Installing an Under Drive Lightweight Pulley on an Infiniti G35

This article will guide you in how to install a under drive lightweight pulley.

Tools needed:
3/8″ Socket Wrench with 14mm & 12mm sockets
1/2″ Socket Wrench with 19mm deep socket
Floor Jack/Jack Stands

Jack your car up. Use jack stand for safety. I only raised the passenger side of my car and it was sufficient.
Loosen the 14mm nut on both idler pulleys and loosen the tension using the 12mm socket.
Remove Belts.

While you are under there, remove the nuts and bolts holding the sway bar bracket on each side.
These are all 14mm. 1 nut and 3 bolts on each side.

With the sway bar out of the way and the belts off, now it is time to remove the crank pulley.
Use the 1/2″ socket wrench and 19mm deep socket. Trying to turn it now will just spin the crank.
(see next pic)

With the socket wrench in place lower your car back to the ground.
Remove the upper portion of the floor jack handle to use as an extension/breaker bar.
Install your breaker bar and ensure that it is tight to the ground in a straight line to break the bolt loose.

You don’t want the car to start while you turn the crank. Remove the ignition/ecu fuse.
You only want to turn the key for just half a second. We are just breaking it loose.
I used a 3/8″ socket with a 3″ extension first and broke the extension. Twice. Worked 1st time with 1/2″.

Now that the bolt is loose, you should be able to spin it the rest of the way by hand. Remove Bolt.

Getting the stock pulley off took a little coercion. I tapped it with the end of the socket wrench a few times. Because it fits so tightly in, you will need to wiggle it side to side while you pull it off.  Notice the difference in weight. The UR pulley weights about 2 pounds. My guess is the stock is around 8-10 lbs. I need to put it on a scale.

Use some WD40 to clean the area up a little. When that is dry use some white lithium grease to lube both sides of the pulley and on the crank where you will install it.

Push the new pulley on, making sure to keep the notch in the right place. Screw on the bolt, hand tight.

Now,  jack the car back up and reinstall the sway bar brackets to their proper position. Use the nuts to hold it in place while you get the bolts started.

We need to tighten down the crank bolt now, but we face the same issue as before: you can’t fully tighten because the crank spins.You need to hold the new crank pulley in place. I used some clamps like the picture. You can also use a tie down or some ring clamps if you can fit them over the sway bar. DO NOT try to use the cranking method to install, you most likely will cause serious problems.

Reinstall the belts, adjust the tension, then torque down the idler pulley nut.
Reinstall the Ignition Fuse.

Start the car to make sure the belt tension is proper and no squealing.

Lower the car back down.

You’re Done!

Originally posted by tollboothwilley