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Unorthodox Racing 95-99 Pulley Review

The UDP (Underdrive Pulley) is an aftermarket replacement for the crankshaft pulley on the Maxima, which drives the accessory belts. The UDP replaces the stock crankshaft pulley with a smaller diameter and lighter weight unit which allows the engine to rev more easily. Unorthodox Racing has developed a pulley system which not only provides light weight but also operates in a very proper and well constructed manner. UR claims on their site this statement, "This version of our crank pulleys increases performance because they underdrive all the accessories (15-20% more power), unlike accessory only kits out there that do not include the crank pulley. This means one you air conditioning is on our crank pulleys give you more power back to the wheels by not letting the air conditioning compressor rob as much power." Lets see what's really going on..



Our Take:


Basing our review on our 1995 Nissan Maxima with Air Conditioning, Audio System, and Power steering still intact this will provide a complete understanding of how well this performs without sacrificing much if any drivability. This CAD designed & CNC'd from 6061 Aluminum billet pulley weighs in at a respectable 1.49lbs compared to the 4.84 lbs from the stock pulley. Due to the smaller radius and weight savings, this makes it much easier for the car to spin the pulley and frees up energy for other components of the car. The result is a faster revving engine, and a small HP gain. Since the pulley is underdriving some accessories, there are some speculations that the (Underdrive Pulley) UDP will have a negative effect on things such as the AC, power steering and electrical output. With our test it seems as though we are sustaining as much power to operate the car with full accessories as we did with the factory unit. If you have or plan to get a supercharger/audio system than this modification is not intended for you because you do not want to underdrive a supercharger/amplifier. UR has taken a note to that and created a Stock diameter pulley for just those application while still saving weight but keeping with the diameter of the factory unit.


Quality Design
Excellent Craftsmanship

None as of yet

  • 95-01 Nissan Maxima
  • 96-01 Infiniti I30

Additional Note:

  • Gates belts, numbers K-060408 and K-040292
  • Crankshaft oil seal -- Nissan Dealer (part # 13510-31U00)

Part Number Information:*

  • Crank Pulleys (Ultra S)

Where To Purchase:

Tools Required for Installation:

  • Breaker Bar
  • Short and Long Extensions
  • Ratchets/Wrenches
  • Air Gun
Materials Provided for Installation:
  • Underdrive Pulley
Removal/Installation Process:
First things first, make sure to disconnect the negative terminal of the car before you start as to not risk finger severing. Jack the car up and remove your passenger side wheel. Go ahead and remove the engine splash cover to gain access to this end of the motor. Proceed to loosen the front belt tensioner to relieve the tension to the accessory belts and remove the belt. Now from the rear of the motor remove the two 10mm bolts from the pictured bracket to relieve tension to the separate set of belts, remove the belt. Removal is slightly difficult if you are not using power tools. Some suggest using a breaker bar on the crank pulley bolt sitting it against the floor and crank the car but do not start it. This will hopefully loosen the bolt holding your factory pulley in place on the crank. With power tools simply loosen the crank pulley nut and proceed with removing the pulley. Before you begin, we would like to emphasize that the key should be out of the ignition before removal/installation. ALWAYS CHECK ALL POWER IS OFF BEFORE WORKING!

With the belts removed and the bolt removed from the crank pulley, using a large flat screw driver or similar tool slowly but firmly pry the factory pulley from the motor making sure not to damage anything in the area you working. With the pulley removed you will see where the crankshaft oil seal can be replaced while you are in the process of this install. Line up the new pulley with the key on the crank and firmly press the pulley into its location. Reinstall the crank bolt and new belts and you are ready to go. Drive Spiritedly.


Final Product:

Parts Review