Drive Shaft problem ? Hunter 386

[Jeff Bacon]

Sorry, posted this in the wrong forum a few minutes ago................. Hi All:Just this past week, I noticed that the Key is loose that fits the slot of the drive shaft where it attaches to the flange which then attaches to the transmission flange (got all of that ?)Everyone thought that my drive shaft had pulled out an inch or so. When we hauled the boat to check, the shaft had not moved at all. However, the key was still loose, and after being pushed up tight, would loosen again after the transmission was engaged.The shaft itself is not loose, the shaft is not spinning in the flange ( the set screws are tight and properly positioned), but, the key is loose again.The service manager said "It's a mystery" and wants to let it go. I'm not all that fond of mysteries.Should that key be tight, or, is it OK to be loose to the point where it can easily be moved with my fingers. Keep in mind that the key cannot actually fall out due to the design of the slot.I hate mysteries...... anyone have any thoughts ?Thanks......... Jeff

 

[walmsleyc]

Yes ...

Even if your flange is currently secure to your shaft, the key may be critical some day. If you were to hit something with your prop, or snag a line, there might be enough force to break the bond (rust, set screws, whatever) that is currently keeping you shaft and flange together. At that point, you be left with no power, and an increased risk of having the shaft come out of the flange.At minimum, I'd put the key in place, and use some "loc tite", but even better would be to find a slightly larger key that fit more tightly. You don't mention if your key can slide out completly. Mine can't. Maybe even a piece of wire will keep it in place.Chris

 

[abe]

First I would get another key....

..then I would wack the old key with a hammer a few times. It may bent a little bit out of shape so that it would fit snug. If you screw that up...well that is why you bought another key. You might also want to fit the new key...that one might go in snugg.Happy hammering,abe

 

[Steve Dion]

Lose the key and you will not have any power!

Jeff:If you lose the key you are not going to have any power. A friend of mine Gary Scheier was on a delivery from Monterey CA. to Hawaii. They lost the key on the boat about 4 days out. The had to sail the entire way. They engine was functional but it would not drive the prop.If the key is loose, you are going to wear out the keyway and will eventually need to replace the shaft and possibly the drive spline too. The keyway material is cheap so don't let this go.I would contact Hunter about this and get their opinion.

 

[Fred Ficarra]

Aw, the key was yet another screw-up by my Hunter

dealer. When my boat was new they didn't install the key. (they didn't do a lot of things and Hunter fired them) They only installed the set screws. And, of course, they didn't properly dimple the shaft for the set screws. Result? New boat, we pulled from the dock of our favorite eatery right next to a low bridge. The 4 knot current would take us into the bridge and remove the mast at the first spreaders. No problem. All sailboats just allow for the current and head for the high center section to get to our marina. (at the time) Well, off we went. Just as we reach the center the engine reved-up and felt like it shifted into neutral. It didn't. We had no drive. I gave the helm to my wife with NO INSTRUCTIONS and dove below. (I didn't have time) It took all of 45 seconds to find the problem and tighten the set screws (that weren't safety-wired) and shout to my wife to put it in gear. By that time the boat was pinwheeling down the narrow straights. Whew! The dealer paid for all the damage. The shaft had to be replaced. They even paid for my labor. I wouldn't let them do the work! Where was I? Oh yeah. The key and your set screws work together. You must have both. Don't freak-out about a loose key as long as it can't come out. But I would find out why it's loose. Sounds like the wrong key.

 

[Bill Roosa]

Maybe the engine and trans moved

If the shaft didn't move then perhaps the motor/trans mounts need looking at!!

 

[Don12364]

How Loose is Loose?

Jeff,It may only be engineering tolerances.Clearly the key needs to be slightly thinner than the keyways of both the shaft and the flange else one could never put it together. Normally the manufacture is not so perfect that the key can be moved by finger pressure - but it could happen.Obviously if the key is slopping about then it is too thin - though you don't want a 'keybound' situation where the key is in contact at both top and bottom as this could result in the shaft running eccentrically.The function of the key is to prevent the flange from turning on the shaft, though the clamp screws on the flange should take all the load and the key is there as backup. Provided the key is the correct thickness and is fully engaged and cannot come out then it also cannot fail to do its job when needed in an emergency. You could get a caliper or micrometer on it in situ and check if it is the correct thickness or it is just a bit of scrap metal somebody found in a bin? I would expect it to be EXACTLY 1/4" thick - ie. 6.35 mm (and not 6.0 mm which would seem loose). My H376 has 0.250" wide key and 0.250" keyways in both shaft and flange so the key is 0.250" square. Somebody might have filed yours though to avoid it becoming keybound and then it has been replaced the thin side in the slot!I do not see this as a mystery and if it were mine I would not worry.