Saildrive Prop Shaft Repair

[svcattales]

The prop shafts on my Vovo 120SD saildrives have been scored by the rubber seals. The seals are still keeping the oil in and the water out, but I want to repair the shafts next haulout if possible.

See pictures below to see the double grooves formed by the rubber seals over many years of use. Can these s/s shafts be repaired or filled by carefull welding and polishing? The cost of new shafts are prohibitive.

[ggray]

I've read that the shaft--or seals--can be shifted longitudinally slightly to yield a different contact point. This was Yanmar, but i expect they are compareable.

Or there may be available a wear sleeve that can be slid on the shaft.

But the shafts could be built up and turned down. Not sure how much that would cost.

[svcattales]

Thanks Ggray,

I need to find a machine shop who might tackle this one. I suspect it is a very specialized skill to weld the stainless without changing the temper of the metal.

[ggray]

Be sure to get an estimate first!

[Dragon Lady]

You should be able to buy thin SS sleeves to fit the shaft, I think they are called seal savers.

[Dragon Lady]

Sorry they are called Speedi sleeves, seal savers are for dirt bike forks.

[perchance]

Originally Posted by svcattales

The prop shafts on my Vovo 120SD saildrives have been scored by the rubber seals. The seals are still keeping the oil in and the water out, but I want to repair the shafts next haulout if possible.

See pictures below to see the double grooves formed by the rubber seals over many years of use. Can these s/s shafts be repaired or filled by carefull welding and polishing? The cost of new shafts are prohibitive.

The usual procedure to repair a grooved shaft is to hard chrome plate and regrind. Provided they are not too deeply scored. Shifting the seal or using a Speedy Sleeve are both good alternatives.

[svcattales]

Originally Posted by perchance

The usual procedure to repair a grooved shaft is to hard chrome plate and regrind. Provided they are not too deeply scored. Shifting the seal or using a Speedy Sleeve are both good alternatives.

Thanks Perchance and Dragon Lady. I really appreciate your great ideas. I'll check into the Speedy Sleeves and the chrome plate/regrind options.

[Dragon Lady]

The hard chrome method is the best but quite expensive if you do it right.
You can put 0.0005' of hard chrome on without grinding but once you go over that you must grind and I would say you have a fair bit more than half a thou wear.
So you will have to grind back all the wear then plate several time to get even build up of hard chrome then grind again to nominal size.
That said you will have the best shafts in the world after that.

[svcattales]

Originally Posted by Dragon Lady

The hard chrome method is the best but quite expensive if you do it right.
You can put 0.0005' of hard chrome on without grinding but once you go over that you must grind and I would say you have a fair bit more than half a thou wear.
So you will have to grind back all the wear then plate several time to get even build up of hard chrome then grind again to nominal size.
That said you will have the best shafts in the world after that.

I'm doing a haulout in 3 weeks and I found a machine shop that would fix the shafts for a good estimate (about $140 for both). I need to ask more questions before I do this, but I think they intended to put a weld bead in grooves and then turn the shafts in a lathe to the original diameter. Is this an acceptable fix or should I pursue the "hard chrome" fix instead? I'm worried about using a welding rod with a dissimilar metal and causing corrosion. Also, I'm concerned about changing the temper of the shaft with heat. Both situations could cause a worse failure than leaking seals.

I did check out the "Speedi-sleeve" solution also. The problem with this solution is the length of the sleeves along the shaft. There is about 3/4" between the groves and the sleeves are only about 1/2" long in that diameter. I would need 2 sleeves per shaft and then have to cut off the flange on the aft most sleeve. There are instructions on how to remove the flange when tolerances are tight and it is scored to allow removal. I would have to carefully dress down the place where the flange is removed so I don't cut the rubber seals during installation. The other thing that worries me about the speedi-sleave is the opportunity for corrosion from dissimilar metals.

I would appreciate some more advice on this subject, because there is an opportunity to make some very expensive mistakes here. Thanks.

[Dragon Lady]

I would be very careful welding the shafts unless the manufacturer says that is OK.
Stress cracking would be my major concern rather than corrosion.
It all comes down to the material that the shafts are made from.
Some metals are safe to weld and some are not.

[rolandcavanagh]

A common technique is 'metal spraying' - they vaporize a compatible metal which bonds to the surface, then grind it back. A good machine shop should know where to get this done - very common on manufacturing and farm equipment. Doesn't damage the microstructure of the shaft, result is as good as new. I wouldn't recommend welding or sleeving. Good luck,

[svcattales]

Originally Posted by Dragon Lady

I would be very careful welding the shafts unless the manufacturer says that is OK.
Stress cracking would be my major concern rather than corrosion.
It all comes down to the material that the shafts are made from.
Some metals are safe to weld and some are not.

Thanks Dragon Lady. Good advice. I doubt that a welder would be able to determine the type of alloy in the stainless and I doubt Volvo would tell me either when they would rather sell me new shafts. I think I'll go back to the sleeve idea. If I put a thin layer of loctite between the sleeve and shaft it should minimize any dissimilar metal corrosion and not weaken the shafts.

[perchance]

We install Speedy Sleeves using 680 Locktite so that should isolate the two metals.
As regards welding the shafts, it can be done provided proper pre-heat/post-heat techniques are used. As mentioned above, spray welding is an excellent alternative.

[svcattales]

Originally Posted by rolandcavanagh

A common technique is 'metal spraying' - they vaporize a compatible metal which bonds to the surface, then grind it back. A good machine shop should know where to get this done - very common on manufacturing and farm equipment. Doesn't damage the microstructure of the shaft, result is as good as new. I wouldn't recommend welding or sleeving. Good luck,

Thanks Roland. Another great idea. I'll check this option too. The machine shop I mentioned specializes in farm equipment repair, so it's possible they use that technique. I need to ask them some more questions.