Stern gland packing

[MoominPapa]

Next month whilst the boat's out of the water I plan to re-pack the sterngear and I'm trying to work out the size of the problem.

 

Looking at the photo below, does the team reckon I'll be able to do the job without removing the bearing? There looks to be just enough space for the pusher plate to clear the end of the studs before in hits the bearing, but will the end of the pusher tube be clear of the rest of the gear at that point? If not I'm going to have to unbolt the bearing and move it back on the shaft.

 

Second question. How do I determine in advance what size packing to buy?

 

MP.

 

[Timleech]

The 'pusher plate', follower, or whatever you wish to call it does not need to clear the studs. You do need the follower to clear the gland by more than the thickness of the packing, though, looks as though it could be a close thing.

 

It's very likely to be 5/16" / 8mm packing. If you can measure the diameter of the follower (cylindrical part) and the shaft diameter, half the difference with be the answer you need.

 

Tim

[MoominPapa]

The 'pusher plate', follower, or whatever you wish to call it does not need to clear the studs. You do need the follower to clear the gland by more than the thickness of the packing, though, looks as though it could be a close thing.

 

It's very likely to be 5/16" / 8mm packing. If you can measure the diameter of the follower (cylindrical part) and the shaft diameter, half the difference with be the answer you need.

 

Tim

 

Thanks Tim, I shall descend below the counter, vernier caliper in hand, this weekend.

 

MP.

[alan_fincher]

I don't think you have the required space to draw the moveable part back out far enough to start digging packing out, and putting new in.

 

Obviously ultimately it is determined by the length of the bit you can only see a small part of, but I fear it will be impossible, rather than just "tight".

 

Tim's method for the packing size, but a very good chance it will be 8mm / 5/16" I would say. A good easy way if you can get clear access is to insert drill shanks down the gap once you have drawn the moveable part back, but (obviously!) not possible here.

 

Why is the another bearing so close to the gland? If it will move on the shaft, is it a big deal to unbolt it and move it away for the operation?

[mrsmelly]

Hi

 

Good advice so far, may i just add that whoever did the instalation should be put up against a wall and shot !!

 

Tim

[Bee]

Unbolt the bearing, remove bolts, look for one or maybe two little grub screws in the bearing `collar`, slacken them right off with allen key, if there are shims or washers beneath the feet don`t mix them up, slide bearing back to clear enough space. reassembly is the reverse of the above except for trying to find the two grub screws which will now be in the bilge and lost forever, should take 15 mins.

[MoominPapa]

Why is the another bearing so close to the gland? If it will move on the shaft, is it a big deal to unbolt it and move it away for the operation?

 

The bearing is there to support the 10ft lorry propshaft, complete with Hardy-Spicer and sliding joints, that runs forward under the floor and the bed to the engine room. It also takes prop thrust, given that the lorry shaft has a sliding joint in it. The bearing will certainly move on the shaft when the relevant grubscrews are loosened, I'm just a bit concerned about if and how it's aligned with the stern tube, and how easy it will be to re-align if I unbolt it from the cross-member.

 

Looks like I may be about to find out. Bee's advice about shims seems good to me.

 

 

MP.

 

ETA: bit about prop thrust.

Edited May 16, 2013 by MoominPapa

[gazza]

Dowel the pillow block to its mounting pad, you will always get it back in line that way.

 

Ps, where would we be without insulting tape to try to hold the world together.....!

[MoominPapa]

Ps, where would we be without insulting tape to try to hold the world together.....!

 

 

I'll have you know that's no-expense-spared self-amalgamating tape, which did keep some grease in the pipe when it split. But not all, hence the big pile squirted out on the top of the stern gland.

 

It will replaced with artfully looped 8mm copper pipe, when I find the relevant tuits.

 

MP.

[gazza]

I have a roll of self amalgamating tape in the spares box, god knows why, every hose on the boat is new. Feel better for having it though!

Used to be an essential glovebox item when running 70's and early 80's fords on apprentice wages!

[MoominPapa]

Reporting back. I did this job today. Without touching the bearing the pusher pulled back far enough to give about a centimetre of clearance, which was enough to deploy the woodscrew trick and extract a couple of very sorry looking bits of string. Also to get in a couple of rings of new 8mm packing. The shaft seemed to be a bit off-centre, the packing was definitely more difficult to ease in at the bottom than the top. It all went back together and is much improved at least to the extent that the grease now goes down the stern tube and not back into the boat. We shall see if it's watertight and overheat-free at the weekend when ithe boat goes back in the water.

 

MP.

Edited June 5, 2013 by MoominPapa