Help moving my prop shaft - in the water

[PNM]

I have a port engine velvet drive transmission with a slow drip at the back of the reduction gear - just in front of the reduction gear-to-prop shaft flange.

I suspect the rear seal.

I've disconnected the prop shaft flange from the reduction gear flange and the prop shaft turns freely - but the prop shaft has not moved aft yet.

I took a little pressure off of the stuffing box but the prop shaft did not move easily. (by the way, the stuffing box did not drip, so maybe I need to release some more pressure.)

How can I best put pressure on the shaft without breaking something? I only expect it to move +/-1/2" because I painted the shaft with bottom paint for metal and don't expect it to go through the aft prop shaft bearing just in front of the prop. But, I would like to move it a little, just to make sure I don't have another problem - before the diver shows up - on the clock.

I plan to have the diver scrape the shaft to about 4" in front of the bearing so I can move the shaft aft far enough for the mechanic to remove the reduction gear. He will replace the seal at his shop.

Final question. How long is the spline between the reduction gear and the VD transmission? That will tell me how far I need to move the prop shaft aft.

Thanks for your help.

 

[SoWhat]

I wrapped my shaft with a scrap piece of EPDM rubber roof. then used a pipe wrench to 'walk' shaft back.

If I recall correctly the rear seal can be installed while tran is still mounted. It can be tapped in with light hammer. Use gobs of RTV during install.

 

[SteveK]

yes turn shaft and push aft at the same time. Walk it back

 

[rslifkin]

When I needed to do this at one point, we used the pipe wrench trick for the first 1/2 inch or so (needed about 3 inches in this case), then used 2 pieces of metal with appropriate holes, threaded rod and nuts as a spreader tool to gently push the shaft back the rest of the way.

 

[Redhook98]

If you have barnacles or other growth on the shaft, it makes it more difficult going thru your cutlass bearing. You will hear crunching.

 

[PNM]

Thanks for your inputs. I will try a piece of rubber with a hose clamp.

I have a place to lever against the floor through an access port. Once started, I think I can also use a lever with protective plastic or rubber between the faces of the flanges.

There is only about 6" between the back lip of the reduction gear and the bulkhead, so It would be pretty tough breaking loose the 200 ft-# torqued nut that holds the flange to the gear box shaft, then removing and replacing the seal without being able to see what we are doing. I am also worried about scratching the race with a screwdriver while removing the seal, since I cannot get my head behind the gear to see what I am doing.

The mechanic has done this for 30 years and thinks pulling the gear box is easiest and lowest cost. He also estimated a $1000 less than another mechanic that was going to do it in place.

I am just doing the pre-removal work to reduce his hours and lower the cost.

And I will use a diver to clean the shaft prior to fulling moving the shaft back, since I coated the shaft with underwater 2 part metal paint.

Have a great day.

 

[diver dave]

I locked the flange against the hull using a couple of bolts and two nuts each, allowing a rod or something to jam it stationary. Without being there, hard to comment on the in vs out of boat option.

 

[BeeJay]

If you have a spare shaft zinc, you could temporarily fix it to the shaft and push or lever off that. Ideally with a bearing puller. Check also that there is not an additional set of threaded holes around the flange that lead to face of the gearbox flange. This is sometimes done to allow to use a number of threaded bolts to break to initial stiction. Of cause we are all assuming there is no thrust collar somewhere along the shaft or line cutter in close proximity to a support or something preventing free axial shaft movement.