Getting shafted

[Topcat47]

Last season, my shaft walked around 1/2 inch up inside the coupling, causing no little embarassment when the DSS leaked on two occasions.

I thought it was the seal slipping back up the shaft so I put an extra Jubley on the shaft. When the boat came out, the true horror wqas revealed and I'm putting it back in the water soom.

Has anyone got an idea of what the torque on the Yanmar coupling Allen screws should be, clamping the coupling to the shaft? I'm adding a couple of grub screws to the coupling as well, but I mainly need to get the clamp tight without stripping the threads or stretching the bolts too much.

 

[Heckler]

on my bene 351, the split coupling is clamped on by allen screws, as tight as i could get them with a 14 mm double ended ring spanner used as the sweat bar on the allen key, 14 stone on an 8" spanner!!
stu

 

[wotayottie]

should have a roll pin or a bolt through the coupling and the shaft ie drill a hole through the lot.

 

[damo]

My local marine engineer thinks that a bolt through the lot is a bad idea - he has recently had one that sheared, due to the weakening of the shaft in that area. (Rope on prop, sudden stress, snap)

A nut on the end will stop the shaft slipping back, without weakening it within the coupling.

 

[rogerthebodger]

Remove the grub screw and drill a dimple into the shaft through the grub screw hole in the coupling and then replace the grub screw. I you can get a dog point grub screw all the better.