Stern gear help

[Alcyone]

We're in the process of fitting a new Beta engine to our Cobra 850. Old engine is out and sold, boat is on it's cradle out of the water. When I asked here about doing this, a few people suggested we look at changing our Stern gear whilst we are at it.

Our stern gland leaks, amaybe around 1/2 a bucket a week, and I found a fair bit of play in the prop shaft this afternoon. I'm new to all this, so some advice/exlplanation would be appreciated.

First the Stern gland.

This is it. When I removed the prop shaft, I found that there was nothing in the rubber tube, apart from grease applied via the white tube and remote greaser. I'd expected some kind of packing?

When I removed this, I found the stern tube:

If I buy a new stern gland, does it just fit onto thie end of this, held with jubilee clips? Also, what kinds of stern gland could I/Should I look at?

The bearing concerns me more:

When I've seen pictures, there usually seems to be raised and recessed areas on the inside of the bearing. Has mine completely worn away? Am I even looking at the right thing?

Any help, as usual, much appreciated.

A.

 

[johnalison]

I can't help you with the bearing question but if you can possibly contrive to get a Volvo seal onto the tube instead of a gland your leaking days will be over.

 

[Tranona]

The Volvo seal is your best bet - if your OD of the housing is suitable. If not, then a Tides seal is also very good as it is also sealed by lip seals, but much more expensive. It does, however fit a wider range of stern tubes.

Is the last picture on the outside of the boat? Have you unscrewed a bronze housing with the cutless bearing inside? That is the bit that needs replacing.

 

[Alcyone]

The Volvo seal is your best bet - if your OD of the housing is suitable. If not, then a Tides seal is also very good as it is also sealed by lip seals, but much more expensive. It does, however fit a wider range of stern tubes.

Is the last picture on the outside of the boat? Have you unscrewed a bronze housing with the cutless bearing inside? That is the bit that needs replacing.

Thanks, guys. I note the Volvo needs 36mm of sttern tube to fit? I will measure tomorrow when I'm at the boat.

Tranona, I did take off a bronze housing, and yes, it is outside the boat. I will try and take a photo - I brought it home to clean it.

Thanks.

 

[Alcyone]

OK, here are both sides of the bronze housing:

 

[Tranona]

That holds the stern bearing. It may well be a composite rather than a cutless - if it is the latter it is definitely knackered as it should be fluted. Cutless bearings are normally 4* shaft diameter - so 4" for your 1" shaft, but some are shorter, so the new one needs cutting down.

If it is not a cutless you may want to speak to NeilY who posts here as his company H4 Marine, specialises in composite bearings.

 

[Alcyone]

That holds the stern bearing. It may well be a composite rather than a cutless - if it is the latter it is definitely knackered as it should be fluted. Cutless bearings are normally 4* shaft diameter - so 4" for your 1" shaft, but some are shorter, so the new one needs cutting down.

If it is not a cutless you may want to speak to NeilY who posts here as his company H4 Marine, specialises in composite bearings.

Many thanks again. It's amazing how difficult to see or understand something is until someone points something out, and it is much appreciated.

I suspected it was knackered after I looked at it following your first post. It does seem to be around 3" long, rather than 4, and is very badly worn, with no flutes - that probably explains the play in the prop shaft.

Pardon my ignorance again, but how can I tell if it is a cutlass or a composite bearing?

 

[Tranona]

A cutless bearing has a brass (usually) shell and a fluted rubber lining. That is what it looks like from your photo - you can just about make out the brass. Some have a Phonelic shell, but is still distinctly different from the bronze housing. You should also find a grubscrew in the housing probably under 30 years of AF that locks it into place. Normally they are a press fit into the housing, so probably best to have a marine engineer press it out and replace it. Make sure it is the same size as your new prop shaft. You might find it best to have the new shaft and bearing done by the same firm. Just had mine done by Lake Engineering in Poole.

 

[NorthUp]

You have a white metal bearing cast into the outer part of the stern tube- its identical to my old set-up. You can get the white metal machined out and a special order cutless bearing fitted, but its pretty thin in the wall, not much rubber left. I went down this route last year, but intend to change to a composite bearing from NeilY over the winter, as I think this will be a more robust answer.

On the inside, I binned the packing gland identical to yours, and fitted a Volvo seal, but had to machine a bronze spigot to screw onto the inner part of the stern tube (its threaded under all that grease!), as there was not enough spigot showing to get a grip of the Volvo seal, not enough for peace of mind anyway!

You can bin the greaser after fitting the volvo seal, its water lubricated.

The Volvo seal is the only thing Volvo ever did right- somewhere on their website there is a pdf detailing the combinations of shaft size v. tube size, but I've lost the link...




edit- and now I've found it-
http://vppneuapps.volvo.com/wwlb/VPAC/default.aspx?language=en


edit again- that link is a bit iffy, so go there, then engine accessories, then transmission, then Bobs yer uncle. The Swedes call it a rubber packing box.

 

[Spyro]

The stuffing box looks ok to me, if you dont want to replace it fit new teflon packing and as you have it dismantled think about replacing the rubber hose. The hose does not hold the packing, it is there to introduce some flexibility into the stuffing box mounting. The packing is held inside the large nut to the left of the greaser tube.
See website for explanation

http://www.tb-training.co.uk/10sgear.htm#bmn31

 

[Alcyone]

Many thanks, guys. Time to get on with it I think! Cheers.

 

[scottie]

I would suggest that the stern gear is as supplied by watermota and will be imperial so if you go down the VP gland get a the correct one
1" is 25.4 mm and this diff is important. If you stick to the existing set up the hose MUST be the correct hose double clipped and may be a bit shorter

If you speak to
Lake engineering they amongst others should be able to help you

 

[Pye_End]

Is it possible to use a white metal bearing with a seal such as the Volvo?

Ie, is the bearing water lubricated or grease lubricated? Additionally, does the Volvo seal require water up the shaft, and if so does enough get past a white metal bearing?

 

[davidej]

and two jubilee clips at each end - tightening in opposite directions!

 

[Alcyone]

Again, thanks to all who responded - I'm in the process of ordering all the bits (I think) I need.

Cheers.

A.

 

[NorthUp]

These glands were designed before the current fad for double clipping everything- there isn't enough stub for two hose clips, and the boat doesn't appear to have sunk yet!
You are correct that the right grade of rubber hose is essential though.



Pye end- I doubt the Volvo rubber will like grease much in the long term, I converted my white metal bearing to cutless/ rubber, though I intend to go to composite this winter.
I have seen one with the metal bearing left in, but it was a rattling fit, and so let water up to the seal. I do not expect it to last.

 

[Alcyone]

Just like to say a big thanks to NeilY of this parish, and his company, H4marine, who sorted out our bearing insert for us.

It's not often you come across someone prepared to take the time to talk to you, give advice, do the work in less time and cost than the quote, whilst keeping in touch through the whole process.

Highly recommended.

Many thanks, Neil.

 

[Mike47]

Hi i am about to take my stern tube out of theboat. It has a slight weep on the lower bolt. In your case was the two parts connected by the same through nuts and bolts. The parts being the external and internal housing.

 

[MoodySabre]

I can't recommend a Tides Seal. See Vyv Cox's website Cox Engineering where there a re pics of various stern glands and my cautionary tale. https://coxengineering.sharepoint.com/Pages/Sternglands.aspx

As the prop shaft will presumably turn the opposite way with the new engine then you'll need a new propshaft and prop anyway so a new seal is the least of your costs. Volvo if poss or a PSS would be my choice. I went for the later as the shaft was worn and the PSS doesn't bear on the shaft.

 

[Tranona]

Hi i am about to take my stern tube out of theboat. It has a slight weep on the lower bolt. In your case was the two parts connected by the same through nuts and bolts. The parts being the external and internal housing.

Welcome to the forum.

Usually best to start a new thread when asking a question rather than tacking it onto a 7 year old one!

Anyway there is not enough information to answer your question as there are different designs of stern tube and different ways of installing them.

First, though, why do you want to take it out? This is very rarely required, and if it is a leak out of the external bearing carrier the first thing to do is remove that, by removing the two locking screws and unscrewing it. The leak might be solved by just resealing the carrier. The locking screws on the outside usually just screw into the deadwood although they may be bolts with nuts on the inside. Only you can tell by looking at your boat. It may help if you say what boat it is as they may well be folks here who have experience of tthe installation. pictures would also help.