A25 drive shaft question

[Sunset]

This past week when coming to a dock the boat failed to reverse, then failed to go forward, and I was left adrift. Unable to find any mechanics' assistance I was forced to investigate on my own, hoping the solution lay outside the tranny itself. After manfully struggling to remove the helm seat and heavy engine cover - and balancing it on the cockpit seat - I was able to see that the stainless drive shaft had come apart from the receiver at the rear of the engine. I found that I could slide the shaft toward the hole where it is supposed to enter the tranny. There are two opposing holes in the tranny housing and two opposing holes on the shaft, about 1/4 inch diameter. Obviously for some kind of cotter pin method to secure. So i fished around in the sludge under the engine and pulled out a pin about 2 inches long, perfectly cylindrical and smooth, same size as aforesaid holes! Woopee!

I was able to re-connect the drive shaft and carry on, proud of my intrepid problem-solving . . . but here's the thing: the smooth pin worked into the holes with the assistance of a hammer, but there doesn't seem to be any way to actually secure the pin in position. The pin does not go right through all holes and protrudes a half-inch from the housing. It seems like it wouldn't take much for it to dislodge again. Can anyone advise me as to how this pin is normally secured? Kicking myself for not having taken pictures to illustrate, and reluctant to remove the box just for that purpose.

 

[LarryM]

If it is Volvo power, it sounds like your shaft coupler might use a 'tapered pin' to secure the shaft to the drive flange. This was used by Volvo many years ago on small marine engines. I think it can only be inserted from one side (because of the taper) and was simply driven in with a brass hammer. That's about all I can remember about those. Hopefully another member will have more details about that type of couplers. If it were me, I would try assembling it with some Loctite and cross my fingers. Here is a typical Volvo coupler.

 

[Sunset]

Thanks Larry. It looks like I've done what's supposed to be done. Your dwg is exactly what I have.

 

[Conrad]

If memory serves, on our first Albin there was a pin (actually a long bolt) c/w threads on the end that went through the hole(s) and was then secured via a washer & nut. But whether that was original or not I couldn't tell you. The other important ingredient is the key & slot arrangement which absorbs the torque - that pin wouldn't have a chance.

 

[Sunset]

I've thought about replacing the pin with a hardened steel bolt and nut. I think that I will go ahead and procure that and keep aboard as a spare in case of a further occurrence.

As for the key and slot: I certainly saw the slot on the interior of the receiving coupler, but no key. If by key is intended to be a protrusion on the shaft itself which would slide into the guide provided by the slot. I wondered about that. Now I am worried about that!

 

[Conrad]

On ours there was a slot in the shaft plus a slot (I assume that is what it is called) in the coupler. The key (ours was brass as I recall) slips into the mated slots and takes the stress of the torque.

 

[Sunset]

Sounds like I should clean out the engine bay and search for that key.

 

[Bensjoy]

A25 Drive Shaft

I had the identical incident occur when I also owned an Albin 25. I believe I put a large hose clamp around the coupling and over the head of the retaining bolt to prevent it from backing out. It might also be secured with a seiziing wire if there is a way to secure it to the head of the bolt.