Restoring Magnesium Cromodora 13x6Js

[ecoangel]

Hi I am looking inot restoration process for these wheels. being magnesium based they need some special care - oven 190 deg C for 2 hrs whenever fully stripped, machined or welded. Apparently this also purges any gases inside porous wheels. Maserati ones have been known to take 12 stagees to restore.

Anyone know the zinc content of these alloys? Modern Mag wheels seem to have less actual magnesium than older ones. Many alloy wheel refurb shops won't touch them. Powder coating doesn't always work. Welding can be difficult etc.

Counter weights need to be stuck on rather than metal clip variety on rims edges otherwize removal can take a lot of the wheel rim along with the counter weight when fitting new tyres!

Looks like Zinc Chromate primer (painted or plated?) a la aircraft industry was used to keep them from corroding away from new.

Anyone had any experience in restoring these wheels sucessfully?

[william]

As a technician in the airline industry where most aircraft wheels are magnesium I can state that the wheels should only be gritblasted with soft grit like crushed cherry pit or wallnutshels. In this case you leave the basic material intact. For painting after stripping the aircraft paint manufacturers like AKZO Nobel aerospace suggest only epoxy primer to be used on magnesium. The chromate primers effectively used on aluminium parts should be avoided as they are to agressive to the old metal. I would avoid welding if possible and try to blend any course irregularities in order to reduce the risk of cracking. In any case, do not ask the same performance and reliability from old magnesium wheels as you can from modern new ally wheels.

[ecoangel]

Thanks William

Do you know what kind of epoxy primer is used? Is it sprayed on?

[bart]

In the pittoresque village of Queenborough, at the mouth of the Thames, is a small company that specialises in fabrication of magnesium wheels. They might have some useful info. Queenborough also has a rather ancient looking foundry where we saw a couple of type 57 Bugatti engine blocks in a corner of their garden! On asking, they said that, apart from several types of bugatti reproductions, they make all sorts of castings ranging from racing engines to litter bins! How unexpected!

The wheels man:
UK Racing Castings - Magnesium Wheels
Units 1-2 Thorndale Business Park, Argent Rd, Queenborough, Kent, ME11 5JP, UK
Tel: +44 (0) 1795 585454 Fax: +44 (0) 1795 585488
Cast magnesium wheels
Email: Alistair@uk-racing-castings.co.uk

[Huib]

Very interesting.

[ecoangel]

Sorry restoring wheels is not really our thing
You would be better going to specialist companies for wheel refurbish/restoration
Regards
Alistair Clinton
UK Racing Castings - Sand Casting Magnesium & Aluminium Alloys
Units 1-2 Thorndale Bus. Park, Argent Rd, Queenborough, Kent ME11 5JP
Telephone 01795 585454 Fax 01795 585488
Web: www.uk-racing-castings.co.ukHuib wrote:
>
> Very interesting.

[john]

which are more reliable ? the bins or the motors ?