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How to Install a MAC Underdrive Pulleys on your 1996-1998 Mustang GT and Cobra

Installation Time

2 hours


1. Disconnect battery.

2. Loosen alternator nut (this will require an air impact gun) DO NOT REMOVE.

3. Loosen the four (4) bolts for the water pump pulley. DO NOT REMOVE.

4. Remove center bolt and washer from the factory pulley/dampner

5. Remove alternator pulley and water pump pulley.

6. Use the three (3) prong harmonic dampner pulley to remove the factory pulley/dampner (Hint: Hold the pulley with one hand when removing it. This will keep the pulley/dampner from falling to the ground when-it clears the end of the crankshaft.)

7. Install hub factory harmonic balancer pulley in counter bore of new pulley. Align threaded hole in each pulley together. The keyway location is not important.

8. Install and hand tighten three(3) 1/4" x 1 1/4" bolts. The-ractory pulley does not completely sit into the underdrive pulley at this point. Carefully tighten the three(3) bolt equaUy in small increments to draw the two(2) puley's together. Remove the three(3) 114" bolts.

9. Apply a hi-temp silicone sealer to the-two(2) pulley assembley keyway. Place pulley assembly onto the crankshaft. (align pulley keyway with crankshaft key )

10. Re-Install the three(3) 1/4" hex bolts using locktite#343 and tighten t o 10-12 ft/lbs

11. Align the keyway on the two(2) pulley assembly with the keyway on the crankshaft and slide it onto the crankshaft. (Hint: Place the two(2) pulley assembly in HOT water for about 15-20 minutes prior to installation.

12. Attach the two(2) pulley assembly to the crankshaft using the new 12mm bolt provided and the original crank bolt washer. Using locktite #242 or equivalent on file bolt and torque to 60 ft/lbs.

13. Install the new alternator pulley and wllter pump pulley using the original crank bolt washer. Use locktite #232 or equivalent.

14. Replace the belt. Consult a shop manual for proper procedure. Note: inspect belt prior to Re-Installing. If evidence of wear exists, replace it with a new belt.

15. Tighten alternator nut using an air impact gun.

16. Tighten water pump bolts evenly.

17. Reconnect battery.