alpha one lower clunk

[sal3030]

Hello, I am brand new to boating but have a lot of mechanical experience and a lot of experience with gearing and motion components. I bought my first boat and it has an alpha one gen one drive. I changed the water pump and after putting the lower back on ten times, I am getting a clunk noise when turning the prop clockwise (forward) and locks going ccw like it should. Reverse is the opposite. I lined up the shift shafts every time. When I start the engine in neutral it sounds fine, when I push it into forward (just into the detent in the shift handle) it sounds like lashing gears. Is it supposed to be quiet? and am I supposed to be able to turn the prop by hand when it is supposed to be engaged with the engine? It didn't make noise when I had the seller spin her up for me. Also, I turned the shift shaft CW by hand, should I use a socket may be I am not turning it enough?

 

[Bondo]

Re: alpha one lower clunk

Ayuh,... Alpha drives should be shifted, "Briskly" resulting in a single Clunk goin' Into gear...

Yes, when spinning the prop backwards in gear, you'll hear the dogs clickin' over each other...

 

[sal3030]

Re: alpha one lower clunk

Can you define "backwards". When in forward gear, the prop locks ccw, but turns with very little effort cw yet clucks with every 1/8 increment. I would think "backwards" would be ccw which it won't turn in forward. Thanks for the fast response.

 

[Don S]

Re: alpha one lower clunk

You are looking at it backwards. Think of which way the propshaft would be turning and you will understand why the prop locks when turned ccw.

 

[45Auto]

Re: alpha one lower clunk

Your drive is working fine.

When in FWD gear, it should free-spin with clicks in the FWD direction (clockwise on most single engine boats), the direction the prop would have to be turning to propel the boat forward.

When you try to spin it CCW in FWD gear it locks against the dogs that will drive it in the CW direction. If it slipped past those dogs, nothing would be driving the prop in the direction you need it to turn to propel the boat!

 

[sal3030]

Re: alpha one lower clunk

45auto, That is what I thought but why are the gears gnashing when I shift from neutral? I admit I did it gingerly not "briskly" as Bondo said. It reminds me of my 1999 tahoe shift into low. It requires a "brisk" push. If I where to turn the prop ccw to a locked position, start her up and try would that help (not that I can do that in open water) just to ease my mind. PS: "45auto" "sal3030" hmmm. I am a fan,own a G36 & Kimber.

 

[Bondo]

Re: alpha one lower clunk

If I where to turn the prop ccw to a locked position, start her up and try would that help

Nope,... 'cause ya Can't start it In gear...

It's workin' as it's Supposed too...
Just shift it Briskly, 'n it'll be just Fine...

 

[j_martin]

Re: alpha one lower clunk

Understand, this transmission has no sliding clutches or synchronizers in it. It has simple dog clutches, with a ratcheted dog clutch for forward. The prop is never glued to the road, it is free to turn, and in most cases has a rubber drive hub in it with a little give. If you had and read an owners manual, it says to shift briskly, not to let it clatter. That's the way it's designed. The reason for the ratchet action is so that if the engine suddenly stops or is stopped when the boat is traveling at high speed, it allows the prop to keep turning, so there's less drag trying to nose in and submarine the boat. It's pretty much a safety issue.

Now, it really isn't a violent shift, unless your idle speed is way too high, then there'll be a resounding clunk and possible damage, but at the design 700 rpm or so, there's just a solid clunk into gear and you're underway.

Letting it clatter hammers metal off the corner of the dog clutches. Doing that as a habit will rapidly put the LU into the shop for major repairs. It's easy to see when that's been done. There's a lot of iron particles stuck to the magnet when you drop the fluid.

There's millions of these things in service, and they serve us well. Learn the ropes and quit trying to redesign things, and you will boat a long way.

hope it helps
John

 

[sal3030]

Re: alpha one lower clunk

John,
Excellent reply, Thanks! I am going to pull out the plug and check the magnet. I planned on doing that later. Is it the centrifical force that keep the dogs meshed assuming the engine is at 700 rpm (it is)? I didn't get a user manual bye the way. I wished I did...

 

[Bondo]

Re: alpha one lower clunk

John,
Excellent reply, Thanks! I am going to pull out the plug and check the magnet. I planned on doing that later. Is it the centrifical force that keep the dogs meshed assuming the engine is at 700 rpm (it is)? I didn't get a user manual bye the way. I wished I did...

Nope,... The dogs are undercut...
That's why the shift switch is necessary it get it Outa gear...

 

[sal3030]

Re: alpha one lower clunk

Ok John, I will close my eyes and cringe when I "briskly" shift int gear. I will also check the magnet, I intended on doing that later anyway.
Sal

 

[sal3030]

Re: alpha one lower clunk

I just looked at my Seloc Manual 3200 and on page 10-46 is show how the lower mechanism works. Very simple indeed. I see why you have to shift quickly. I didn't realize the vertical drive shaft bevel was meshed and in constant motion with both forward and back gears, it is the shaft that gets engaged. It makes sense as to why if you apply the force at the prop in the cw tortion the dog pops. When the torsion comes from the gear the dogs drive the prop not vise versa. Thanks gentlemen. When my wife comes home and can get away from my two boys I am going to try her out.
Sal

 

[sal3030]

Re: alpha one lower clunk

Yes it worked. Thanks to you all. I didn't realize though that my rabbit ears (circular ones) slid off while I wasn't looking. Burnt up my water pump now I have to do the original job over. Practice makes perfect I guess. Uhhhh....

 

[cr2k]

Re: alpha one lower clunk

If your idle speed is correct you shouldn't have to cringe.