Separating prop shaft from gearbox to allow replacement of Volvo shaft seal

Modulation

Modulation

Well-Known Member
Joined
30 May 2001
Messages
495
Location
finder
Visit site
My shaft seal has done 20+ years with minimal maintenance and problems. This year, however it't started to leak and it needs to be replaced. To do this I need to uncouple the shaft from the flange which attaches it to the gear box so that I can draw the shaft back a bit thus facilitating removal of the old seal and fitting of the new one. The trouble is that the flange which attaches the prop shaft to the gear box looks pretty corroded - at least around the bolt and bolt heads. AND the flange isn't in 2 parts which bolt together. It's a single unit with a cut into its diameter - that, presumably, to facilitate the original assembly when the shaft was inserted into it prior to tightening up the bolts and closing the cut over the shaft.
I've done a search on the forum to see how to approach this but most replies seem very pessimistic with the only reliable solution being to cut the flange up with an angle grinder and replacing it completely. Clearly to be avoided if possible so any other ideas/ experiences welcome.
Would a penetrating oil offer any serious help?
Thanks all.
Photos attached
 

Attachments

  • 2013_0705OandJ0184.jpg
    2013_0705OandJ0184.jpg
    92.7 KB · Views: 2
  • 2013_0705OandJ0185.jpg
    2013_0705OandJ0185.jpg
    91.6 KB · Views: 2
I would split from gearbox ,support the shaft then push back towards your seal assuming the rudders not in the way. Lot of penetrating oil night before remove the fixings " wedge split " your coupling and remove with a puller the coupling from the shaft ie pull it off backwards. Check your shaft is true and has no crevice corrosion then rebuild with new fixings. All assumes reasonable access which from the photos you appear to have, good luck!

John

Ps that's not in the great scheme of things a corroded coupling
 
If you look on my website under 'stern gear' you will see a good desl of experience and examples of the problems people have faced. The easiest way to get the shaft out of the flange is to split it from the gearbox, put a thick nut or something similar against the shaft, then re- attach the flange using longer bolts. This will push the shaft out. Diagram on the page.

However, your first problem will be to loosen the additional bolts that presumably locate the shaft in the flange. A good dose of penetrating oil will be a useful start.
 
I did mine when I fitted a volvo seal by removing the coupling bolts, replacing with longer HT ones and tightening evenly down on a socket that was slightly smaller diameter than the shaft. I obviously removed the through bolt and grub screws that went from the shaft side coupling into the shaft.
Lots of penatrating oil first-and leave it to soak if you can.
Good Luck.
 
Once you've removed the through bolt and the 2 Allen bolts, you can use the Allen bolts to open up the clamp, making it easier to remove the shaft (and to reinstall it too). Reverse the Allen bolts, screw them in to the threaded holes, place a piece of sheet steel in the slot each side, and tighten the Allen bolts against the sheet steel, prising the coupling open slightly.
 
Many thanks for all your extremely helpful replies.
I am going to the boat tomorrow with a great deal more confidence than I had before reading the replies!
 
Lots of penetrating oil.... over days, not hours.

If in doubt, cut it off, its far cheaper to replace than the output flange on your gear box!!!!!
 
Modulation said:
My shaft seal has done 20+ years with minimal maintenance and problems. This year, however it't started to leak and it needs to be replaced. To do this I need to uncouple the shaft from the flange which attaches it to the gear box so that I can draw the shaft back a bit thus facilitating removal of the old seal and fitting of the new one. The trouble is that the flange which attaches the prop shaft to the gear box looks pretty corroded - at least around the bolt and bolt heads. AND the flange isn't in 2 parts which bolt together. It's a single unit with a cut into its diameter - that, presumably, to facilitate the original assembly when the shaft was inserted into it prior to tightening up the bolts and closing the cut over the shaft.
I've done a search on the forum to see how to approach this but most replies seem very pessimistic with the only reliable solution being to cut the flange up with an angle grinder and replacing it completely. Clearly to be avoided if possible so any other ideas/ experiences welcome.
Would a penetrating oil offer any serious help?
Thanks all.
Photos attached
Click to expand...
Thats an easy one! The nut and bolt is used to tighten the split up. A bit rusty, so dose with freeing oil, try and clean the threads above the nut and undo it. You could split the nut if necessary with a cold chisel.
Leave the flange connected whilst working on this. Get an old screwy in the split to wedge it open a bit. Then undo the flange bolts, again a bit of work with freeing oil. Check to see if there is a nut inside the flange. If there is, remove it, then see if easing the split allows it to pull off the shaft.
On second look, get the bolt out, thats what secures the shaft and loosen the allen screws, even easier, no internal nut on the shaft.
S
 
Last edited:
You must log in or register to reply here.

Share this page

Top