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Replacing Hurth - move engine forward?

williwaw

williwaw

Tom Kluberton
Seems to be a good bit of chat about repairing and replacing transmissions but I'm wondering how to go about the remove/replace procedure..

Williwaw's Hurth 150 is leaking itself dry in less than 6 hours of running so I bought a new one from TAD and plan to install it in the spring when I get back to P-Cola.

My thinking has been to pull the engine mount bolts and slide the Perkins forward just enough to yank the transmission.out (it's only 35#) Then ,the Perkins is heavy but generally self contained - looks easy enough to slide forward.

Anyone have experience or watch as the pro's did it? Seems the only alternative is to haul the boat, then pull rudder off and move the prop shaft backward. Ugh - too much work.

Also - I see in some of the photos that the red nylon vibration damper is installed - does that require shortening the prop shaft? or will the connection slide back far enough on the shaft for that red doughnut to fit?

An uninstalled red doughnut came with Williwaw, but cutting the shaft seems like too much work.

Any wisdom is greatly appreciated - thx.
 
Tom

Another problem that I have some experience with. When we first purchased Dana, she came with a drive saver (Red Doughnut) already installed. The drive saver is 1" thick. The shaft moved aft to accommodate the drive saver and the prop was not able to be removed from the aperture without dropping the rudder. I didn't like that so at one point when I had the rudder down and out I had the shaft shortened to allow the prop to be removed with only having to remove the drive saver and sliding the shaft forward 1". I don't remember the actual dimensions of the modifications to the shaft but it wasn't very much removed. I wouldn't be without a drive saver in the system. At one point, leaving a dock, I sucked a dock line into the prop and stopped the shaft abruptly. The drive saver failed immediately with no damage to the tranny or the engine. It also isolates the shaft from the engine electrically. Which is a good thing in the prevention of electrolysis. I hope this helps.

Jim
 
I have a Red donut drive saver, installed by previous owner. The shaft length accommodates this. I have removed and replaced my Hurth transmission without ever moving the engine. Just remove the donut and shift the shaft aft a bit. The transmission unbolts and you can lift it out. I am not all that strong and I did it without help. I would suggest, however, if you are removing the transmission, take the time to replace the unit inside the bell housing that protects the engine from gear changes. I am embarrassed to say I do not remember what it is called, but it has several springs that absorb the initial shock of engaging the gears. Mine wore out after many years, when the last of the springs broke and then I had no power to the shaft. It is not a hard job to replace and once things are opened up, it is a good to do it on an old Perkins. Finally, if your boat is out of the water, you can have someone check the shaft for wear. For that you probably do need to drop the rudder, although I once had a yard replace the cutlass bearing by pulling the shaft into rather out of the boat. Good luck.
 
Terry, its the Damper Plate.
What Terry said is spot on. No need to move engine. Unbolt everything at rear flange. I can't remember if I took the coupling flange off the shaft to remove the trans.. But I had the coupler & trans out and had the holes (that were egg shaped) welded up & re-drilled. After you remove the flange bolts, use a dead blow hammer tapping around the outside to separate. Don't drive a screw driver between the flange surfaces. 4 or 6 bolt (can't remember) later the trans will slide out. Put red donut back in, its a good thing to have. If you take the flange off the shaft, put a bit of anti-seize on the taper so it'll come off easier next time.

The damper plate is a spring loaded shock absorber between engine and trans. The springs can break (replace assembly) or fatigue... in which case the springs will move freely in their space. Replacement becomes a judgement call at that point. If you noticed a clunk going into gear or rattling, it could be time to replace the damper plate. The "bell housing" has to come off to replace it, IIRC. The rule of thumb is if the trans is out and you don't know the last time the damper plate was changed...replace it. Depends how frequently you want spend your sailing time stuffed in the 1/4 berth access hatch! If you're putting a new trans in it'd be smart to do the whole job completely, my 2 cents.
 

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Oh my, that's a lot of information.

It's heartening to hear I may be able to get the Hurth out without moving the engine. and I may be able to fit the red donut without cutting the shaft. Looking back at old photos it does appear there are a few inches between the prop-nut and the rudder, and I recall the shaft union having some extra keyway cut. I might gain some space by sliding the union back - especially if the shaft fits inside the red donut,

I did buy a new drive plate with the new ZF15 - do have a good "clunk" going into gear.

I'm back in Alaska for the winter so won't be wrenching until March - first thing will be to locate the red donut. Then I'll see how it goes. Thanks everyone for information.
 
I have a new (unused) shaft saver I am willing to part with. I could not install it because I put on a feathering prop and the blades could not feather with it. I don’t remember the measurements but it pushed my prop back where the feathered blades would hit the rudder. I don’t remember the cost but I’ll research and take 50%. Now I have to put my hands on it. I know it’s stuffed away in some compartment on the boat.
 
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