[Public-list] VOL IT

[Don Campbell]

	Having read some of the replies to Jack's question, I thought I should
send this to the list since most of you missed that the keyways on the
couplers could be cracked. 
Don # 528

-------- Original Message --------
Subject: VOL IT
Date: Fri, 07 Jul 2006 21:39:15 -0400
From: Don Campbell <dk.campbell at sympatico.ca>
Reply-To: dk.campbell at sympatico.ca
To: "Walsh, Jack" <jackwalsh3 at verizon.net>

Hi Jack;
    I have had the same problem. It happened to me in  the  Welland
Canal a couple of years ago and sailing is not allowed there! I managed
to get forward motion  from the pressure of the shaft driven forward by
the prop onto  the end of the tranny shaft!
    The keyway in the coupling is just a 1/8 x 1/4 slot in both halves.
However, the amount of metal between the keyway and the edge of the
coupler, particularly on the half on the  tranny is really thin and this
often breaks allowing for a lot of play for the key. The original key
was brass or bronze.  There is no Woodruff keyway  in the shaft either,
but a 1/8 x 1/4 slot as well, so the key is 1/4 x 1/4. When I took both
halves of the coupler off, both keyways were broken out. You may need a
magnifying lens to see it but once you know it is there is is really
obvious.
    I went in to the main supplier for Atomic 4 parts in Toronto to get
new ones and as usual, none were available but used ones were. All were
in the same state with broken keyways so I brought the boat home 100
miles  without reverse and   only a very weak forward, still having to
go through the canal and took both halves to a local machinist. He made
me a pair for less than the cost of the  used ones. The problem with the
standard ones is that they have the keyways aligning on both halves
insead of having them at 180 degrees apart - that is,  the front one
should be on the bottom while the back one should be on the top to
balance the shaft properly, so they did that too. (But the shop requires
both halves to get the balance correct because the three bolts that join
the couplers are not perfectly symmetical, so not interchangable for
alignment and would not align at 180 in any event since thay are 120
degrees apart). Then there is the problem of the nut on the back of the
tranny shaft that holds the front half of the coupler to the
transmission shaft. It is held locked on with a lock washer by bending
the 3 small sections up against the sides of the nut. If or rather when
this lets go, the threads on the shaft become ruined very easily since
reverse gear backs the nut off, as mine were, so you need to replace
both the nut and the shaft. Since no-one wants to sell just the shaft,
you will probably have to buy the whole transmission or get a shaft
machined. The nut was about $40 as it is a special half normal
thickness  one and the lock is another part.
    This is a nutty system really, as there are so many things that were
not done correctly the first time. Even finding replacement keystock
that is bronze is not easy and with the mix of metals there anyway, the
galvanic action between mild steel and stainless is such that using
either material for the keyway is probably preferable to using bronze
and adding a third metal.
    The other thing that is never easy is the location of this stuff.
There is only one way to get at it and that is to stand on your head ,
get over the motor some how,  and take off both sections of the coupler
without dropping the keys into the bilge. (You can also pull the motor ,
which I did,  as it was easier to replace the transmission out than in.
Moyer's manual is quite good for the photos and description of the
procedure but it is not required if you are able to remember what you
have done as you take things apart.There is a seal to replace on the
coupler that affixes to the transmission so you need two pretty rugged
screwdriver-wedges to start the coupler off and then a gear puller is
best for the balance of the pull there. That coupler  really needs to be
checked as the broken keyway scores the seal so oil leaks into the
bilge. Moyers have the seal.
    If you need to align things once the coupler is fixed, I have a
simple and cheap way to do that if you have a coat hanger, some masking
tape and a grinder. A second person helps a lot too, more for eyes than
strength.
I hope this helps.
Don #528

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