Yanmar 1GM

[steve6367]

Has anyone ever had any problems with the shaft "sliding" through the coupling? It seems to rely on clamping the shaft and does not seem to be doing a great job. I have tightened the 4 bolts as tight as I can and will see what happens. Is there a correct setting for these?

 

[PIGLETSDREAM]

Sorry don't know the answer, but try here cos someone will

http://yanmarhelp.com/msgboard.mv?parm_func=showpostform

 

[steve28]

I have, the solution was to crossdrill the coupling and pin it as well. this solved the problem.

The conclusion i came to was that in my case the shaft was 1 inch and the coupling was 25mm and the diffrence was what made it slacker.

mine only came to light after having the misfortune of running over an unmarked pot which had a 8mm stainless cable inside, the ropecutter cut it no problems but the shaft coupling didnt agree. /forums/images/graemlins/smile.gif

steve

 

[blackbeard]

Not altogether sure that drilling through shaft and coupling is an altogether good idea. This was done on my Hunter 245, following Hunter's instructions when the previous owner built the boat from kit. The coupling bolts were perhaps not done up as hard as they should be. Result of this was the top and bottom of the bolt (the one through shaft and coupling) on the engine bay floor; possibly the result of an over hasty gear change or the propellor hitting something.
Advice from this forum was that the bolt wasn't necessary. Hunters also thought that it wasn't essential.
Since doing up the coupling bolts as hard as I can I haven't (yet) had any problems in this area. They are fairly substantial (at least the ones on my coupling) and unless you are a gorilla it's unlikely AFAICS that you will over tighten. Ultimately it may be a good idea to have something that will, in extremis, slip a bit, if your prop hits something really solid for instance - may avoid something expensive breaking.

May be a good idea to inspect these bolts from time to time and make sure that they remain tight so the coupling grips the shaft.

There is quite a big difference (0.4 mm) between a one inch coupling and a 25mm shaft - enough to cause a problem I would think, and I wouldn't trust a (necessarily fairly slim) bolt through shaft and coupling to hold everything together.

Mike

 

[cjepearson]

I have a 2GM20, and exactly the same happened to me yesterday. I motored away from the mooring, then sailed a bit, then tried to motor again, only the shaft was now about 10cms from the coupling. A sleepless night later, I managed to pull the shaft back into the coupling and re-tighten the allen-key bolts. It all seems rather un-professional. I will try Loctite, and maybe longer bolts with locking nuts, but why can't Yanmar do that in the first place?

 

[blackbeard]

Re: Yanmar 1GM and a rope cutter

REALLY impressed by that rope cutter. Have just installed a Stripper but I didn't really expect it to do more than cut rope - if it can do for a steel cable that's impressive.

I have to say I was quite disappointed with one aspect of the Stripper - when I opened the box - no Mermaid! (perhaps somewhat to SWMBO's relief)

Mike

 

[roboandkate]

Mines on a 1" shaft but it does have a grub screw. I had assumed this was original but may be it's a fix.

The advantage of this is that a small pit in the shaft isn't going to weaken it significantly, and should you hit something with the prop it's likely to give.

Do the screws up with an allen socket and a T bar with extensions, this should get the bolts as tight as possible.

 

[GaryE]

Yep, happened to me as well, on a 2GM. Answer was to remove the thing & clean / degrease it. Pay especial attention to the bore, and run a tap through the threads for the clampbolts (M8). Make sure the bore is not too badly damaged, or will not grip properly. Re-assemble with new bolts, (copper grease on threads & under cap of bolt), and a smear of loctite "bearing lock"on the shaft. I havn't got a torque, but if you use an long leg allen key, (without a 3 foot pipe on the end!), and apply a bit of heave, you woun't be far off.

 

[JimMcMillan]

If these are the original screws(mine have been drilled out and bolts fitted)they are set screws and it is possible you have reached the end of the thread without fully clamping the shaft. Clean out as suggested and fit a spring washer. this should give enough extra thread to do the job.

 

[toad]

I have the same system on a 3GM with grub screws into a dimple on the shaft, it has been like that since new(fitted by a Yanmer dealer).

 

[ShipsWoofy]

Is a little odd. I bought new motors in 2002 and they came with 3/4" couplings. Apparently this is the norm. I had them machined out to 1" and they have never given me a problem.

I wonder if your had a similar problem and were not bored out very well.

I have a spare 3/4 coupling (brand new) if you would like to make an offer. you could get it bored out and fit it with confidence.

 

[billcowan]

My coupling is just an enormous blob of rust, though I think it has extra lumps on one side indicating that it might have had screws. Never comes undone though. let sleeping dogs lay I say.

 

[steve28]

pehaps i worded it wrongly, the new coupling i bought which had to be bored out to the correct shaft size already had the hole for the crossdrilling, all i used was a roll pin through the hole.
As for the stripper, all i heard was a big bang followed by some black smoke then everything went back to normal operation, when i inspected the stripper it was slightly brighter on one of the teeth, other than that no damage.

steve

 

[steve6367]

Thanks for all the advise so far - I am going to have a closer look over the weekend and see what I can do. I've never had it move far at all - but it does definatly slide foward until the shaft hits the plate of the flexible coupling and stops it. This takes a long time, but would seem to indicate that all is not quite right.