Coupler Removal and Install

TRBenj wrote: Yep, no good... tolerance should measure negative with an interference fit. Pete will remind us by how much.

The number I've been told ( by an old machinist} is .0005 inches per inch of shaft size for an interference fit when the shaft has a keyway and key for the coupling. (like this shaft for an inboard) I figure there are a variety of numbers used by different people for all kinds of different applications

Even a split coupling should be a very light press fit on the shaft, or in other words you don't slide it on with a couple thousandths clearance and expect to be able to tighten the bolts and have it hold very good.

This is from a guy that does his hack jobs in the backyard, maybe a real Machinist like Duane will add some info about this   

Yep, no good... tolerance should measure negative with an interference fit. Pete will remind us by how much.

Travis,
That is a solid coupling and the fit to the shaft is a heat shrink/interference fit.

Travis Eacret wrote: After pressing the shaft out of the coupler I sanded both as described in the original post and now the coupler slides on cold, no heat required. Did I sand to much or will this be ok? I didn’t take to much of the shaft but The inside of the coupler had a fair amount of corrosion I removed.

Travis,
Knowing what type of coupling you have is important. A split or taper type are fine to slid on but a straight interference fit isn't. What year boat is it in? Was the corrosion black? If black, then that's typical of fretting caused by misalignment.

Welcome to CCfan. Can you post any pictures?

After pressing the shaft out of the coupler I sanded both as described in the original post and now the coupler slides on cold, no heat required. Did I sand to much or will this be ok? I didn’t take to much of the shaft but The inside of the coupler had a fair amount of corrosion I removed.

Got all of the parts sorted. Drive shaft had a .070 bow in it, luckily I work right down the street from the prop shop, and they were able to straighten it. Also got new strut bearings from them, and got them installed last night.

One thing I am having a hard time finding out for sure is what to do at the vdrive when aligning. I am working on getting the rough adjustment done right now with the shaft coupling centered on the vdrive coupling, while being centered through the log. By making sure the side-to-side, and up-down play is equal on both sides. As is ken gibbons how to notes an aligning a inboard shaft.

In all the how to's I've seen there is no mention of loosening any bolts at the vdrive. I assume you would have to, to allow it to move with the engine adjustments. Maybe not for a very small amount, but mine seems off quite a bit. As of right now the engine/vdrive need to go about an 1/8 to port. I've loosened the nuts on the bottom side of the vdrive mounts, which are slotted port/starboard, so hopefully when I go to shove the motor around it will follow. I need a bigger 2x4 or something as I couldn't get it to move much.

A link to a better how-to for a vdrive would be great, if anyone has seen a one.

T_Bone wrote: Even with that it took quite an amount of force to drive it out of the coupler. I had to make a shaft pusher. Maybe once I clean up the coupler it will go back in better?

TJ,
On a spit coupling, once it's on the bench, you can typically "open" it up some by driving something like a screwdriver into the split(s).

T_Bone wrote: . Upon further investigation it looks like something is bent/miss-aligned. I am thinking the strut is off a bit.

Yes, keep in mind alignment always starts at the strut.

My 95 vdrive has a split coupler,I take it yours does not? I don't know how you would even work on getting a 500 degree coupler on in that restricted area,but it needs to go on the shaft first. If I ever have to take off my other DD's couplers it's going back on with a tapered one.

Wow... this is a life saver. I have been out in my boat for the past couple of hours scratching my head once I got to the all intensive "removing the coupler" part. Like the man above I started using a harmonic balancer puller but there is much room and it just didn't feel right. Learning from my past experiences in mechanics I realized that means stop or pay the consequences in blood or $$. After reading all that I have decided to go wait until tax time and go with the A.R.E. system... or perhaps the split coupler. I don't want to deal with walking through my house with a 500 degree piece of hot brass then dodge 4 kids... run outside with it being 30 degrees... kick my dog out of the way... shoulder through the shop just to burn my new carpet or all the way through the hull of the boat. This is highly educational.. thank you for saving me from crying into the night foot fungus!

John,
It's great when things go as planned. Most of the time they don't!
Regarding the engine moving, yes, there is flex in the hull. Getting the alignment as close as possible limits misalignment to be equal in all directions. With a misalignment in one direction, that direction is where all the stress is on the shaft and trans. You're cool as long as you got it down to the .003" mark. The alignment can be frustrating at times!

Wonder if something like this would help by spraying the shaft right before attempting to slide on the hot coupler. Can states cools down to -60*.
http://www.grainger.com/Grainger/CRC-Freeze-Spray-4YPK4?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1

i was with a company called inline machining all week optically aligning shafts, pretty slick tools these guys use, but, anyways, they get on Nuc subs and have to align them to 20 millionths of an inch, so the enemy doesnt detect any vibrations...the guy says it takes him a couple weeks and he explained how they measure that small of a number and its pretty complicated...so I guess .002 aint to bad to do.
anyways, the uppers kept quiet because when we put the boat in the water we lost .250 of sag on one side and .150 on the other...the engines were originally up .300 on blocks (dry land) but to obtain a perfect alignment the boat should be in the water for at least 24 hours, any boat

Yea, I only had a minute and the only thing I did was see how the coupler and transmission interfaced. Unlike my original coupler after I mistakenly thought I could tap that onto the shaft, this coupler and the transmission faces are flush with each other all the way around. I will break out the feeler gauges and everything before I assemble everything, but it "looked" good when I eyeballed it. I didn't realize a piece of paper is .001..

I will watch those videos again before I think about assembling anything.

Thanks again guys!

I didn't measure it yet, and I'm not sure how you could. I don't think a piece of paper would slide between the 2 faces anywhere.   

Yes, it's a 3 blade OJ. It really only makes a noise when guys leave too much throttle on in the turns with the Perfect Pass set. I normally like to drop at each end anyways and then you don't notice anything.   

I will check the shaft and everything along the way. New coupler just showed up, and it fits perfectly with the trans shaft piece. That's a good thing and that was my first red flag. I may not be able to replace everything until next week, but I've got my fingers crossed..

Thanks again for all your help!! You guys really know these boats!