Steel tyres on alloy rims

[Jon LawesParticipant @jonlawes51698]

I've just finished making the mild steel tyres which on the 2" Burrell I'm building will be riveted to the aluminium front wheel rims using iron rivets. This seems like a lot of dissimilar metals so I thought about using something like Upol etch primer on both surfaces before bringing them together.

Is this overkill or am I worrying about nothing? Is there a better product you can recommend?

Thanks,

Jon.

[Jon LawesParticipant @jonlawes51698]

[old martParticipant @oldmart]

When assembling aircraft parts, a compound was always used to seal the joints between housings and bushes, for instance. You could assemble your wheels using a coating of wet primer paint which will stop the ingress of water and damp. After assembly, just wipe off the excess with a solvent damped rag.

[Jon LawesParticipant @jonlawes51698]

Posted by old mart on 25/01/2022 12:04:57:

When assembling aircraft parts, a compound was always used to seal the joints between housings and bushes, for instance. You could assemble your wheels using a coating of wet primer paint which will stop the ingress of water and damp. After assembly, just wipe off the excess with a solvent damped rag.

Ah I remember it, I can't remember what it was officially called but I think we called it "goat sh*t".

Thanks, thats a good idea.

[old martParticipant @oldmart]

Wet primer was just one of the specifications, we also used JC5A, Mastinox and certain PRC products which would be difficult and expensive to get hold of.

[JasonBModerator @jasonb]

Not noticed any problems on my MJ Fowler after 10 years with the tyres or rear strakes, neither the spokes which are done with copper rivits. Same goes for the Minnie after 25yrs all bare metal contact but I don't expect either to be air worthy.

[Dave Smith 14Participant @davesmith14]

Duralac is the yellow conformal coating used to protect interfaying surfaces in a lot of Aerospace applications. The permanent joints on my tender and loco chassis are using it.

[old martParticipant @oldmart]

I wouldn't expect a precision model to be kept outdoors or in damp conditions, but it is easy to seal the joints when assembling and removes a littly worry.

[Jon LawesParticipant @jonlawes51698]

Thank you, I suspect I will be able to find a source. Duralac does ring a bell.

[vic francisParticipant @vicfrancis]

Fine advice from old mart! Precision models left outside , well I have seen a few suffer this sad fate; the damp shed… perhaps due to various unfortunate circumstances.I have a couple as well; it is the metalwork which needs thought, I wondered about plating , or lacquer coat. I have a gm showmans which had this fate of the damp shed… took alot to get it reasonable, but the metalwork has some staining / pitting … anyway a coat of lacquer, but what type ? Seen it flake badly in time. What do you chaps think?

keep the good work going Jon!

regards

vic

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Bob WorsleyParticipant @bobworsley31976]

I would have thought that using iron rivets into aluminium rims is the problem due to impact damage? Need a softer metal, copper or aluminium?

Bare copper and aluminium together isn't a good idea, just look at copper tags on aluminium chassis with a bit of damp, total disintegration, why tags are always tinned.

[JasonBModerator @jasonb]

For tyres and strakes the contrast of a copper rivit will show so steel/iron are usually used for those but a shallow 60deg CSK is best to avoid excess force to fill the CSK.

On the strakes which will be painted and need a full snap head forming then copper is the usual choice to avoid swelling the leg of the tee rings and what is suggested in the build articles for the Burrell, Minnie and Fowler A7 all of which have cast aluminium rims

As I said earlier my Minnie is not showing any problems after 25yrs of bare steel on aluminium with copper rivits

[Dave HalfordParticipant @davehalford22513]

Oddly back in the day I had an Aussie Ford Falcon Fairmont. It had composite wheels with alloy centres and steel rims without any issues, whereas Landrovers alloy door panels on steel frames would corrode where they touched.

[Nigel McBurney 1Participant @nigelmcburney1]

I would not worry about disimilar metals and corrosion you will possibly have more problems getting the rivet heads to look correct,use softer copper rivets which also may also require annealing, I cracked the cast alloy front rim on an Allchin trying to get decent rivets for the spokes,in the end turned the front rims from solid steel blanks,

[Bob Unitt 1Participant @bobunitt1]

I had a similar problem with a model cannon I made to live on the mantelpiece, people tend to pick it up to look at it and the steel components suffered badly from corrosion by sweaty fingers. I painted it over 10 years ago with Rustins Metal Lacquer, since when there's been no corrosion whatsoever.

[Tim StevensParticipant @timstevens64731]

The problem you are likely to face is 'electrolytic corrosion'. This involves two different metals in contact, and damp or wet conditions. This creates a feeble, but continuous, electric cell – and the more reactive* metal is corroded most. With iron and aluminium, the iron will rust a bit but the Aluminium will corrode to a white jelly of aluminium oxide. Separating the two metals will only help if there is NO contact – iron rivets in aluminium and you've no chance. Unless you live is Death Valley etc. Or you could completely cover the rivetted area with a permanent layer of insulator bonded on all over. Not easy.

If you use rivets of aluminium (ideally the same recipe as the rim) then you have a better chance, but the, steel spokes will then become the problem. Aluminium spokes will then help, and lift the area away from the main source of damp.

* yes, normally we think of aluminium pans etc as not reactive. This is because of a surface layer of impervious oxide which prevents the metal showing. Electricity will cut through this layer, and the corrosion starts in earnest.

And copper rivets, or brass, will be worse than steel ones – sorry!

Cheers, Tim

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