"Dad" > wrote in message
.. .
>
> "FBNE" > wrote in message
> ...
>>I had to replace the alternator on my 2001 and discovered there are
>>two versions of alternator. One for auto trans and one for manual.
>>The AT alternator has a clutch, the MT does not. Basically,
>>what/why? What does the clutch do and why does it make a difference?
>>Mine is an AT version.
>
> Millions of vehicles are now factory-equipped with an Overrunning
> Alternator Decoupler (OAD) rather than a conventional solid pulley
> or one-way clutch pulley. A failure to install the correct
> replacement design could cause severe damage to a vehicle's belt
> drive system.
>
> An OAD Decoupler is similar in appearance to other pulley designs
> but plays a vital role in synchronizing the belt drive system. When
> replacing an OAD-equipped alternator, the only acceptable choice is
> another OAD unit.
>
> Many new vehicle accessory drives are realizing a 1.5% to 2% fuel
> economy improvement with an OAD. These improvements are possible by
> utilizing a Lean System design philosophy. Lean systems can
> significantly reduce the common parasitic losses found in accessory
> drives, due to the belt bending that occurs during operation. The
> parasitic loss reduction is a result of a holistic approach to
> accessory drive - drive layout, OAD, and tensioner design/matching.
>
> Couldn't have said it better myself, we all know that. ;-))
>
By the way the pulley number is Goodyear 49908 and cost $90 and if it
fails your alternator will not charge but does not need to be
replaced. No need for a $360 alternator with a new clutch.