Magnesium

[211]

Hi All
would be really interested in what the opinions are on magnesium and its end of life. Eventually we are going to have to recognise that a lot of hubs (for example) are made of the metal will / have reached their end date and decide how we account for it - or be flexable in accepting the issues and find a solution. That may be to allow some lattitude on hubs - I dont know, but Im interested to start a conversation on the subject.
My point I guess is in light of not being able to ride my 74 KX because the sprocket carrier is cracked and the bikes had a reputation even back in the 70s of the brake backing plate breaking and trying to kill you. Maico is another example.
 :)Please - keep it constructive
DT

[Nathan S]

Are there any brands that don't have a viable alloy hub option from the same racing era?

[davidmc]

Early Magnesium Road Racing ( Light wieght Campagnolo ) wheels were only used for 2 Seasons by Factory Teams in the 70's,
Castings and Technologies have improved heaps since then and a lot about the life of was unknown at that time, hence precautions!
 In the early days most of the casting for the really thin lightwieght stuff was done in Italy where the sand and envoiromental conditions were favourable.
It took quite a while for Japan to make their own Racing Mags.
For sure Magnesium can be very porous and can erode.
As for the life, its case by case, how long is a piece of string?

[KTM47]

As I have said previously, Look at the Historic Road Race rules. 

They had recognised this problem a long time ago and permit replica parts to be approved.

The key to it is be approved, there would need to be a list of approved parts.

You may not be able to get an exact replica.  Machining a hub from billet alloy would be cheaper and probably stronger than a casting.  Castings are only viable if there is a reasonable number made.

I have proposed the above in my response I will send to MA RE the rules.

Kevin

[William Doe]

Dave I am in the same position re the 74 KX hubs , I don't have a solution as yet . Was going to look at getting a price to CNC a sprocket carrier and backing front backing plate . Cost for single items will probably make it non viable but will look into it .

 

[JohnnyO]

God the last thing I want is to have my KX's knocked back at scrutineering because they have magnesium hubs, bloody hell drop the subject and maybe raise it if some hubs start breaking!

It's more about allowing billet alloy backing plates and some alternate hubs to be legal as a safety issue..
Don't get excited It says nothing about banning magnesium does it?

[John Orchard]

God the last thing I want is to have my KX's knocked back at scrutineering because they have magnesium hubs, bloody hell drop the subject and maybe raise it if some hubs start breaking!

It's more about allowing billet alloy backing plates and some alternate hubs to be legal as a safety issue..
Don't get excited It says nothing about banning magnesium does it?

Cool, just reading between the lines.  Kinda always on the defensive  ;-)

[211]

Please !
its not about banning the parts its about alternatives.
I have fitted a 75 KX front wheel to my 74 KX as its an alloy pressure casting and a good part although the brakes are still crap. Im the first to admit it isnt legal to use hence its a garage queen and something Im not used to having. I have the same problem with the KX450 and ATM im looking at F11 hubs to see if that fits including the 74 sproket mount - Bill if you have an F11  a measure would be handy.
I spent some time restoring a 74 YZ250 and in the course of selecting a rear wheel to use I dropped it and the hub smashed into 10 parts - I guess this is the point.
The RR stuff is same problem but presents a lot more serious problem for them; Im just looking 2-5 years hence when we will have to decide how to keep old bikes still on the tracks.
DT

[SON]

COMMON SENSE ISN'T THAT COMMON

[bazza]

Didn't Rob Tumes go down in a heap at Mt Kembla Nats when front hub fell apart on his KX ? think he went to ts185 front hub, but not sure.

[oldfart]

Dave - Bill ,     I think Bazza is right - swap the front and rears out for TS 185.
 

[Nathan S]

So:
74 KXes can use TS185 hubs (and brake plates?);
YZ-As can use MX-A parts.

What other bikes have magnesium hubs?

CZs run them, but don't have a problem?

[pokey]

Shhh stew.  don't tell everyone how light and strong the front 185 hubs are even though they are bigger than TM125.

 Lace them to a decent ally rim and you have something that brakes okay with a lot less weight. I really don't know why Suzuki didn't use that hub on more  models.

[JohnnyO]

Many magnesium Maico front backing plates have failed sending the rider over the bars. That's why you see so many billet alloy ones about...

[tony27]

So:
74 KXes can use TS185 hubs (and brake plates?);
YZ-As can use MX-A parts.

What other bikes have magnesium hubs?

CZs run them, but don't have a problem?

CZs run a different magnesium alloy than Japanese bikes but it doesn't stop them having issues, I've seen photos of completely white hubs that have snapped in places.
There is a company in the England that makes replica hubs in LM25 aluminum alloy specifically for the owners of british thumpers running CZ wheels & forks, new hubs are also available from a supplier in Poland who may be getting them made by the original makers in the Czech republic
Never seen an issue with the front back plates which are also magnesium