vibration and noise at certain speeds

Update:

It was easy to get the rusted nut and washer off, but it took me a long time to clean off the staining they left on the driveshaft threads and front boss of the prop. I alternated spraying with carb cleaner and powerblaster, cleaning with soft rags only. I didn't want to use a steel brush and embed pieces of steel in the metal, only to end up with more local rusting. It looks really good now, and there is no pitting.

I went ahead and lapped the prop to driveshaft taper. Prussian blue showed about 66% contact to start with (pretty good, I thought); now I've got 85% to 90% contact. About 9 or 10 lapping revolutions. Secured with a new brass nylock nut and it's good to go.

I wasn't able to detect (visually) and shaft wobble or whirling. Haven't broke out a dial indicator or done an alignment yet--working my way through plenty of issues getting the boat ready for the kids on our upcoming vacation.

Separate posts coming about the packing box and driveshaft.

Thank you for your help, gentlemen.

Steve

Thanks, Chris. I've ordered a locknut and key. Also ordered the GFO packing, both 3/16" and 1/4", and some safety wire.

I'm curious about the prop... if it is tight then why/when should it be lapped? I understand the benefit of more contact area, but am wondering what problems arise if it hasn't been lapped on.

Also curious about the rudder shaft. Does it not need grease because of the materials it's made of, or is a little friction beneficial to the steering feel?

Thanks! I'm learning.

Steve

Thanks, Chris and Peter. I will check the packing box drip rate and warmth on the lake. I think repacking the box is something I'll look at this Fall or next Spring, unless there's a problem. I agree--I'll sleep better having done it.

My son and I did the best inspection we could at the business end of the boat. Here is what we found:


CUTLASS BEARING:

-- The ends of the rubber bushing show little wear (if any), and the rubber thickness looks pretty constant all the way around, both front and back of the strut cylinder.

-- I grabbed the prop and tried to move it, motor not running (obviously!) and shifter in neutral. I cannot feel any play left-right, up-down, fore-aft. That really surprised me for some reason. Maybe the cutlass bearing was replaced not so long ago.


PROPELLER:

-- The prop is a brand new ACME 540, bought by the previous owner. I am concerned about the mounting--it is mounted with a steel washer and nut, both of which are rusting! I will remove those and pull the prop (puller coming). I will check if the prop needs to be lapped to the shaft. Do you guys recommend mounting with a nylon lock brass prop nut, or the dual lock nut system, or a nut with cotter pin (not sure if there's a hole in the shaft)? If the brass lock nut, does a brass washer go on first?


RUDDER:

-- I also checked the play in the rudder. It moved more than I expected. The movement is angular canting in the mount above the hull surface. The mounting plate (with four screws) does not move at all. It's hard to quantify angles of movement, so I will give you how far the bottom of the rudder moved when the rudder "canted" in it's mount. Left-right and fore-aft: the rudder bottom moves a little less than 1/16", probably about 50 thousandths. I can make the mount give a dull "thud". Up-down: maybe 25 thousandths of play, no "thud". I've looked at photos of the part and it looks like there is a zerk fitting, but I'm wondering if the fuel tank has to be pulled to access the fitting (or maybe drop the rudder mount plate)?. Is the play I have normal, or do you think it needs some marine grease, or do you think a bushing is worn out? No issues with the operation of the steering--just this play in the rudder when I'm laying on the ground tugging on it.


Thank you, gentlemen, I appreciate your knowledge and experience.

Steve

Steve - Putting the tranny in gear on trailer isn't recommended, but if you realty want to then just wet the strut bushings with water (soapy is better) & maybe even spray up into the log. Keep the time in gear short.

The packing box just needs to not leak too much nor get tool hot, so if it is doing neither of those, then your good to go.     However, replacing the packing is a $10/ 2 hour project so why not set your mind at ease? There is a 'How to' Thread here somewhere.

The cutlass bearing can be checked visually by looking at each end of strut, they typically wear more on one side. Another way is to move the shaft & see how much clearance there is.

The best way to detect bent shaft is to do an alignment. If you can get it aligned within .003 inch, next turn the shaft to all 90 deg clockings & see if it stays within .003, if so then most likely the shaft is good. If you still are getting vibration after that check, then maybe the shaft is bent right at the prop taper. A dial indicator would be the best check at that spot. See Bones71 post

Good luck & let us know what you find.

Pete, some good reading on alignment

I had to read through again and decide this morning, Surveyors normally get thier information from guy's that work on boats, ....but about 25% of the transmissions i see are failed from Mis-aligned boats, i have about 10 bad cases that spin 1" shafts on my shelf that are grooved on either the side of the case or up and down.
No its not a perfect world and the article seems as if your boat is out of line its OK, Alignment is important enough that someone took the time to write about it, but it is mis-leading. it is the same as saying your boat has a miss at idle but it still runs so dont bother fixing it.
he goes on saying a MA boat is due to worn mounts but doesnt say hey....maybe you should put some new mounts in to get it close to a new boat again.
Im going out on a limb here, I deal with surveyors quite regularly, I dont call them to ask them questions, the (majority of them) dont take this the wrong way, lets put it this way...I have fooled many of them with a pile of transmission parts basically they have no f-ing idea what they are looking at. they are normally the biased opinion for the insurance companies. I'll end that there.
when you get a transmission that fails 2 times and on the third time the guy brings you the boat and you check the alignment and its out .021 at the faces and you get that (not so critical) alignment within the .003 or under and rebuild the trans the 3rd time and send him on his merry way and you never hear from him again.....I would say alignment is pretty damn critical

Madcap, no problem, it was good reading if i knew absolutely nothing about maintaining a boats alignment and if you take his advice i will gladly rebuild your trans lol

Funny thing, my cutlass bearing has some play, about .015 inch. Both the bearing & shaft are new, had this play at installation, I didn't think it was wrong at the time. So SkiDim's bearings are not good?

I take all i ever said about alignment back, some good reading but some bad reading also, decide for your self

Gary, If it's noticable by hand, then I'd say it time to think about putting in a new cutlass.

I should no better, from some of the conversations I've had with people over the years

on a certain website of all horrific accidents, a guy got his hair caught in the lathe, it wasnt pretty....everytime i run the lathe i think of this guy and im picking my finger nail as we speak because the chuck bit me yesterday

eric lavine wrote: i forgot to mention not to wear a scarf while watching the shaft turn too....

Long hair, loose shirt-tails, shoe strings, baggy shorts...this isn't much different than working on a lathe or table saw, but I've seen some things!

Eric!! You forgot to mention the water on the cutlass. In this thread it was a issue and I blamed someone on PN, Wake World or Tubing News for mentioning putting a boat in gear with the bearing dry!!
running boat on trailer
I'm going to have to send Chris over to your shop to make sure your posts are correct! Don't go and tell me it's ok for a second to run it dry ether. The shaft will probably vibrate in the cutlass to the point it will be a blur and you won't see any wobble.

your going to need two water supplies as well if you kick it into gear otherwise you might destroy the bushings in the strut if you do not keep it wet.

if you unbolt and check the gaps and the gap stays in the same place after rotating its alignment, if you check the gap and spin the shaft 180 degrees and the gap follows to that side its a bent shaft. but 9 times out of ten the shaft bends after the strut, so put on your fake a lake and run the boat in the drive and have someone kick it in gear (be frickin careful) that unbinds me from the liability......
watch the tip of the shaft, if its bent you will see it, if your wondering about the little wobble it may have, its bent.
no need to put an dial indicater on it if you see wobble