Alpha Gear Jumping?

[bullsnot]

Looking for an education on these alpha drives. I just completed an OMC to Alpha stern drive conversion. The drive hasn't even dipped a toe in the water yet. Just finished installing yesterday.

I followed the instructions to the letter when adjusting the shift cable. The very last step was to install the prop. While installing the prop I had it locked in reverse.

Now when I fire up the boat and test the shifting it seems like it wants to jump out of reverse. When I try to lock it in reverse with the engine off you don't have to try very hard and you can push the prop and get it to jump. This isn't a cable adjustment issue as I took the cable off and tried it manually with a helper.

Is my brand spanking new lower bad? Is it possible to round off the clutch dogs just by tightening a prop nut to 55 lbs?

 

[Scott06]

Typical unless you keep constant pressure on the prop like the water will - CCW in forward, CW in reverse with a bungee cord or like it will pop out. So what you see may be normal. Does it stay in if your running it on the muffs ? If you can shift in and out of gear and prop spins correctly I think you're ok. When you get it in the water if it doesn't come out of drive check the shift interrupt mechanism, it's got to stumble the engine for an instant to unload the prop to get the dog clutch to disengage.

 

[bullsnot]

In short, yes it will shift into gear and spin on the muffs.

The reason for my concern is this. When I put it in reverse on the muffs it chatters a bit and seems like it wants to try and jump out. I thought maybe the cable adjustment was off. So I stopped the engine and took the cable off and tried it manually and my 10 year old son pushing on the prop says it won't lock going CW. I try and the same thing. Putting it in forward it locks rock solid. I'm concerned because I locked it in reverse when I was tightening the lock nut on the prop it was pretty solid but as I was nearing the torque spec it jumped and now I can't get it to lock very solid. Very moderate pressure and you can get it to jump by hand.

 

[bullsnot]

I'll give her a water trial and see how it goes. Maybe I'm just being paranoid cause I just dropped some coin or maybe I'm just used to the OMC's. You put those in gear and they are there until you shift them out.

 

[Bondo]

Ayuh,.... No way in 'ell can you strip the shift dogs by tightenin' the prop,... Just Not possible,....

If it don't shift properly in the water, go back to yer shift cable adjustments,....

 

[bullsnot]

Thanks bondo. That's what I was thinking but wanted to be sure.

 

[achris]

Yeah, like Bondo said.... you put 55lb-ft on it. The engine will be putting something like 250lb-ft on it! (or more) Also, the dogs are undercut, so putting more and more torque on the shaft will draw the dogs in tighter (which is why we have a shift cut-out switch )

I would be removing the drive and checking it fully engages just by turning the shift shaft. Then check the shift cable (drive end) slide has no longitudinal (in-out) movement, (but is still free to rotate). Then lock one end of the cable and try pushing and pulling from the other end. You should feel no, or very very little, movement.

Chris.......

 

[bullsnot]

I took her out for a water trial yesterday and she worked perfectly. The first time I put it in reverse it started jumping and sort of grinding for about 2 seconds and then suddenly she slipped into gear and worked perfectly after that. Just needed to break in a bit I guess.

I cannot believe how smooth and easy this drive shifts. Should've done this conversion years ago. The break in procedure is a bit annoying but it is what it is.

Thanks for chiming in guys.

 

[bullsnot]

I think there is something to be learned in this situation.

Look I completely understand that an engine puts much more torque on the drive than I can in my driveway with a ratchet but that is with full engagement and water resistance. I stand by the fact that something happened when I torqued that prop on. Reverse would never again fully engage until I got it in the water.

My guess is when I torqued the prop on the clutch dogs were barely engaged and when it "popped" it caused a small blemish that wouldn't allow the dogs to engage until it was broke in with enough force from the engine and the water resistance. I think with the tight tolerances these have break in is critical to get the dogs to fully engage.

My take away is I would never torque a prop on a brand new Alpha by using the reverse gear alone until the drive is broke in.

My 2 cents.