When we say junk bearings, are we talking about the aftermarket bearings that one must buy because an aftermarket fan does not come with a bearing installed, or are we including the Porsche bearing that is already fitted into a factory fan when you buy it from a dealer? Thanks!

Edward

 

The fan, fan bearing setup and housing are Porsche designed and engineered parts. They are used only on Porsche cars. Although they are produced by suppliers to Porsche, they are not used anywhere else. Unlike some Bosch electrical parts that are shared with many Porsche, Audi, VW and many others, There is no manufacturers part number to go chase. You are not going to go direct to the manufacturer because they will not sell it to you and since Porche owns the tooling they control everything for these parts. Also there is hardly a part more functional than high speed small clearance fan inside a difficult to manufacture magnesium case. For this one, go straight to Porsche and find a friendly dealer (Suncoast, Gaudin, etc) and be done. Not the place to try to save money because you won't.
On the other topic; Powder coating has terrible adhesion . Always has and always will. It is tough and the surface is resistant to scuffing etc. It is thick and heavy. The big reason for powder coating is it does not involve VOC s and is compliant to air standards.That is why many companies tout powder coating because they cannot use wet paint. This also applies to wheels. The real wheel refinishers will use wet paint especially on BMW as that is the only way to get the proper silver.
Buy the Porsche parts. For other stuff look at OEM .
Just an opinion. (the paint part is fact)

 

I have to admit sounds like they are stretching the truth a bit. I manufactured Aluminum and Magnesium castings for the aerospace industry for 30 years as a first tier supplier. My grandfather pioneered some of the first magnesium alloys a number of aluminum ones as well for Bendix and Dow chemical from the 1930's to the late 50's. He did most of the R&D on chemical conversion processes for mag parts still used today and I was an ASNT level III inspector for penetrant and radiographic inspection. Aluminum corrosion has never been much of an issue unlike magnesium.

I agree once the oxide coating has been disturbed by abrasive blasting it is more susceptible to corrosion. The anodizing is a nice touch assuming the alloy is low in silicon otherwise it will show up as little white spots in the finish but many of your calipers up until the late 80's early 90's were if anything cad plated and not anodized or painted. I wouldn't powder coat them personally and a proper paint with a chemical resistant clear is probably all you need. Although I always inspect every part of my cars and touch up whatever is needed. Also if you vapor hone or ice blast them under low pressure you can remove the paint without much issue regarding the anodizing.

Unfortunately there are many parts being sold in OE boxes with Porsche part numbers on the box but are no different than the aftermarket units. Finding supplier is becoming a challenge. Fuel pumps and alternators are having issues from the factory. Sadly the factory bearings for these are not as good as the old bearings and failing prematurely. Rob has discussed this in length in one of his craziness threads. I would research it. One thing I would caution is spark plugs. We have had issues on the newer cars with the same part number but not Porsche marked and they are giving us problems so research what you are buying from both the factory and aftermarket before buying.

Regarding the fan it isn't all that complicated to cast and I am not impressed by some of the castings I have seen. I made far more complicated parts and the micro-shrinkage in the castings are apparent once blasted. These should have a dow 7 coating performed prior to paint and within an hour or so of blasting. If not an acid etching primer should be applied as soon as possible after blasting and cleaning.

 

I agree with everything you said. As to the comment about the fan being easy to cast is true but only with superior tooling. Top quality tooling is expensive and while Porsche stepped for the high cost, aftermarket people cannot afford it and still make the profit that they want. As I am a tooling guy, The good stuff costs money, a lot of money.

 

I’m retired some time now. I made 2 pound castings with over 300 toleranced dimensions. 14 cores in a 14 x 18” flask. Actuator Pump for a B1. Many degrees of complexity very few could match. I was known as the sliced bread shop. If you wanted 1 or 100 i made it and always passed the quality criteria that many falsely claim. The big quantities went to the big Midwest foundries. I can’t tell you how many stopped in my shop and couldn’t understand that it was a far more complex process than people understand. Foundry’s we’re always to blame and most rightfully so.

I would think in some ways rapid prototype has hurt the industry. I was mentored by one of the best “model builders” of the day. I have great respect for the field.

The better the tooling the better the casting. No argument it starts there. But people have to be realistic about production costs in the US. I watched a great industry fall to inferior cheap imported products. People accept most of the stuff sold today as quality. My opinion of quality may differ.