sand casted old magnesium wheels safe?

For the guys with old magnesium wheels, I was browsing internet for old magnesium wheels and came across this... pictures of old magnesium wheels after they had been media blasted... notice the corrosion is revealed AFTER paint is stripped... Im not sure corrosion on magnesium wheels are 100% repairable as sand casted magnesium wheels are just not suitable for wheels. As a precaution, dont run those old magnesium wheels at high speed! Stay safe.

Yikes

From a metallurgical/engineering standpoint, Magnesium has a very finite lifespan, not only taking into account corrosion but fatigue (be it thermal or frequency) cracking. Auto wheels are not pure Magnesium, but a magnesium alloy. This (with the proper applicaion of corrosion inhibitors, chromate process, etc) can all but eliminate the corrosion aspect. But you still have the other aspects of them being brittle, and their tendency to store stress from impact (on a molecular level) and fatigue cracks. This is one reason why it's recommended to NOT powder coat these wheels, the coating is so thick and resilient it will hide cracks until a massive structural failure occurs.

 

For what it's worth, if I remember correctly BBS only gives a two year working lifespan on their Magnesium wheels, most of which aren't even offered for sale any longer outside of the dedicated track use stuff.

 

If it's a street car, just stick to the Aluminum wheels. Even if you have a brilliant set of original magnesium wheels, stick those babies on the wall and put some Al repros on the car for daily driving duties.

 

Edit: At one point that was a bad ass set of panasport wheels! Someone going vintage datsun racing?

indeed! Problem is that most old magnesium alloy wheels will have already some corrosion in one form or another and even with the application of corrosion inhibitors, would be addressing the issue after the fact. And structure wise, the wheel would not be 100% structurally. The scary part is that I see people jsos out there trying to repair old magnesium wheels and touting that once repaired they would be structurally sound... Looking at pictures like this, why would anyone risk running on those wheels especially on a high priced classic? Whats even worse is that visually, you wouldnt be able to tell on the extent of corrosion unless you media blast the wheels...

indeed! Problem is that most old magnesium alloy wheels will have already some corrosion in one form or another and even with the application of corrosion inhibitors, would be addressing the issue after the fact. And structure wise, the wheel would not be 100% structurally. The scary part is that I see people jsos out there trying to repair old magnesium wheels and touting that once repaired they would be structurally sound... Looking at pictures like this, why would anyone risk running on those wheels especially on a high priced classic?

 

Some wheels maybe/possibly could be repaired, but it would be to the extent of X-Raying them and doing extensive testing for nearly invisible fractures. But IMO, a restoration to that extent would be only for a concourse level car and sure as shit wouldn't see road duty. I venture to say you could have the tooling built and cast NEW Magnesium wheels for less than the cost of repairing and testing the originals. And definitely for less than the cost of repairing the car you fcuk up when the wheel explodes.

 

Or for a couple hundred bucks you can buy some aluminum replicas, beat the shit out of them and not give even half a fcuk.

Some wheels maybe/possibly could be repaired, but it would be to the extent of X-Raying them and doing extensive testing for nearly invisible fractures. But IMO, a restoration to that extent would be only for a concourse level car and sure as shit wouldn't see road duty. I venture to say you could have the tooling built and cast NEW Magnesium wheels for less than the cost of repairing and testing the originals. And definitely for less than the cost of repairing the car you fcuk up when the wheel explodes.

 

Or for a couple hundred bucks you can buy some aluminum replicas, beat the shit out of them and not give even half a fcuk.

 

Yes, repair could be made, but using the wheels other than just rolling it onto a show or anything at medium to high speed would be pretty moronic... No way the wheel after repair will be 100% structurally... With new magnesium wheels, only viable methods are low pressure casting or forged where the material is virtually guaranteed to be free of porosity that is inherent in sand casting... Best to have the old wheels without tires mounted just sit there in a dry climate controlled area, especially since even condensation or moisture in the air inside tires can corrode the wheels...

old magnesium wheels are just suitable for expo in a museum. LP400 has others structural magnesium pieces, not only wheels: better change them all

 

old magnesium wheels are just suitable for expo in a museum. LP400 has others structural magnesium pieces, not only wheels: better change them all

 

We actually just recently made some tooling to sand cast the upright suspension knuckle from an older mclaren race car that was originally magnesium for this very reason.

 

Expensive tooling to make but a handfull of parts, but given the application cost wasn't really a concern.

Look out S1 guys... scary stuff. I would put on the most original looking replacemets i could find.

That's the plan.

But what causes this? Same as anything else? It is easy to see the above wheel being left out in the element most of its life. Most Countachs are kept indoors, some climate control.

Is it just age that eats them away?

I have photos prior to my being painted before it was delivered to me in 03. The wheels, visually, looked pretty much perfect.

Look out S1 guys... scary stuff. I would put on the most original looking replacemets i could find.

 

all 4 liter cars have magnesium wheels, from LP400 to last LP400S

 

...not only, very early 5000S cars still had them (but i think we are talking of 5 cars or so....)

I thought magneium was pretty durable. I have a Lawnboy push mower that was built in 1967 with a full magnesium deck. It has been used every week since 1967...no cracks, corrosion, or failure. Those wheels sure look scary

But what causes this? Same as anything else? It is easy to see the above wheel being left out in the element most of its life. Most Countachs are kept indoors, some climate control.

Is it just age that eats them away?

I have photos prior to my being painted before it was delivered to me in 03. The wheels, visually, looked pretty much perfect.

 

Corrosion can occur at anytime under even the most ideal conditions... Its simply moisture getting under paint or moisture trapped within the pores of the magnesium... Sand casted magnesium are porous and once moisture gets under the paint, corrosion starts from the inside... Moisture can be just from simply the humidity from the air or the air within your tires... Sand casted magnesium is like chrome wheels. Some can last a while, some can last longer... But they all corrode eventually...

 

Problem with sand cast magnesium is that no one can tell visually if the wheel is 100%. And there is no way to tell how bad the corrosion is or when they start... It may have looked great, but the above wheel with paint didnt show the type of visual corrosion either... It was only after paint stripped that revealed the extent of damage/corrosion.

 

But hey, if jsos people out there like to continue to think repair is a cure all solution, no problem... 1 less countach always ups the exclusivity...

Hard to believe that wheel showed no signs of corrosion, were there before shots? was that wheel even holding air? Is there a link to where you found this? I'd like to read more. Thanks

a customer of mine owns a F40, a car with a magnesium clutch housing: it's destroyed and the housing is falling down, it has to be fully redone. Car has 4500 km (3000 miles) since new, one owner from new. Be careful with old 400 and 400S magnesium wheels... and LP400 uprights too...

 

ciao

Countach magnesium wheels are coated with a very thick primer and are topcoated. If scrached or chipped down to the Magnesium corrosion can occur, the corrosion looks like a white powder. QV is right, if they get to the point of the pictured wheels thats not safe. If you have concerns with your wheels have them stripped checking for corrosion and tested for cracks. As with any part made of any material failure can happen. To this point I have not heard of a countach magnesium wheel failure, I'd be more concerned about old fuel and oil lines failing burning the car to the ground, far more documented cases of that happening. Be careful with any countach, far too cool of a car to destroy!

Countach magnesium wheels are coated with a very thick primer and are topcoated. If scrached or chipped down to the Magnesium corrosion can occur, the corrosion looks like a white powder. QV is right, if they get to the point of the pictured wheels thats not safe. If you have concerns with your wheels have them stripped checking for corrosion and tested for cracks. As with any part made of any material failure can happen. To this point I have not heard of a countach magnesium wheel failure, I'd be more concerned about old fuel and oil lines failing burning the car to the ground, far more documented cases of that happening. Be careful with any countach, far too cool of a car to destroy!

 

I would imagine if people think those wheels shown above are still repairable, there is something extremely wrong with them lol... FWIW Regardless of how thick the primer is, simply the age of the primer and any coating over time is suspectible to allowing moisture get through... Actually, scratches on magnesium wheels are easily produced by tire wrenches when mounting hard to mount low profile tires onto the wheels. Also, any areas near lug bolt where installation strips of coating are also most prone... Any areas where water may be left to sit on the wheel is prone to corrosion... Any moisture in air in the tires then immediately hit the magnesium and commence corrosion. While perhaps the chances of ct mag wheels failing might be less, there is really no way to tell or even keep watch on the integrity of the wheels. Even strip checking or tests can only do so much and can be effective for only a finite amount of time. Unless you plan to send the wheels out to be checked every year like race car manufacturer, it just simply doesnt make sense... It is for this very reason why manufacturers swapped to aluminum wheels, and for jsos people out there thinking having it stripped, checked and patched is a finite solution would be wrong to think that. Those sand casted magnesium wheels have shelf life and really shouldnt be used other for display purposes. I just cant imagine people blindly going out and pushing 100mph on those wheels thinking wheels are fixed... Just want to make sure any bravo wheel owners dont use those wheels for the sake of originality, have the wheel fail at high speed, and wreck their pride and joy...

Fill them with nitrogen! Filling them with air from a compressor usually had lots of moisture unless has built in water separator.

Guess when storing the car, get it up on stands and pull the core out of the valve stem and air them out.

Fill them with nitrogen! Filling them with air from a compressor usually had lots of moisture unless has built in water separator.

Guess when storing the car, get it up on stands and pull the core out of the valve stem and air them out.

 

Yes! just hope nitrogen, heat, and magnesium dont create explosions as well.lol ... The wonders of magnesium wheels... lol... Better to just store them and not use them... period... Just not sure why jsos people still insist on using structurally questionable wheels all for the sake of originality...

Yes! just hope nitrogen, heat, and magnesium dont create explosions as well.lol ... The wonders of magnesium wheels... lol... Better to just store them and not use them... period... Just not sure why jsos people still insist on using structurally questionable wheels all for the sake of originality...

Because we have a pair! LOL!

 

Your concerns are noted.

Because we have a pair! LOL!

 

Your concerns are noted.

 

you mean cajones? lol... Well, I guess riding on old decaying mag wheels usually means more thinking from the pair than the brain... lol. I think some clarification was needed on mag wheels because the general public typically get misinformed. Shouldnt have jsos people have blinders on when it potentially has safety issues... Besides, staying period correct is one thing, losing control and damaging your car or causing injury to yourself and others are probably more serious things to be noted...

 

On another note, here is another wheel with paint still on there... old bbs mag wheel from the 70s....

you mean cajones? lol... Well, I guess riding on old decaying mag wheels usually means more thinking from the pair than the brain... lol. I think some clarification was needed on mag wheels because the general public typically get misinformed. Shouldnt have jsos people have blinders on when it potentially has safety issues... Besides, staying period correct is one thing, losing control and damaging your car or causing injury to yourself and others are probably more serious things to be noted...

 

On another note, here is another wheel with paint still on there... old bbs mag wheel from the 70s....

Those do look very bad, very obvious corrosion.

Those do look very bad, very obvious corrosion.

Notice that the bolts are fused onto the center and the corrosion is coming from under the paint... This is when its terminal... But its like a cancer... you dont know if its affected until its too late... Magnesiums are like chrome wheels now...

 

Similar to mags, I fail to understand why manufacturers are offering chrome wheels when clearly the wheels are going to corrode from salt and deicing agents... we see in a year or 2, most chrome wheels are already corroding and some already dont hold air... With chrome, its a clear case of consumers wanting it, but not understanding the product wont last... Same goes for mag wheels.. And in this case, there is an even greater attachment because the wheels are iconic...

 

Best suggestion is get the replicas for spirited runs and leave the mags for concourso week... And yes jsos people will cry foul on the replicas... But hey, at the end of the day, its a car, and anyone with the means to afford a car at the price its commanding now sure as hell wont risk life and limb for period correctness...I for one can think of too many things that I cherish more than a car...

 

Here is another wheel which was a bmw alpina magnesium race wheel.... bolts fused on the center.....