[C320-list] Transmission Drive Flange Bolts Fall Out

[Rick Sulewski]

Chris, 
On my boat with a Westerbeke engine, the only bolts in the drive system that are safety wired are the 2 bolts that help secure the dimpled prop shaft to the shaft coupler (flange). The four bolts that secure the prop shaft coupler (flange) to the motor drive coupler are secured with lock washers. Absent the lock washers that are fully collapsed/very tightly secured, one could anticipate loosened bolts over time without lock washers, given the normal vibrations from a 3 cylinder diesel.  As with most high vibration machinery, periodic inspections are recommended...and never experienced such a problem after 1,350 hours.
Rick  95' C320 Hull #277 

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Chris Burti
Sent: Friday, August 14, 2015 12:59 PM
To: 320
Subject: Re: [C320-list] Transmission Drive Flange Bolts Fall Out

I'm going from memory, but aren't those bolts drilled for safety wire?

On Mon, Aug 10, 2015 at 1:24 PM, Ken Geiger <kendgb at aol.com> wrote:

>
>
> 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
>
>
>


--
Chris Burti
Farmville, NC