Seperating stainless steel from aluminium fitting.

[SeaStu1]

I'm trying to remove my rudder at the moment for repair / replacement. All the underwater fittings have come away with ease, however the stainless bar from the rudder comes up through the cockpit and onto the aluminium tiller head. The stainless bar has a threaded end with a nut to secure the tiller head. The nut has come off, however the aluminium and stainless l can't seperate. I've tried drowning it in WD40 and using a mallett to hammer the stainless bar down but it won't budge.

Any suggestions of how to seperate the two? I could hacksaw through the stainless and job done but l'm going to have a go at repairing the rudder so it may need to go back. Thanks.

 

[david_bagshaw]

warm it gently with a gas torch , not particularly hot, 150 deg c, as you dont want to soften the ally. ally should expand more than the steel, helping it break free.

 

[Boo2]

I've tried drowning it in WD40

Try drowning it in PlusGas which worked well for me or some people swear by ACF-50 which is supposed to be even better but I haven't tried it.

Boo2

 

[Bosun Higgs]

you need to expand the ally. first effort try a kettle or two of boiling water. only if that fails try a hot air gun. Preferably do either with tension applied as from a puller

 

[PetiteFleur]

I would second all the suggestions so far. Make sure when hitting the shaft that the Ali. tiller end is well supported, maybe jamming a piece of metal either side of the shaft to take up any gap between the bottom of the tiller end and the bush.
When you reassemble make sure you use Duralac between the two surfaces which should make it easier to remove in the future.

 

[rob2]

I'm wondering how the torque is transferred from the stock (stainless) to the rudderhead (ali). Just dropping one onto the other with a nut on the end will usually slip. Most that I've seen have a square on the end of the stock, but some have a pin or bolt through the rudder head engaging in a groove in the side of the stock. If there is a pin or similar, it will have to be withdrawn or driven out before the head can be lifted off.

Another possibility would be for a taper fit with a Woodruffe key to prevent rotation, just like fitting a propeller on the shaft, and these are notorious for needing heat and a god puller to remove them.

If you could post a few pics of the fitting from a few angles, it might be possible to be more specific.

Rob.

 

[SeaStu1]

The aluminium tiller does have a stainless steel grub screw, allen key style. I had thought about a gentle blow torch but like the idea of some boiling water to expand the ally! I will give that a go first, if it doesn't shift l will get a photo or two. I also wondered of one of those 3 legged gear pullers like used on cars would help move it?

 

[CelebrityScandel]

The aluminium tiller does have a stainless steel grub screw, allen key style. I had thought about a gentle blow torch but like the idea of some boiling water to expand the ally! I will give that a go first, if it doesn't shift l will get a photo or two. I also wondered of one of those 3 legged gear pullers like used on cars would help move it?

I think you will find that hot water will not be sufficient but a hot air gun might be. Really depends on the extent of the corrosion and the size of the shaft seized on to.

My first attack if ordinary means have not released it is if you are able to get a gear or wheel puller of size appropriate to the job on it (one can often hire or borrow them from a boatbuilder or engineering workshop), set that up as tight as you can and if that does not release it give the centre screw of the puller (the one that sits on top of the shaft you are pulling the tiller from) a good hard hit with as big a hammer as you think is appropriate to the size of the job. The shock coupled with the tension will often break the frozen joint.

 

[SeaStu1]

It still won't budge!

It still won't budge after trying all the suggestions except a good thump with a hammer.
This is the next step, although I'm going to lock on a couple of nuts before I do this to protect the thread, which oddly appears to be 1/2" not M12 as I was expecting. Another further less risky options will be gladly received!

 

[davidej]

I wuold definitely put the puller on -do it up as tight as you dare then use the hammer on the central shaft of the puller. That way the inpact goes straight into the joint.

 

[vyv_cox]

Unless you are certain that the rudder has no thrust bearing of any type, i.e. is hanging from the tiller attachment, I would advise that you do not try hitting the top of the shaft. In general hammering a boat, along with most other engineering equipment, is not a good idea. A puller has to be the answer here, along with heat which should be very effective considering the big differential between the coefficients of expansion of the metals involved.

I cannot see a keyway in your photo so assume it is a plain taper. Can you see if this is the case? It's easy to overtighten one by applying the typical load of a normal nut and bolt. It may be that the hammering method used for propellers will work, hitting both sides simultaneously with as heavy a pair of hammers as you can find.

 

[sarabande]

I've heard of farmers using vinegar and heat to break the corroded crud in the interference fitting. A bit like Hannibal and the Alps.

 

[Bosun Higgs]

I've just had a hell of a job getting a stainless tube out of a socket on my alloy bow roller and my biggest problem is one that I think you will have - the lump of ally was so big and such an effective heat sink that even a propane torch burning on it for 109 minutes didnt expand it enough. Even the stainless tube got to red heat but wouldnt budge.

If you cannot get it out with heat then you have two choices. One is to saw off the stainless but you will still have a problem. The other is to slit the ally from top to bottom on the far side and ease it open with a small wedge. You can then get it welded back again.

 

[stuey_two]

Many years ago, I had a similar problem with removing the flywheel from the crankshaft on my minivan. I tried using a big conventional puller without success, then hired a hydraulic puller - from HSS, I think.
This worked a treat but caution is needed, the flywheel came off with a bang when it did release.
This was not a problem then, the flywheel was held onto the shaft with a (loose) bolt.
A nut on your threaded rudder shaft is essential or the whole caboodle could take off!

 

[FWB]

ACF 50 has been recommended, I would go further and recommend the marine version Corrosion Block...
http://www.acf-50.co.uk/marine.htm

 

[maxi77]

There was mention of a grug screw of some type. The apparent lack of a keyway makes me think this could be locating the tiller on the stock, and thus it would need to be removed before the tiller will come off the stock.

 

[KellysEye]

You could try taking if to a fabricator and ask them to use a press. However we had the same problem with stainless bolts in an aluminium winch. A 20 ton press couldn't separate them. Worth a try though.

 

[VicS]

You could try taking if to a fabricator and ask them to use a press.

I think the trouble with that suggestion may be that sandwiched between the rudder blade and the tiller fitting is a large hull!

 

[SeaStu1]

Nice observation Vic! Anyway, problem solved by using a 3 legged puller to get some tension on it and then a few swift hits with a heavy hammer done the trick. Thanks for all the suggestions.