Saving Old Seagulls

In an answer to another topic on this Forum, John wondered why British Seagull never used stainless steel fasteners on their engines.

When I was a lad, I had a mentor who was a motorbike-racer.
He was always trying to save on weight, and made numerous parts for his bikes in aluminium. As he was convinced a sleek surface was faster than a rough one, he polished everything to a near-mirror finish.
Everything... except for the odd rusty nut here and there.

I wondered why he didn't replace these with Stainless Steel ones, so I asked him and got a lecture in return, from which I only remember that it has something to do with heat. Stainless steel would have a tendency to seize when heated and should therefor never be used on parts that get hot.
(well, that's what I think he said)

Is there anyone on this Forum that can confirm this?


As for the "710-cans", mentioned in the Subject-line:

Did you know the dairy department offers a great 2-stroke gadget?

After finishing a healthy yogi-drink,
one is left with a tiny plastic 100 ml can, with screw top,
that is a perfect gauge for mixing 10 : 1
Simply use one can of OIL for each litre of petrol !

Fact. Some grades of stainless steel are prone to siezing when mated with the same material. For this reason, stainless fasteners are made to different standards than other fasteners. However, the fasteners which normally give trouble in Seagulls are not stainless in stainless, the female thread is either cast-iron or aluminium alloy so the problem should not arise. I am putting my money where my mouth is and replacing the 1/4 BSF bolts in the gearbox assembly with stainless steel.

David

Dont forget to use Duralac on the threads. Stainless steel in Aluminium *ABOVE* the waterline is bad enough if nothhing has been used on the threads,, and under water its ten times worse. Also most grades of stainless are not really suitable for underwater use, so dont leave your engine in if not in use.

Stainless is spelt STAIN LESS, not RUST PROOF

Oddly enough, zinc plated fasteners are actually better in Aluminium FOR AS LONG AS THE PLATING LASTS than stainless.

I like Hermetite red non setting gasket compound on the threads of all steel fasteners on the Seagull known to give trouble, to seal and protect the thread and keep the water out.

Let us know how it works out after a season or so.

Not to forget: electrolysis.

This phenomenon occurs where two different metals are in contact under water.
A small electric currect will flow, destroying the 'lesser' element.

On ships a ZINC anode if often used to deal with this problem.
The idea is that this 'lowest' metal is given up to protect the more 'noble' metals.

The use of galvanized mild steel bolts could have to do with this, since a layer of zinc is applied by the galvanizing.
When these bolts start to rust, it is a clear sign that the zinc has gone . . .

Is there any risk that Stainless Steel fasteners will reduce the life of the aluminium gear housing, due to electrolysis?

Hello Malcolm,

you are so right about Stainless! however I am looking at a range of S/S nuts and bolts etc to replace most if not all the mild steel ones on the Seagull. I have experimented and found they resist the use I give them and come apart easily, but I do coat them in a lithium grease.

what would you recommend?

I was also hoping to have a S/S combi spanner.... What do you think?

all the best,
john
SOS

Well the 'gold' standard anti-corrosion compound for riggers working with stainless fittings and fastenings on Aluminium masts has been Duralac for a *very* long time.

http://www.llewellyn-ryland.co.uk/duralac.html

*ANY* decent chandler stocks it.
A tube will last an average user who does their own maintenance a verl long time.

I dont suppose you want to get involved in repacking it in 5 ml sachets like computer heatsink compound or chipshop ketchup but it might be worth asking the manufacturer if it is possible to get it packed that way.

Make a nice little kit, e.g. - Set of Stainless Steel Seagull crankcase bolts, locknuts and Duralac anti-coorrosion compound.


Lanocote from Davey & Co has also got a good reputation and is more or less a grease so is more suitable for fastenings that need to be undone frequently. Unfortunately its *much* harder to get over the counter. Again a little goes a long way.

There have been independant studies done in America by a cycle firm on the best lubricants for preventing Stainless threads galling, but IIRC they were in air not immersed in salt water which makes a MAJOR difference. I cant find the results right now It might be an idea to supply stainless bolts and bronze nuts as that combination is superior for thread life. Do warn your customers NEVER to assemble stainless threads 'dry'.

Found them but their site is down at the moment.
http://www.sandsmachine.com/grease_t.htm

You can read the test of the page at
http://web.archive.org/web/200503051524 ... ease_t.htm
but there are no pictures. Worth a look though.

Well done Ian,

I thought I could rely on you to have that sort of info at your fingertips! I like the idea of making up sets for owners, good idea.

I am still sorting and collecting samples, have just realised the top of the crank washer, mild steel, has rocketed in price, over £5.00 for one, it's just a washer! Like to do that in S/S too!

More when i get them sorted.

thanks again,
Regards,
john
SOS