The 6 speed has the freewheeling pulley, with a SPRAG clutch, to allow the alternator to freewheel and bleed off some inertia between 'abrupt' higher RPM engine speed changes. This helps to prevent belt shredding and or jumping ship. Tips are not as likely to have the more abrupt RPM changes between shifts so Porsche did not put the freewheeling pulleys on those alternators.
Some info here.
http://www.ntn.co.jp/english/products/review/pdf/NTN_TR75_en_P124.pdf
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2013 991.1 Carrera S Cab
2004 996 Turbo CAB X50 sold
2003 996 cab 6 speed Sold
1972 RS 3.2 twin plug short stroke crank fire, roll bar, sold
DE instructor since 1985
Last edited by FPB111; 02-06-2012 at 10:47 PM..
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