Rob I've got a few sets of these rims. I am considering selling a set if you are interested. Private message me if you would like to discuss. I've found a few sets of Mag rims to chose from so freeing up some cash would be nice right about now.

By the way I am in Seattle, WA

Cheers,
_Anton

 

Cobalt if you do not mind I would like to ask you a few questions about magnesium rims. May I pm you? Concerns the right questions to ask the sellers of the mag rims I am considering buying and the methods in which they used to repaint their rims. So far my choices are 2 excellent used sets never painted and 2 sets fully restored. I've been searching the forum and find that your responses are very informative on the subject of the maintenance and care of magnesium rims.

Cheers,
_Anton

 

Hi There RS2coupe. I can add only a little value but can tell you from my experience four years ago i repairing and refurbishing the RS magnesium alloys that they are not easy to get right. If the wheel is badly "curbed" or buckled you will need to find a specialist that can weld magnesium. Not as easy as it sounds as its tricky stuff to work with. Then the wheels need to be bad blasted and etch primed with a special primer that etches the surface and "seals" it ready for the paint layer. If this is not done correctly you will get oxidation of the magnesium and bubbling under the paint will occur over time. To be perfectly honest having owned and run these they are a PITA as a long term ownership proposition on a regularly used vehicle. Th ownership experience was akin to owning the OEM speedline RS rims on my 993RS. They require care and regular inspection. Magnesium is light but its only viable application apears to be racing mag wheels where a team will replce them on a regular basis. Magnesium wheels (depending on content) are prone to fatigue. If you look at any of the original 917 race cars from the 70s most will be running new replica magnesium centres as they xtay the originals which are almost always 100% unstable even tho they look ok by eye. Insurance wont cover fatigued magnesium wheels on a 2 million usd car! So magnesium looks ok, is light and wonderful for low sprung weight but doesnt age well and is hard to restore correctly. In todays world you can buy spun alloy onepiece wheels in 18" that are approximately the same weight as 964RS manseium SM cups. If I owned a 964RS today Id rip off and refurbish the original wheels, put them in storage and buy some alloy road wheels.....Cheers M

 

Hi Macca.

One of the sets I am looking at has wheel weights. The seller states that the cups he is selling came from the factory with them. Does this sound right? The rims are unfinished which I think is a plus to be able to see the condition of the rims.

What steps must I have him make through a wheel shop to assure me the rims are true?

One set is in Germany and the other UK.

Cheers,
_Anton

 

Hi Anton,

I have no idea what the factory wheel weights look like. Im guessing the factory would put weights on from new as wheels rarely ever balance true with rubber on them.

A rim shop can put the wheel on a machine to tell you if they are true. They will likely re balance and ifthere is a shimmy after balancing it will be obvious. If they have never been painted or repaired then youll likely see where damage/impact has affected them on the rim lip.

Good luck.

Cheers

 

Thanks Macca... Will get on with regards to your advice and hopefully come two thumbs up.

Cheers,
_Anton

 

I agree in part.

Depending on the alloy used magnesium is quite durable. It suffers in the casting process from something called microshrinkage. It is basically incomplete forming of the dendrites a condition that occurs during solidification the material. It is invisible to the naked eye and can only bee seen through X-ray or sectioning the part, polishing it and then viewing under very high magnification. This should have been resolved prior to any wheels being produced or eliminated during NDT. If magnesium in non painted form has had proper chemical conversion (acid etch) prior to being put into storage it will last a long time without any degradation. If it is not treated and allowed to sit exposed to the environment it will start corroding rather quickly.

Constant use of magnesium wheels can result in failure if used on rough roads. It is not as forgiving regarding impacts as aluminum and has a tendency to crack more easily. However, if cared for properly with proper coatings, no surface exposed to the environment and no major impacts they should be OK. Just like the cooling fans on our motors if they are touched up and not allowed to become exposed to the elements they last a very long time spinning at very high revolutions. Assuming the coatings are fine any cracking that might occur would be as obvious as on any other wheel.

I would agree that for a DD these are far from ideal and I would only recommend owning them as a light use set for special occasions. if you have a car that they came with originally keep them store in a dry place well protected and save them for future value of the car.

I also have a question about the RS wheels? I am under the impression based on the info I have that the RS wheels are like the 964 Turbo 3.6 Speedlines and use aluminum alloy centers 993.362.136.81 = 8 x 18 weigh in heavier than the turbo wheels at 27.5 pounds and the rears 993.362.140.81 = 10 x 18 also heavier weigh in at 29.7 pounds so these would be aluminum centered. AFAIK the only cars that received magnesium alloy centers were the cup cars. They look the same as the RS speedline but have magnesium alloy centers saving roughly 6 pounds per wheel for identical size.

For those interested in microshrinkage. Here is a case of something totally undetectable by the naked eye. The first picture is showing microshrinkage under black light after being processed through fluorescent penetrant (aka magnaflux, zyglo etc) Mostof the green you are seeing is bleed out of the penetrant and is not all microshrinkage the second is the small area in black sectioned polished viewed under 500 x magnification. Remember the eye cannot see this without these aids and you are only looking at the section in black under magnification.

As far as strength magnesium is not weak. The last picture is a small section of a casting that only broke after a semi fully loaded weighing over 30,000 pounds drove over it. It failed but took a tremendous amount of weight and it did not crumble but took some time before fracturing. This casting is about the wall thickness of a wheels barrel. If this were pressure cast non heat treated cheap Chinese aluminum wheels this would have been in far worse shape.

 

Anthony, Macca.... thank you for the information. I feel more confident now knowing what to ask and how to go about a purchase of these rims. Really kind of you guys to respond and offer your knowledge.

I'm actually going to call Porsche and see what is still available to buy.

With the insight you guys have given thus far I am going to take my time on this purchase due to the high cost of the rims and the possible issues used magnesiums may have. No sense in rushing into a purchase then to find a problem later.

Cheers,
_Anton