clutched gearbox and stuff for 40+

[Shearwater]

I want to convert my SJP long shaft to a clutched version of it. Maintaining the original Seagull looks, but with a little bit more convenience. I understand that it is mainly a matter of replacing the gearbox assembly. So I'm in need of :
- gearbox 1:3.5 of the clutched type in good condition.
- waterpump housing and gasket
- the right propellor
- clutch rod

I have all the other bits such as gear lever, drive shaft and tube (the bulb for the thread for tiller is there), exhaust of my SJP. Or am I overlooking things?

[Charles uk]

There is no clutched version of the 3.5 : 1 gearbox, you will need to find yourself a model 55, 2.5 : 1 gearbox & swap the whole bottom end including prop, water pump housing & clutch rod, just about everything below the long shaft power head.

Good luck!

[Shearwater]

I thought that the clutched gearbox of the Century and the 40 plus had the same gearboxes and have ratio of 1:3.5. Such as this one:
http://www.ebay.co.uk/itm/British-Seagu ... 1868394211 The description says that it is 3.5/1

What would 1:2.5 instead of 1:3.5 do to the power output?

[Charles uk]

No that's a 2.5 : 1 box & will require a 3 bladed prop not the 4, when used on the 40 series motors .

That would inply the vendor knows little about what he's selling.

[headdownarseup]

I'm fairly certain the seller is one of us.

Nothing wrong with the description of this gearbox. Fits both century and 40+ (late models though as this is a sealed gearbox)

[Charles uk]

Am I wrong Jon is this a 3.5 : 1 box?

[headdownarseup]

You're NOT wrong Charles, this is definitely a 2.5:1 ratio on this gearbox. I've just checked on my gearbox i have stripped down at the moment.
Incidentally this same gearbox with the century pumphousing and 4 bladed prop was the set up for a model 75.
(btw this is the same pumphousing i'm still looking for on my "other" frankenstein motor)


Jon

[Oyster 49]

I do think adding a clutch to the 40 makes it a lot more usable. Just make sure the right prop is used. The standard SJP prop is stamped 40+ but is too coarse a pitch for the clutched gearbox. I had that problem on an engine I bought, it would barely run beyond tick ever with the drive engaged. as Charles says you need the 3 blade prop to go with that gearbox.

In think if fitted to a century a different prop again is need to allow for the higher power power head.

[JERSEYMAN]

I once picked up a 40 plus, I got it started right away no problem but when I put it in the water barrel to check circulation it would not start, out of the water, started no problem, in the water no go again then I noticed it had a 5 blade century prop on, I fitted the correct prop and it started well in the water, a lesson was learnt on using the correct prop but to me it seems unbelievable that the extra blade made so much difference....the motor would not even fire not to mention run.

There's a reason there are so many props for these motors, I can't help thinking that British Seagull got it fairly right.

[headdownarseup]

Absolutely Rene...
why mess with perfection?

If it was good enough all those years ago, i'm sure it's plenty good enough today.

The British Seagull engineers spent a LOT of time carefully working things out so that we didn't have to make the same mistakes!


Jon

[Shearwater]

An update on my clutch project. I managed to get all the things need for a conversion and assembled the lot. I actually haven't run it yet but everything seems to work well. Her a few pics.

[headdownarseup]

Handsome looking motor.
Looks good mounted on the back of the boat too.
Have you tried it out yet?

Jon

[Shearwater]

No, haven't tried it yet. There is a little bit of work to be done before it can run.
It is exactly the type of motor that I like at the back of my clinker ply dinghy

[headdownarseup]

Keep us posted when it does make it's maiden voyage.
I'd be interested in knowing how well it goes coupled to a clutched bottom end.

Slightly odd, but interesting.


Jon

[Oyster 49]

Exactly the same as a FPC I would imagine the larger transom bracket is a good idea with a long shaft 40, better support.