how big a problem is sd 50 cone clutch

[kcj]

Originally Posted by Tornadosailing

Can someone elaborate on the need for a Dremel and cutting wheel? What exactly needs to be cut?

Re Dremel
1. I needed the Dremel to cut out the deformed tab which holds the top nut on the cone. Some can get it off with out cutting. I could not.

2 doing the upgrade kit—you need to grind away part of the housing to fit the larger top nut....Dremel works. A machinist lathe would be better

[HeinSdL]

This winter I serviced my SD40 (having neglected it a little bit for a couple of seasons and having occasionally not engaged in fwd gear) and have the following thoughts.

1. The two seals on the prop shaft were quite corroded (or at least the circular springs holding them in place, also effecting the quality of the rubber itself). Given how often I hear of water entry into these units, I will definitely add these items to the list of regular replacements. Replacing them turns out to be quite straightforward but I did devise some special tools (remove prop and anodes, take out 2 M8 bolts, insert 2 M8 studs, replace triangular anode fixing brackets and then with 2 M6 bolts gently push out the whole assembly).

2. Lapping procedure can be done without a yanmar 'degree', only point is that the special tool required to hold the central axle is expensive, better to buy the spline which also sits in the saildrive and weld that onto a metal bar to hold firm.

3. While you have the axle out of the unit, add a second notch so old nuts can be re-used.

4. The actual shift lever also has some shins. I havent touched these yet but if the drive again fails to engage reliably, taking out 1 shin will push the shifter closer towards the cone assembly, thereby also encouraging the cones a bit more to engage.

5. Oil. It would appear choice of oil is really important. Last season I think I used the mercury brand which may have contributed to the slipping. It's simply too good? Too good at lubricating meaning the cones lose grip?

So let's see how this season goes...

[arsenelupiga]

i know exactly when my starboard cone started slipping and why.

Reason was because my folding prop has not folded and rotated during sail. I have noticed this at some point and switched to reverse which has resolved issue. Do not bother switching to reverse as always propellers fold. I have now changed this practice.

However, this is exactly time I got first slippage. Presume non 100 % engagement wears out mating surface in hour or so.

Lapping is no big deal.Panache was really helpful. I fear slipping cone NOT any more

[Tornadosailing]

Originally Posted by HeinSdL

5. Oil. It would appear choice of oil is really important. Last season I think I used the mercury brand which may have contributed to the slipping. It's simply too good? Too good at lubricating meaning the cones lose grip?

So let's see how this season goes...

In another thread we discussed at length the choice of oils. It would seem that the oil you put in the unit is at least as important as maintaining proper clearances. Probably more so. The cone clutch design is built on the same principle and with the same materials as a manual transmission synchronizer. Manual transmissions don't last with GL-5 in them. I'll be changing the oil in my Saildrives to GM Synchromesh fluid on Thursday. Synchromesh is GL-4 with friction modifiers added to help the cone clutches in a transmission (synchronizers) work smoothly.

[HeinSdL]

Originally Posted by HeinSdL

5. Oil. It would appear choice of oil is really important. Last season I think I used the mercury brand which may have contributed to the slipping. It's simply too good? Too good at lubricating meaning the cones lose grip?

I correct my comment above, having been on the boat last weekend and having taken another look at the oils I used. For the 2017 season I used Yanmar GL-5 grade oil in my SD40 and the cones slipped. Now I have Mercury GL-4 grade oil and the cones are good. (Though I also lapped them which no doubt helps too. But the GL-5 vs GL-4 discussion for me is now completely clear, as per earlier comments too.)