Prop shaft removal

[rleslie]

I want to replace my prop shaft and shaft seal, but have run into a major problem.

I can not get the shaft out of the coupling and I can not get the coupling removed from the transmission . I believe I'm dealing with the original coupling and shaft (1982) and every thing is rusted shut.

I have sprayed everything with 3 diferent penetrants every day for the last three weeks. Nothing will budge.

Any suggestions???

Roger

[Alan Wheeler]

You may have to use some heat via an oxy/act set. Heat the coupling only, this causes it to expand. Wrap the shaft in a wet rag and even dribble water onto it as you heat the coupling. This will keep the shaft as cool as possible, stopping it from expanding as much as the coupling. if you can get at the end of the shaft/coupling easy enough, then a large gear puller should budge the thing. If you don't have a gear puller, then a little persuasive force from a large hammer. Careful you don't damage the shaft with the hammer.
The coupling should be fixed to the shaft with a square keyway and a set screw locking down the key. Sometimes there is no keyway and just several set screws, but that would be a small shaft system.
A little tip, if you use break fluid as a penatrant while heating, the break fluid can stand a lot more heat than actuall penatrants. Penetrants will burn away with little heat and tend to run away from heat. Brake fluid will run towards heat more more and will work into the rusted area between shaft and coupling. Be very careful with brake fluid running onto paint. It will eat paint for breakfast.
Good luck.

[rleslie]

Alan,

Thanks for the advise. I have a small propane torch kit and will try heating the coupling. I did not know about the break fluid - excellent information.

Assuming I can get the shaft out, I'm still left with the problem of removing the shaft coupling from the transmission coupling. Are the couplings normally threaded? I can get to the heads of the bolts and have considered sawing the heads off, but if the bolt is threaded into the coupling, I'll be creating more problems. There is a lock washer and nut on the opposite end (towards the trans.), but can't get to them well enough to cut.

Thanks
Roger

[Alan Wheeler]

Problem is, if you cut off the heads, you will still have to remove the threads later if you want to reuse the coupling. Couplings are expensive to replace.
I also doubt the propane torch will get hot enough. You need a oxy/actylene set and hit it hard with a good amount of heat. The trick is to heat the coupling as fast as possible before heating the shaft to much. And we are talking real hot. If you have a small heat source, by the time you have heated the coupling, the shaft would have got too hot as well. Give it a try though, maybe it will help.
As for the trany end, I doubt anything is threaded on the shaft itself. Most likely you have a flange on the trany shaft that the coupling is bolted to. This can be done in two ways. The flange has a ring of bolts around it, or it has one large central nut.
You really need some proper tools. You need a good set of pullers. Hydraulic preferably. If you don't have the tools to do the job, the job will be difficult.
When you reassemble the system, make sure all threads have an antiseize compound on them and including the shaft and keyways. You can protect the entire coupling with a good coat of Zinc rich paint or PA10 primer or similar.
What is the Trany. Maybe someone has intimate experiance with one similar.

[ozskip]

Be very carefull about heating couplings while still connected to a transmission.You must seperate the two coupling halves whether the bolts shear trying to undo them or not a impact wrench is very usefull as the the virbration loosen the corrosion.Or as you have all ready thought of cut the heads off and seperate the coupling. Remove the studs from the coupling is not as hard as people think heres one trick that works well place the earth clamp of an arc welder on the coupling and strike an arc and weld the end of bolt this will 1/ heat the bolt and makes it expand and when it cools it cracks the corrosion around the thread2/ the electric current burns the corrosion.In many cases i have been able to screw it out with my hand but a stud remover will do the trick.Idea shown to me 30 years ago and has not failed me get great on steel into alloy or any two dissimilar metals. Greg

[Alan Wheeler]

Yes Greg made a point I failed to comment on. Right behind the trany coupling, is a seal that stops oil from the trany escaping around the turning shaft. Heating that part will be death to the seal. And just to expand Gregs comment about the arc welder, it works well, but be sure to fit the earth connector to the flange. You DO NOT want any current to flow through to the trans and across gears and bearings. I have seen bearings destroyed this way. Clamping the earth directly to the flange is very safe and the above warning should not put you off giving this method a try.

[Alan Wheeler]

Roger, one other thought, If you still have trouble, can you take a photo and post it. We maybe able to help more if we can see what exactly we are dealing with.

[rleslie]

http://pg.photos.yahoo.com/ph/stoutwench/album?



the photo is under STOUTWENCH, the last pic

[Alan Wheeler]

Mate, looks like the shaft ain't the only thing needing some
TLC back there.
So if I understood your first post, you are renewing the shaft as well? OK, take an angle grinder with a cutoff disc, preferably a thin 1mm disc and cut right through the shaft. Then cut the heads off the bolts. I suspect the removal from the trans will be simple with a gear puller. Gear pullers are not expensive and will make that part of the job simple. I think going this way is going to be the path of least resistance and skined knuckles
By the looks of the thing, I would think the shaft will be well worn at the stern bearing and a new shaft will be your best bet. You can repair worn shafts, but as this one doesn't look that big, it is probably just as easy to get a new one made. Then you know you have a good straight shaft with no possible stress fractures in it. I would look at fitting a new coupling and I would suggest an anti-vibration coupling being used. This will stop vibration from engine/gearbox being transmitted to the hull via the shaft. I presume the engine is mounted on proper mounts and thus there should be a small amount of movement in that assembly. this movment is place on the shaft and thus the shaft is forced to move in its bearing/seal assembly which creates stress and wear.

[rleslie]

I intend to replace the shaft, install a P.S.S. shaft seal, replace the shaft bearing (already have a new one pressed on), install a R&D flexible coupling and (I'm not lookig forward to this one) remove the back end of the trannie to see what condition the trannie seals and coupling are in.

Thanks for your advise on the process. I agree with your assessment. Cutting the shaft and bolts will probably be the easiest way to proceed.


Thanks Again and I'll post a picture of the completed operation.

Roger

[Alan Wheeler]

Good idea's. I wouldnt' take the trans apart though. Look for any sign of excessive oil weaping from around the rear seal once the shaft coupling is removed. If it is leaking, then you need a seal. If not, then don't touch it. You need to check the oil inside is clean and changed at the required intervals and that there are no stranger than normal whines and noises coming from the box when operating. IF anything like that is happening, in means an overhaul.
I Look forward to the photo's.

[rleslie]

After days of fruitless attempts to remove the bolts, I used my 4.5" grinder and had the shaft and 4 bolts cut in under one hour. Fast & easy!!! I appreciate the advice.

Before I order the new shaft and coupling, I have one more question. I've been quoted $325 of a new 1.25" x 5' ss shaft, $107 for a rigid coupling and $189 for a "shaft saver". The shaft saver fits between the two couplings. Is this the best way to go?

Any suggestions on specific couplings will be appreciated.

Roger

[delmarrey]

http://www.shaftsaver.com/newpages/benefit.html

As for the coupling, It should have the same dimentions as your old one. And it should have two square head seat screws with a with hole in the heads for a safety wire. One of the setscrews should be over the keyway.

And for the prices on the shaft, if it comes with the prop. taper and keyways the prices sound reasonable. I couldn't make'm myself for less. ..............._/)

[Alan Wheeler]

I presume the "Shaft Saver" is a flexible piece that fits between the two rigid couplings. Having a flexible drive coupling instead of a rigid one, is well worth the expense. However, I don't know the unit you have suggested, and cannot suggest if it is the best or not. Plus, I know they are expensive, but ouch.
The shaft itself, being SST is difficult to machine. So the cost would be about what I would expect.