Prop shaft too long?

Heckler

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The current flexi-coupling supplied by R&D does not fit perfectly, as it does not fully site over the register, and keeps the whole clamp 2mm away, I have written to them asking if that is acceptable, but I guess not.

coupling-not-fitting-.jpg


coupling-not-fitting-1.jpg


At the moment I would go for any coupling that would fit. Given that the old coupling had to be cut off, I don't think I can remove retaining pin?

The retaining pin has a diameter of 42mm and the register is 60mm
Thats not going to last 5 mins! That nut and bolt that was the retaining pin in the previous pics wasnt 42 mm! If it is still in the shaft it wouldnt take me more than twenty mins to either drift it out or drill it out! Does the shaft turn by hand? If it does then the bolts arent bottoming on the box face . Are the thread tapped holes all the way thru the flange? If so then the diag that they are bottoming out is wrong and the bore of the plastic is too small.
S
Ok your terminology is wrong, your retaining pin is a spigot! Looks like the hole in the centre of the flange is too small. Send it back and start again instead of bodging with spacers etc
 
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Jokani

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skipper_stu, thanks for putting me right on the terminology, this is now correct?:

register-spigot.jpg


If so it is the spigot that is 42mm, I think the hole in the centre of the split coupling is only 38mm - I have so far returned 2 couplings, the last came direct from R&D marine who do not make a coupling with a 42mm hole, nor does it seem does anyone else - the only option I seem to have is to use a spacer of some sort, the R&D solution was to use the flex-coupling as the spacer.

Unless I can find a coupling that fits direct then I think the first thing I need to do is confirm why the R&D flex-coupling is not fitting. If it is the length of the bolts then fine, if not the I need to return it and instead use a simple coupling like those suggested at Ambassador.
 

Heckler

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skipper_stu, thanks for putting me right on the terminology, this is now correct?:

register-spigot.jpg


If so it is the spigot that is 42mm, I think the hole in the centre of the split coupling is only 38mm - I have so far returned 2 couplings, the last came direct from R&D marine who do not make a coupling with a 42mm hole, nor does it seem does anyone else - the only option I seem to have is to use a spacer of some sort, the R&D solution was to use the flex-coupling as the spacer.

Unless I can find a coupling that fits direct then I think the first thing I need to do is confirm why the R&D flex-coupling is not fitting. If it is the length of the bolts then fine, if not the I need to return it and instead use a simple coupling like those suggested at Ambassador.
Thats the issue, the 38mm hole should go over the spigot. If it did then the face of the flange would go up to the other face. Having said that it still doesnt make sense, if its supposed to be a flex coupling then it wont flex because the spigot would be stiffening everything up! If you put a spacer in then it makes the prop side worse. I would send the coupling back, not fit for purpose. Get a solid coupling, if there is a key in there then you really dont need the bolt through the shaft, so leave the remnants in the shaft. What is the exact size of the shaft?

S
 

Jokani

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The shaft is 25mm - I would get a solid coupling if I could find one. But I can't find one that fits the 42mm spigot, everything is smaller.
 

Heckler

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The shaft is 25mm - I would get a solid coupling if I could find one. But I can't find one that fits the 42mm spigot, everything is smaller.
If the bolt pcd is ok on this one and you have a local machine shop I would get one of these http://www.asap-supplies.com/marine...pilt-half-coupling-for-propeller-shaft-808414
and get a key way and register machined on it. In fact a decent machine shop would make one easy peasy!
I will find the details for a machine shop in Wrexham, he is a yotty himself. Give us a min
S
 

Heckler

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The shaft is 25mm - I would get a solid coupling if I could find one. But I can't find one that fits the 42mm spigot, everything is smaller.
Here is Tims details, I know its going off track, but worth giving him a bell
Tim Rouse, AWR engineering, for all turning and machine work, 01978 661928 Wrexham.
S
 

rogerthebodger

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Thats the issue, the 38mm hole should go over the spigot. If it did then the face of the flange would go up to the other face. Having said that it still doesnt make sense, if its supposed to be a flex coupling then it wont flex because the spigot would be stiffening everything up! If you put a spacer in then it makes the prop side worse. I would send the coupling back, not fit for purpose. Get a solid coupling, if there is a key in there then you really dont need the bolt through the shaft, so leave the remnants in the shaft. What is the exact size of the shaft?

S

The spigot could also be termed a centring ring that used in the case of a flexible coupling used where the prop shaft does not have have an inner bearing and flexible stern seal. It allows angular misalignment but not radial (always keeping the shafts centred but allowing the engine to be angular displaced from the prop shaft.

Have a look at the bullflex I posted it comes with optional centring ring.
 

Jokani

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All sorted, I feel slightly embarrassed! R&D were correct, they supplied the flexi-coupling with 2 sets of bolts, one longer than the other.

I was try to fit the coupling with the longer set and they were bottoming out.

Here is the coupling correctly fitted:

flexi-coupling-2.jpg


flexi-coupling-1.jpg


flexi-coupling-3.jpg


Everything now fits, have gone from this:

engine-rear-3.jpg


To this:

engine-rear-5.jpg


engine-rear-6.jpg


I managed to get the propshaft all the way up to the failsafe plat in the flexi-coupling. This meant that the length of shaft protruding from the cutlass bearing housing was 40mm, which is perfect for me to fit a rope cutter. Se even got away without have the shaft reduced :)
 

Spyro

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Surely if you'd introduced the flexi coupling to the gearbox flange without the bolts in place you would have known if it fitted flush? Am I missing something?
 
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