Shear pins for outboard - DIY ?

[sarabande]

I am down to my last spare shear pin for Mariner 3.3 2str.


With ebay selling ONE pin for nearly a fiver, I am tempted to pickup a piece of rod and make a few of my own. The pins appear to be aluminium.


Does anyone know what spec of UTS / fracture point I should be looking for please ? Diameter is 3mm but other info very welcome.

If I make a dozen or so, there will be some spares going (for postage only )

 

[Binman]

Could you explain what they are and what they are used for,I proberly know them under a different term,Thanks

 

[sarabande]

metal pin which holds the propeller to the drive unit, and which snaps as a safety feature if you ground the prop too quickly (or try to do a fast-running start, as I found out )

 

[VicS]

Could you explain what they are and what they are used for,I proberly know them under a different term,Thanks

listed as "pin, shear" if you have a Honda

 

[JVL]

I am down to my last spare shear pin for Mariner 3.3 2str.


With ebay selling ONE pin for nearly a fiver, I am tempted to pickup a piece of rod and make a few of my own. The pins appear to be aluminium.


Does anyone know what spec of UTS / fracture point I should be looking for please ? Diameter is 3mm but other info very welcome.

If I make a dozen or so, there will be some spares going (for postage only )

Fencing wire not HT , there the secrets out!!

John

 

[NormanS]

I made mine from bronze welding rod.

 

[Heckler]

I am down to my last spare shear pin for Mariner 3.3 2str.


With ebay selling ONE pin for nearly a fiver, I am tempted to pickup a piece of rod and make a few of my own. The pins appear to be aluminium.


Does anyone know what spec of UTS / fracture point I should be looking for please ? Diameter is 3mm but other info very welcome.

If I make a dozen or so, there will be some spares going (for postage only )

IIRC they were originally brass, then they started using steel. I used a 4mm bolt as a stopgap till I got some new ones. They look like stainless to me!
Stu

 

[thinwater]

I cut a stack from brass rod. Seemed to sheer just about the same. As you say, cheap.

 

[vyv_cox]

A very long time ago when I had regular access to a scanning electron microscope I analysed one and found it to be copper-nickel. I was using copper-nickel brazing rods of about the same diameter at the time, so I cut a few out of one. Seemed to work OK.

 

[macd]

A very long time ago when I had regular access to a scanning electron microscope...

Now that's pretty classy name-dropping, Vyv. You don't get many of them at Toolstation

 

[JumbleDuck]

Now that's pretty classy name-dropping, Vyv. You don't get many of them at Toolstation

Years ago a posh school was trying to recruit me as a physics teacher and I was given a tour round the place. "We won't go in there" said the head of physics "because we'd disturb some sixth formers who are using our electron microscope". Ah, the joys of the private sector.

 

[RichardS]

Could you explain what they are and what they are used for,I proberly know them under a different term,Thanks

You might not have one at all. As from 2014 Suzuki no longer fit them to the DF2.5s. It's one of the reasons I bought it, albeit not a deal-breaker.

Richard

 

[reeac]

Years ago I sheared one by engaging gear at a fast idle and the chandlers had a choice of strong ones (s.s?) or weaker ones. Seemed a pity that the customer had to choose. I went for the strong one.

 

[lw395]

I once made one from a brass woodscrew taken from the soleboards of the boat I was sat in, while moored in the middle of a harbour.
Always carry a spare!
Brass rod seems OK.
Ali might corrode to the stainless shaft, if you manage a couple of seasons without a breakage.

 

[vyv_cox]

Now that's pretty classy name-dropping, Vyv. You don't get many of them at Toolstation

In 1977 when I first used one they were pretty rare and highly temperamental. Nowadays they are far more common, and reliable. Very many engineering manufacturers have one, or easy access to one.

 

[C08]

I replaced a Tohatsu 3.5 shear pin recently-£2.20 and it was about 3mm. You could probably source one fro a different manufacturer that would be ok. There is lots of rod material that would fit and would only cost pence to make but as you infer the problem is having something that is not too strong and is going to shear correctly and protect the lower leg mechanism.

 

[BobnLesley]

As others, we use (Mercury 3.3) 1" lengths of 4mm brass machine screw - I bought a bag of 100+ at a jumble somewhere for about £2.50 - which I reckon are slightly softer/weaker than the genuine article. I tend to be extra careful about being at tick-over when I engage gear and have a bag of 3 or 4 spares in the toolkit; it works for us and I'm sure I've got enough to outlast the engine.

 

[charles_reed]

IIRC they were originally brass, then they started using steel. I used a 4mm bolt as a stopgap till I got some new ones. They look like stainless to me!
Stu

Original Tohatsu are bronze, Mercury are stainless.
I prefer the Mercury, they're a little less fragile.
I have used a "modified" split pin on one occasion.
I'd not consider normal steel as that would rust.
If you're too aggressive with the shear value, the prop goes, that's much more expensive.
Haven't needed one in the last 5 years - I bought Tohatsu ones from Fairweather Marine for under £1 each on the last occasion.

 

[rob2]

IIRC the brass (or bronze) ones are intended for use with plastic props whereas the stainless ones are used with the ali props - on a Tohatsu, anyway, and that's the base engine. I've ben fortunate enough never to break one, but a friend did regularly and usedbrass rod which lasted as well as OEM parts.

Rob.

 

[KINGFISHER 9]

I thought I'd check in advance of any problems and maybe order a spare only to find that my 4hp Yamaha hasn't got one ... some sort of rubber device instead.