Dog clutches

Any questions? We will try and help.
Doc
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Joined: 18 Jul 2009, 07:28

Re: Dog clutches

Postby Doc » 21 Jul 2009, 12:03

Hi Peter,
Your motor needs to sit as low as it can, coming from your flywheel you would need a Z-Drive. A dog clutch is only a warm up clutch, ignition turned off - engaged - restart. And moreless the same when stopping. You would need a extra 6"in lenght to move the motor forward. Motor would go up in height ,hatch clearance might be a problem. It would a lot easier to make a stand for a water hose to point at the back of skeg to cool fibre bush ,when starting or tuning at home.Note you can come off flywheel end, you will have to change PROP. Oil Pump. Sump. Relocate Starter Motor to front of crankshaft. Doc.

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Sunbeam11
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Location: Canberra

Re: Dog clutches

Postby Sunbeam11 » 21 Jul 2009, 23:23

Hi Doc.....thanks for more info.
I like your idea on the stand for keeping water on the Skeg. :idea:
Oh gees... what a lot of work to turn the motor around (for me anyway...I'm not very mechanical...Im a chippy) too much work and cost......I'd rather spend it on building a nice motor (with out the clutch) and the hull.
I am really locked in with the position of the motor, as my hull, being short in length (19 ft.) for a triple cockpit...I dont have a lot of room to move the motor forward... hard up to the second bench seat now.
Also, early photos showed only the twin aircleaners out the top of the hatch...so I dont want the engine sitting any higher if I can avoid it. Also I've got some great bits of the old engine I want to use again,,,but they only work in current configuration.
I'm running out of options by the look of it..... :(

On another interesting topic.....Correct me if we are wrong... but my sons boat (his first boat, a 1980 model Spyder hull ski) has a dog clutch and we just lock it in and out all the time at idle revs when going round to pick up skiers etc....is that incorrect use or causing undue stress??????even strictly at idle???? as my thinking is..cutting engine and restarting all the time is hard on starter motors and batteries and sometimes on fickle/tempramental engines.....harder starting problems ie. flooding carby,hot starts etc. i'm interested in feedback....
cheers
Peter G

Doc
Posts: 256
Joined: 18 Jul 2009, 07:28

Re: Dog clutches

Postby Doc » 22 Jul 2009, 05:49

Hi Peter,
They say if the revs are low enough it shouldn't be a problem engaging. The coupling slides on a spline , three lugs at each end marry up. These are machined sq. edge, so i suppose if you hear any crunching while engaging revs may be to high or chance of damaging coupling lugs.
Cheers Doc.

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bootlegger
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Re: Dog clutches

Postby bootlegger » 22 Jul 2009, 08:35

Dog clutches are fine to engage and dissengage while the engine is idling. A prop relaese is a different lettle of fish all together.
One thing you havent invetsigated is a soft clutch. They make them for modern engines using the original car clutch with and adapter. That would work. You could still get the motor lower enough by modifying the sump and turning the oil pick up around ar better still dry sump it. It would be still higher than driving from the timming case end though.

Doc
Posts: 256
Joined: 18 Jul 2009, 07:28

Re: Dog clutches

Postby Doc » 22 Jul 2009, 08:58

Using a soft clutch will need a flywheel which runs the starter motor. Soft clutch more suited for V-Drives and Z-Drives , motor is mounted level. We are still taking about a Ford side valve?

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Sunbeam11
Posts: 80
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Location: Canberra

Re: Dog clutches

Postby Sunbeam11 » 22 Jul 2009, 20:53

thanks for the great feedback fellas..... :)
I think I am really stuck with leaving the engine driving of the timing case end....
yep...and I'm adamant about sticking with the V8 side valve engine, (luv em...one reason why I had to have this boat)
She has the flywheel up front...which as suggested using a soft clutch seems good...but still means turning engine around........and you should see the shape of the existing sump........it has been totaly made from scratch (all galvanised) with water chambers running through it to cool the oil and its been profiled to be as low as possible... it looks like a winged keel.
Dave P, Ive heard of dry sumps..but I know stuff all about them...so I will do some research...
Gees... lol....(am I trying to justify the easy way out :?: ).....the height thing is still a bug bear ( you all know this anyway)...as it makes the angle of the drive shaft steeper (not good as well as new skeg etc.) and I dont think it would suit the boat, having any more motor poking out above the hatch/deck.
Again fella's I appreciate the options offered and its certainly helped me get the options sorted out early before I waste time an money.

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bootlegger
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Re: Dog clutches

Postby bootlegger » 23 Jul 2009, 10:22

Doc wrote:Using a soft clutch will need a flywheel which runs the starter motor. Soft clutch more suited for V-Drives and Z-Drives , motor is mounted level. We are still taking about a Ford side valve?


Cassells sell a soft clutch set up for centre mount. No Z drive. I also have a 6 cylinder Falcon here midmount running off the flywheel end.

Doc
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Joined: 18 Jul 2009, 07:28

Re: Dog clutches

Postby Doc » 23 Jul 2009, 13:26

Dave ,
Midmount is fine when you have the space , when using a flywheel clearances and the shaft angle means the motor will go forward and up in height. Manifold will have to be modified for opposite lean for carbies plus cooling becomes a problem. With the flywheel end down and front of motor up the water enters the front[water pump area ,left & right ] and will exit straight up to the highest exit point in the head . Without cooling the rest of the motor. I would stay with the existing setup .
Doc.

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Sunbeam11
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Location: Canberra

Re: Dog clutches

Postby Sunbeam11 » 23 Jul 2009, 22:56

yep...gents....its looking that way, i.e to keep it as a direct drive of the distributor end.
I will just have to have a good starter motor, a strong battery and always kept in tune.
Although I'm still interested in having a look at the soft clutch setup as well Dave....just for future reference.
On the water pump detail......the old motor has a 10mm thick solid brass adaptor/engine mount covering where the left and right waterpumps were (drive end) and an external Jabsco waterpump driven of the fly wheel end, up front.
anyway, thanks fellas for the feedback, its apreciated.

Sea Urchin
Posts: 10
Joined: 13 Aug 2009, 22:58

Re: Dog clutches

Postby Sea Urchin » 15 Aug 2009, 01:07

Hi Folks

Just for interest, Tawco products are still available from Luxfords: www.luxfords.com.au
When I made enquiries about a year ago, they were really very helpful and appeared to have most parts available.

Another course of action is to salvage a wreck. I picked up an 18 footer on a reasonably good trailer for $250 (delivered!). The motor was a basket case but the marinising gear which included a dog clutch was all in very good condition. One man's stalled project is another's treasure chest...

Cheers

Joe


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