How to replace sheave inside the boom

[vladis]

Hello

I was checking the outhaul line of the in-mast furling system when I noticed that the plastic sheave inside the boom is completely broken. The sheave rotates on a axis and, in order to replace the sheave, I need to extract this axis. I add 2 images showing the referred to axis from both the right and the left side of the boom. Do you think that hitting the axis with a hammer and a punch, it will come out?

Kind Regards, Vladis

[jdl01]

Albeit, I am in Canada, but I have had my best luck with rig info by going directly to the Selden agent in our area. At the base of your mast, probably port side, is a hand etched alpha numeric code for your unit which Selden can interpret to know exactly what mast, boom and vang your boat is spec'ed with. The company has been very helpful to me; hopefully you will be equally lucky.

[sailbleu]

Feb 6, 2015 23:29:18 GMT vladis said:

View Attachment

Hello

I was checking the outhaul line of the in-mast furling system when I noticed that the plastic sheave inside the boom is completely broken. The sheave rotates on a axis and, in order to replace the sheave, I need to extract this axis. I add 2 images showing the referred to axis from both the right and the left side of the boom. Do you think that hitting the axis with a hammer and a punch, it will come out?

Kind Regards, Vladis

If in doubt ,.... Check it out.
I' m always very careful though when it comes to the combination alu/ss.
Using a small punch will widen the axis end causing the axis to get blocked even more.

You could clear the bad sheave (hammer and chisel) heat up the axis with a hot air blaster - or even better - a small acetylene/ oxigen torch ( if you can reach the axis without collateral damage) and so compromise the aluoxide that has been built up due to ss >< aluminium contact.
Then punch it out preferably with a correct sized punch or pipe.

Good luck

[On y va]

Feb 10, 2015 0:41:55 GMT jdl01 said:

Albeit, I am in Canada, but I have had my best luck with rig info by going directly to the Selden agent in our area. At the base of your mast, probably port side, is a hand etched alpha numeric code for your unit which Selden can interpret to know exactly what mast, boom and vang your boat is spec'ed with. The company has been very helpful to me; hopefully you will be equally lucky.

Except this is a Z-Spar mast.....So Selden can't help here.

Before you do any hammering, heating or use flame throwers, start with spraying some WD40 or similar for several days on ALL the parts, so outside the boom, inside the boom.
Try and see if you can distingish any ribbed area of the stainless pin. That is the side you have to start tapping on.

for the rest: as sailblue said.

[MalcolmP]

Before doing anything I would send photos and an email to Z spar UK then give them a call - they are always helpful

www.zsparsuk.com/#!contact-us/c1lmq

Don't think it will help with this issue but just found a useful z spar guide here: www.usspars.com/wp-content/uploads/PDF/OperationalManual2013.pdf  that might help on other issues

[sailbleu]

On y va ,

Wd40 does not help on/with aluoxide , unfortunately.
As you well know aluminium and stainless steel are simply not compatible , but destined to be together on a boat.
Brutal force or heat however can disturb their love/hate relationship.
And indeed , on the axis is a ribbed end that serves as a ...head. This to prevent the axis turning around in the supporting hole.

Regards

[On y va]

sailblue: I ment to clean it without the use of acid based fluids, which will destroy the anodisation. Not ment as lubrication. I should have mentioned that.

[vladis]

Hello,

Thank you for all the tips! I was able to remove the pin! I sprayed with WD40 one hour before using a medium (or heavy) hammer and a punch, but I think that the WD40 made litle difference. It was not necessary to use heat. As you say the pin has a ribbed end which corresponds to the side shown in the picture fn my first post. However I tapped on from the oposite side in relation to the picture. Once the small ribbed part was out, the rest came very easily. If I had tapped from the side shown in the picture, that ribbed portion of the pin had to go through 4 (or more?) walls before coming out.

I left here a picture of the pin (left) and of the in mast halyard swivel (right). Z-Spars UK (yes they are helping me) told me that a screw with a sleeve (a stopper to avoid the swivel to rotate inside the mast) is missing. I do not remmeber how that stopper looked like.



Kind Regards, Vladis

[On y va]

Vladis, now the pin is out: is the ribbed end wider/thicker than the actual pin diameter? Just for me to know.

[vladis]

On y va:

The pin diameter is 8,0mm except on the ribbed end where it measures 8,2mm. So this ribbed end should be the one to come out first!

Regards, Vladis

[Deleted]

Thanks all for the advice. I just had to replace my in boom sheaves and a few taps on the pin with a punch did the job. Otherwise I may not have had the guts to do it. In the end it was easy!

[bumsailor]

Hello, this is great information and thanks for the pictures. Just to be clear do you tap on the pin from the port side or the starboard side. Also where would you purchase a replacement sheave?Thank you so much

[bumsailor]

I just punched out the pin from the left side. All went well. 

[Mistroma]

Just for information, WD40 isn't a great penetrating agent. You can buy expensive specialist agents and they will out perform WD40 by a huge margin.

OR you can use diesel. It doesn't quite match up to be very best alternatives but is usually available for free on a boat. I have used diesel many times to help free up things on a variety of things (car, boat, tools). Well worth trying.

I usually apply a small amount at intervals a couple of days apart is time permits. It obviously works best if it can pool on a vertical surface. However, even a drop or two on the end of a cocktail stick can be a great help.

I remember reading a review of penetrating agents a very long time ago. I think bolts and pins were left in identical poor conditions and the tests averaged torque required to loosen nuts or force required to push out pins. WD40 was better than nothing but top end stuff was miles better. Diesel came out quite close to the expensive stuff. It is possible that there's now some magic cheap spray on the market.

[Mistroma]

Feb 11, 2015 13:56:23 GMT On y va said:

sailblue: I ment to clean it without the use of acid based fluids, which will destroy the anodisation. Not ment as lubrication. I should have mentioned that.

WD40 shouldn't be acidic. I seem to remember that it was about 60%-80% white spirit with small amounts of other hydrocarbons. Probably mostly alkanes with some cyclics and a very small amount of aromatics. Nothing there to damage anodising. I haven't checked recently manufactured WD40 and it might have changed formulation. I originally used it as a water dispersant rather than a penetrating agent.

[ohana]

I had actually found one of these stainless steel pins working loose on my boom last year. When I tapped it back into place, the teeth on the pin did not seem to bite well into the aluminium casting. In the end, I replaced all the boom sheave pins with the same dia stainless steel bolts, with plain shank over its length and only threaded end. I fitted these with nyloc nuts and trimmed the threaded length to make them as neat as possible. Perhaps overkill, but having seen one work loose, I had lost confidence with the original setup.

At the same time, I fitted some 0.25mm thick PTFE washers to either side of each sheave. I made these from PTFE sheet from EBAY, easy to cut! The idea was to allow the plastic sheave to run more freely, rather than binding and wearing on the rough aluminium surface. Hopefully also make the sheaves last longer!  These have worked really well.