Inboard outboard air cooled engine

[maxum247]

Re: Inboard outboard air cooled engine

Okay guys need some help! Made the coupling to go on the drive shaft this evening. I took two peices of galvanized pipe 2 in. long, one peice is 3/4 and the other I beleive is 1/2 in. and drove them together, cut them to length and ground the ends for a good clean finish. They are a tight fit not an easy job to get them driven together. Don't beleive they would ever slip, I wouldn't want to try to drive them apart. Anyway driving them together sort of took up any slake that would have been between the coupling and drive shaft, got lucky there didn't know what I was going to do to shim that!
The drive shaft isn't cut to length yet, but here are some pictures and my question is, I plan to use what I beleive is called a roll pin to hold the coupling in place. This is a hollow steel pin with a slit cut down one side (Roll Pin) correct? The shaft is about 1/2 in. in diameter maybe a little larger. What size roll pin should I use 3/16 or 1/4 in. and should there be one in the middle of the coupling or one top and one bottom of the coupling with the shaft diameter that I have? I picked up a peice of heavy rubber hose with wire running through it about 5in. long that is a snug fit over the coupling as well as the engine crank shaft, will use two hose clamps on crankshaft and two on coupling, by the way both the coupling and the crank shaft are 1in. in diameter with the coupling made up this way. That worked out real nice having the outside diameters end up even! Thanks for any advice in advance!

 

[MikDee]

Re: Inboard outboard air cooled engine

I don't understand, is this coupling you made up supposed to go over the motor shaft, and L. unit shaft,? and do you intend on drilling thru the coupling, & both shafts to put a roll pin in top, & bottom? That will work, but it seems very rigid, & overkill,,, lol,,, plus drilling thru the shafts will weaken them some, but the roll pins will be like heavy duty shear pins, because a shear pin is softer metal like brass, and that's probably what's on your prop now, and that drives the boat.

My whole idea with the hose coupling idea, was to give good grip to the metal shafts using the rubber, backed up by a split sleeve PVC, or metal, that you can compress tightly with hose clamps as need be,,, because metal, on metal, slips easily, much easier then rubber on metal, plus you're not comprimising the strength of the shafts by drilling into them.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

Hey! Well done. I would drill it out and use 3/16 it is just to hold it in position and stop it from spinning on the shaft, right? Or you could drill it out and tap it and use a set screw with blue locktight on it. Then all that is required is a slight indentation in shaft instead of having to drill all the way through. If you ever have to take it apart again, the locktight will help prevent corrosion long enough to do your sea test and decide if we are using a good coupler. Again! Good job. I sure would like to be there, pics. help but it is not the same when inventing.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

I don't understand, is this coupling you made up supposed to go over the motor shaft, and L. unit shaft,? and do you intend on drilling thru the coupling, & both shafts to put a roll pin in top, & bottom? That will work, but it seems very rigid, & overkill,,, lol,,, plus drilling thru the shafts will weaken them some, but the roll pins will be like heavy duty shear pins, because a shear pin is softer metal like brass, and that's probably what's on your prop now, and that drives the boat.

My whole idea with the hose coupling idea, was to give good grip to the metal shafts using the rubber, backed up by a split sleeve PVC, or metal, that you can compress tightly with hose clamps as need be,,, because metal, on metal, slips easily, much easier then rubber on metal, plus you're not comprimising the strength of the shafts by drilling into them.

As I under stand it, what he made is a bushing to attach hose on. to bring both shafts to the same dia. motor crank and L U shaft. That is the L U shaft befor cutting to length

 

[MikDee]

Re: Inboard outboard air cooled engine

If I am understanding this right, you're gonna butt up the 1" O.D. shaft on the motor to the 1" O.D. of the coupling, then slip the coupling over the 1/2" L.U. shaft, and put in a roll pin, or use a set screw to hold it in place,, ok, But, if I'd known you wanted to do this, make a stepped down coupling, I would have suggested you make it of 3 pieces of pipe (pipe nipples) example:

1" I.D. pipe which should fit over the 3/4" I.D. pipe, which you know fits over the 1/2"I.D. pipe. This way, you can slip the coupling over both shafts, and drill them out, and put a roll pin, or better yet, a "Shear Pin!" maybe? If you wish through the top, & bottom, shafts. You would not need any rubber hose at all then, except maybe a narrow band to hold the shear pins in, or a hose clamp over each shear pin should hold it in place.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

If I am understanding this right, you're gonna butt up the 1" O.D. shaft on the motor to the 1" O.D. of the coupling, then slip the coupling over the 1/2" L.U. shaft, and put in a roll pin, or use a set screw to hold it in place,, ok, But, if I'd known you wanted to do this, make a stepped down coupling, I would have suggested you make it of 3 pieces of pipe (pipe nipples) example:

1" I.D. pipe which should fit over the 3/4" I.D. pipe, which you know fits over the 1/2"I.D. pipe. This way, you can slip the coupling over both shafts, and drill them out, and put a roll pin, or better yet, a "Shear Pin!" maybe? If you wish through the top, & bottom, shafts. You would not need any rubber hose at all then, except maybe a narrow band to hold the shear pins in, or a hose clamp over each shear pin should hold it in place.

I think he just is using the bushing to bring both shafts to the same dia. then useing your idea of a rubber coupling. I think he needs some type of rubber coupling between the two shafts. Vibration & alignment problems otherwise. I suspect that in the end he will go to a lovejoy,now that both shafts are the same.

 

[maxum247]

Re: Inboard outboard air cooled engine

Lone Duck is correct! The shaft will be cut to length and the coupling will be placed on the top end of the lower unit shaft so that both the engine crank shaft and lower unit shaft are equal in size. The roll pin is to hold the coupling in place so it doesn't spin on the lower unit shaft. There will be a gap left between the two and the wire reinforced hose will be slipped over making one connection, two hose clamps top and two bottom to connect the two shafts.
Lone Duck you may be correct about the lovejoy coupling, it would be easy to buy one end 1in. and the other 1/2in. put it together and it would be ready to go in a matter of minutes rather than hours, but the fun in it to me is designing and figuring out how to make things work. I like working with metal so this is right up my alley! I once filed a ring out of a big prop shaft nut about 1 1/2in. in diameter. Matter of fact I made two or three one for myself, a friend and one lady size ring just to say I did it. Come to think of it I beleive I still have that ring around somewhere! Anyway sorry for rambling, 3/16 it is! Next is to get the lower unit seals changed and get the lower unit installed in the boat then I can progress forward and start getting the motor mount built up! Thanks again for all your help!

 

[MikDee]

Re: Inboard outboard air cooled engine

As I mentioned, I didn't think it was necessary, or that you wanted to compromise the shafts in any way, or by drilling thru them, because later on after the "shakedown cruise" you may want to get one of the couplings I showed you from Northern Tool,,, but if that's the case, I would suggest you make the coupling to fit over both shafts, as I posted previously, something like this:



P.S. I would think you'd need a small weld on each coupling anyway, because a friction fit on them will eventually come loose, but that's only my opinion.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

Your welcome. I am having almost as much fun as you.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

I was just sitting staring blankly at the tv building the coupling in my head and realized that we can't place the shafts too far apart. We need just enough to take care of the vibration, but not so much as to cause the coupler to bend and set up another vibration that could take out your LU bearings. Which a solid coupler would also do. Time this project is done we will be enginers that reinvented the coupling.

 

[maxum247]

Re: Inboard outboard air cooled engine

I had the same thought the last couple of days, about the best I can do is leave a space somewhere between 1/8 to 1/4 in. and hope for the best. May need to pick up another lower unit just in case! Wonder if a swivel coupler would work?

 

[MikDee]

Re: Inboard outboard air cooled engine

I was just sitting staring blankly at the tv building the coupling in my head and realized that we can't place the shafts too far apart. We need just enough to take care of the vibration, but not so much as to cause the coupler to bend and set up another vibration that could take out your LU bearings. Which a solid coupler would also do. Time this project is done we will be enginers that reinvented the coupling.

Lone Duck, A small space between shaft's, that's a given! But, excess vibration, that doesn't necessarily mean a solid coupling would do that.

To me the ideal temporary solution if both shaft's were the same size, is just a heavy piece of rubber hose connecting them, with a lightweight but strong piece of metal, like stainless steel tubing, sliced down the middle (to allow it to compress tightly over the rubber) then some heavy duty clamps to hold it all very snuggly (while keeping it spinning true, and coencentric in place); causing minumum vibration.

I like the idea of keeping the grippy rubber on the metal shaft's, then a metal collar tightened up over that for strength, because I feel there's less of a chance of slippage, vibration, and it spinning out of round this way.

In fact, I would bet that this type of coupling I've proposed, would keep the shafts running truer then a "Lovejoy" style coupling, irregardless if the motor, or the L.U. shaft actually flex, or move around, due to vibration, or torque, and release load! but we'd have to somehow allow, or make up for the difference in shaft size. This way the strength, & integrity, of the shafts not being damaged in any way, is not compromising them. They do make "tee bone" style hose clamps that are a bit stronger (and can go tighter) then the screw type, that can be used here also.

My coupling design is also based on the split, clamp on, coupling design used on some inboard boats, (see my previous link) but with rubber in the middle as a cushion for flex, & vibration.

Finally, maxum257, This is the way I would do it, but now that I've gotten my point across, I'll give it a rest, and let you do as you want

 

[MikDee]

Re: Inboard outboard air cooled engine

I had the same thought the last couple of days, about the best I can do is leave a space somewhere between 1/8 to 1/4 in. and hope for the best. May need to pick up another lower unit just in case! Wonder if a swivel coupler would work?

No swivel! No, no, please, you don't want to introduce forces that may make the joint swing out of round, getting worse, & worse. If anything firmly rigid on the coupling, read my last post, you'll get the idea,,, even if the motor, or L.unit starts bouncing around, you want the coupling to hold it all together straight, & true!

It's My Way, or the Highway!,,, er!,,, Waterway!,,, lol,,, just kiddin, I'm only lookin to maybe save you some grief in the future.

 

[Lone Duck]

Re: Inboard outboard air cooled engine

Lone Duck, A small space between shaft's, that's a given! But, excess vibration, that doesn't necessarily mean a solid coupling would do that.

To me the ideal temporary solution if both shaft's were the same size, is just a heavy piece of rubber hose connecting them, with a lightweight but strong piece of metal, like stainless steel tubing, sliced down the middle (to allow it to compress tightly over the rubber) then some heavy duty clamps to hold it all very snuggly (while keeping it spinning true, and coencentric in place); causing minumum vibration.

I like the idea of keeping the grippy rubber on the metal shaft's, then a metal collar tightened up over that for strength, because I feel there's less of a chance of slippage, vibration, and it spinning out of round this way.

In fact, I would bet that this type of coupling I've proposed, would keep the shafts running truer then a "Lovejoy" style coupling, irregardless if the motor, or the L.U. shaft actually flex, or move around, due to vibration, or torque, and release load! but we'd have to somehow allow, or make up for the difference in shaft size. This way the strength, & integrity, of the shafts not being damaged in any way, is not compromising them. They do make "tee bone" style hose clamps that are a bit stronger (and can go tighter) then the screw type, that can be used here also.

My coupling design is also based on the split, clamp on, coupling design used on some inboard boats, (see my previous link) but with rubber in the middle as a cushion for flex, & vibration.

Finally, maxum257, This is the way I would do it, but now that I've gotten my point across, I'll give it a rest, and let you do as you want

Yup! Thats what he is doing, now that he has made both shafts the same size. He is using your idea of hose etc. I agree NO swivel !

 

[MikDee]

Re: Inboard outboard air cooled engine

Yup! Thats what he is doing, now that he has made both shafts the same size. He is using your idea of hose etc. I agree NO swivel !

Actually he's not, he's using just a rubber hose over the coupling, not a split pipe, clamped down over the hose. Without this, split pipe sleeve rigidity, the tiny space between the motor shaft, & coupling, will cause the whole assembly to run out of round, possibly vibrate, & fail.

I just reread his post, and feel the heavy hose with the wire in it, just might do the trick though! I guess it's worth a shot, it's just a try it, and see

 

[maxum247]

Re: Inboard outboard air cooled engine

MikDee, didn't overlook the spilt coupling idea you have, just wanted to try it with the rubber hose and clamps first to see how it would work! If need be I'll give the split tubing over the rubber hose idea a try! Whats a "tee bone" clamp anyway? By the way what I was calling a "roll pin" I found out at the hardware store today is actually called a "tension pin". Thanks for all the help!

 

[Nos4r2]

Re: Inboard outboard air cooled engine

I assume you're blocking off/have blocked off the impeller too? It'd be quite embarassing if you started pumping water in as soon as you started moving too

 

[maxum247]

Re: Inboard outboard air cooled engine

I assume you're blocking off/have blocked off the impeller too? It'd be quite embarassing if you started pumping water in as soon as you started moving too

Pipe it out the back and call it a rooster tail with all the speed I'm going to get from this thing! Actually the impeller and pump have been removed! But I will still need to make a cover plate to keep the water pressure from driving the water up thru won,t I? Didn't think of that! That would be embarassing wouldn't it! Hey! Thanks!

 

[Lone Duck]

Re: Inboard outboard air cooled engine

I like the rooster tail. Heh Heh

 

[maxum247]

Re: Inboard outboard air cooled engine

Okay! Here's one for you, the engine is going to sit a little high in the boat unless, and I already know the answer to this question! Can I cut any of the length off of the engine crankshaft without throwing things out of balance? I need about an 1 1/2in. to get the engine where it needs to sit height wise! The crank is about 3 in. long now.

Lowering the lower unit is possible but with the shallow water here I'd rather not! I'd rather have the engine sit high if I have to! Curious more than anything!