# Kanzaki/Hurth KBW10 Transmission trouble



## bristol299bob (Apr 13, 2011)

I have a Kanzaki/Hurth KBW10 Transmission, mated to a 2QM20 Yanmar. They are both 35 years old, have ~1800 hrs, and have been babied all their lives (by previous owner and now by me)

About a year ago the transmission started to have trouble shifting into forward first time in the day. It's reproducible at the linkage on the trans body, so I'd think that this is not a linkage adjustment issue.

When it happens, I shift into forward and it does not engage. So far I have been able to resolve it by throttling down, then back up (no need to touch the shift lever). Once engaged, I have no more problems for the rest of the day. there is no noticeable slipping once it engages.

It has never happened in reverse.

It is happening more and more frequently now. Linkage is adjusted, fluid changed regularly (and recently). I use ATF per the label on the trans body (it has had ATF it's whole life). I understand that some folks swear that these transmissions should have 20 or 30W oil. the label says "ATF or SAE 20/30HD". 









So I am wondering what are my options. (I do all my own work but I've never rebuilt one of these beasts)

1 - Pull the trans, buy new parts, rebuild it.
2 - Find a used trans
3 - Buy a new one.

In regards to #1, do I need special tools to rebuild it? 
In regards to #2 or #3, this transmission is not made anymore, are there recommended "bolt on" newer units?

thanks in advance
bob


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## Brent Swain (Jan 16, 2012)

When a hurth gets reluctant to shift into gear, its time to change the fluid. It will look super clean on the dipstick,but will look like mud in a container, when you drain it out.If it's still reluctant, run it a bit, then change it again. That may solve your problem, before taking things apart.


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## bristol299bob (Apr 13, 2011)

Thanks Brent, I'll do that in the morning. Do you think I should stick with ATF, or go with 30W? 

best,
Bob


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## wnelowet (Sep 18, 2000)

This Transmission uses ATF. Best get it from a Yanmar dealer.


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## aeventyr60 (Jun 29, 2011)

Buy a good quality ATF from the auto parts store. Penzoil brandd etc. Try flushing out the casing a time or two. Those things can be rebuilt by a quality tranny shop. repalcement parts can be machined...well at least in the third world.


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## christian.hess (Sep 18, 2013)

rinse it a few times with cheap stuff then add really good atf that yanmar specs...do this first like mentioned

always the simple stuff

if it still slips or ois hard to shift a simple rebuild done by YOU is a great way to get another 35 years from said tranny


before you decide to rebuild get a manual for your engine and tranny...some trannies have shift mechanisms(bells) that are adjusteable some dont, some simply need the whole rotating gear assembly replaces etc...I can remember on my 2gm if it was adjusteable or not.

anywho replacing the bearings and output seal will make it last even more

ps. dont get quotes for rebuilding just yet...my advice if you do need to rebuild go to an old automotive rebuilder or motorcycle shop and go to them with a rebuild kit say bearings seals, bushings etc...somewhere around $350-500 including parts would be reasonable to me if having the labor done for you...just you $200 max man.

the simple reason is any marine place is going to quote you at least half what a new tranny costs, which btw on ebay and other places you can get for around $1.5k


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## RichH (Jul 10, 2000)

The Kanzakis' have a 'detented' slip-ring gear that is responsible for the shifting. This slip gear (similar in function to a synchronizer gear in an auto manual transmission) works with steel balls being engaged via springs into the R or F section of the trans. This slip gear can easily wear out, simply from long term hard use or improper routine maintenance adjustment of the shift lever on the exterior of the trans. You'll usually hear a 'slight' grinding when the trans. is in F and the engine is in idle if this is the case.

Many of the 'master' Yanmar distributors no longer repair such transmissions .... On the east coast its increasingly and usually: East Coast Marine Transmission ... an excellent and precise marine trans. 'rebuilder'.


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## MarkSF (Feb 21, 2011)

wnelowet said:


> This Transmission uses ATF. Best get it from a Yanmar dealer.


You can buy quality synthetic ATF just about anywhere.

BTW, Universal recommend changing the oil in my Hurth once a year. I was sceptical about this, and left it two years. The stuff I drained out was dark, and smelled bad. So I am saying it really does need changing frequently - whenever you change the engine oil would not be a bad idea.


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## christian.hess (Sep 18, 2013)

x2

thank rich for the correct terms regarding the bell and ring assemblies.

and to prove all points here I had my auto tranny on my truck give me error codes and throw me into limp mode(new to me car) issue was slamming shifts and slipping.

first simply adding the correct level atf cured the bad shifting, then a simple drain and new atf cured all the issues including error codes...same applies to any tranny really.

next is a simple filter and gasket change and Im good to go for another oh dont know 60k miles(already has 200k)

back to trannies


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## RichH (Jul 10, 2000)

Most Kanzaki's have an INTERNAL 'filter/screen' ... that should be cleaned out EVERY time you change the ATF/oil. This filter/screen guards the small lube oil pump of the trans. If the filter/screen becomes blocked, guess what?


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## Maine Sail (Jan 6, 2003)

RichH said:


> *Most Kanzaki's have an INTERNAL 'filter/screen'* ... that should be cleaned out EVERY time you change the ATF/oil. This filter/screen guards the small lube oil pump of the trans. If the filter/screen becomes blocked, guess what?


Guys please don't go looking for this on a KBW-10 gear it does not exist.

It does not exist because this is a Hurth gear not a real Kanzaki. There is also no lube pump in the Hurth HBW/Kanzaki-Hurth KBW gears they are splash lubed..

It also does not exist in the most widely used small genuine Kanzaki cone gears on small Yanmars such as the KM2 or KM3...


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## Maine Sail (Jan 6, 2003)

RichH said:


> *The Kanzakis' have a 'detented' slip-ring gear that is responsible for the shifting. This slip gear (similar to a synchronizer gear in an auto manual transmission) works with steel balls being engaged via springs into the R or F section of the trans.* This slip gear can easily wear out, simply from long term hard use or improper routine maintenance adjustment of the shift lever on the exterior of the trans. You'll usually hear a 'slight' grinding when the trans. is in F and the engine is in idle if this is the case.
> 
> Many of the 'master' Yanmar distributors no longer repair such transmissions .... On the east coast its increasingly and usually: East Coast Marine Transmission ... an excellent and precise marine trans. 'rebuilder'.


This would apply in a real Kanzaki cone gear such as the KM2 or KM3 but it does not apply to the Hurth/Kanzaki's such as the OP is discussing.


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## RichH (Jul 10, 2000)

Maine Sail said:


> Guys please don't go looking for this on a KBW-10 gear it does not exist.
> 
> It does not exist because this is a Hurth gear not a real Kanzaki. There is also no lube pump in the Hurth HBW/Kanzaki-Hurth KBW gears they are splash lubed..
> 
> It also does not exist in the most widely used small genuine Kanzaki cone gears on small Yanmars such as the KM2 or KM3...


The 'filter/screen' is on Kanzaki/Hurth transmissions larger than what is coupled to the 2 cylinder Yanmar 2QM series. The hidden 'filter/screen' (PN 27-18) is found on Kanzaki *KH-18* and larger transmissions of that production time, and is matched to the 3QM, etc. series engine as standard. The Kanzaki KH-18 is a Hurth-type friction disk system with NO cone clutch. The shifting of these transmissions is such that the optimum pressure is automatically applied to the clutch plate in direct proportion to the input shaft torque ... if the 'shift lever' is not carefully adjusted (and occasionally maintained), the shifting fork will not apply the correct pressure and one can then experience loss of either forward/reverse through the development adverse wear in the drive plate assembly.


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## Maine Sail (Jan 6, 2003)

RichH said:


> The 'filter/screen' is on Kanzaki/Hurth transmissions larger than what is coupled to the 2 cylinder Yanmar 2QM series. The hidden 'filter/screen' (PN 27-18) is found on Kanzaki *KH-18* and larger transmissions of that production time, and is matched to the 3QM, etc. series engine as standard. The Kanzaki KH-18 is a Hurth-type friction disk system with NO cone clutch. The shifting of these transmissions is such that the optimum pressure is automatically applied to the clutch plate in direct proportion to the input shaft torque ... if the 'shift lever' is not carefully adjusted (and occasionally maintained), the shifting fork will not apply the correct pressure and one can then experience loss of either forward/reverse through the development adverse wear in the drive plate assembly.


Rich,

I was just trying to save folks the hassles of locating these times on the gear that is _actually_ being _discussed_ the KBW-10...

Yes on the larger gears a lot internally is different for both Hurth/ZF and Kanzaki. Yanmar has used many different types of gears over the years but the KBW-10 is basically a Hurth HBW-10 and it does not use a screen.

The most critical aspect of any of the small HBW/KBW gears is changing the fluid often. If the gear is left in forward after sailing change it ASAP because the plates can shed small bits of metal into the fluid.. The bronze thrust washer can wear rapidly if the fluid is allowed to become contaminated with bits of metal. I change our Hurth/ZF ATF at every oil change. It is actually easier than changing the oil, takes about two minutes, and a lot less costly, about $3.50...

Here's one where the customer never changed the ATF on an HBW.. Cost him over 2.5K when all was said and done because the entire engine had to come out.

Thrust washer was destroyed:









Worn plates:


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## christian.hess (Sep 18, 2013)

impressive how so many things are so similiar in such different uses...my honda xr600 clutch looks exactly the same

op change your atf, or "flush" a few times with cheapo stuff and do research what your yanmar specs for atf

TODAY not back in the day

they will be updated both in manuals and specs on your atf bottle

most of them go back many decades spec wise and will state if ok to use or not

good info from both rich and maine sail btw


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## casey1999 (Oct 18, 2010)

Maine Sail said:


> The most critical aspect of any of the small HBW/KBW gears is changing the fluid often. If the gear is left in forward after sailing change it ASAP because the plates can shed small bits of metal into the fluid..


What if the gear is left in "reverse" when sailing? Will the same damage occur? I run mine in neutral as I believe Yanmar states you should.


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## RichH (Jul 10, 2000)

Maine, the importance of this thread for ALL onlookers, I believe, are threefold:
1. Regularly change the transmission oil.
2. Be very aware of transmission 'sounds' ... such as the beginnings of 'metal to metal' sounds, as well as slippage. As if these are ignored, that slight metal to metal sound is THE indicator that internal damage is of high probability of beginning to occur. A visualization of the drained trans. fluid is the fastest way to tell thats something 'amiss' internally. 
3. Engine mounts 'sag' over time and therefore should be adjusted, probably yearly. 

 maintenance and 'prevention' is far less expensive than repair and rebuild.


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## Maine Sail (Jan 6, 2003)

casey1999 said:


> What if the gear is left in "reverse" when sailing? Will the same damage occur? I run mine in neutral as I believe Yanmar states you should.


This all depends upon which Yanmar gear you have. The KBW is really a Hurth HBW so according to Hurth/ZF they can be left in neutral OR locked in reverse but never forward.

If you have a Kanzaki gear with a cone clutch then you want to use neutral only...


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## casey1999 (Oct 18, 2010)

Maine Sail said:


> This all depends upon which Yanmar gear you have. The KBW is really a Hurth HBW so according to Hurth/ZF they can be left in neutral OR locked in reverse but never forward.
> 
> If you have a Kanzaki gear with a cone clutch then you want to use neutral only...


Yes, I have the Kanzaki gear, so all is good. Thanks. 
I also change my gear oil when I change the engine oil- 2X per year.


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## casey1999 (Oct 18, 2010)

Just a little confused on the Kansaki cone clutch transmission. Say the gear is left in forward while sailing. How does the transmission get damaged. Apparently I am wrong (and I do leave trans in neutral while sailing), but how would the transmission see movement if it is connected to the engine- and no way the prop will crank the diesel engine. I would think if the transmission is in either forward or reverse the transmission would be locked and no wear or damage could occur.


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## christian.hess (Sep 18, 2013)

some engines(props) will rotate if left in forward this is especially true in trade wind sailing or surfing down big waves the momentum and forces involved are more than the prop can handle

thats why they make shaft brakes that manually clamp the shaft

its also a reason some boats have shaft driven generators as the props have so much drive force might as well free wheel it and make some energy

ps. its also how electric conversion kits have REGEN features that produce back power into the battery bank via the motor itself

anywhoo


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## casey1999 (Oct 18, 2010)

christian.hess said:


> some engines(props) will rotate if left in forward this is especially true in trade wind sailing or surfing down big waves the momentum and forces involved are more than the prop can handle
> 
> thats why they make shaft brakes that manually clamp the shaft
> 
> ...


If it were true that your prop could spin your diesel engine then there would be diesels starting up all the time due to this "drift starting". I have never herd of that happening. And if your diesel did not start, but simple kept rotating, then a lot of damage would be done to the engine due to lack of lubrication.

When I first got my boat, I sailed a few times with the engine in reverse as I thought that was correct way- even sailing at 10 knots the engine would not rotate. However the transmission was hard to get out of reverse and into neutral when I did this (now I know better). But the transmission was not spinning while sailing, nor the engine (yanmar 3gmd).


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## christian.hess (Sep 18, 2013)

they do and it is especially true on old tired diesels

My 2gm would do this on fast downwind sails I couuld see the shaft in GEAR in FORWARD move and once it started it would really go...the engine wont start however it will flood. this was my experience, this has to do with what kind if ignition you and starting mech you have

some old diesels have hand cranks its not as hard as you think...any old tired engine will pop to life easily

now its not common because most diesel engine owners dont go trade wind sailing in 30 knots surfing down big waves in gear do they?

your last sentence is the key phrase here

when an engines moves not under its own power you dont get the same lube flow

same applies to a tranny

the oil or atf in this case is not warmed up plus you have a constance effort against the clutch cone and or shaft, gears that arent NATURAL

if that makes any sense think about it

if a car engine in gear is pushed it will indeed suffer more damage than one under its own power, specifically from lack of lube and temp

some engines and or tranny combos specifically say to not even freewheel or be in neutral


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