Yanmar SD50 Saildrives - Have the Cone Clutch Problems Been Solved ?

[ChrisseH]

Have had similar problems with the SD50 in my yacht. The engine and sail-drive is from 2007 having now some 1200 engine hours, of which maybe 200 hours for battery charging and heating water at neutral.

I noticed the first symptoms in the early fall of 2015. At idling rpm forward the water flow behind the transom was almost negligible, only giving the yacht a speed of 1 knots, compared with the normal 3.5. When increasing the rpm this engaged the system and the boat worked as normal. No problem with reverse. At the time I suspected that the 18" folding propeller caused the problem. When hauling the boat for the winter the propeller seemed however normal and in the spring I put extra effort on disassembling, cleaning and lubricating the propeller. As usual I also changed the gear oil (Quicksilver).

When launching the yacht in May 2016 everything worked fine for a few weeks. Thereafter the symptoms gradually returned. After driving at normal cruising speed I also noticed that the system disengaged when decreasing throttle to very low rpm. At this point I still suspected the propeller as I thought that the remaining boat speed might fold in the blades. Reverse worked fine all the time and after reversing the boat to a stand still, also shifting forward worked neatly. Also this supported the theory that the propeller was the challenge. During the summer the situation however got worse and now I started to have problems also reversing. At this point I started to suspect that the problem after all was not the propeller. We managed still to use the boat until the winter haul in October 2016.

I yesterday removed the shift lever assembly and noticed that the clutch shifter had worn on both sides. Not much, but more on the lower (forward gear) side. In the User's Manual it says that the shifter should be checked annually and replaced if worn out more than 10 mm. As is impossible that the slot in the cone clutch could decrease the vertical thickness of the shifter to 10 mm I am raising the question what the 10 mm value in the manual really means? Maybe it is the horizontal length of the worn out area on the shifter? The length which, in my case is some 12 mm on the lower and maybe 8 mm on the upper side. The thickness of the worn out material cannot be more than maybe 0.2 mm, but I would suspect that this distance has an equal impact on the clutch cone's end position.

As I always have thought that a worn clutch is generating slip especially at high power and as this is not the case, I am trying to find other causes first. The local Yanmar service guy has never heard about about such symptoms and I am allergic to just let the guy start to investigate the problem at their standard hourly rate.

Questions: Would you agree that any wear on the shifter will have a direct impact on the end positions of the cone clutch? Have you noticed similar wear on your clutch shifters? And if so, have anyone of you replaced the shifter?

[boatbod]

Once the cones finally bite and lock together they find their own position. What normally happens is that they sometimes don't bite and then slip against each other, hence the low speed problems you experienced. Never seen one slip at high speed unless it hasn't locked up to begin with.

Wear in the shifter could be a contributing factor, but needing to lap the cones is the first suspect with an sd50.

[Aqualibrium]

I think you are looking for the easy way out, 1200 hrs or 1000 loaded hrs is at least twice the normal life of an SD50 clutch.
I have done both of mine twice and only have 700 hrs on the engines, the first one failed at less than 150 hrs, (this was due to a Yanmar assembly stuff up in the factory causing an engine to overspeed on launch day!)
Bite the bullet get the gear to relap the clutches and you will be amazed how simple it is. well under 2 hrs to do it now.
Special tools required
1. Vice
2. Aluminium angle iron soft jaws for vice to grip spline without damagingit.
3. 27mm socket
4. Long breaker bar to remove left hand threaded nut
5. Never seez for reassembly

check out a few tips I put on an earlier post to make sure you get it right.

It is extremely satisfying to know that you can be independent of tradesmen of varying quality for this job that will come back time and time again.

[ChrisseH]

Thanks boatbod and Aqualibrium for you advice. Got my clutch cone lapped and both forward and reverse gears are now OK. Remains to be seen for how long…


Purchased the splines sleeve and the 16mm lefthanded nut from Dieselpartseurope’s webshop, had the splines sleeve welded on a piece of iron and opened up the cone clutch assy and lapped the clutch cone with lapping paste of grain size 325. Luckily the washer under the 16mm nut was not worn at all.


I am puzzled by the variation in engine hours different boat owners have experienced the slippage. Maybe engine hours is not a good measure of the wear? Maybe the number of shifts would be better? I mean if some boaters just use the engine to get out and in from the marina and mostly sail, then the number of shifts will be large relative to engine hours. In my case when it is mostly calm before noon we use the engine a lot.

[boatbod]

I suspect, but don't know for sure that the amount of motor-sailing is a more important factor in cone life. Sail too fast and the cones might slip.

[bad kitty]

We fitted Panache's kit on our 2 SD40's approx. 200 hours ago.
Been flawless since then, so fingers crossed!
Thanks Panache,

[mark lennoc]

I have a Yanmar 3J series diesel with a Kanzaki KM35 transmission. I seem to be getting some slippage once I start motoring but it soon disappears and everything is normal. I see that the Kanzaki is also a cone clutch. Has anyone else had any experience with this type of pr:smitten problem?

Thanks

[brianc]

Question about the vent idea…most people on here have said that it’s not necessary to add an expansion tank, however, I installed a tube vent, it rises about 18” above the top of the drive, and there was maybe a tablespoon of gear oil that came out the top. So is this normal and I need an expansion tank or is it pointing to some other issue? The gear oil level was higher than “normal” after it cooled completely, but appeared to be because of air, not water ingress. I added the vent because one oil test came back with a tiny bit of water, and I’ve had the issue of the magical variable oil levels, so I thought maybe that would help with that issue as someone else mentioned, but can’t remember if that was this thread.

I don’t have a problem installing an expansion tank, but it seems like it shouldn’t be so variable.

Also, I have experience with “milky” gear oil in a Volvo, and it’s very obvious, but is that the same for the blue high performance gear lube? If there is water, it isn’t obvious.

Thanks! Brian

[Brickwede]

Hello all,
I have a working solution for Yanmar SD40 and SD50 Salidrive avaliable.
On my Belize43 it works in both saildrives.
See here:

https://www.youtube.com/watch?v=zo0QcoQcagk

(german languarge but it is simple to understand)
or here: Repair report - Saildrive SD50 clutch upgrade kit - Hochseekatamaran Gerda Martha

[bad kitty]

Well we fixed our SD40 sail drive issues.
Ripped them out & put in shafts & v drive gearboxes.
Finally, a permanent solution to that junk!