Clevis Pins Stuck in Masthead

[CloudDiver]

I remove the masthead for my C-22 to clean things up an have a closer inspection of standing rigging condition (most of it will probably get replaced).

The clevis pins for the sheaves came out with no issues, but the pins for the forestay and backstay are both stuck fast with bimetal corrosion. I sprayed a little PB blaster and let it sit for awhile but they still aren't backing out with a punch and mallet. I don't want to hammer on it very hard because breaking the casting will be $150 to replace.

Two further steps I could take, I can submerse the whole casting in a bucket of Aluma Prep (an acidic cleaner for welding aluminum) which will dissolve the corrosion residue. I can also heat the casting around the pins so a little expansion might give enough wiggle room to back out the pins.

Last resort, because drilling stainless is a PITA, drill press.

If anyone has any suggestions other than what I mentioned above please let me know. I'm in no rush and don't want to do more harm than good.

 

[Jackdaw]

Heat, PB Blaster, repeat.

Hit it with PB while it is still warm and expanded. Repeated cycles might loosen it. PB Blaster has a relatively high flashpoint.

 

[Ken Cross]

I don't think I would consider the acid as an option. It will mess with all your metal surfaces.

I agree with Jackdaw.
Ken

 

[shemandr]

I loosened some set screws in a bow rail with repeated application of PB. It took a while but it worked.

 

[Joe]

As Jackdaw said....... heat.... I used a butane torch for exactly the same purpose. Clevis pins in the aluminum mast head had frozen into place.

 

[Rick Webb]

Dry Ice

Heat the casting and then apply (wearing gloves, but you of course knew that) a piece of dry ice to the pin.

When I was a munitions guy in the Air Force we had some pins that we sprayed with Freon to shrink and the friction from the expansion was all that held them in. Don't think you can get away with Freon in a spray can any longer. Worked great on beer too.

 

[caguy]

I agree with the butane heat and pb blaster however when you do get them to move by hitting them with a hammer look at the pins carefully before they go into the hole completely. They may have mushed and will be more difficult to get the expanded end to pass through. I had to file mine down before finally driving them through with a punch.
Good luck.

 

[CloudDiver]

Too late... I see they are mushed a little because of the cotter pin hole basically making a weak area. Its ok, I wasn't trying to hammer them through yet. Tapping on the head to go the other direction I got some movement so the PB blaster is working. Will let soak in more PB blaster then file down the mushed end tomorrow, they should come out.

Thanks for all the suggestions to all.

I agree with the butane heat and pb blaster however when you do get them to move by hitting them with a hammer look at the pins carefully before they go into the hole completely. They may have mushed and will be more difficult to get the expanded end to pass through. I had to file mine down before finally driving them through with a punch.
Good luck.