without a lot of information, I would go for the third option

PS. Do you have a removable cockpit sole?

Gary

 

[geoffdan]

Thanks Gary,

You've provided the solution. No easy access to the gearbox or prop shaft, so shaft push back will have to do. I'll make the most of it and redo the stuffing box.

What Gary said. You should be able to slide the engine forward enough to get the box out. Though, if you have a shaft seal of the older type with packing, rather than a face seal, you might be able to slide the prop shaft back enough to get the box out.

Thanks Downwest. It'll be a shaft push back as you and Gary suggest. I can get the gearbox out through an access hole in a side locker.

 

[Stemar]

Top tip - as soon as the end of the shaft is clear of the coupling, tighten a jubilee clip round the end so it can't escape

 

[geoffdan]

Thank you.

 

[DownWest]

Done this a couple of times on a 27ft. Access was awful, only past the engine, or from the stb stern locker. So we cut a hatch in the port quarter berth side wall. Much easier with that!
No need to remove the flange from the shaft, just unbolt it. Limiting factor is the distance to the rudder, or how close the stern gland is.

 

[geoffdan]

Thanks. I have access through the port locker, and I think I've got just enough distance to the rudder to slide the prop shaft back enough to make the swap. Mine is a 7.1m Spacesailer, in Tasmania. This is a great forum. Thank you all contributors.