Problems Removing propeller shaft

Mike Davis · Post by **Mike Davis** » Mar 29th, '11, 18:09

My cd31 needs a new cutless bearing. In order to do this job, the propeller shaft needs to come off. After removing the propeller and the set screws, I proceeded to loosen and take off the 4 bolts on the coupling connecting the shaft to the transmission.

The problem is the shaft will not release from the aft part of the coupling. I also cannot loosen the two rings on the stuffing box, even with Spartan wrenches. They are totally frozen. Any suggestions as to how to loosen stuffing box and take out shaft is greatly appreciated. Thank you.
Mike Davis

Maine Sail · Post by **Maine Sail** » Mar 29th, '11, 19:47

Mike more often than not the shaft needs to be cut out. If you have room you can build a press off plate. If it is old and rusted then I would strongly advise against using the transmission flange to press off the coupling. It takes very, very little force to bend the gear box output flange more than .003" which is what you are trying to align for.

Alternatively you can cut the flange off but this will throw ferrous dust all over the inside of your boat and rust will ensue.

What ever you do DO NOT let anyone near your boat who says they have or will use a slide hammer. This is a HUGE no-no and will brinell the gear box bearings leading to a gear box re-build which is far more costly than a new shaft..

This DIY bent his gear box output flange $$$$$$$ AND snapped the coupling and he still never got it off. It was cut it off with an angle grinder after warning him about the ferrous dust. He later agreed he should have just cut the shaft..
There are very few occasions where a coupling can actually, be re-used anyway as they are a very close tolerance interference light press fit. The layer of rust broken free almost always ruins this fit.

Steve Laume · Post by **Steve Laume** » Mar 29th, '11, 20:32

Mine came out very easily once I removed the engine and transmission.

Sorry if I am no help at all, Steve.

Matt Cawthorne · Post by **Matt Cawthorne** » Mar 29th, '11, 22:07

I have removed the prop shaft 2 or 3 times during my 18 years of ownership. Each time I have used the transmission coupling as a press off plate. I have never noticed it being a problem, but then again, I tighten the bolts very evenly. Perhaps I was just lucky. If you choose not to use the transmission coupling, I would suggest making a steel plate to use as a press off plate. Put a spacer that is slightly smaller than your shaft ( I use a socket wrench ) between the plate and your shaft coupling. Tighten the bolts and the coupling comes off of the shaft. Much less messy and far less expensive than buying a new shaft. Perhaps if you cannot get it free this way you can cut the shaft.

Tom Keevil · Post by **Tom Keevil** » Mar 29th, '11, 22:32

We have also pressed ours off against the transmission without a problem. As Matt suggested we used a socket to push the shaft out as the bolts were evenly tightened. We have realigned the engine a number of times since then (for other projects), and there has never been a problem. Soak it for a long time (days) with penetrating oil first.

Mike Davis · Post by **Mike Davis** » Mar 30th, '11, 05:14

In order to press of the shaft from the coupling, it appears to me that the coupling bolts need to be longer in order to put a spacer in between the two sides of the coupling. The bolts that are on the coupling are too short to fit a spacer and then tighten them. Do I purchase four longer bolts with the same tread as the coupling bolts?

Maine_Buzzard · Post by **Maine_Buzzard** » Mar 30th, '11, 06:13

Yes- Get bolts that are longer by the distance of the spacer used to press the flange off.

Get some heat on the coupler too. You can buy ceramic heat blankets in the plumbing section of any hardware store, they are about 8x8". Place it under the shaft and heat with a propane or MAPP torch.

The cast iron flanges on both ends are likely to crack. You would be well served to buy a steel disk the same diameter as the flange and drill four holes to take the bolts. Onlinemetals.com will sell a 3/4" slice of aluminum for $12 plus shipping. Easier to drill, if you have the room to slide the shaft back.

Jeff and Sarah · Post by **Jeff and Sarah** » Mar 30th, '11, 09:39

I can not stress enough that if you pull the shaft you should install a new coupler. I had a shaft replaced in Charleston and they reused the old coupler. At the time I didn't think much of it. As I approached a closed drawbridge the first day out of the yard, I put the boat in reverse and the prop pulled the shaft out of the coupler, disconnecting it from the engine. The swift current pulled us towards the bridge and were it not for a proactive bridge operator I could have lost the boat. The mechanic at the yard said he "cleaned up" the coupler which is the worst thing he could have done since I'd bet he cleaned up the inside too. Adding to the problem, he didn't correctly install the set screws. Anyway, the new rule on Prerequisite is a new shaft means a new coupler (not that I plan on replacing the shaft often, if ever again).

Boyd · Post by **Boyd** » Mar 30th, '11, 10:46

I stand on the side of those who recommend cutting the shaft off. The downside risk of transmission damage is just too great a risk. Sure some have done it and gotten away with it. Just too scarry for me. I tried making a puller plate but even with that the coupling wouldn't budge. I broke the bolts.

The real culprit in keeping the flange on is the dimple left by the stop screw. The shaft and coupler are machined to an interference fit and just the added dimple makes taking this off a lot harder.

I used a Sawsall to cut the coupler nearly in half from two sides and then split it with a cold chisel. A really uncomfortable job to say the least and yes you still get metal shavings all over. At least the saw makes courser dust than a grinder and is a bit easier to clean up. I saved the shaft that way. In the future I would just cut through the shaft and buy a new one for the trouble.

Always use a new coupler that is custom ground to match the shaft. Otherwise you risk it coming off as others have noted. I added a hose clamp just ahead of the stuffing box on the shaft so that if by some miracle the shaft pulled out the prop would not hit the rudder.

If you do manage to keep the old shaft, have it centerless ground so that all wobble is removed. It doesn't cost much and will straighten it out to within thousandths.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fl

Mike Davis · Post by **Mike Davis** » Mar 30th, '11, 11:09

If I ever do get to pull the shaft, does anyone know where to purchase the coupler?
Don Casey recommends the spacer technique to pull the shaft. If I had a great mechanic near my marina which is in Brooklyn, NY I would let them do the job. But I don't know of one that I can trust. They too can bend the shaft.
Also, where does one get a new shaft for a cd31?

Randy Capstick · Post by **Randy Capstick** » Mar 30th, '11, 11:22

Deep Blue Yacht Supply has a shaft puller tool on their website.

http://www.deepblueyachtsupply.com/shaf ... ge-pullers

I've dealt with them when I replaced my shaft/coupler/cutlass bearing and dripless seal on my CD28 and highly recommend. I just wish I had purchased the shaft puller at the time because it would have made the job a lot easier.

Randy

Maine Sail · Post by **Maine Sail** » Mar 30th, '11, 12:24

Jeff and Sarah wrote:I can not stress enough that if you pull the shaft you should install a new coupler. I had a shaft replaced in Charleston and they reused the old coupler. At the time I didn't think much of it. As I approached a closed drawbridge the first day out of the yard, I put the boat in reverse and the prop pulled the shaft out of the coupler, disconnecting it from the engine. The swift current pulled us towards the bridge and were it not for a proactive bridge operator I could have lost the boat. The mechanic at the yard said he "cleaned up" the coupler which is the worst thing he could have done since I'd bet he cleaned up the inside too. Adding to the problem, he didn't correctly install the set screws. Anyway, the new rule on Prerequisite is a new shaft means a new coupler (not that I plan on replacing the shaft often, if ever again).

Sadly, Jeff this guy should not ever be considered a "mechanic", a "hack" maybe, but a mechanic, no..

Scary how many "mechanics" are clueless as to what an "interference fit" is or should feel like when being put together..

Boyd · Post by **Boyd** » Mar 30th, '11, 12:50

I bought mine from the prop shop I do business with. They ground the shaft and matched the coupler to it all at one time.

Frank and Jimmies in Fort Lauderdale did the work, but I suspect any prop shop can sell you one.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fl

Maine Sail · Post by **Maine Sail** » Mar 30th, '11, 12:56

Boyd wrote: The real culprit in keeping the flange on is the dimple left by the stop screw. The shaft and coupler are machined to an interference fit and just the added dimple makes taking this off a lot harder.

There should not be a dimple or scar on the shaft if the shaft was made well. If the shaft was built to ABYC and SAE specs it should have cone or dog point setting screws and spotting sets (pre-drilled dimples) on the shaft to accept the set screws. Rust and corrosion are the big culprits in welding these couplings to the shaft unless the set screws were improperly installed to begin with...

Cathy Monaghan · Post by **Cathy Monaghan** » Mar 30th, '11, 15:58

Don't forget to totally disconnect the stuffing box and use LOTS of PB Blaster on the shaft coupling. You may have to come back everyday for several days and re-apply more PB Blaster. With any luck, after it's had a good soaking in the stuff, it'll come apart.

To remove the coupling from the shaft, you'll need to go out and buy really long bolts that are the same size as the bolts for the coupling -- they should just be at least 6 inches long. Then you'll need at least a couple of pipe nipples. The pipe nipples should be 5/8 to 3/4" wide, but now wider. Get several sizes -- 1, 2 and 3 inches long.

Now to remove the coupling from the shaft:

1. With the shaft coupling separated from the transmission's half of the coupling, place the longest pipe nipple between the transmission's coupling and the shaft's coupling lengthwise with the pipe up against the shaft.

2. Use those really long bolts you purchased and bolt the couplings together with the pipe nipple sandwiched inbetween up against the shaft. Make sure they're tightend down evenly.

3. Once you've got them all tighten evenly so that the pipe nipple is centerned against the shaft and won't fall out, begin to tighten each nut only 1 or 2 turns at a time, no more, for each nut.

4. Keep working your way around the coupling, one nut at a time, making only 1 or 2 turns at a time, until the couplings come back together. (As you tighten the nuts, the pipe nipple will push the shaft back out of the coupling.)

5. Remove the nuts and separate the couplings so that you can add the next pipe nipple. Remove the 3" nipple and tape one of the others to it lengthwise (you may only need to use the two shorter nipples). Place the 2 pipe nipples back between the two couplings making sure the nipple is up against the prop shaft and bolt everything back together.

6. Proceed by turning each nut, only 1 or 2 turns at a time, working your way around the coupling until the shaft pops out of the back of the coupling.

Hope this helps.

Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay

The Cape Dory Board

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Here's how I removed mine....