Problemes DRAFT SD 50 YANMAR Cone réparations

Bonjour,

je n'ai aucun intérêt direct dans cette saga mais les fils durent depuis des années sur LATITUDE 38. Ca touche plus souvent les catas qui ont en général des SAILDRIVE
Apparemment YANMAR s'est planté et les "cones" s'usent très vite au point qu'il est recommandé pour les grands voyageurs d'en avoir un en stock. la réparation est considérée facile par certains et compliquée pour d'autres
je n'en sais pas plus

les liens
taper dans Google

draft sd50 cone repair procedure draft rev1.docx

et vous aurez pleins de liens
ci dessous d'une discussion sur LATITUDE 38? EN ANGLAIS SORRY

MORE HELP FOR YANMAR SD CONE CLUTCHES
We're operating on the assumption that the Yanmar SD cone clutches have somehow not all cured themselves into perpetuity, and thus offer the following help to owners of boats with those transmissions.

The suggestion is to Google "Draft SD50 Cone Repair procedure Draft Rev1.docx," which will take you to a portal, . There readers will find a 3 MB file showing them how to try to effect repairs. Depending on the severity of the problem, the cone clutch can either be lapped successfully, or have to be replaced. In either case, it can apparently be done by a cruiser with average mechanical skills.

A gentleman named Nigel Davis wrote about his experiences with the SD50 cone clutches on his Lagoon 400 catamaran. His starboard SD clutch started slipping after 500 hours. The local Yanmar agent in Hong Kong fixed it by re-shimming the cone clutch — as opposed to the much more common solution of lapping of the cone. That cone clutch is still running fine after 400 hours.

He then took his catamaran to the Philippines, at which point the port cone clutch started to slip, which was after 900 hours of use. "I was about as far away from help as I have ever been," he wrote. "Operating on one engine is not too bad once you get the hang of it, but I recommend everybody practice before they need to do it, especially maneuvering in tight spaces at slow speeds."

He reported that, using the instructions that a number of Lagoon owners have posted on various sites, he was easily able to remove the clutch himself in only about 30 minutes. But he was unable to undo the top nut on the clutch unit.

"You need a 27-mm socket and some way to hold the spline still without damaging it," he reported. "Others have used aluminium strips in a large vise in lieu of Yanmar's special tool. This technique did not work for me, as the spline slipped in the vise and cut the aluminium even when the vise was done up very, very tight. In the end I brought the clutch back home to Hong Kong, where the dealer fitted a new cone and re-shimmed it. He says lapping is not a long-term fix."

The Internet instructions say to "use a 27-mm spline socket available from Sears" to hold the spline. However, Nigel was unable to find a suitable spline socket, either locally or on any international websites. Nigel asked the Yanmar dealer what he used to hold the spline, and the agent said he uses a part from a trashed saildrive that the spline fits into. Apparently the Yanmar special tool is too expensive for even the dealer.

By the way, the best cone clutch repair instructions I've found were those that seemed to actually be issued by Yanmar on . These have more detail than those put together by fellow owners, although all help.

I hope this helps.

Joy Weis Kass and Walt Kass
Joy of Tahoe, Lagoon 440
Currently at Marina di Ragusa, Sicily, Italy

Joy and Walt — Thanks for forwarding those additional instructions from Yanmar and for Nigel's comments.

Latitude readers may remember that we — actually our crew Dino — did most of such a repair on both of Profligate's cone clutches about 18 months ago. We also went on a wild goose chase in search of the recommended 27-mm socket that was supposedly available at Sears and everywhere else. We not only couldn't find one in Mexico, we couldn't find one in Colorado either. We later found out that we didn't need one.

We made repeated attempts at getting the cone clutch assembly apart by putting it into a vise cushioned by aluminum plates. Nothing, not even attempts using a very long extension, worked. Someone later suggested that maybe the nut had been put in place with Lock-Tite. So we heated the nut up to break the Lock-Tite and tried the vise again. The assembly came apart rather easily! The fact that nobody had mentioned the Lock-Tite wasted a day or two of our lives.

As for the agent re-shimming Nigel's cone clutch, perhaps that had been the problem. The tolerances are so tight on each saildrive that they, as we understand it, have to be custom shimmed. Doing something like that is far above our register, so it's lucky that we didn't have to do it.

We and Dino lapped the cone clutches, after which they worked fine. That was 18 months ago, so while it may not be a permanent fix, it's worked that long. We don't mean to disagree with the Yanmar dealer in Hong Kong, but we don't think there is such a thing as a permanent fix on the SD saildrives. Among our semi-solutions is, as ridiculous as this sounds, to shift as seldom as possible.

As for Nigel being able to get the hang of maneuvering with one engine at slow speeds in tight quarters, we need to point out that there is a huge difference in trying to do this on a cat with keels — such as the Lagoons and our Leopard 45 'ti Profligate — and cats with daggerboards such as Profligate. It's quite possible in the former boats, and very, very difficult — if not impossible — in the latter. It also makes a lot of difference which engine goes out.

As far as we're concerned, using the instructions from Yanmar and others, it is quite possible to remove, disassemble, and lap a SD cone clutch assembly. Some cone clutches are too badly damaged to benefit from relapping, in which case you need to replace the $600 part. Other cone clutches can be relapped for further use for an indeterminate amount of time. We recommend that anyone with SD transmissions always carry at least one spare cone clutch.