Removal of Hurth Transmission

[Bill Kroes]

Hello,

NS36-24 has been hauled out for the winter, so now seems like the right time to repair a small leak in the outboard (load side) transmission seal.   We have a repair shop lined up to replace the seals and probably the bearings,  but have had no luck finding someone to remove/install it for us.   Looking at what is involved it doesn’t appear too complicated (famous last words) as a project to attempt ourselves.    The transmission is a Hurth HBW-150 V-drive.  I’ve prepared an outline of a work plan for removal, but it has gaps and I was hoping other users could offer advice or suggestions.  I would also appreciate any input around some of the surprises we might encounter along the way.   Two photos are attached for clarity:

1. Drain the remaining oil
2. Disconnect the shifter cable
3. Remove the propeller shaft set screw/bolt and four flange bolts.  
   • I assume that the set screw/bolt is what secures the shaft to the flange.   Is this correct?
   • Once the flange is removed is there any risk of the propeller shaft sliding out?
4. Remove the six bolts securing the transmission to the engine flange.
   •  these bolts appear to be clean and dry with no obvious corrosion.   I had no trouble loosening one as a test.  
   • The lower bolt on the port side appears to be inaccessible.   I cannot see a way to access it without removing the starter motor.  (Does this make sense?)
5. Carefully slide the transmission off the splined engine shaft and the propeller shaft.   (Here is where I have questions)
   • Once the shaft flange is removed I should have 4-6 inches of clearance.   Is this enough room to clear the engine and propeller shafts to allow us to lift the unit out?
   • Will we need to move the propeller shaft back?  If so, should this move easily or require help?
6. Is there anything likely to drop out once we move the transmission off the engine flange such as keyways, shims etc?

Any advice or suggestions would be appreciated

Thanks
Bill Kroes
NS36-24 "Canatara"
Sarnia, Ontario

1. 

[Paul Miller]

I’ve had mine out a couple of times and it’s not hard. I have the same transmission but on a W33. 

-You don’t need to drain the transmission fluid but you could.

-The shaft should be retained by two square headed set screws and there should also be a small set screw on top of the key securing it in place. It too should be loosened.

-on my boat there was no fear of the shaft sliding out as my stuffing box had a good grip on it and I had a shaft collar for backup. A hose clamp will prevent it from getting away. Also if you have a zinc forward of your strut it can’t get away.

I actually had to make a tool to push the shaft back as it was very stiff. I used a 4’ piece of pipe (1” I guess) that would slip over the shaft and drilled / tapped it for one of the set screws. I slipped it over the end of the shaft and tightened the set screw into the recess in the shaft and then pushed on the pipe and twisted it with a tee handle consisting of a rod through a couple of holes near the outer end.

That worked. It also works to pull the shaft back in afterwards.

-I can’t comment on your bolt as mine is a different configuration.

-If I remember correctly 4”-6” might be close but it will tip a little if that helps.

Your bigger problem could be the shaft. Mine definitely had to move back and if you have a zinc close ahead of the strut, that won’t be possible. Good to find that out first.

- no shims to worry about but and the only key is the one in the coupling.

Have fun.

Paul M

NS30U #211, Sandpiper 

Cowichan Bay, B.C.

[Paul Miller]

One more point, if you have a dripless seal it will you won’t be able to move the shaft in the water without compromising the seal. I think you’d have to do it out of the water.

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Paul M
NS30U #211, Sandpiper

Cowichan Bay B.C.

[Mike BIANKA]

Bill:

Before I converted BIANKA to electric propulsion I had to remove the dead engine. I thought I had a deal with a diesel mechanic to buy the engine with the stipulation he would help me remove it. Well it did not quite work out that way but, that is another story.  Expect things not to work out as planned but, be happy if it does. You can read how the removal of my boat's Hurth Transmission went and hope you don't run into the same problems or if you do at least you are ready for them.  Exhibit A:  https://biankablog.blogspot.com/2007/12/removing-transmission-well-at-least.html

Mike

BIANKA

1986 30U

Long Island

[Tim Sgrazzutti - 1984 NS30U #244]

Bill,

The shaft and coupling diameters are an interference fit, pressed together, with the square head bolts for insurance only.  Their ends are conical, set into dimples in the shaft, and they should be safety wired together.  Do not separate the shaft from the coupling, or you will need to have it refitted, and the flange refaced true on a lathe.  

The best approach is to remove the propeller and anode, split ring if you have one, only the four hex head bolts, and pull the shaft and coupling into the boat as an assembly.

This is also a good opportunity to replace the cutless bearing, and perform any maintenance on the packing gland (hose and/or packing).

Good luck!

On Sunday, November 14, 2021 at 12:39:33 PM UTC-5 nonsuch...@gmail.com wrote:

[Bill Kroes]

Thanks to all for responses so far.    

Tim,  I think what I understood you to say is that the shaft coupling on the forward end of the v-drive transmission should not be removed and that the shaft must be entirely drawn up into the boat before the transmission can be removed?   That is a surprise to me  (Am I understanding you correctly?).   If this is the case, I'm not sure how I would do that given how close the coupling is to the engine room wall (see photo 2).    Also, I thought I'd read about folks removing the transmission with the boat in the water.   That wouldn't be possible in this case obviously

Paul,    when I read your comments it sounds like you moved the shaft back in order to remove transmission.    Logically you must have removed the shaft coupling before you could do this?   Did you need to use some sort of tool to do that?    Was re-installation an issue?

Thanks again

Bill

[Paul Miller]

What Tim says is correct in a “best practices” scenario, however that sort of precision is rarely found in the real world in my experience. A loose or poorly fitting coupling can cause trouble up to and including a broken shaft but if the fit is snug and the faces align a coupling can be removed and replaced carefully many times with no dire consequence.

Yes, you will need a puller. They aren’t expensive and can probably be rented or borrowed if you don’t want to buy one. If the coupling comes off without a puller, it is likely time for the re-machining that Tim mentioned.

Re-installation is not a big issue but as it is a close fit, care must be taken not to damage it. A little lubrication will help and any pressure or hammer blows should be straight down the shaft line so as not to “tip” the coupling. Any hammer blows should of course be cushioned by wood or similar.

In my installation, yes the shaft had to move back.

I’ll ask again as it is important. Do you have a conventional stuffing box pr a PSS seal? If it is PSS seal, the position of the shaft is what holds the seal together and you can’t move it while the boat is in the water.

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[Bill Kroes]

Tim,

We have a conventional stuffing box.  The boat is on the hard so it should make moving the shaft easier I hope.   I have two three arm type pullers(see photo),   I guess they should work if I can separate the coupling enough to get the puller arms around the flange? The problem may again be the clearance to the wall.   Thanks again for the input

Bill

[Joe Valinoti]

The last time I had the tranny removed was to replace the drive plate.  It was done in the water and while it was out, they redid the stuffing box.  Seemed to be quite simple without any problems.   I know that they checked the alignment as one should.  

Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA

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[Peter Grabow]

Hi Bill,

As others have posted (especially Paul M's input) it is a fairly straight-forward job.  My mechanic and I did this in the summer of 2020 with the boat in the water. Hurth V-Drive 150 with a Westerbeke 27A.

The shaft had very little room to move in either direction due to the Kiwiprop's hub at the far end of the shaft and zincs between the cutlass bearing strut and the hull... we were a little concerned we may not be able to pull the shaft back into place due to the limited space between the aft end of the transmission and the stuffing box, but we were able to get a decent grip on it (hand only, no tools) and slide the transmission over the shaft and move the shaft back up the inch or so needed with no difficulty.

It pretty much aligned itself, and feeler gauges confirmed the coupler spacing was uniform.

The most difficult part was freeing up the bolts holding the transmission  in place... about a week prior to the scheduled removal I began applying PB Blaster to the bolts and tapping them with a hammer... all of the bolts came out without much fuss except for one which had the head shear off.

Though my mechanic (in whom I have great trust) said the clutch plate looked fine to him, I decided for the extra $125(?) that it may as well be replaced since the transmission was 34 years old and had not been touched since the original installation (except for fluid renewals).  I didn't want to be saying later shoulda'... coulda'... why didn't I?

No draining of transmission fluid needed. My Hurth 150-V does have an 'oil-cooler' set-up so if yours does, make sure you shut the engine raw-water intake if you are doing this while in the water! Also, with mine I removed the horizontal piece of wood that retains the engine compartment cover (behind the steps) and the 'slotted' floorboard beneath the steps, and there was sufficient room for the transmission to come straight out - there is a notch in the stringer that allows for this.

If photos are needed, please let me know.

Regards,

Peter Grabow

S/V CAKE WALK III

1987 30 Ultra 430

Jersey City, NJ

On Sunday, November 14, 2021 at 12:39:33 PM UTC-5 nonsuch...@gmail.com wrote: