Excessive Wear on SD40 Yanmar Cone Clutch

[Northeaster]

4Waves - I do not have a saildrive. I have an older 2Gm with the Km2a cone clutch. I do have a spring joint om mine, at the end of the cable, where it attaches to the gear select lever.

Do not think that proper cable adjustment (ie ability to move lever / cable enough to completely throw the gear selector in Fwd and reverse) is not important, just because you have a spring joint.

[J Ventura]

You should never sail with the gear engaged , precisely because it creates slippage , which wears out your cone clutch. Like it says in the manual.

[Northeaster]

JVentura - When you say it should not be engaged (while sailing), do you mean in Forward?

There have been other threads on free spinning vs in gear, and it does vary somehwat by Manufacturer / type of clutch. However, I believe that the common thought / recommendation for a Yanmar, with a cone clutch, is to sail with it locked in Reverse.

I only do coastal sailing, for a few hours at a time, and am usually in Rev or free-spinning in neutral. If I were sailing days on end, accross oceans, I would definitely want to cut down on any possible wear.

I would think neutral / free-spinning prop would prematurely wear the cutlass bearing. Forward would also turn the transmission gears, ww=ould it not?? / possiblly leaving some types without proper lubrication.

I believe that reverse will keep the shaft, and other parts from spinning, and therefore wearing prematurely.

Feel free to correct me if I am wrong!

[J Ventura]

I meant in reverse , the most common mistake. I'm not very familiar with other saildrives so can't say if they recommend diferent uses but Yanmars I have worked with by the dozen , inshore and across oceans , straight out the shipyard or in used boats. The effects of engaging the gear in reverse while sailing are apparent if you compare the viscosity , smell and minuscule debris in the fluid , and the wear on the cone clutch if you pull it out. The best advice I have for anyone with doubts regarding their equipment is read the manual. If you don't have a manual , call the makers because if they are any good they will always be happy to answer any technical questions , with the authority we need to clear any doubts.
As far as I know the issue is not wear caused by free spinning , spinning is what those parts are designed to do , is the "unnatural" pressure exerted on the cutch when the prop is locked.
Happy sailing!

[Meck]

J Ventura, don't take this to personally, but I still don't understand what you posted... Slow down a little, your contribution is much appreciated if it's understood!

Cheers,
Meck

[Chief Engineer]

http://sagaforumet.com/yanmar-manual/GM/gm-manual.pdf

Talks about oil on transmission

[J Ventura]

Meck , I would never take it personally and I'm sorry if my post is hard to understand . I really don't know how to make it any clearer.The original question regarded excessive wear on the cone clutch . The saildrive is usually left in gear while under sail. The yanmar manual advises against this to prevent slippage and wear . I'm not qualified to discuss the finer mechanical points but it's pretty obvious to me . This is basically what I'm saying .
Cheers!

[Chief Engineer]

Think about it this way. Would you tow your car in gear or out of gear?

[JustCatamarans]

We have posted a few responses to these issues in the past, bottom line is you must be very very sure your prop pitch and dia match the engine, overworking the engine will cause the cone to slip past its designed parameters, it is not so much a design flaw as an operator error.

[Captain Bill]

Keep this in mind, I have nearly 1300 hours on my clutches and so far no issues. I NEVER leave the transmission in gear when sailing. I also have feathering props. I've never used a folding prop so I can't tell you if they spin the transmission while folded, but my feathering prop definitely does not.

[Meck]

This thread is making no scene at all.

Is not reverse considered being in gear???

[Captain Bill]

Yes, reverse is in gear, I leave mine in neutral.

[Ram]

i keep mine in netural ,this way the transmission is not turning- no wear-no problum-

[sailvi767]

One point to mention. I believe that Yanmar calls for the engines to be left in neutral when not running under sail. They do not want you to lock the shaft by placing the engines in gear.

[wegcjw]

In reply to Arne. The clutch of my SD40 saildrive (Used with a 40HP Yanmar 3JH3CE engine) has begun to give trouble this year after 250 hours use since 2001.

When running with clutch fully engaged, there is no problem because the torque transmitted to the vertical shaft through the helical spline, drives the clutch cones into firm contact regardless of wear. The greater the engine power the harder the cones are driven together. In this mode the clutch self-locks and will disngage only when the torque is removed by slowing the engine down.

The slipping problem arises first when engaging forward gear gently. The control movement is designed to push the cones into preliminary light contact and thus activate the screw-driven self-locking mechanism above. However, if, due to wear, this initial light contact fails to run the moving cone up the helical spline, then the clutch does not self-lock but contrinues to slip. Usually, if you try again with a rather violent movement of the engine speed lever, the clutch will engage with a bump. But for how long before it fails completely? Mine is going in for clutch replacement tomorrow and like you I am disturbed to realise that any repair will buy me at best only another 250 hours.

I had thought that the probelm was specific to the, now discontinued, SD40 but your report suggests that the SD50 is no better. - Well maybe 450 hours rather than 250. It looks as though we have to live with the problem.

Good luck,

Colin