Underdrive pulley
Safety Car
Joined: Sep 2006
Posts: 3,922
Likes: 4
From: Cheektowaga NY
St. Jude Donor '08
Team Owner
Joined: Oct 2004
Posts: 27,420
Likes: 64
From: San Clemente CA
The alternator turns slower. It's interesting that many who complain of charging problems have under drive pulleys but still maintain that's not the problem.
Last edited by VET4LES; Mar 23, 2008 at 02:50 PM.
Melting Slicks
Joined: Aug 2005
Posts: 3,218
Likes: 3
So far, I'm having just as many charging issues as I did stock. My 05 has had battery drama for all 70k miles of its life, stock and modded. Multiple batteries, dealerships, etc., could not fix it. My dad's stock 02 Z06 has battery drama. I think it's just a GM problem. If it's parked for a month the battery dies. A week, still good. My car is daily driven though, so no worries.
Also, you can always get an alternator overdrive pulley...
Moderator
Joined: Dec 2002
Posts: 40,885
Likes: 4,337
From: Lakewood Ranch, FL
My research shows that an UD pulley will provide a consistent 9RWHP gain with no real downside. It is NOT worth doing though as a stand alone mod, but IS worthwhile if you are getting a cam swap or a built motor.
