Yanmar-Kanzaki clutch slipping

[wsmurdoch]

You might want to print these Yanmar service bulletins and give a copy to your mechanic.
From February 8, 2008 http://www.shaftlok.com/YANMAR_MSA08...al+Sailing.pdf
and from October 11, 2011 https://j109.org/docs/yanmar_technic...tqtb11-017.pdf .

Bill

[Mirage35]

Thank you, Bill. It's not exactly the same model number (mine claims to be a Tuff Torq TTMC35A) but it's close enough that I suspect the recommendations stand.

It's the first definitive, from the manufacturer, information that I've seen on this subject so far.

[kenbo]

I have the service manual for this KM series of transmissions. Unfortunately the file size exceeds the upload limit for this site. It's in .pdf format and if you have interest PM me with your email address and I'll send it to you.

[Compass790]

Originally Posted by mark lennoc

Okay guys, I believe you. No more sailing in reverse!

I will be changing the oil and see if that helps.

Also, where do you find the manual?

Thanks

If you go to the link Kenbo gave you in post #7 & read thru the replies you will find another link that will give you the transmission manual.
You may need to access the owners/operators manual if you wish to confirm the no sailing in reverse rule.
Don't forget to thank Kenbo

[RaymondR]

Not sure what the gearbox was but I had a Yanmar in my old boat which began to show the symptoms you describe and when I disassembled the gearbox I found that the problem was that a bellvue spring had slightly worn into a thrust washer and consequently the cone was able to slightly misalign and was prevented from fully engaging. I turned the thrust washer around and it solved the problem.

[Tudorsailor]

I had the problem with the gearbox slipping when in reverse. Not ideal in the med when reversing into a berth and wanting to slow down and stop!

The short version of the story is that a Yanmar man in Croatia took the box out. He put a stronger spring in that keeps the cones engaged and he enlarged the hole that allows oil out from between the cones when they come together. I have a feeling that enlarging the drainage hole was the key. Having had this done, I have had no more problems
TudorSailor

[mark lennoc]

I changed the oil yesterday in the gear box and although it looked pretty clean on the dipstick it looked very dark in a glass jar. I will see how this works out but if not then out comes the kit and kaboodle. interesting comments from Raymond and Tudor and if I end up going into the gear box I will definitely make those changes.
Thanks again to everybody that has sent along a comment - it is really great to have this network of helpful souls.

[kenbo]

Originally Posted by mark lennoc

I changed the oil yesterday in the gear box and although it looked pretty clean on the dipstick it looked very dark in a glass jar. I will see how this works out but if not then out comes the kit and kaboodle. interesting comments from Raymond and Tudor and if I end up going into the gear box I will definitely make those changes.
Thanks again to everybody that has sent along a comment - it is really great to have this network of helpful souls.

Mark,

Both Raymond and Tudor have "a" type or down angle gearboxes. If you have a "p" or parallel output shaft you will not have springs. Also if Yanmar/Kanzaki/Tuff Torque engineers thought more powerful springs were better they would have fitted them in the first place. These are elegantly designed machines where the motto "more is better" doesn't always apply. If you split the cases, do it right, you won't regret it.

As an aside, cone clutch gearboxes like to be shifted crisply and cleanly. You don't have to wait for the revs to drop in neutral, this is another source of premature cone wear.

Your gearbox takes .5l liter of SAE 20 or 30 non detergent motor oil. 20W if you're in moderate or cold climes, 30W if in the tropics. DO NOT overfill.

[mark lennoc]

Great info Kenbo! I guess I would need to tell if I have the a or the p type gearbox. I strained the used oil from the gearbox through a pair of my dear old dad’s very white underwear and there were a small amount black particles, definitely not metal.

I am hoping that the oil changes might help but if not then I will have to remove the whole business and take it to that mechanic that will have a copy of the manual by the. Yes, I would love to get a copy from you so will send you my e mail address.
Thanks very much.

Here is my e mail address. mark2lennox@gmail.com

Mark

[Pete O Static]

I have a 2011 Jeanneau which typically share the same engines and transmissions as Beneteau. Mine is a 3YM30 with a Kanzaki transmission, shaft drive.


FWIW There is a great big factory installed placard at the helm to lock the prop under sail by selecting "Reverse" only, as selecting "Forward" may damage transmission.


So although any advice on here is well intended, I would consult Yanmar for your specific power train.

[mark lennoc]

Hi Pete
So you are saying that your plaque says it’s okay to sail with the throttle in reverse. What about leaving it in neutral?
This seems to be contrary to what people have been saying so far. I will try to get an answer from a Yanmar mechanic if possible.
Thanks for the info Pete

[Pete O Static]

Mark


My placard says that if you wish to stop the shaft from turning while under sail, you MUST use reverse only. FWD will damage the transmission.

Yes you can leave it in neutral but then you are stuck listening to the transmission as it free wheels. I have a folding prop, so to lock the shaft, I use reverse as per the placard.

As I said, Yanmar 3YM30, shaft drive, in a late Model Jeanneau 36. So based on the conflicting reports here, It might be wise to consult Beneteau directly.

[a64pilot]

There are different types of Kanzaki transmissions out there, some like mine have clutch packs, and at least on mine sailing in reverse is OK.
I believe but am not sure that the clutch pack transmissions use automatic transmission oil.
In other words just because it’s OK on one Kanzaki transmission, does not mean it’s OK for all.
However I believe that all Kanzaki transmissions won’t be harmed by sailing in neutral.
A folding / feathering prop is one way to sail in neutral and not have the shaft rotate, a shaft lock is another. Sometimes it takes a momentary pause in reverse to feather the prop.
I’ve seen one member post that he had made a shaft brake that used a golf tee as a lock, that way if he forgot to unlock the brake, no harm was done.

[RaymondR]

Originally Posted by Pete O Static

I have a 2011 Jeanneau which typically share the same engines and transmissions as Beneteau. Mine is a 3YM30 with a Kanzaki transmission, shaft drive.


FWIW There is a great big factory installed placard at the helm to lock the prop under sail by selecting "Reverse" only, as selecting "Forward" may damage transmission.


So although any advice on here is well intended, I would consult Yanmar for your specific power train.

What is going on in your cone clutch gearbox is the double cone is sliding backwards and forwards on a helical spline when you shift gears. The spline is helical so that the more torque that is placed on the clutch the harder the cone is driven along the helical spline into the cup of the clutch.

If you put the gearbox into forward to stop the prop from spinning whilst you are sailing the torque generated is in a direction which tries to wind the cone out of the cup. Consequently the cup and cone will try to disengage and when the friction becomes low enough the cone will slip in the cup. The slipping will generate heat and wear consequently leading to early failure.

However, by placing the gearbox into reverse the torque generated by the propeller whilst sailing acts in a direction which will tend to "screw" the cone along the helical spline and force the cone tighter into the cup - the faster you sail, the more torque is generated and the greater the "stopping" ie. rotational force the clutch is able to withstand.

I actually managed to turn my engine over once when it was over-propped sailing-surfing down a monster building swell near Rotnest Island. Scared the hell out of me.

The springs on the clutch assembly are cup shaped washers which I believe are called "Bellvue" springs. They are pre-loaded against disk shaped "thrust washers". The functional purpose of this arrangement is to unsure that the forward and reverse cups do not get misaligned. That is that the cups engage with the cones all around their conical circumferences when engaging. If the cups and cones only become partially engaged at a single point on their circumferences insufficient friction will be generated and the cone will not be driven along the helical spline sufficiently to fully engage the clutch. Hence the phenomenom of the slipping clutch.

Bellvue springs have only a minimal amount of "spring" and hence only a very small amount of wear into the face of the thrust washer is required to negate their "springing" action.

I hope all that's clear to you folk.

[Mirage35]

So, with the help of folks on this thread, I finally got real information on my transmission (Kanzaki MC 35A2-A3, aka Yanmar KM35A2). The information in Yanmar technical bulletins clearly states that with a folding or feathering prop one should shift briefly into reverse to fold the prop, then back into neutral. I assumed that an Autoprop counted as either folding or feathering.

So I tried it. Shifted into reverse; it jammed there. Dropped speed, started the engine with the tranny in reverse, put it back in neutral.

New plan: I'll leave it in neutral when sailing, the prop may fold / feather or it may not. I'll stop worrying about it.

RANT
I can't believe how hard it is to get information about some marine parts. I tried for two years to find out where this transmission came from and get any info about it. And then the Yanmar technical bulletin starts with a complaint about the customers: "We keep getting questions about ..." Well, if you actually put this kind of information on your website maybe people would stop asking the same question all the time. Or if you had a dealer network that knew something about the parts and was willing to talk to people.

And don't get me on about Nanni engines.
/rant