How does the LU clutch work on my 4434 1950 E7.5hp?

[samo_ott]

It started giving me problems like the drive spring had jammed up as when I took it out of neutral the engine would grind to a halt. Other symptoms were the engine staying in neutral and not going into gear when engaged. So it flip flopped on the issues.

I have never taken the LU apart but just did so. (and it was a strange LU to open up) About 90% of the fluid inside was water (where can I get the seal kit is another question)

Other than that the insides were impeccable. Not a scratch or wear mark on either gear, bushings or the housing. Everything looked perfect. Which was odd.

But I have no idea how the clutch/spring assembly work. I only have the 1953 parts manual to see the parts breakdown and don't know if it is the same as mine. There does seem to be some minor differences to what I saw inside mine. The spring does not look broken and turns freely on the prop shaft. Is it supposed to do that? This LU is like no other I have taken apart so I'm hoping someone else has done it and can help me out. Thanks.

p.s. Would pictures help?

 

[F_R]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

It has been too many moons since I've had one of those apart, but I sort of remember there was a change in the release lever. The basic theory is that the spring is wound around two hubs and grips like a rope wound around a tree. The harder you pull, the tighter it grips.

Neutral works by something interrupting the leading end of the spring, which tends to try to uncoil it. As it uncoils, it gets larger in diameter and loses it's grip on the hub. Once it loses it's grip, it stops rotating, so it doesn't unwind any more.

Try posting your question over at the Antique Outboard Club's website, www.aomci.org

 

[jay_merrill]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

Take some pics - I'd love to see the inside of that gearbox!

 

[samo_ott]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

FR, what you explained looks like it is that way. I'm not sure how it does it though or what's wrong but that's kinda how I envisioned it by looking at the pieces. I have a '52 parts engine (4443) also and it looks the same on the outside, thus I'll open it up tonight and see what it looks like on the inside or swap LU's or swap prop shafts, spring and all.

Another question, the '50 has a 3 blade brass prop and the '52 has a 2 blade. Which is the correct one or did it change?

Anyone have any idea where I can get a seal kit for it? I don't see it listed on any of my normal sources.

 

[F_R]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

The brass prop has to be an aftermarket replacement. You aren't going to find a "seal kit". Evinrude never did put the stuff in a kit back in those days, and nobody else is interested. You may be able to find individual seals if you have the part numbers.

 

[samo_ott]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

My dealer does not put the LU parts in a kit now either! I still have to order them individually which I hate. Thus I usually get the Sierra kit as it all comes together for $20 or so.

And you're right, I just went back and looked at the photos of the early non shifting 7.5's and they all had 2 blade props. Guess mine is special. I wonder if it works better than the 2 blade prop. As they're so easy to change I will test once I get it running again.

 

[samo_ott]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

Jay, here are the photos for you. This is my parts engine which is seized, the impeller was shredded when I took the LU off so I can see why it was seized! I couldn't see why my LU didn't work and tried to fix it but had to use the LU off the parts engine. All is running well now.

 

[jay_merrill]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

Pretty cool - looks like a very simple setup!

 

[R.Johnson]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

That prop is probably an old Michigan Wheel.

 

[wbeaton]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

I have a similar 3 blade brass prop on 1954 Fleetwin. Its a Michigan Wheel AM417 (fits 1954-58). I tested it against the stock prop and it performed better for me. These were my results:

2 blade 5.5 hp prop (8 x 7.5) = 13.2 kmh/8.2 mph
2 balde 7.5 hp prop (8 x 8.5) = 15 kmh/9.3 mph
3 blade 7.5 hp prop (8 x 7) = 18 kmh/11.2 mph

The 3 blade prop got me on plane faster and pushed me quicker than the others. I'd like to convert all my 7.5 hp's to them. I'm now on the lookout for them at every swap meet.

 

[Chinewalker]

Re: How does the LU clutch work on my 4434 1950 E7.5hp?

I rebuilt the lower end in my 7.5 neutral clutch motor a few years back. If I recall, there is a small tab or raised tip at the engagement end of the spring. This contacts the lever when it is dropped and disengages the spring from the shaft. That tab was worn on mine and would not engage the tab. I disassembled everything and put the spring in my bench vice and straightened the last 1/4-inch or so to raise it up. I then ground the tip square so that the tab would engage it squarely when dropped. It's really a fairly simple system and worked well when I put it all back together.

As a side note, for the impeller, I took a standard 18-3001 Sierra impeller and laid it on a benchtop belt sander to lower the profile to fit the waterpump housing. The shaft bore diameter and blade configuration is otherwise the same. Peed like a racehorse when I was done...

- Scott