[C320-list] Transmission Drive Flange Bolts Fall Out

[Ken Geiger]

Northern Dream,  hull #765 is a 2000 year build with a Yanmar 3GM30F engine s/n E25479 with Marine Trans 
(from an old Survey) .  

Trans S/N and other info not known but I can update that when next aboard.

I have pictures of the nuts and bolts for those interested.  

Ken

 



 

 

---- Original Message ----
From: Chris Burti <clburti at gmail.com>
To: 320 <C320-List at catalina320.com>
Sent: Mon, Aug 10, 2015 12:38 pm
Subject: Re: [C320-list] Transmission Drive Flange Bolts Fall Out


Ken,
Engine, transmission and Hull Number info would be helpful...please
share.

Thanks,
Chris Burti,
Commitment, #867
Farmville, NC

On Mon, Aug
10, 2015 at 9:51 AM, Ken Geiger <kendgb at aol.com> wrote:

> A few days ago
while motor sailing we heard a low vibration sound.  While
> continuing, I
inspected the transmission output area and at first saw
> nothing shaking but
then observed 2 bolts laying on the floor under the
> drive flange.
>
> We
stopped the motor and I found 3 of the 4 bolts had fallen out and the
> fourth
bolt was loose with the nut still attached.  I found all the nuts
> bolts and
washers under the engine and replaced them and got back under way.
>
> Later
at anchor I removed each bolt and nut, cleaned and re tightened with
> some
blue loc tite that we had on board.
>
> The 4 bolts were M10- 1.25 x 33 mm
long except 1 was 35 mm long. The bolt
> used a 15 mm wrench and the thin nut
used a 17 mm wrench.  The bolt head
> had a #7 forged on it.  There was a lock
washer used but placed under the
> bolt head. On auto applications these nuts
and bolts would be high strength
> and perhaps these are as well.
>
> I
intend to investigate replacing the above coarse thread with M10-1.0
> fine
thread bolts that will be more resistant to loosening; fine thread
> bolts are
used on auto drive shaft flange applications.
>
> There is limited space
between the back of the transmission flange and the
> transmission but I will
also investigate using a nylock self locking nuts
> there.  There is also
limited wrenching space between the bolt heads and
> the driven flange that may
present problems finding a suitable bolt.
> Perhaps this is why the bolt head
is 15mm across the flats.
>
> I also will had a look at the motor mounts and
cutlas bearing as the prime
> source of the vibration that loosen the
bolts.
>
> A quick search of this forum found no similar discussion.
>
>
Comments welcomed.
>
> Regards
>
> Ken Geiger
> Northern Dream #765
> on
Georgian Bay
>
>
>
>


-- 
Chris Burti
Farmville, NC