The magneto back plate of the Maytag is made of some breed of what I believe the Americans call 'pot metal' (or worse) and is beginning to exhibit some of the self-destructive properties of that material. Is there anything which can be done to stabilise the alloy and prevent the condition from progressing?
Sadly if its Mazak or similar then no. Once the crystal growth has started the end is inevitable.
regards Roland Denied a days fishing by very heavy overnight rain - all rivers bank-high :-(
If it's pre-Zamak (early '30s) then AFAIK there is _nothing_ that can be done to stabilise it 8-( The problem is intergranular precipitation of iron impurities in the original alloy. Later alloys (Zamak, or Mazak in the UK) switched to newer forms of high-purity zinc to avoid this.
The diecast model crowd have an opinion that low-temperature storage can slow this process down, but there's no evidence that this has the slightest effect.
All I can sugget is to take mouldings of it in silicone now, so that you can produce another one.
"Andy Dingley" wrote:-
Hmm. The Maytag 72 wasn't introduced until the late 30's and I'm pretty sure mine is a post war example so hopefully the material should be ok. Maybe what I am seeing is just surface corrosion, I must admit there is none of the swelling or distortion one usually associates with this process.
Surely Roland,
Having a high river bank should be to your advantage, the fish are nearer and not so far to dip your hook :-))
Martin P
Hi Nick,
I don't mean this to be a plug for my website but the following page may be of use, specifically focused on the Fowler parts which are made of the same, rotten material!!
I vaguely recall seeing a short article where the offending article had been stripped, cleaned in acetone, dried, gently heated & coated with twin pack epoxy. The metal was porous enough to absorb a fair amount of it and whilst not a complete cure, it certainly slowed down the deterioration and beefed up the remaining metal.
It will amuse you all to know that Phil Irving (he designed the post war Vincent engines) called the zinc alloy from which Amal carbs were made as " ... the mechanical equivalent of chocolate fudge" !
Regards,
Kim Siddorn.
These two websites should give you most of the info you need to date and overhaul your Maytag 72. I found them usefull for my Maytag 92. Apologises if you already have this info as I am fairly new to this site.
Andy M
John Ambler Sussex, UK Return E-mails to snipped-for-privacy@skiprat.net
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