[C320-list] Transmission Drive Flange Bolts Fall Out

[Chris Burti]

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