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How to install a BBK Underdrive Pulleys on your 2005-2010 Mustang

Installation Time

2 hours

American Muscle
Shop Parts in this Guide


Step 1 Raise hood and disconnect negative (–) battery terminal.

Step 2 Leave serpentine belt in place and loosen the crankshaft pulley and waterpump pulley bolts.

Step 3 Using an air impact wrench, loosen and remove the alternator pulley nut. Applying additional tension to the belt will aid in keeping the alternator from spinning.

Step 4 Remove belt, carefully noting the routing for reinstallation once pulleys are installed.

Step 5 Remove pulleys from vehicle and simply reverse the process to install the BBK pulleys. Install all of the pulleys finger-tight, then install the belt to tension pulleys while tightening to factory torque specs.

Step 6 Carefully follow the belt routing to ensure that the belt is tracking properly. It is very easy to incorrectly install the belt with one groove off a pulley—this would destroy the belt immediately!

Step 7 Reinstall negative (–) battery terminal and start vehicle. Watch belt carefully to ensure proper alignment, etc..

*This pulley system requires the use of a 6-rib 96” length serpentine belt.

This guide applies to Vehicle years: 2005, 2006, 2007, 2008, 2009, 2010 and Submodels: Bullitt, GT