Porsche Enthusiasts Club Forum

Just got a cheap set of spare alloys for the track off Ebay. A mate collected them for me as he lived very near the seller. They are a set of 996 Carrera 4 wheels.

When I got them I noticed crazed cracking over the outer surface, looking much like the crazing you get in the glaze of old pottery or china. At first I wasn't too worried as I thought the wheels had just had a bad refurb, however on closer inspection where the finish is coming off you can see marking to the alloy in the same pattern as the cracking. This of course could just be dirt or oxidation thats got to the alloy through the cracks, but it raises doubt over the integrity of the alloy. Its difficult to be sure.

Just wondered if anyone else had seen anything similar. I suppose the only way to be able to tell for sure is to get the wheels x rayed!!

I was reading a letter in the BMW club magazine over the weekend about hair line cracks in alloy wheels and apparently it is a very common problem across many makes of wheels including Porsche. It's all down to the lunar landscape that passes for a road surface in this country.

Hopefully in your case, it is just a problem with the paint, but I would definitely get them checked by a reputable tyre fitter as they will be well aware of the problem.

My gut feeling is that its just the finish thats cracked as it appears on all 4 wheels and is over the whole outer surface where the finish is much thicker.

Will have a better idea once I've tried them on the car. If theres 4 loud bangs and I have to drive home on the disks I'll know I've got a serious problem

Its where they've been refurbed with silver powder coat and then clear powder over the top.

Some combinations of silver/clear dont work well together and you get the hairline cracks.

It took me a good few attempts to get a combination that didnt get the cracks.

In the end the silver came from one manufacturer, clear from another.

Your best bet is to sand the top surface down and then go over with 2-pack basecoat and clear, the cracks wo'nt come back through and the paint will adhere to the powder , no problem!