model 90 conversion

[headdownarseup]

Hi all.

I have a model 90 longshaft which i'm currently giving a "once over".
My usual boat will accomodate a STANDARD shaft motor with ease, but a longshaft motor is just too much for it.

Now, what i'm looking to do is convert the motor from longshaft to standard shaft, a difference of around 6 inches in length.
The motor has already been apart when i first got it, and i noticed then that there was a removeable length to the drive shaft, the same length of 6 inches, presumably a standard factory issued part, which makes things a bit easier to convert.

So, what i'm after is a standard length drive tube for a model 90, not worried about lack of chrome as it will probably get painted anyway.
I also need the upper part of the clutch actuating rod for the FNR gearbox. A standard length exhaust tube and water feed pipe.

Can anyone help?

Jon

[Charles uk]

Only 2 drive shaft lengths for a model 90, std 19 13/16" & long 25 13/16" so not factory.

[Oyster 49]

Why don't you just cut the required amount of the tube and exhaust etc.?

[headdownarseup]

Not quite as easy as cutting to length as the drive tube is flanged at the top and bottom.
I had thought about taking the tube to a machinist to turn down in a lathe, but he's not really interested, plus i dont have a lathe or i would have done this ages ago so i'm sort of stuck at the moment.
Everything else for the conversion is a piece of cake to do except the drive tube.

19 inches (or there abouts) is more or less right for what i need.
The other thing about these later tubes is the clutch pivot stud. It's much bigger than a silver century type, (it's actually a bolt that holds the lever to the tube) and the clutch lever with all the relevant fittings looks almost the same as a kingfisher version.

Charles
When i mentioned "factory fitted" what i meant to say was the square drive shaft has a removable section 6 inches long, which is the dimensions we're talking about here to convert from long to standard. Sorry for any confusion.

Can anyone help?

Jon

[Collector Inspector]

Shim up the transom?

13/16"?

Basha fine adjustment......since welded after perfect for hull. I know.....not a Gull.

Concept!

Then again maybe a pic or two?

We all love pics aye.

B[/color]

[headdownarseup]

This is turning out to be a real head @£&k at the moment.
It's too dark for taking pics right now but i will get some put up tomorrow evening when i get in from work. Hopefully things will start to make sense.

Basically what i'm trying to do is use all the original components including the transom mount (except the thumb screws and clamps) but this time bolting the whole arrangement onto the back of the boat. (not to mention the "other project" i have on the go at the same time with this which is building a remote steering/throttle/gear set up for the same motor)
I've had to carve a section of wood 6" wide x 3" thick by 10" deep but cut into a wedge to take out the effect of the transom on my boat. The biggest difficulty i have ALWAYS had with this boat is that i can only realistically use a century powered motor of some sort. The fact that the transom is nowhere near vertical only adds to my problems? Height adjustment is something different entirely with a model 90. An old 102, no problem as there's a "thingy" already on the drive tube just for that purpose.

Just been thinking about the drive tube today (as i do at work) and thought "what about using a kingfisher tube, standard length of course".
The model 90 has the same gearbox as a kingfisher (possibly the osprey too) Charles, are you there?
Are they the same!
Are there any wrecked motors out there that would donate some parts?

Pics should help sort things out

Bear with me

More tomorrow

Jon

[Charles uk]

Exactly the same, but the majority of Kingfishers & 170's were long shafts for work boats, now everybody wants to use them on smaller pleasure boats so need short shafts that's why Seagull no longer have any stock left.

Short shaft drive tubes are now at a premium.

Why not bolt 2 bits of 4 x 2 or 6 x 2 cut at an angle lengthways so the back edge is vertical ish & screw an 1 1/4" plywood motor mount to both of them long enough to support a long shaft motor, according to Seagulls own dyno reports, long shafts gave 0.1 hp more than short shaft model.
This way would save you a lot of time, trouble & money.

[THCL500J8]

Im having the same thought, I made a bolt on pad out of Form Ply for a tinny years ago because he only had a long motor, its still in use.

What a about something like the motor mount on one of these 60's plywood hydro's?

[headdownarseup]

Woodwork never was, and still isn't my strong point, but i get what you're saying.

(just wish you'd told me this earlier as my transom now has 4 extra holes in it to accomodate the "revised" motor mount ) Never mind.

If i were to go down the route of re-machining an existing tube, how easy/difficult would it be to get this done.Is there anything special i need to know about these later tubes i.e are they the same wall thickness from top to bottom? (except for the top and bottom flange)

I might also have to re-think the woodwork on the back too. sigh...

I doubt if 0.1hp will make a lot of difference to my old tub anyway. You already know how it goes......... sloooooow but then again i look at it as a floating caravan not a speed machine (it does me for what i use it for)

Going back to tubes for a moment, the only real difference i can see between a late silver century long tube and a 90 long tube is the bore size of the clutch pivot stud/bolt. Is that correct?
Just thinking as i have a new old stock longshaft for a silv. cent. stashed away for something but never got round to doing anything with it. Looks to be in very good shape, no trace of corrosion inside the tube either.My idea is to cut to length and re-machine the lower flange, drill and re-tap the thread for the clutch pivot. Hey presto!

What say you?