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#617845 - 10/19/09 06:53 PM
Magnesium Wheels?
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Jedi Trainee
Registered: 01/03/03
Posts: 338
Loc: Chesapeake, VA U.S.A.
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I have a set of vintage American Racing Specter wheels I bought on eBay a few years ago. They are 13x5.5, prpoer PCD and offset and will look great on my GT6. The wheels seem to be in pretty good shape except they need polishing, but I have some concerns. I was reading on a different board that concentrates on racing topics not long ago and a poster I consider an "expert" said that old magnesium wheels should not be used. (They were discussing some vintage mini-lights)
I'm not sure my wheels are magnesium, but I think they might be - they are extemely light and they have been coated on the inside of the rims with "goop" to seal them. (I have read that magnesium is porous and tends to leak air)
This leaves me with a couple of questions:
How can I tell if these wheels are really magnesium or if they are aluminium?
If they are magnesium, are they safe for street use or for autocrossing?
Thanks,
Tony
_________________________
Tony Etienne
'72 GT6Mk3
The answer to the Ultimate Question...' 'Of Life, the Universe and Everything...' said Deep Thought. 'Is...' said Deep Thought, and paused. 'Is...' 'Forty-two,' said Deep Thought, with infinite majesty and calm.
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#617947 - 10/20/09 08:27 AM
Re: Magnesium Wheels?
[Re: tomshobby]
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Jedi Trainee
Registered: 02/02/04
Posts: 282
Loc: Rochester, Minnesota
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If they are Magnesium I have seen them sell for a lot of money. I thought the racers liked them because of that. But this was something I heard years ago and maybe they don't allow them anymore.
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#617956 - 10/20/09 09:29 AM
Re: Magnesium Wheels?
[Re: tomgt6]
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Jedi Knight
Registered: 05/20/02
Posts: 892
Loc: Richmond,Texas
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Magnesium wheels have pores, and corrode easily. Moisture gets into the pores and starts the rot, which can spread inside and be totally invisible externally. It's also pretty hard to detect, or rather, it's hard to test wheels and be certain they don't have issues.
So don't use old mag wheels except on a display-only car, and certainly not any genuine old Minilites. In any case, modern aluminium alloys are a lot better than back in the 60s.
_________________________
Roger
Ancient Briton
'72 Lotus Europa
'05 Lotus Elise
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#617985 - 10/20/09 11:54 AM
Re: Magnesium Wheels?
[Re: poolboy]
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Jedi Warrior
Registered: 09/23/05
Posts: 794
Loc: port coquitlam,b.c.,canada
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you might find this site helpful: http://www.roadsters.com/wheels/Rob
_________________________
"what's this bill on the mastercard!!!!!"
"ok, what did you buy now!"
"you need to stop buying stuff on e-bay!!!!!"
from
"she who must be obeyed"
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#618048 - 10/20/09 06:15 PM
Re: Magnesium Wheels?
[Re: UltimateQuestion]
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Silver Member
Obi Wan
Registered: 08/02/06
Posts: 2174
Loc: Downingtown, PA, USA
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I have a set of vintage American Racing Specter wheels I bought on eBay a few years ago. They are 13x5.5, prpoer PCD and offset and will look great on my GT6. The wheels seem to be in pretty good shape except they need polishing, but I have some concerns. I was reading on a different board that concentrates on racing topics not long ago and a poster I consider an "expert" said that old magnesium wheels should not be used. (They were discussing some vintage mini-lights)
I'm not sure my wheels are magnesium, but I think they might be - they are extemely light and they have been coated on the inside of the rims with "goop" to seal them. (I have read that magnesium is porous and tends to leak air)
This leaves me with a couple of questions:
How can I tell if these wheels are really magnesium or if they are aluminium?
If they are magnesium, are they safe for street use or for autocrossing?
Thanks,
Tony Tony This thread may help! American Racing Silverstones
_________________________
Frank J. Angelini
Downingtown, PA
TR3A TS58476LO The Grey Lady(currently being restored)
TR250 CD1510LO
A conference is a gathering of important people who individually can't do anything but together can decide that nothing can be done.
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#618094 - 10/20/09 09:58 PM
Re: Magnesium Wheels?
[Re: Brosky]
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Silver Member
Jedi Warrior
Registered: 08/16/07
Posts: 778
Loc: Minneapolis, MN, USA
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Aluminum burns too. It shares many properties with magnesium. It takes more heat to get it going, however.
After the 1989 Oakland, CA firestorm, I had the opportunity to go up into the hills to see what was left. Automobiles were pretty interesting. ALL that was left was steel! Rubber, plastic, glass, paint -- and cast aluminum wheels: all gone. The cars that had steel wheels were still sitting on 'em. The cars with alloys were sitting on the ground!
_________________________
Speak softly and wear a loud shirt 1959 TR3A TS51006L: Wintering in the body shop, where what that fool done to me can be undone. www.moseso.com
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#618138 - 10/21/09 05:59 AM
Re: Magnesium Wheels?
[Re: Moseso]
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Jedi Trainee
Registered: 09/01/06
Posts: 306
Loc: Maryland, USA
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You'll find a lot more information on magnesium wheels in aircraft maintenance articles and such than in automotive ones. They are more common there.
Highly corrosive, subject to fatigue fracturs, sensitive to cleaning methods, etc. Personally, if I had a set of genuine old magnesium wheels, I'd sell them to someone who really wants them, and buy new(er) aluminum wheels.
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#618216 - 10/21/09 11:36 AM
Re: Magnesium Wheels?
[Re: foxtrapper]
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Jedi Trainee
Registered: 02/23/07
Posts: 239
Loc: Germany, Saarbruecken
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I never heard that magnesia wheels do burn. They are not pure magnesia just a fragment of the wheel is magnesia, the rest is aluminum. Cheers Chris 
_________________________
To boldly go, where no man has gone before.... 
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#618335 - 10/21/09 06:02 PM
Re: Magnesium Wheels?
[Re: MadMarx]
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Silver Member
Darth Vader
Registered: 04/28/06
Posts: 2862
Loc: Windsor, Wisconsin
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I never heard that magnesia wheels do burn. They are not pure magnesia just a fragment of the wheel is magnesia, the rest is aluminum. Cheers Chris The American Racing magnesium wheels were all magnesium.
_________________________
Tom
76 TR6
74 RWA Midget
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#618457 - 10/22/09 04:06 AM
Re: Magnesium Wheels?
[Re: tomshobby]
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Jedi Trainee
Registered: 02/23/07
Posts: 239
Loc: Germany, Saarbruecken
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The American Racing magnesium wheels were all magnesium.
Pure magnesium wouldn't work because the yield strength of this stuff in pure is not strong enough. Only the combination as an alloy create the needed strength. If an aluminum wheel would weight 6 kg an pure magnesium wheel would have 4 kg. But if you alloy aluminum with magnesium you get a lot better metal and can redesign the wheel to get also a 4 kg wheel with aluminum. There are several technical usable alloys with Mg: Mg-Al-, Mg-Mn-, Mg-Si-, Mg-Zn- and Mg-Al-Zn. MG-Si is used for crank housings or gearboxes. Unfortunately they get brittle after some years of use. A common Porsche problem with cars of the 70ties. Cheers Chris
_________________________
To boldly go, where no man has gone before....
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#618535 - 10/22/09 01:24 PM
Re: Magnesium Wheels?
[Re: UltimateQuestion]
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Bronze Member
Jedi Trainee
Registered: 09/22/05
Posts: 200
Loc: Laguna Beach, Ca
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I restored a set of Americans Alloy wheels. I presume they are "Mag" wheels. First thing I did was to make sure the wheels were true. Then I had steel inserts installed to "index" the lug nut holes. You have to make sure the lug nuts holes are round and not oval. These wheels are "lug-centric". If the lug nut holes have been pounded out of shape, then the wheel will run out of center. Then I had the rims machine polished. Then I painted the rest of the wheel. I have had these rims on my car for over a year, 2000 miles. No problem. If you want, I can email you some pictures. richards  hollywoodcenter.com [img:center]  http://[/img] [img][IMG] http://i140.photobucket.com/albums/r10/RMSTR6/IMG_0505.jpg[/img][/img] [img:center]  [/img]
Edited by richards (10/22/09 01:35 PM)
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#618546 - 10/22/09 02:02 PM
Re: Magnesium Wheels?
[Re: MadMarx]
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Silver Member
Darth Vader
Registered: 04/28/06
Posts: 2862
Loc: Windsor, Wisconsin
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The American Racing magnesium wheels were all magnesium.
Pure magnesium wouldn't work because the yield strength of this stuff in pure is not strong enough. Only the combination as an alloy create the needed strength. If an aluminum wheel would weight 6 kg an pure magnesium wheel would have 4 kg. But if you alloy aluminum with magnesium you get a lot better metal and can redesign the wheel to get also a 4 kg wheel with aluminum. There are several technical usable alloys with Mg: Mg-Al-, Mg-Mn-, Mg-Si-, Mg-Zn- and Mg-Al-Zn. MG-Si is used for crank housings or gearboxes. Unfortunately they get brittle after some years of use. A common Porsche problem with cars of the 70ties. Cheers Chris That is true and also that aluminum wheels are alloys of aluminum. I was referring to the fact that they are one piece construction and not with separate spokes and rims.
_________________________
Tom
76 TR6
74 RWA Midget
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