So many bolts on Centraflex M160 coupler - which ones to remove it?

[aaronwood66]

The time has come for me to replace the engine mounts on my Beta Marine 35 engine. Thanks to this wonderful forum, I (think I) know what my plan of action is and how to do this.

 

I realise I will have to remove the prop shaft to raise the engine, but am having trouble understanding which of the many bolts will do this on my coupler - a Centraflex M160. I don't know if it's because my boat is 20 years old, but I can't find any manuals, videos or articles that explain how. Other videos show very different couplers than this, that tend to have 4 bolts only - but this does not correspond to what I see on mine.

 

I have attached a couple of photos to show my setup, and if anyone can help me identify what the A,B, C bolts are, and which need to be undone to remove the prop shaft.

 

Thank you in advance for any help

 

 

[Tracy D'arth]

Remove all B  Put 2 of Bs in the holes nearby that did not have bolts in and nip them evenly to release the taper collet that Bs held. Prop shaft is then free. Cs drop the coupling off, don't touch As.

Edited February 11, 2023 by Tracy D'arth

[Tony Brooks]

I know the OP said that he wants to remove the coupling. but from the reason he gives I am not so sure, I think he may just want to disconnect the shaft from the gearbox. If that is correct then I think C will free the assembly from the gearbox half coupling, but what I don't know is are the threaded bits fixed studs or loose bolts.

[Tracy D'arth]

They are fixed studs.  

I read it as he wants to release the shaft so it slides back in the gland enabling him to lift the engine off the mounts.  Those nuts at C are awkward to spanner off, you can use sockets on B 

[Tony Brooks]

2 minutes ago, Tracy D'arth said:

They are fixed studs.  

I read it as he wants to release the shaft so it slides back in the gland enabling him to lift the engine off the mounts.  Those nuts at C are awkward to spanner off, you can use sockets on B 

 

Thanks, he has all the info he needs now.

[aaronwood66]

3 hours ago, Tony Brooks said:

I know the OP said that he wants to remove the coupling. but from the reason he gives I am not so sure, I think he may just want to disconnect the shaft from the gearbox. If that is correct then I think C will free the assembly from the gearbox half coupling, but what I don't know is are the threaded bits fixed studs or loose bolts.

Thanks @Tony Brooks - I worded it incorrectly, but yes, I meant I I wanted to disconnect it from the gearbox.

 

 

3 hours ago, Tracy D'arth said:

They are fixed studs.  

I read it as he wants to release the shaft so it slides back in the gland enabling him to lift the engine off the mounts.  Those nuts at C are awkward to spanner off, you can use sockets on B 

Thanks @Tracy D'arth - I am going to go with the B bolts - many thanks for your help!

[adrianh]

It is by far easier to undo the nuts marked C and just push the shaft away from the gearbox.

I have the same setup and have done this when changing the gearbox/coupling plate on a few occasions.

These are M10 slim style nyloc nuts ( I think  - ie 17mm AF spanner, if 19mm then M12 ) so it is always best to fit new on re assembly to make sure the do not work loose.

The bolts marked B should be very tight so they will not be easy to undo and should be torqued up evenly to achieve the correct grip through the taper sleeve which they secure.

If not tightened correctly you can end up with a slipping drive and ruined prop shaft - best left untouched !

 

The A bolts just keep the plate in place that picks up the drive rotation should you be unlucky enough to shear the rubber bonded element from the centre hub.

A safety design feature required for commercial usage I believe so that some form of drive always exists.

[aaronwood66]

2 hours ago, adrianh said:

It is by far easier to undo the nuts marked C and just push the shaft away from the gearbox.

I have the same setup and have done this when changing the gearbox/coupling plate on a few occasions.

These are M10 slim style nyloc nuts ( I think  - ie 17mm AF spanner, if 19mm then M12 ) so it is always best to fit new on re assembly to make sure the do not work loose.

The bolts marked B should be very tight so they will not be easy to undo and should be torqued up evenly to achieve the correct grip through the taper sleeve which they secure.

If not tightened correctly you can end up with a slipping drive and ruined prop shaft - best left untouched !

 

The A bolts just keep the plate in place that picks up the drive rotation should you be unlucky enough to shear the rubber bonded element from the centre hub.

A safety design feature required for commercial usage I believe so that some form of drive always exists.

 

I am really grateful for your timely reply, as I was attempting to remove the 'B' nuts today and they were so tight that I didn't have any luck budging a single one today - no wonder, from what you've said! I think the C bolts may be my best bet, and there are only 4 of them. Thanks also with what bolts these are likely to be - I will let you know how I get on  

Edited February 14, 2023 by aaronwood66

[aaronwood66]

Thanks again @adrianh - I managed to take the nuts off you suggested and it worked like a dream - I can now lift my engine

[BEngo]

When you have put it all back together again, dont forget to check the stern gland is not dripping too much.  Pushing the shaft back swill have disturbed it

 

 

N

[Tracy D'arth]

9 hours ago, aaronwood66 said:

Thanks again @adrianh - I managed to take the nuts off you suggested and it worked like a dream - I can now lift my engine

When you have changed mountings you will have to re-align the engine so that the prop shaft is exactly in line.

[aaronwood66]

2 hours ago, Tracy D'arth said:

When you have changed mountings you will have to re-align the engine so that the prop shaft is exactly in line.

From what I have seen this looks like a fiddly job, but I am the patient type  And I have just bought a feeler gauge to get the correct fit