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JackF

Magnesium wheels, Do they become brittle with age

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I was talking with the fellow who bought the Turbo some time ago and he is putting different wheels on the car. It had the Campy mags. He said that the magnesium wheels get brittle over time. Is that correct? He is changing wheels so he can get some good rubber under it, as the 13" performance tires are limited. 

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I don't believe they do but corrosion on the inside is a major concern. I've ran magnesium alloy wheels from the 60's on various Hot Rods with no problems, 1 set were 12 spokes which have 1" wide spokes & are spindle mounted, no problem, also my Anglia Gasser drag car I owned had 60's Halibrand wheels & I was doing wheel stands , wheels 3 feet in the air with no problems, engine was a 300 cu in GMC straight 6 , a very heavy lump .

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Magnesium rims, at least those cast solely or largely from magnesium, get brittle with age.  Those Campys on your turbo, however, were made of Elektron, which is a magnesium alloy.  The alloy form mitigates many of the...disadvantages...of magnesium, like bursting into flames, casting inconsistencies (voids or potential fissures created during the initial casting), and material decomposition over time (the brittleness as well as pitting).

 

Indeed, pure magnesium racing rims have a history of failures and it is recommended that magnesium rims used in racing be magnafluxed and/or x-rayed regularly to detect pending failures in the rims.

 

Campy's and other modern alloyed magnesium rims?  I've never heard any specific failure stories related to them -- but there might be stories, I just haven't heard them.  I was very cautious restoring my Campys, avoiding powder coating, the 300-degree+ heat of which is supposed to compromise magnesium alloy rims.  But I've met LOTS of owners who have had their Campys powder coated, and still no stories of failures.

 

So, my opinion is that Campys in good condition -- no cracks or bends -- would be entirely safe on a factory turbo.  But I'll also admit that I would probably not use them for racing.  Why not?  Just cause.

 

Lots of rim shops -- including long-established rim shops -- will not TOUCH a magnesium alloy rim, they treat them -- rightfully or wrongly -- as if they were cast of pure magnesium.

 

Regards,

 

Steve

 

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Edited by Conserv

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Dah, Steve beat me to it.

 

Magnesium's so reactive...  it makes aluminum look stable!

 

Old magnesium racing wheels DO have a history of failing.

But they were also cast in an era where casting was done

by lots of places, of varying quality and experience, and

meant for a racing season at most. 

 

A friend has a very old magnesium Alfa turbine rim 

with a hub that looks like swiss cheese.

 

Were Campangolos modern wheels?  I dunno.  I haven't heard of any failures either,

but I have never seen any on the track!

 

t

 

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