H34 shaft replacement

[Charlie98117]

I am planning to replace my 25 yo dripless shaft seal and thought it would be easier to cut off the shaft and replace it rather than try to pull off the corroded flange. Wondering if I'll need to drop the rudder to remove the shaft or will it slide out alongside?

 

[Don Crowther]

You could cut it in 3 pieces to remove it.
But the new one might go if the cutless bearing wasn't installed yet.
Are you doing this on land or in the water?

 

[Charlie98117]

Definitely on the hard, plan on installing a new cutlass bearing too. So the shaft would slip by the rudder if I remove the cutlass first?

 

[Allan12210]

I would still give removing the coupling from the shaft a try before cutting it up. Mine was on very tight but I still managed to get it off to install the maintenance kit for my dripless packing. A tool I used was a steering wheel puller. That way you don't risk bending the transmission side of the coupling as some previous posts have warned. It is thin enough to fit in the relatively small space created when you uncouple the two halves and slide the prop shaft back from the engine. I have a puller shown in the picture that I bolt through a couple of the holes in the shaft coupler. Soak the coupler and shaft with PB blaster. Then I replaced that long bolt with a short one (maybe 1-1/2" long with the same thread. I think it is a 5/8" fine thread bolt. That develops a lot of pressing power so go easy as you tighten it and tap around the perimeter with a hammer. As you bottom the bolt when the shaft is moving out, remove the bolt and put a spacer (like an old nut or socket) in there and repeat. That will save you the cost of a new shaft and either dropping the rudder or the strut if you can't get enough swing to feed a new one back in. Raising the engine could work too, but you still have to go through the realignment process too which can be a pain. I took the money I saved and applied it to a split coupling available at PYI . That solves the issue in the future.

 

[Charlie98117]

Thanks for the response Alan. Your flange looks like new! Mine is pretty badly corroded so I was thinking it would be a difficult job to get it off and perhaps worth the $400 for a new shaft and flange. If the shaft will move aft enough to get a puller in there I should give removal a try first I suppose.

 

[Richard Bryer]

You can pull the flange from the shaft by using longer bolts and placing a short piece of pipe - I use a piece of brass pipe about 1.5 " long and 7/8 dia-as a spacer between the end of the shaft and the transmission flange. tighten the bolts a bit each in turn to press the flange off the shaft. I use brass because it is softer than iron and will bend first.
I was not able to get the shaft out past the rudder- I raised the engine by hoisting it with my mainsheet pulley set attached to a piece of 4X4 across the companionway. I didn't need to re-align after setting it back down.

 

[Charlie98117]

You can pull the flange from the shaft by using longer bolts and placing a short piece of pipe

I've seen that approach but also caution that it might break the flange on the transmission. The corrosion on my flange is pretty thick so I was thinking it would be difficult to break loose. I'd be afraid to put much force on it but who knows, with some PB Blaster and gentle taps it might work.

 

[Pizzazz]

The recommended procedure is to lift the engine by 4-5 inches and slide the shaft below the engine. It is not too much work. Unbolt the engine, may be remove the exhaust hose if it is short then inflate a basket ball below the engine. Once you have enough clearance support the engine, take the ball out, slide the shaft out. A piece of cake. You will need to align the engine afterwards but you have to do this anyway if you are replacing the cutlass bearing.

You do not want to remove the flange from the shaft because it is factory aligned and it is unlikely you will align a flange on a new shaft as well. Actually, if you order a new shaft it will come with its own flange with instructions not to remove the shaft. The other benefit of this procedure is that you can do it in the water with minimal risk.

 

[Charlie98117]

As an epilouge for this thread I finally got around to doing the project. I sawed the old shaft to remove but it was obvious the new wasn't going in without lifting the engine or dropping the rudder. IMHO lifting the engine was definitely the way to go, just needed to remove the 4 engine mount nuts. Didn't have a basketball but I did have a mainsheet and winch. I tied off the main halyard around the boom for reinforcement and dropped the mainsheet through the companionway. Engine lifts up, new shaft goes in, easy peasy.

 

[njlarry]

Allen, does the split coupling need to be machined fit to the shaft? If so how does that process work?
Thank you.
Charlie, thanks for the pics. Congratulations on a job well done.

 

[Capt Robbie]

Before you spay pb blaster on the flang, coupling, and bolts.
Brush everything you are trying to get apart with antifreeze fluid.
Let The antifreeze set for a few days it breaks down rust and corrosion. Then spay with penatrating oil "pb blaster".

An old school auto mechanic showed me this trick to get old seize bolts free with out snapping them.
Works about 95% of the time.

Hope this helps

 

[heart of gold]

This is a great thread with some very good information. Thanks for posting

 

[Capt Robbie]

The anti freeze trick works well if time permits

 

[Allan12210]

Allen, does the split coupling need to be machined fit to the shaft? If so how does that process work?
Thank you/QUOTE]

Njlarry,

I suppose the face should be faced to insure it is perpendicular to the shaft axis. But since I didn't remove my shaft, I just installed it. It has a fairly long contact length with the shaft I decided it was probably true. It was really nicely machined so I figured the end was square. After 4 years I have not noticed any unusual vibration. Inspection of the cutless bearing after 3 years did not show appreciable wear. Looks like everything ran true.

 

[FDL S2]

The anti freeze trick works well if time permits

I saw this post back in February, I had never thought to use anti freeze to free rusted bolts, but I tried it on a rusted transmission mount my old truck. Three days later and a little Kroil and it came off slicker than snot.

Thank you five months later.

 

[nfg2u]

When a new flange is attached to the shaft it will need to be milled in a lathe to be true. I just did the same job and replaced both flanges, the one on the transmission and the one on the shaft. I had the shaft sent out to be checked by the prop shop. They did some minor corrosion repairs and checked it for true. Then my deisel shop attached the shaft flange and took off enough of the face to true the flange to the shaft. Thats the only way to get the tolerance that is needed when doing a re-alignemnt. I bought a $50 1/4 ton hoist.
I think marine engine alignment is like religion. I just do the best I can and what feels right. ;-)

 

[Ilanortho]

What kind of alternator is on there (not to get off subject?)

 

[nfg2u]

Balmar 100 amp 60-100-SV with an external regulator.

 

[Ilanortho]

Thank you. Nice work! Ilan

 

[John L]

Look for my post in Hunter big boats John L,Apr 10, 2017. H34 prop shaft replacement.