Prop shaft coupling

[Spyro]

Yes, particularly those which rely on a split clamp where there is a perfectly good reason why a locking screw is not fitted. Other types do not rely on clamping but on other means of securing the coupling to the shaft, hence the additional physical fastening.

Rather pointless argument really. The loss of a shaft from a coupling is a very rare event and almost always due to improper assembly. So if you follow the instructions for either type they are just as secure.

Yes I'd agree you are having a rather pointless argument. One poster has told you exactly what I suggested might happen happened to them.

 

[Tammany]

My yanmar 1gm10 propshaft is purely held by pressure. No grub screws etc. It's hard work getting it off so can't see it coming off on it's own anytime soon. If it did it would fall back to the skeg and no further. I know as I tried as wanted to remove the shaft but there isn't enough lateral movement with the prop in place which I can't get off.

 

[eddystone]

Just in case it's useful for someone fitting one of these for the first time I was able to experiment with the old seal and a weight bar, which just happened to be 1" diameter.

The problem with the lips protector is that when you insert it into the end of the seal, the split along the length, which is necessary for extraction, rides over itself so that the shaft won't go through. Also, because the lips face forward the shaft will not pass through without the protector - catch 22; the picture of the protector on the end of the shaft shows that it is exactly right when the split edges are butted. So, one has to exert some serious finger pressure to stretch the the seal and manipulate the protector to so that the split is buted together and doesn't override; then with copious amounts of grease the shaft will slide through the seal - obviously in real life you need someone outside pushing the shaft so you can hold the protector in place.

 

[fisherman]

And is perfectly satisfactory on low HP engines. In fact, the big problem is usually getting it off! Of course if the 4 bolts are not done up and the shaft does not reach right to the end there is a possibility that it will slip and wear the shaft.

Mine is 135hp. Hasn't slipped yet. Just pinched, no pins or grub screws. I often think of it if I have a crash stop.

 

[lampshuk]

Resurrecting this thread because I have a follow-on question:
I have a Volvo with 1" shaft and clamp on the end of the shaft with 6 bolts and a simple grubscrew (similar to the one on Vyv's web site except the grubscrew doesn't locate into anything.

After much effort and fiddling I have removed the allen bolts and grubscrew from the collar and detached the clamp flange from the gearbox.
Vyv's site shows how to use the flange bolts to press the shaft out, but how do you get it back in again? Leave it in the oven for an hour or so then re-fit?

 

[Poey50]

The problem with the lips protector is that when you insert it into the end of the seal, the split along the length, which is necessary for extraction, rides over itself so that the shaft won't go through. Also, because the lips face forward the shaft will not pass through without the protector - catch 22; the picture of the protector on the end of the shaft shows that it is exactly right when the split edges are butted. So, one has to exert some serious finger pressure to stretch the the seal and manipulate the protector to so that the split is buted together and doesn't

I know this isn't the main point of the thread resurrection but, just in case someone finds this through a search, it's worth mentioning that starting with a warm Volvo seal I found the lip protector fitted properly - that is the lips were more pliable, the split parts did not overlap and the protector nestled perfectly into the seal such that the shaft passed through easily.

 

[Brent Swain]

There is also the possibility it will slip right out when you are reversing and only stop when it hits the rudder. This may or may not be after it has come right out of the shaft seal. I'm glad mine has the grub screw, actually it's more of a cone pointed 10mm bolt with a lock nut on it.

I read of a boat crossing the Gulf of Tehuantapec, and seeing a blue hole where his prop shaft had been. The missing grub screw had let his prop shaft pull out and sink.
Several friends had this happen when launching.
I prefer a bolt right thru. Hex head. Allens can be hard to get out.
n

 

[vyv_cox]

Resurrecting this thread because I have a follow-on question:
I have a Volvo with 1" shaft and clamp on the end of the shaft with 6 bolts and a simple grubscrew (similar to the one on Vyv's web site except the grubscrew doesn't locate into anything.

After much effort and fiddling I have removed the allen bolts and grubscrew from the collar and detached the clamp flange from the gearbox.
Vyv's site shows how to use the flange bolts to press the shaft out, but how do you get it back in again? Leave it in the oven for an hour or so then re-fit?

Hardwood wedges were mentioned further up the thread. I use a small chisel tapped into the clamp faces. This opens the coupling enough to allow it to slide on the shaft.

 

[lampshuk]

Hardwood wedges were mentioned further up the thread. I use a small chisel tapped into the clamp faces. This opens the coupling enough to allow it to slide on the shaft.

Thanks, Vyv.
I did give it a few thwacks with a steel driver, but the metal looks so thick I doubted that would work with mine. However, it sounds like it is worth persevering . Part of the problem, of course, is that there's scarcely room to swing a mouse, let alone a cat.

Is it safe to do this with the flange attached to the gearbox?

 

[MoodySabre]

The shaft on mine slid back in without having to open up the coupling. Good luck.

 

[Malish]

Hardwood wedges were mentioned further up the thread. I use a small chisel tapped into the clamp faces. This opens the coupling enough to allow it to slide on the shaft.

I use a couple of bricklayers line pins
https://www.screwfix.com/p/footprint-bricklayers-line-pins-pack-of-2/1223k
not too long, nice head on them to tap.

Re the lip protector overlapping itself - put a little bit of mr Volvo's grease on the outside of the lip protector to ease insertion and ensure the two edges are butted agianst each other - worked for me yesterday!