Thread: Rear main seal
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Old 12-14-2005, 12:37 PM   #17
MNBoxster
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Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by wild1poet2
thanks for the info..... you would think center boring or altering the casting process would be straightforward.

Let's hope the Cayenne RMS works.
Hi,

Well, it just isn't as straightforward as you may think. In traditional Casting, where post-cast Machining is performed, the Mold allows for the excess material which the Machining subsequently takes away.

Porsche's method (adopted from Audi), does not allow for this excess material, so simply machining the Block halves to provide for the Center-Boring won't work. They'd be looking at redesigning the molds and possibly the Block halves themselves to provide additional support where the Boring takes place. The metallurgy may even require some tweeking. This would be extremely costly and possibly unrecoverable from the Price Point and anticipated Unit Sales the Marketing Dept. has set for these Cars. Remember, this Market Niche is already overcrowded as it is with more new Two-Seat Drop Tops still being introduced. Unofficial Surveys (Porsche won't release any stats on RMS Failures) have pointed to about 20%-25% of all cars being affected. But, releasing this kind of info in an already overcrowded Market could kill the Model completely.

Block Casting is a very difficult thing. Years back GM, (the Buick Div. actually), decided to make an all-alloy 265 C.I.D. Smallblock V8. Their first attempts yielded a reject rate of more than 99% (less than 1 Block out of 100 Cast was usable). After 5 years, they managed to reduce the reject rate to 85%, yielding 15 usable Blocks for every 100 Cast. This was so potentially unprofitable that they sold the rights of the Engine to Rover, who reformulated the Metallurgy and re-engineered the Casting Process to achieve a reject rate of only 9%, producing 91 usable Blocks for every 100 Cast, and the venerable Rover V8 was born.

Also, if Porsche did reinvent the M96/M97 Block, it would be akin to admitting fault in the earlier design which could have recall cost implications (given the near 500,000 986/987 and 996/997 Cars sold) that would jeopardize the financial strength of the Company, something unlikely to be accepted by the Boardroom in Stuttgart.

No, despite all the Boxster's excellent qualities... and there are many of them, I can't help thinking that deep down there beats the Heart of a Lemon. Good Company PR, Past Reputation, and Near Fanatic Fan Loyalty (some of which I assume will speak in opposition here) have done much to disguise the fact...

Happy Motoring!... Jim'99

Last edited by MNBoxster; 12-14-2005 at 12:40 PM.
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