The dependable eska

[Capt Ron]

Re: The dependable eska

One more thing about hoses, especially heavy duty hose, it takes a set from being rolled into coils or on spools. Even a short section of hose will try to curl and form a slight arc when laid on the bench. When used to connect two rotating shafts it will work itself to destruction.

Lovejoys would be the best store bought solution and they have one more advantage. Each half can have a different shaft diameter (within reason).

Capt Ron

 

[mckeemm]

Re: The dependable eska

Hi,

So the hose type coupling has sparked quite a debate! I take all your points as valid but let me tell you why it appealed to me in the first place and maybe we can all agree on the best way to solve this puzzle.

I have a good 1955 Johnson 5.5 with a powerhead that was completely disassembled for rebuild by a previous owner who balked at the price of parts and gave up. He gave me the motor in boxes. I may want to rebuild this power head in the future so I don't want to alter either the drive shaft or crankshaft.

The 3.5 Briggs has a 3/4" splined shaft I believe. The 6.5 at the surplus store has a 1" splined shaft. The drive shaft on the Johnson is kind of odd. It's like combination square drive with four splines at the corners approximately ?? diameter.

Problem: How do I get them coupled without alteration to the lower unit shaft? Does anyone out there have a scrap crank that I could cut the end off and weld to a 3/4" or 1" keyed shaft coupling?

Another problem is the length of the shafts on these Briggs engines is way too long especially after adding a coupling. What is the best way to shorten them to lower the center of gravity of the whole rig and minimize the height of the spacers to be built?

In the meantime I'll Google "shaft couplings"

Mohawk

 

[sunkentreasure]

Re: The dependable eska

Lovejoy couplings are rated in horsepower, so you select one that suits your engine. As far as splined shafts, measure the absolute outside diameter of the shaft and order a Lovejoy that will fit. The setscrew on the coupling will fit between the splines to secure it.

Now, none of that addresses the length problem you mentioned. It would probably be best to locate a junker outboard or just the shaft and work with that. Shorten the shaft, order the appropriate coupling and file or grind a flat where the setscrew is located. Install the coupling half using Loktite on the setscrew, drop the rubber spider in place and install the other coupling half on the engine crankshaft. Lower the engine on the lower unit and voila! This is assuming that you have made some provision (like an adaptor) to bolt it to.

Another method might be to use the old ouboard crankshaft end as an adaptor since it already fits the splines. I would cut it off and mate it to the matching part that fits the Briggs crank. Of course, this would require some welding and machining but would result in a very solid unit. There should be some allowance for a sliding fit, so close measuring is called for. Welding the shafts together would work but they have to be exactly aligned or you'll have vibration and bearing issues...plus disassembly would be a little akward.

Cutting crankshafts isn't all that hard. You can buy hacksaw blades that are pretty tough.

Finally, if you just HAVE to use the hose method cut a hole in the outboard leg as suggested to make assembly easier then fabricate a cover plate/gasket held in place by two screws.

It seems to me that the biggest problems would be getting the length correct and fabricating an adaptor for assembly. Either is not a major problem and would result in a nifty little four stroke.

 

[mardom61]

Re: The dependable eska

Not sure if this will help, but Princess Auto in Canada has couplers. The link below is for 3/4" shaft and is rated for up to 10 H.P. at 3600 rpm. I believe most lwan mower engines top out at 3600 rpm. The catalog also states that it uses 3/16" key. I have a 4.5 hp ted williams and I too am considering a 5 to 6 h.p vertical shaft swap.

http://www.princessauto.com/farm/dr...2-coupler-flex-l095-x-3/4-in_?keyword=coupler

Parts can be ordered online

 

[Capt Ron]

Re: The dependable eska

mardom61,
This is a Lovejoy type of coupling that has been discussed earlier. Price is good.

Capt Ron

 

[mckeemm]

Re: The dependable eska

Hi,

I was planning a trip to the local Princess Auto outlet this week I'll check out what they have.

I checked my Briggs 3.5 quickly with a tape measure and the shaft looks like it's 7/8". The drives on the various outboards in this hp range are about 1/2".

One trick might be to cut the extra length off the motor crankshaft and use it to make the adapter. You could shorten the outboard drive shaft, bore a hole in the cut off piece of crank shaft set it over the outboard drive and weld it on using the coupling in between.

it would work if there is enopugh room for the coupling.

Mark

 

[Capt Ron]

Re: The dependable eska

In an earlier post I stated that SC requires a title and registration for any O/B motor 5hp and over.

After looking for a solution on the website to upgrading a 4hp Sears to a 6.5hp Briggs I finally called SCDNR for an answer. It was like talking to a 3 year old child but I managed to get transfered to the right department...Investigations.

The 4 year old woman there took my name and address so that the forms could be sent and told me that I would need to take pictures and write a thesis on what I did, how I did it, and why I did it. Plus send a receipt for the replacement motor along with $10 to have the request reviewed... What if they decide to reject my request, will all my work be for not?

I'd really like a concrete answer before hand.

Plus she didn't say it but I know that I will need to pay county taxes on the motor and send a copy of the tax receipt with the application. Is this red tape worth the effort? Well, I'm bored and need a good project to keep me out of trouble. Besides 6.5 hp would make my Avon zip along just fine.

One more thing, I'd like to use an external fuel tank. I think that a simple system of feeding the orignial B&S tank from an external tank may work. I use this system on my Honda EU2000i generators to run both off a 6 gallon boat tank. (But then the Honda's have fuel pumps...rats). More research!!!

When I get the forms from DNR I'll decide to continue or not.

Capt Ron

 

[Alphawolf45]

Re: The dependable eska

I am a machinist with well equipped machineshop. I have pondered attaching 4stroke lawnmower engine to good lower end off a 5hp Firestone OB...Such project is not one problem for me , just takes sufficient tiime and money...But I wonder if the unit would be homemade/dorky looking, hate to show up at the lake with something I am embarrassed about..Such concerns put me in mind to buy new and purty Briggs engine in order to guarantee best looking unit when finished..But such new 4 stroke Briggs engine is 200plus bucks and for that much cash a guy can get good used (2 stroke) outboard boat motor of same hp and not have to do much work........(granted, grafting 4stroke engine to good lower unit is a good option to end up with a 4 stroke engine)
.
.More Likely instead I'll get a larger horizontal shaft engine and construct one of the mudhog(?) boat engines that have the propeller sticking straight out the back of the boat about 6 foot..At least then the resulting shopbuilt contrivance will give my boat capabilty to go places that conventional 5 or 6 hp outboard will not go.Cant anybody laugh at that.

 

[mardom61]

Re: The dependable eska

Capt Ron,

did not know that was the name, thanks. I see they can also be purchased at northerntool.com although more expensive.