Does anyone have any experience with magnesium rims vs. aluminum ones? I am looking to purchase a set of Group IV gold rims and was wondering beside magnesium being lighter, what are the pros and cons? Back in the day magnesium wheels were prone to cracking and oxidation. Is that still the case? Any informative response is greatly appreciated.
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The advantage is as you state, lighter for lower unsprung weight. Are you purchasing a set of 40 year old magnesium rims or a new set from Marvic?
I apologize, but I don't know who is Marvic.
I was looking at the rims on Mr. Fiat. They have magnesium as well aluminum alloy Group IV wheels listed.
Please inform me as to Marvic.
Thank you in advance.
Thank you husker. I wonder if Mr. Fiat gets their wheels from Marvic.
I have read numerous posts that state sand gravity casted magnesium wheels are prone to cracking, and they are nearly impossible to repair. Alternatively, it is impossible for forged magnesium wheels to crack. The cost must be a large factor as to why manufacturers rarely do forged magnesium wheels anymore.
Having said that, any members experience cracking issues with new magnesium wheels which were casted as opposed to forged? Magnesium wheels are a huge investment, and I am trying to decide between functionality and price vs. originality. I am willing to fork up the money for magnesium rims, but not if they only last a few years.
Mr. Fiat gets the magnesium rims from Marvic and WAS getting the aluminum rims from ROIN in Italy. Marvic was only making a magnesium based wheel. There was demand for replacement mag rims for the vintage race crowd and Marvic stepped up. ROIN makes a number of different rim styles for multiple vintage cars. Search the web and see their sites.
And you can save yourself a huge mark-up by buying direct. Contact the two makers directly.
Thank you panterapatt. It is much appreciated.
If it were me, I would buy the ROIN rims. He can paint them any color you want. Running a wide magnesium-based rim on the street would not be my preference.
Magnesium rims will start to work harden after about ten years, eventually possibly resulting in cracking which, if it gets bad enough, will result in failure. This can be prevented by periodically checking the wheels for cracks (magafluxing does not work so Zyglow dye testing is required to do this), then annealing (stress-relieving) the wheels by baking and then slowly cooling them in a specific way. Cracks, if they are not too bad, can be welded but this takes finding an experience welder who can work with magnesium - good luck with that one. Corrosion is also a very bad problem if the finish on the wheel gets scratched (or if someone repainted the wheel without the required chromate primer to seal it) and moisture is allowed into the porous magnesium. Outgassing is an issue too, but too complex to get into here.
I know of at least one Pantera that was in a very serious crash because a corroded Campy failed.
In terms of durability, it seems to me that would depend on two factors. First, I would expect the mileage would have a bearing on it, and most of our cars are not daily drivers, so I would be surprised if the work hardening rate would not be commensurately low. Second, if a wheel is well maintained, and with any scratches being immediately re-sealed, the corrosion should be limited (although I inspect the hub area for corrosion whenever the wheels are off the car because that is a contact point on which I have observed it is not possible to maintain a perfect seal). In short, if your car is not a daily beater with bad curb rash, I would think you would be safe going for a lot longer than ten years without Zyglow testing and annealing - but this is just my personal opinion which is worth exactly what you are paying for it.
Mike Drew and Jack DeRyke have written about this quite comprehensively here and elsewhere, and I suggest looking that up. Or, if there is enough interest, I can re-post the information.
All this was also explained in the February 2018 POCA Newsletter which is available in the club archives for download.
I have purchased 2 sets of magnesium Group 4 wheels from Marvic, the wheels are a work of art and Marvic are wonderful people to deal with. The current US$/Euro FX rate would make them a bargain price too!
Note that Marvic only produces the rears in the Group 4 race version of 14" wide, they work well with the 345/35 PIrelli tire and fill the flares a little more than the 13" road version and those came originally with a spacer anyway.
I recently replied to a question on the e-mail regarding wheel weights,
10" 2 slot Campagnolo 19lbs
10" 10 spoke Marvic repro Campi 14lbs
13" 10 spoke OEM Campagnolo 16.5lbs
14" 10 spoke Marvic repro Campi 17lbs
Looks like Roin have added to their De Tomaso range, I don't have comparative weights for their aluminum wheels.
When I last communicated with Andrea Roin which was a few years ago:
1. prices are Euro 850,00 each front 10"x15" and Euro 950,00 each rear 13"x15".
2. I confirm wide 10" and 13" x 15" (as original)
3. The backspacing is fixed and measured front 115 mm and rear 135 mm
4. material used is aluminium 6082T6 in two pieces welded
5. Delivery time at today is about 5 weeks from confirm order
6. wheel are painted as original (nitro paint). You can choose color.
For further information please ask.
Best regards
Andrea Roin
RoinTechnology
info@rointechnology.it
www.rointechnology.com
Via Monte Comun, 35 37057 San Giovanni Lupatoto - VERONA - ITALY
Tel. +39-0458779288 - Fax +39-0459786925 - Mob. +39-3402735464
This is great information; thank you. I sent them an email and hopefully they will respond tomorrow. I will keep you posted.
Julian, this was news to me re: Roin Aluminum Campy Group 4 wheels - "material used is aluminium 6082T6 in two pieces welded".
Do you know if the Marvic wheels are also made in two pieces, welded together?
The Roin wheels were always a 2-piece welded rim. Just like most "custom" wheels that Foose and Boyd and Phil Schmidt make (made). When done, they are solid as a cast wheel. The Maric is a cast wheel per their website and the foundry they use. Roin also make a 3-piece design with split rims and a bolt-up center like the Gotti, BBS, etc. I see that Roin now make at 15" diameter 14" wide GP IV rim which is what I would buy and mate with the 10" front rim. I am thinking of moving in that direction and selling my Gotti's.
I received a response from Marvic today, so here is their most current pricing for their magnesium Gr4 rims:
Pantera Gr4 10"x15"...1,900 Euro each
Pantera Gr4 14"x15"...2,100 Euro each
Freight they say will be around 500 Euro for the set of 4 wheels to the U.S. with a 10 week delivery from purchase order. 30% up front at order, and the rest of the balance is due when wheels are ready and before shipment.
wowzaa! so about 9 grand for wheels. Tires are another 2.5. Mounting them (very carefully) and balance. $12K.
Question, do these need longer wheel studs than normal. I had been "told" the real Campy GP IV rims needed to have a longer stud installed. Was never able to confirm this with those that own them. Julian would know for certain.
Did you contact Roin to get updated prices?
The Group 4, GT5/5S cars have longer wheel studs to accommodate the 10 spoke magnesium wheels.
$2.5K for tires? At what discount store? $3.6K for all 4 corners is much more accurate as of a few days ago. Pirelli P Zero 345/34/15 in the rear and Pirelli Centurato P7 285/40/15 in the front. Not to mention the fronts are nearly impossible to find.
I have contacted Roin twice and have not heard back yet. Sent an email as well and am waiting for a response.
