Saildrive Prop Shaft Repair

[perchance]

Make sure they do a run-out check for straightness AFTER the repair. Run-out specs vary with manufacturers but should be no greater than .005".

[svcattales]

Originally Posted by perchance

Make sure they do a run-out check for straightness AFTER the repair. Run-out specs vary with manufacturers but should be no greater than .005".

Thanks again for the help Perchance. How is a "run-out check" done?

[GordMay]

Runout is measured with a dial indicator/gauge, whilst rotating the shaft in a lathe. The dial indicator measures any deviation from round, at various locations along the shaft.

[svcattales]

Originally Posted by GordMay

Runout is measured with a dial indicator/gauge, whilst rotating the shaft in a lathe. The dial indicator measures any deviation from round, at various locations along the shaft.

Thanks Gord.

I went back to the welding shop who gave me the estimate and discussed their technique. They don't do metal spraying and they agreed that conventional welding might be too risky. They did offer to make sleeves for the shaft and turn down the diameter of the shaft slightly so with the sleeve the shaft will be back to original dimension. I'm not sure I want to do this, but it's another option.

I found another machine shop that claims to do metal spraying, but they wouldn't make any judgements until they see the shafts. I can't show them the shafts until I haul the boat so this is an "iffy" plan.

I think I'm back to speedi-sleeves if I can get the right size. I ordered new shaft bearings which are a press fit onto the shaft with the same diameter that I'll need for speedi-sleeves. When the bearings show up I can check inside diameter and then see if I can find a match in speedi-sleeves. Anyone know the cost of speedi-sleeves? I'll need four of them.

[Jeannius]

I'm following this one with interest Greg as I have one shaft that looks like yours. So far I've just had the shaft 'shimmed' to move the point of contact and that seems to be working just fine.

[Dragon Lady]

There are a few different opinions here, strongly suggest you check with the manufacturer before doing any repairs unless the shop is going to guarantee the repair.
That would include repairs to you boat if the worst happens.
If you are going to weld, you must know the spec of the shaft material.
Hope it works out for you.

[svcattales]

Originally Posted by Jeannius

I'm following this one with interest Greg as I have one shaft that looks like yours. So far I've just had the shaft 'shimmed' to move the point of contact and that seems to be working just fine.

I'm interested in how you shimmed the shaft to move the contact point? I couldn't figure out how to move the shaft in or out since it appears to be captive on both ends.

I'll report back when I decide on the appropriate fix and after the repair is done. The UPS guy just delivered the shaft bearings and their inside diameter is 1.25" as close as I can measure and that is one of the sizes of speedi-sleeves. I'm going to a machine shop for an accurate measurement since I need a measurement down to the .001". I'm assuming that since the bearings are a "press on fit" that dimension should work for spreedi-seals too. According to the catalog, the speedi-sleeve can be .003" bigger or smaller than actual shaft diameter;.e.g, the 1.25" speedi-sleeve fits a shaft diameter between 1.247 & 1.253.

[kiltym]

I have SD20's. There is a set of shims on the shaft to allow you to adjust the wear point on the shaft.

I think you will have 2 installed by default, if you remove one you will have a clean surface for the seal again. This was done on one of mine last year by a Yanmar mechanic. There are 2 seals, so presumably 2 sets of shims but I can't remember off the top of my head.

We had speedi sleeves put on before, but on this one we removed them. The mechanic said if you put the sleeves on you have to use different seals as the diameter is obviously bigger. And he also said there is no real good reason to do this since Yanmar already has shims installed for this very purpose.

Of course it was also a Yanmar mechanic that put the sleeves on in the first place.

I guess they went to two different Yanmar schools.

Had I known what I do now, obviously removing the shim seems like the correct procedure.

Not sure if it's possible on Volvo's or not but wanted to add the info to this thread to help others perhaps.

[Jacana]

Recently had both of my shafts built up and reground total cost $1023.00 .The cost to re-build the seal surface was $250 per shaft,rest went towards new seals o-rings and anodes.Guaranteed to be better than original,my SD20 legs have done 3000 hours on the motors and around 30,000 ks.under sail.Have done over 100 hours since rebuild and are silky smooth.
Cheers
Geoff.

[svcattales]

I'm hauling out next week. It's decision time on the prop shafts and I need some last minute advice.

I visited 3 different machine shops and talked to two others on the phone. I could not find a "metal spraying" shop in my area and I definitely don't want to risk welding. That leaves me with 2 options: 1. a machine shop will mill a few thousands of an inch off the shaft and put on a sleeve that will bring the shaft back to same diameter. OR 2. put on Speedi-sleeves myself.

I like the machine shop sleeve option since one sleeve will cover both sealing grooves. This process involves cooling the shaft and heating the sleeve and sliding the sleeve into position while hot. My concern on this process: will there be small crevices where seawater can get in between the sleeve and the shaft or will this be so tight that no water can get in. If any seawater gets in this could be an oxygen starved environment that causes stainless to corrode. What do you think... will water get in?

The Speedi-sleeve option requires 2 sleeves per shaft and it will be a thinner sleeve than machine shop option and may not last as long. On the plus side, I can put a thin layer of loctite on the shaft and possibly get a better water-tight seal between the shaft and the sleeve. Also, the loctite may prevent any galvanic action between shaft and sleeve. The Speedi-sleeve increases the diameter of the shaft slightly so seals may not seat as well.

Which option would you choose... machine shop sleeve or Speedi-sleeve?

I would appreciate some last minute advice.

[perchance]

I wouldn't be too concerned about the increase in dia. from the Speedi sleeve. The seals you are using have a small "garter" spring to keep the seal lip in contact with the shaft.In my line of work we use these sleeves all the time with no issues.

I have no personal experience with your drives so can't comment on the shim removal mentioned in a previous post.
In general the shims in a drive are designed to set gear lash, bearing preload or pinion height.
I would not recommend fooling with the shimming without consulting someone familiar with your particular drives.

[colemj]

On our Volvo 120S saildrives, the shims are placed under the seals in the seal housing. Adding or removing shims would change the relative position of the seals on the shaft. They are available from 0.1mm to 0.5mm and can be stacked. These are not shims that change the position of the shaft - just the position of the seals on the shaft.

Mark

[perchance]

That sounds like a clever idea.

[colemj]

Just want to clarify - I didn't put the shims there, it comes from the factory that way. Different sized shims can be ordered.

Mark

[rolandcavanagh]

I'll preface this saying that I'm a lazy and cheap Mechanical Engineer, meaning that I look for an effective solution that is easy and inexpensive, and I've been around a lot of mechanical stuff... If it were mine, I'd be looking at:

1. Repositioning the seals - adding a shim behind the seal to move it to a new place on the shaft - if there is room. Result is shafts with grooves that will get new grooves years from now. (I'm interested in the discussion about shimming the shaft, but, as others have said, I'd have to know what the arrangement is)

2. Chrome plating or metal spraying then grinding. Both are well accepted common practices. I agree with the shop that wouldn't quote it until they saw them, respect that as a sign of a good shop. End result is shafts better than new.

Sleeves work fine in safe environments, but with one side exposed continuously to sea water, I'd be very concerned about galvanic action or bonding agent (glue) failure or cutting the seal during installation, etc, etc. I'd consider this a "get-home" solution...

#1 should be easy to investigate - is there room for the seal to be further out say .015" or .020"? If so, have a shop turn a circular shim.
#2 I'd be calling around lining up shops to take the parts to for estimates. I'd plan on a day running around, and the possibility of rush charges if in a hurry. Could find the services on the Internet, but have to ship and "trust" that they will be done right.

Easy for me to say... if it were mine... hope this helps.