New SD50 clutch cone after 250 hours

[Elcano]

Hi,
I seemingly have a problem with my drive system.
Last year in July I got a new clutch cone, because of slipping. After only 200 hours the slipping problem appeared again and the mechanic told me today that I need another new cone because it is done! After 250 hours unbelievable but true!

I observed the following indicators:
- The sail drive oil was pitch black quite early after the last change (I did use the right oil)
- even after the cone change last year, with 2500 rpm I hardly reach 5 knots of speed in calm conditions, which points to a prop/pitch problem
- 2 experienced sailors recently told me that my tachometer does not indicate the correct revs. The shown revs are too high. I replaced the original Yanmar pulleys with Balmar pulleys to be able to run a broader belt. Not sure if this had influence on the tachometer.
- I have a EWOL prop and had a call with their customer service. His opinion was that the pre owner did not maintain the prop well, which means, did not greas it and did not change the anti-shock-hub regularly. He recomenda that I send the prop to them so they can repair/service it.

All in all a vey confusing situation for me. Can anybody make some sense out of it?

Thanks for experiences and opinions.
Cheers
Thomas

[Charlie-Bravo]

Hello Thomas
A most unfortunate story you tell.
I do not have experience of your exact engine or clutch, but below are my comments based on the clues you give.


- “The sail drive oil was pitch black quite early after the last change (I did use the right oil)”

This would be the cone wearing away.

- “even after the cone change last year, with 2500 rpm I hardly reach 5 knots of speed in calm conditions, which points to a prop/pitch problem”

          If your clutch is slipping your prop won’t be going round at the expected speed, giving the symptom you describe, so not necessarily a prop pitch problem, more of a prop rotating slower than the engine revs would be expected to drive it at, it could also be a combination of both prop and clutch , with my shorter boat, smaller engine and lowly fixed 2 blade prop I can beat 5 knots at 2500 rpm.

- “2 experienced sailors recently told me that my tachometer does not indicate the correct revs. The shown revs are too high. I replaced the original Yanmar pulleys with Balmar pulleys to be able to run a broader belt. Not sure if this had influence on the tachometer. “

          A check of rotation speed is easily measured with a cheap tachometer from eBay or Amazon, and may give a more accurate assessment than that of 2 experienced sailors (though fine fellows I am sure they are), a wider pulley belt will not effect the tachometer reading. A slipping clutch will allow your engine to rev a bit higher as the resistance from the propeller is effectively lower on the engine, the power of the engine and pitch of the propeller is matched to allow your engine to be able to reach maximum revs under full load ……. just. If your prop is not pitched correctly this could also allow the engine to rev too easily, without increased speed.

- “I have a EWOL prop and had a call with their customer service. His opinion was that the pre owner did not maintain the prop well, which means, did not greas it and did not change the anti-shock-hub regularly. He recomenda that I send the prop to them so they can repair/service it.

         All feathering propellers require a little love, maintenance and close inspection, and if yours is not close to being perfect, then it will not perform quite as it should, but it won’t ruin your clutch cone. Perhaps a service is not a bad idea if you are not confident at doing it, but it’s not a cure for the clutch.

The clutch it would seem is not fully engaging, and so, slipping from new, this may be down to poor adjustment of the release mechanism, or even a faulty release mechanism , (other mechanical issues are also possible) if the actual reason for the slipping failure is not detected , you will no doubt wear out another cone quickly.

I wish you luck with further investigations, …… and perhaps use a different mechanic.

Do come back and tell us when the solutions are found.

CB

[Elcano]

Hi CB, thank you very much for your answer. Really gives some orientation.

Regarding the tachometer. Could you please tell me a bit more about the Amazon tachometer. It is not the wider belt but the different diameter of the pulley that causes the deviation. Had a call with the Balmar technical support and they were telling me that. So buying that Amazon tachometer and adjusting the boat tachometer is hopefully the way to solve that. If you know how to adjust the boat tachometer, please do not hold back 😄.

About an hour ago, the current mechanic, which is new, found that one of the washers under the cone was not in place and was „floating“ in the saildrive. So the new theory is that the missing washer caused the excessive wear. Not sure 🤔.

Regarding the prop. It is remarkable that the old Yanmar mechanic and the technical support of the prop manufacturer were both saying that a faulty anti-shock-hub of the prop can cause this problem. I bought a non folding prop as a spare prop and will try this afternoon if there is any difference.

Will keep you updated.
Cheers
Thomas

[Don Reaves]

Here's a post I made in February, 2023 regarding tachometer calibration:

You don't actually need a tachometer to get a good measurement of RPM. I calibrated my tach using a free app on my iPhone that's intended for musicians. I have it listen to the engine and give me the frequency. Then a simple calculation based on the number of cylinders and the fact that there are two revolutions per power stoke will give you an accurate value. I found that my tach reads 9-10% high over most of the range.

For my 3-cylinder engine, I just multiply the frequency of the engine's sound by 40. For a 4-cylinder engine, you would multiply by 30.

[Charlie-Bravo]

Don’s phone tachometer technique will work and requires nothing that you don’t have to hand other than an app.
The Amazon solution at £18.99 is titled -

FITNATE Professional Digital Tachometer, Non Contact Digital Laser Photo Tachometer RPM Tach

Probably not the greatest bit of kit on the planet, but would give a read out of rpm, my tachometer has a rubber wheel ……. purchased a bit before lasers became common for diy kit , and it sits patiently in the cupboard most of the time, so Dons solution would save yet another lesser used tool in the box.

Change of pulley diameter may well change the rpm reading as it will change the gearing ratio of the belt drive, but depends on where your engine rpm is measured from. most rpm signals come from a small magnet hiding on something like the crank pulley, and work by inducing a small electrical current as the magnet passes a little coil of wire …… much like a bicycle speedo set up, the shorter the interval of electrical ‘bursts’ of induced current, the faster it figures your engine is going, …… all deduced by a tiny ‘chip’ (non potato ) to circuitry delivering the result either as a digital or analogue read out of rpm , …………. (you did say “don’t hold back” but I resisted.)
Modern tech has often removed the bicycle speedo bits, and just get their pulses from the alternator, being as it has magnets and coils of wire already in position ( it’s all jolly clever stuff, but don’t help you sail better , so only google it if really needed). 
So if your rpm is measured from the alternator, and your posh new pulley on the alternator is of a smaller effective diameter, with the driving pulley remaining the same diameter as it used to be,  the alternator will be spinning a bit faster than it used to, and if nobody told the rest of the gadgetry about the pulley change it could be why the rpm reading is not correct, you probably have a slightly smaller drive pulley as well as the alternator pulley, but the ratio between the two may be a little different to the original set up.
Recalibrating the rpm reading would probably require a new or reprogrammed chip to translate the electrical pulses to correct readout, Balmar pulley conversions are quite popular, no doubt others here have come across the same issue, some may have found the solution and will join in soon, a makeshift interim measure might be to add a few stickers if it’s an analog read out, although your ears will probably tell you all you need to know about the revs.

The anti shock hub , this used to be called a cush-drive on old bikes, some made of rubber blocks and some of springs, and are also often found in car clutch plates, and did indeed ‘soften’ the power take up a smidge twixt crank and wheel. It would theoretically soften the engagement of drive, and could be kinder to the clutch and transmission, but, I question the dynamics on a boat as the prop is sitting in water, not like a bike tyre on tarmac, so the prop drive is ‘cushed’ by the water. …… perhaps I’m wrong, nobody’s perfect.

A floating washer lurking in the oil and not where it is supposed to reside sounds like a better hint at a proper mechanical reason for something adrift with the assembly, washers are not known to randomly escape, usually a nut or bolt will have also come adrift to allow the escaped washer its freedom, …… unless it just got dropped in there by accident .

Your fixed prop , if the Yanmar and EWOL tech are correct, should eat your cone alive in no time at all ! as it has no anti shock what so ever, let’s hope they are wrong.

Eagerly awaiting the real reason for it all, I wonder how long others with the same model as yours get out of their clutch cones.
I like a good mystery. (as long as it’s not on my boat !)

CB

[NZL50505]

Some light background reading that might provide further context:

jeanneau.proboards.com/thread/6907/sd50-cone-clutch-problem

jeanneau.proboards.com/thread/9468/sd60-saildrive-reliability-after-hours

[Charlie-Bravo]

These linked vids are most informative.
It would appear that the thrust bearing wear eventually stops the full engagement, but at least there is an upgrade kit for it.

CB

[rick63]

Hi,

Understand your issue as I also have had SD50 problems. Replacing the cone after 250 hours is not required. All you need to do is get the cones ‘lapped’ this process removes the glaze from the cones. I have fitted the modification kit mentioned in the other threads. I have had 1500hrs out of the same clutch with regular lapping of the cones (every 350-400 hrs). The oil will become dark in colour and I change the oil every in the sail drive every 75hrs or annually.

[j24sailor]

Aug 26, 2023 8:25:06 GMT NZL50505 said:

Some light background reading that might provide further context:

jeanneau.proboards.com/thread/6907/sd50-cone-clutch-problem

jeanneau.proboards.com/thread/9468/sd60-saildrive-reliability-after-hours

We are having a similar problem and our boat is out of commission at the moment because of a similar problem. We can't go forwards or backwards. Just ordered this upgrade kit and it arrived today. Sounds like your problem is a slipping cone clutch as well. Will keep you updated but you might be very interested in watching the video and the one from Colin from below decks who did this on Parlay Revival. Good luck James

[NZL50505]

I lapped my SD50 cones at 500hrs when it started slipping badly (it was about 25hrs earlier that I got the first warning signs).

I also:

1. Replaced leaking seals
2. Replaced incorrect saildrive oil from GL5 to GL4
3. Fitted a breather pipe to allow for expansion

I’m now over 1,000hrs and so far no signs of slipping. If I continue to sail only locally I’ll just keep going as-is and wait to see if / when slipping recurs. My mechanic thinks it’s possible that the 3 steps outlined above might even eliminate the problem altogether. But if I plan to go offshore I will repeat the lapping and probably also get the upgrade kit which will apparently improve the selector operation.

But so far so good 🤞

[Elcano]

Here are some interesting news about my clutch problem. Indeed I needed to replace the cone lapping was not enough, according to the mechanics. But they found something interesting. It seems that the mechnic in Italy installed the cone the wrong way around. I know, when I first heard that I also could not believe this. But the mechanics here gave me the old cone and showed me signs/wear on the cone that makes their assumption plausible. Beside that, on the bottom of the cone are two half springs. One of them was not in its place because the cone was the wrong way around (sorry for my descriptions  ). Here are some pics:









So in the end, this was a huge f*** up and I will try to recover some money with a lawyer, but you know...

Another issue could be the prop I have. The pre owner installed a EWOL (www.ewoltech.com)  prop and a missing maintenance especially of the anti-shock-hub could also cause additional wear on the transmission/clutch. This is what the technical support of EWOL told me. 
If anybody has ideas on this topic I appreciate opinions.

So this is it so far. I hope the problem is solved now. Time will tell 

Cheers

[NZL50505]

When you put the SD50 back together just make sure:


1. Use GL4 and not GL5 oil
2.Replace seals
3. Fit expansion hose (requires top bolt to be replaced with breather tube version. This is a standard Yanmar part that a good Yanmar service agent will have in stock or can order for you.

[Elcano]

Sept 14, 2023 6:42:55 GMT NZL50505 said:

When you put the SD50 back together just make sure:


1. Use GL4 and not GL5 oil
2.Replace seals
3. Fit expansion hose (requires top bolt to be replaced with breather tube version. This is a standard Yanmar part that a good Yanmar service agent will have in stock or can order for you.

Thank you, will double check with the mechanics!
I take the oil that is recommended in the sd50 manual. Could you explain what you mean with GL4/GL5

[NZL50505]

A few years ago Yanmar recommended using SAE90 GL5 oil but after a few years they quietly shifted their recommendation to either GL4 or 5 and now only GL4.

Long story short - Yanmar is an engine company and not a gearbox company and they failed to realise that a saildrive unit operates more like a low speed differential unit than a high speed gearbox. Hence they mis-spec’d the oil. Apparently ZF told them they got it wrong.

There’s a lot more to it but trust me - or others with experience with failed saildrives - you want to use a SAE90 GL4 oil like Mercury / Quicksilver and not GL5. Note - often the GL rating is in small print on the bottle so you need to check carefully.

A decent Yanmar service agent should also confirm this.

[Elcano]

Thanks a lot, I am very grateful for all the help here in this forum.
Checked the Quicksilver bottle and it is GL4!!

Cheers

[NZL50505]

Sept 16, 2023 7:15:35 GMT Elcano said:

Thanks a lot, I am very grateful for all the help here in this forum.
Checked the Quicksilver bottle and it is GL4!!

Cheers

Perfect! That’s what you want. I keep a couple of bottles onboard as backup for top-up or service in a place where they only have GL5.

[Elcano]

Yep, ordered 

[Elcano]

A small update and a further question.
So far so good, clutch works, but I found oil around the saildrive (within the rubber seal, so you can see it from above). Wiped it a couple of times, but it appears again. As far as I saw, it comes out the gear selector/shifter). Called the mechanics again and they told me I should not worry and it is better for the rubber seal to have some oil around it  . Asked them about the breather pipe and they told me that Yanmar told them there is nothing like that for the SD50, only for the SD 60. Is that correct? I do not think so.

Can anybody send me the a picture of the installed breather tube on a SD50? I tried to contact Yanmar but they did not answer so far.

Will search for another mechanic, because they clearly have some deficits.

Cheers