Saildrive folding prop wobbles

iandwall

iandwall

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I have a Volvo 120S saildrive with a 2-bladed folding prop. When I got the boat last May the prop was apparently loose on the prop shaft. In fact it wasn't a loose locknut, but possibly wear in the prop or maybe a missing spacer.

We added a nylon spacer behind the prop which seemed to do the job, but now the boat is out again it's the same as before. Around the yard there are a few others with a similar 'wobble'.

Is anyone familiar with this, and have a solution (other than buying a new prop of course)?

Thanks
Ian
 
The blades always wobble once they wear a bit (about 4 or 5 years), eventually you may have to have them bored out and new pins made, but if the hub is loose as you suggest that is very different. I have never encountered a loose hub so I am surprised that you have seen several. If it is a bronze prop. on a ss shaft it may need an anode as I think the leg anode does not protect the prop.
 
If you go to www.ropestripper.com (ambassador marine) you will see clear illustrations of different saildrive/ prop combinations, written for fitting a stripper it will also show you what should be there before. There is a washer thing behind the prop. which they remove to fit the stripper, the splined shaft and then the cone nut arrangement. I am about to take my prop. off to fit said stripper so I can take some pictures of what is there for you if that helps.
 
Where is the wobble. Hub/spline, spline/shaft or shaft/leg. There is a line cutter behind the hub which incorporates a spacer, if this is missing hub is likely to wobble as the shouldered shaft will prevent tightening without the spacer. If between Hub/spline may be the pressed insert is loose in the outer hub, which can be replaced, I think.

I have a VP 2 blade folding prop assembly ( Hub No 3858508L) for sale if you need replacement.
 
It's not shaft in the leg, but without taking the prop off I can't be sure about whether it's the insert on or not. The line cutter is there, so if the spacer is integral to it, thats presumably there. Otherwise may be thats the problem.
 
If the propellor splines are worn the bush can be renewed.

IMAG002.JPG


Steel Developments have a rebushing service (click here)
 
Took mine off this morning, coming forward (sorry aft) from the leg, the first thing is a stainless steel bush about 30mm. long which acts as a spacer for the anode, then the hub, then a bronze bolt device which incorporates a ss steel stud which screws into the end of the shaft with a tab washer to lock it. The spacer is omitted when the stripper is fitted. I took photos but they are not as clear as the ones on the Ambassador website www.ropestripper.com because they have cleared all the grease away for theirs.
 
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Having taken my prop off and had a good look at it I have discovered that the splines and the biggest part of the hub are stainless steel, they are isolated from the bronze hub by a delrin or similar sleeve abot 2.5 mm thick which goes right throug the prop from the front to the retaining nuts. Everthing inside is stainless and only the outer 10mm. or so of the shell plus the back where the pivot pins are is bronze. Obviously this is to isolate dissimilar metals. ( I hope Volvo has taken similar trouble with the leg itself) This insert might be where you problem lies; alternatively your prop. might be one of those with the spline kit inserts shown above. The latter can probably be replaced but if it is a thin sleeve like mine I suspect it would be very tricky. It may be difficult to replicate the movement with the prop. off the shaft, but if it is as loose as you suggest I am surprised that the inner part of the hub will not turn inside the outer shell. Worth trying to rotate the prop back and forward while the shaft is held, worn splines will not allow very much movement but the worn sleeve may permit more.
Hope this helps but it sounds as if it might be a new prop.
 
iandwall said:
I have a Volvo 120S saildrive with a 2-bladed folding prop. When I got the boat last May the prop was apparently loose on the prop shaft. In fact it wasn't a loose locknut, but possibly wear in the prop or maybe a missing spacer.

We added a nylon spacer behind the prop which seemed to do the job, but now the boat is out again it's the same as before. Around the yard there are a few others with a similar 'wobble'.

Is anyone familiar with this, and have a solution (other than buying a new prop of course)?

Thanks
Ian
Click to expand...

The prop hub must be secure on the splined shaft - there is no provision for movement here and packing or whatever must be applied to stabilise this part of your rig. The moveable blades are something else and if only they are the problem you may have to refit the bearings/securing bolts etc.

PWG
 
iandwall said:
Thanks for all the info - mines an aluminium prop (should have mentioned that in the beginning really), so may be different.
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Are you sure? I was not aware that anybody made aluminium folding props. I have only seen bronze ones, but I think some of the early ones may have had an aluminium core to the hub.

As others have said, there is no way the "wobble" can be between the splines on the shaft and those in the hub. It is much more likely to be a failure (not uncommon) of the rubber bush in the hub.

Find out what make of propeller it is and go back to the manufacturer for advice.
 
prop wobble

iandwall said:
I could well be wrong - I just assumed its aly because its painted the same as the saildrive leg - I'll have a much closer look.
Click to expand...

Hope I have understood your question correctly and that is that the prop hub is loose on the shaft at the anode end.
If indeed that is correct then the problem is the bush inside the hub is worn. It has been said that these can be pressed out and renewed but it is not advised. So sad news is that a new hub is required. Had the same problem and went for a fixed blade in the end.
Apparently the problem with these Alloy props is that the blades are too heavy therfore over time the bush wears out. I have had 2 of these hence the change to fixed. New hubs are not cheap.

Good luck
 
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