Prop. shaft slop, for lack of better word.

[Beck]

While checking my 48 spl noticed with the engine in forward I can turn prop (measuring tip of one of the prop blades) about 3 inches before contact is made with gears. About 35 to 40 degrees cw to ccw before contact is made with gears. I then put it in reverse and checked. This time only about<br />3-5 degrees, which seems more like it should be.<br /><br />Can someone tell me what might be going on and point me in a direction.<br /><br />Some of my earlier post I said when comming off of wot I heard some type of knocking sound we thought it was out of timing but motor always ran great. I always wondered if perhaps this slop/play in forward could have been the noise, you hear it when engine winds down and boat slows down. I'm thinking the water in pushing prop backwards and this is the noise?<br /><br />Any opions would be appreciated.<br /><br />Beck

 

[Beck]

Re: Prop. shaft slop, for lack of better word.

I might add I never ever experienced any problem with shifting or with it comming out of gear. Always ran perfect, but for the knocking when slowing down quickly from wot. <br /><br />It just seems that is too much play while in forward.<br /><br />I can't imagine this being one of the times "if it isn't broke don't fix it" ??<br /><br />Sincerly,<br />Beck

 

[Paul Moir]

Re: Prop. shaft slop, for lack of better word.

No that's perfectly normal. What you're measuring is the number of degrees the propshaft has to turn before the clutch dog ears mate with the forward or reverse gear ears. You'll notice sometimes the ears will hang up on each other until you turn the prop enough for them to engage. That is to say, it won't go entirely into forward until the prop is turned a bit.<br /><br />Mabey a visual will help. Here's a typical forward gear:<br />

<br /><br />And here's the clutch dog:<br />

<br /><br />The clutch dog is locked to the rotation of the propshaft but is allowed to slide along the splines you see in the center. The gear is free to spin on the propshaft. When you put the engine in forward, the clutch dog slides into the front of the gear, and the three ears on it mesh with the three ears on the gear - locking the gear to the propshaft. (The gear spins continuously with the engine)<br /><br />As you can see, since there's only three ears there's a good amount of rotation before they 'click'.<br /><br />I hope this explains it!

 

[Beck]

Re: Prop. shaft slop, for lack of better word.

Paul thanks for the speedy response,<br /><br />It sounds like your telling me is that it is not uncommon for the prop to turn aprox. 30 degrees in forward to be in gear and 4-5 degrees in reverse. Boy am I glad to gear that. It just seemed like forward and reverse should be the same.<br /><br />Thanks again,<br />Beck

 

[lawyertob]

Re: Prop. shaft slop, for lack of better word.

Originally posted by Paul Moir:<br /> Mabey a visual will help. Here's a typical forward gear:<br />

<br /><br />And here's the clutch dog:<br />

<br /><br />The clutch dog is locked to the rotation of the propshaft but is allowed to slide along the splines you see in the center. The gear is free to spin on the propshaft. When you put the engine in forward, the clutch dog slides into the front of the gear, and the three ears on it mesh with the three ears on the gear - locking the gear to the propshaft. (The gear spins continuously with the engine)<br /><br />As you can see, since there's only three ears there's a good amount of rotation before they 'click'.<br /><br />I hope this explains it!

Paul,<br /><br /> That was a GREAT explanation. Where did you get the great illustrations? My manual has mostly line drawings of parts and I was wondering if there was someplace I could go to look at better pictures. Sometimes a picture makes it all come clear...like the pictures above where you can see how far the clutch dog might have to turn before it engages the gear.<br /><br />Thanks,<br />Joe

 

[Paul Moir]

Re: Prop. shaft slop, for lack of better word.

Beck - I should have been a little more clear about the 30° vs 4-5°. Yes it is perfectly normal for the propshaft to swing 30°, but it is not normal for it to swing 4-5° in reverse. I think that in reverse the clutch dog was hung up on the reverse gear (the face of the ears on the dog hit the face of the ears on the reverse gear). So you were just measuring the lash in the system (ie, from play between gears and play between splines).<br /><br />I think you'll find that if you turn the propeller while engaging reverse, the ears will mesh properly and you'll get a 30° swing in reverse too.<br /><br />You can actually bend the linkage if you push on the shifter arm while the ears are hung up. So be careful.<br /><br />Joe - those pictures came from the catalog at www.theshadconnection.com Although the store is closed, they've been kind enough to leave the catalog up as a useful reference.

 

[Beck]

Re: Prop. shaft slop, for lack of better word.

Paul Moir,<br /><br />Thanks for the explanation. <br /><br />Beck

 

[lawyertob]

Re: Prop. shaft slop, for lack of better word.

Originally posted by Paul Moir:<br /> <br />Joe - those pictures came from the catalog at www.theshadconnection.com Although the store is closed, they've been kind enough to leave the catalog up as a useful reference.

Paul,<br /><br />Thanks, I added it to my list of boating links for the next time I need a better look at something without having to take my motor apart. <br /><br />Thanks again,<br />Joe